Emergency Application — North Dakota, et al., Applicants v. Environmental Protection Agency, et al.

Supreme Court briefAug 16, 2024

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USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

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ELIMINATION OF THE MERCURY SUBCATEGORY FOR

LIGNITE CAUSES IMMEDIATE AND IRREPARABLE

HARM TO THE NORTH DAKOTA LIGNITE INDUSTRY

AND TO BASIN ELECTRIC

28.

EPA established the lignite subcategory for mercury because

lignite units and lignite coal are markedly different than bituminous and

subbituminous coals. Lignite has a higher mercury content in many

instances and presents greater variability than other coals. The higher

sulfur content found in lignite fuels inhibits the ability of injected

sorbents to reduce mercury emissions at lignite plants. The mercury

content also results in higher levels of SO3 formed, which significantly

limits the mercury emission reduction potential of emission controls at

lignite plants.

29.

Basin Electric has used the same technology (combination of

sorbent injection plus a chemical additive (oxidizing agent)) as its

primary mercury control strategy since the MATS rule came into effect

and is not aware of more effective control technology.

30.

There is no evidence that the units at Antelope Valley and

Leland Olds could achieve compliance with the New Mercury Limitation

on a sustained basis with the currently installed equipment as is required

to meet a 30-day rolling basis while operating at full load.

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The MATS RTR sets a mercury limitation for lignite units

without any technical basis that it can be met on a continuous basis, in

general, and provides no compliance margin to account for the variability

in unit performance and emissions control capabilities from unit to unit.

32.

Basin Electric is irreparably harmed by the final MATS RTR

because it is unknown if Antelope Valley and Leland Olds' existing

mercury controls can achieve the New Mercury Limitation of 1.2 lb/Tbtu

on a sustained basis at full load.

33.

The Final Rule places Basin Electric in an impossible position,

given the Rule's impending compliance date. Noncompliance with the

Clean Air Act is not an option.

34.

To have any possibility of meeting the New Mercury

Limitation, Basin Electric must modify the existing system at both

Antelope Valley and Leland Olds to produce a higher injection rate and

make the systems more robust. Even though EPA has not demonstrated

that the New Mercury Limitation will provide any health benefits, Basin

Electric must complete this modification project to lower the emission

rate. The modification costs and ongoing operation expenses are

significant.

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Specifically,

these

technologies

will

require

over

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$4,000,000.00 in capital expenditures upfront for the four units

collectively, as well as increased labor costs for installation, operation,

and maintenance of the technology and equipment and associated

training, along with additional sorbent injection, will result in increased

operating costs over the long term. We must begin expending these

dollars immediately, and certainly before the resolution of this case, in

order to meet the deadlines set out in the Final Rule.

35.

Costs to comply with the New Mercury Limitation are

exorbitant and damage Basin Electric. Costs will be passed along to its

member cooperatives and end users who are harmed via higher

electricity prices. The capital and operational costs to Basin Electric, its

member cooperatives, and end users cannot be recouped.

THE NEW FPM LIMITATION WILL CAUSE IMMEDIATE AND

IRREPARABLE HARM TO THE ELECTRIC COOPERATIVES

AND TO BASIN ELECTRIC

36.

EPA's New fPM limit of 0.010 lb/MMBtu will require upgrades

at Leland Olds and Laramie River.

37.

Basin Electric's harm is immediate. Basin Electric would need

to begin engineering and constructing, at a minimum, ESP upgrades at

Leland Olds and Laramie River as soon as possible to have any

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opportunity to meet the new compliance date for the MATS RTR. If ESP

upgrades are required, Basin Electric would need 36 months to complete.

It is likely that the 36-month estimate will be further protracted due to

the lack of contractors available to perform the work.

38.

If ESP upgrades were not sufficient, baghouse technology

would be required. If a baghouse is required, Basin Electric would need

approximately 48 months to convert to baghouse technology.

39.

Costs of compliance with the New fPM Limitation are overly

burdensome, for the following reasons.

40.

ESP retrofits are expensive. They may cost an estimated

$67,262 per fPM ton removed. See Cichanowicz Technical Report.

41.

Baghouse installation is extremely costly. It is estimated to

cost $282,715 per fPM ton removed. See Cichanowicz Technical Report.

42.

Electric cooperatives have limited financial resources to

undertake projects of this magnitude coincident with other environmental

compliance projects.

43.

To comply with the MATS RTR, Basin Electric is forced to

take measures that immediately increase compliance and operational

costs. The MATS RTR impacts Basin Electric's ability to supply

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affordable, reliable energy to its customers. Added costs will place

upward pressure on rates for rural customers, particularly when

combined with the effects of EPA's other recent electric utility sectorfocused rules.

THE MATS RTR CREATES GRID RELIABILITY CONCERNS

44.

Lignite power plants, which provide a significant source of

electric power in North Dakota, are important to the regional economy.

45.

Thus, the Final Rule, with its reversal of EPA's position on

lignite-fired sources, impacts North Dakota more profoundly than other

areas of the country. These concentrated impacts affect the ability of the

North Dakota utilities to maintain adequate generation resources.

46.

Most (if not all) of the lignite plants in North Dakota must

make some changes as result of the Final Rule. These changes will

require an immense amount of coordination between different regulated

facilities and likely involve serious risks to the reliability of electric grids

providing power to the region while the removal equipment at each of the

impacted facilities are taken offline to undergo the additions and

upgrades required by the Final Rule.

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The North American Electric Reliability Corporation has

predicted continued future shortfalls in North Dakota.' The MATS RTR

intensifies an already tenuous, overburdened grid in transition.

SUMMARY OF HARM TO BASIN ELECTRIC

48.

Basin Electric is harmed because it must immediately

commence costly compliance testing and project development to evaluate

whether it can meet the MATS RTR emissions limits and applicable

compliance deadline.

49.

The MATS RTR could potentially cause Antelope Valley,

Leland Olds and Laramie River which are dispatchable, reliable

generating resources, to operate differently at a substantial cost and

permanent loss to Basin Electric.

50.

Even if the MATS RTR is overturned, the direct costs to Basin

Electric, its member cooperatives, and end users cannot be recouped once

spent. These damages are permanent.

[Signature Follows on Next Page]

1 NERC, 2024 Summer Reliability Assessment (May 2024),

https://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/NERC_SRA_2024.pdf.

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I declare under penalty of perjury that the foregoing is true and

correct.

in A. McCollam

Dated:

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6 iciz-oz y

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ROBERT MCLENNAN

DECLARATION OF HARM IN SUPPORT OF MOTION FOR A STAY

PENDING REVIEW

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







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313a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 4 of 204

1





























FERC, MISO, https://www.ferc.gov/industries-data/electric/electric-powermarkets/miso.

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314a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 5 of 204





































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315a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 6 of 204







10.









MILTON R. YOUNG STATION

11.









12.









2 2

-5(Page 132 of Total)

316a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 7 of 204





13.







2



14.







15.















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317a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 8 of 204







16.















17.













See 

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318a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 9 of 204





A8achment A

Seeid. 

MATS RTR RULE REVISIONS

18.













19.





20.





-8(Page 135 of Total)

319a

USCA Case #24-1119

21.

Document #2058570

Filed: 06/07/2024

Page 10 of 204







LIGNITE COMBUSTION

22.







 2



See A8achment A

23.











LEC Comments filed June 23, 2024, https://downloads.regulations.gov/EPA-HQ-OAR2018-0794-5957/attachment_1.pdf

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320a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 11 of 204















24.











25.











-10(Page 137 of Total)

321a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 12 of 204

















See A8achment A



ELIMINATION OF THE MERCURY SUBCATEGORY FOR LIGNITE

CAUSES IMMEDIATE AND IRREPARABLE HARM TO THE NORTH

DAKOTA LIGNITE INDUSTRY AND TO MINNKOTA

26.









See 

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322a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 13 of 204





A8achment B



 3



Id.

27.





















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USCA Case #24-1119

28.

Document #2058570

Filed: 06/07/2024

Page 14 of 204



















Attachment C. 













Attachment D

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USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 15 of 204































29.





-14(Page 141 of Total)

325a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 16 of 204







30.







See Attachment A













A8achment A)

-15(Page 142 of Total)

326a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 17 of 204

MRY Unit

Average Hourly Mercury Emissions Value Achieved at Full

Load (Sorbent Trap Data)

18 ppm MProve and Non-Brominated PAC

Unit 1

2.17

Unit 2

1.61

31.



















MRY Unit

Average Hourly Hg Emissions

Value Achieved at Full Load

(Sorbent Trap)

Brominated PAC

Average Hourly Hg Emissions

Value Achieved at Full Load

(Sorbent Trap)

Non-Brominated PAC

Unit 1

2.57

2.17

-16(Page 143 of Total)

327a

USCA Case #24-1119

32.

Document #2058570

Filed: 06/07/2024

Page 18 of 204















33.





















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328a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 19 of 204





A8achment A



Figure -1 — MRY Unit 1

Existing System Mercury Removal Performance Capabilities using

Brominated PAC











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329a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 20 of 204









































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330a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 21 of 204





































-20(Page 147 of Total)

331a

USCA Case #24-1119



Document #2058570

Filed: 06/07/2024

Page 22 of 204















See Attachment

A























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332a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 23 of 204





Example MRY Unit 2 Cost Underestimations Summary Table 

-1

EPA

Example

Hypotheti

cal

800 MW

EPA

Assumed

MRY U2

Costs

447 MW

Est.

Actual

MRY U2

Costs

447 MW

$2.6 M

$0.3 M

$1.9 M

Current Hg Removed

1,295 lb

77 lb

149 lb

Parameter

Current Hg Compliance (4.0 lb/TBtu) Cost

Current C/E ($ per lb Hg Removed)

2,004

3,845

12,754

Hg Control System Annualized Capital

Cost

Not

included

Not

included

$472k 2

BPAC Cost @ 5 lb/MMacf

$7.5 M

Not

included

$0.6 M

$1.3 M 3

$0.2 M

$1.6 M 4

M-Prove Cost

Future Hg Compliance (@ 5 lb/MMacf)

Cost

$7.5 M

$0.8 M

$3.4 M

Future Hg Removed

(EPA Assumed @ 1.2 lb/TBtu)

1,447 lb 5

110 lb

216 lb

Future C/E ($ per lb Hg Removed)

5,083

7,040

15,678

22,217

28,176

14,360

Incremental C/E ($ per lb Hg Removed)

Note 1 – EPA example only based on sorbent. EPA assumed current compliance cost includes sorbent and chemical fuel additive.

Est. actual cost based on 2023 MRY Unit 2 usage rate & pricing for both sorbent and chemical additive.

Note 2 – Cost of $5.0 million dollars from S&L project database was annualized using a capital recovery factor calculated based

on annual interest rate of 7% (pre-tax marginal rate of return on private investment, EPA Cost Manual Section 5) and 20 year

evaluation period (EPA Cost Manual Section 6).

Note 3 – Cost based on EPA assumed rate but using 2023 MRY BPAC pricing.

Note 4 – Cost based on 2023 MRY Unit 2 usage rate & pricing instead of assuming same as sorbent costs.

Note 5 – Based on calculated value for EPA example inlet Hg of 1,542 lbs (current Hg coal content) – 95 lbs (future emitted

amount). However, the EPA example identifies 1,468 lb for the incremental cost effectiveness calculation.









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333a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 24 of 204



































 





-23(Page 150 of Total)

334a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 25 of 204

















 















-24(Page 151 of Total)

335a

USCA Case #24-1119



Document #2058570

Filed: 06/07/2024

Page 26 of 204







THE NEW fPM LIMITATION WILL CAUSE IMMEDIATE AND

IRREPARABLE HARM TO THE NORTH DAKOTA UTILITIES AND

TO MINNKOTA







See 





Attachment E









Attachment E 

-25(Page 152 of Total)

336a

USCA Case #24-1119



Document #2058570

Filed: 06/07/2024

Page 27 of 204

















Attachment

E 

Id 







Id.











-26(Page 153 of Total)

337a

USCA Case #24-1119



Document #2058570

Filed: 06/07/2024

Page 28 of 204



See A8achment B





See A8achment B































-27(Page 154 of Total)

338a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 29 of 204

THE MATS RTR CREATES GRID RELIABILITY CONCERNS

DUE TO EARLY RETIREMENTS OF COAL-FIRED UNITS











































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339a

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Document #2058570

Filed: 06/07/2024

Page 30 of 204





3







 4





New Source Performance Standards for Greenhouse Gas Emissions From New,

Modified, and Reconstructed Fossil Fuel-Fired Electric Generating Units; Emission

Guidelines for Greenhouse Gas Emissions From Existing Fossil Fuel-Fired Electric

Generating Units; and Repeal of the Affordable Clean Energy Rule, 89 Fed. Reg. 39798

(May 9, 2024); Hazardous and Solid Waste Management System: Disposal of Coal

Combustion Residuals From Electric Utilities; Legacy CCR Surface Impoundments, 89

Fed. Reg. 38950 (May 8, 2024); Supplemental Effluent Limitations Guidelines and

Standards for the Steam Electric Power Generating Point Source Category, 89 Fed. Reg.

40198 (May 9, 2024); National Emission Standards for Hazardous Air Pollutants: Coaland Oil-Fired Electric Utility Steam Generating Units Review of the Residual Risk and

Technology Review, 89 Fed. Reg. 38508 (May 7, 2024).

NERC, 2024 Summer Reliability Assessment (May 2024),

https://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/NERC_SRA_202

4.pdf.

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340a

USCA Case #24-1119



Document #2058570

Filed: 06/07/2024

Page 31 of 204









A8achment F





























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Document #2058570

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Page 32 of 204

 5





























See, e.g., Hanchey, “Mortality Surveillance During Winter Storm Uri, United States –

2021,” Disaster Med Public Health Prep (Dec. 2023),

https://pubmed.ncbi.nlm.nih.gov/37974501/; Sharma, “Winter Storm Elliott death toll

climbs to 56 as thousands still without power in -40 temperatures,” Yahoo News (Dec.

26, 2022),

https://www.yahoo.com/news/winter-storm-elliot-power-outages-154557710.html.

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

















SUMMARY OF HARM TO MINNKOTA



















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







































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

































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









Table A: MRY 1 and 2 Mercury Compliance Costs

Activity

Cost

Notes

Future mercury testing to

determine lowest achievable rate

$600,000

This is a minimum value.

Inlet Hg Monitor

$150,000

To track coal quality

WFGD Additive Dosing System

$750,000

To attempt to reduce mercury

emissions further

WFGD Oxidizing Reduction

Potential (ORP) Monitoring

System

$7,500

For WFGD dosing system

feedback

MRY Unit 2 Capital Costs:

Mercury New PAC Silo and

$5,000,000

injection equipment capital cost to

reach the lowest achievable rate

Based on industry data from

similar projects; This is the total

project cost without financing

costs.

MRY Unit 2 Operating & Maintenance (O&M) Costs:

WFGD Additive costs (based on

annual operation)

$1,412,000

Based on MRY usage rate and

supplier pricing

Mercury control additional PAC

costs (based on annual operation)

$1,300,000

Based on EPA hypothetical 5.0

lb/MMacf injection rate for 800

MW unit

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Activity

Cost

Notes

Mercury control additional

Potassium Iodide costs (based on

annual operation)

$1,600,000

Cost based on 2023 MRY Unit 2

usage rate & pricing instead of

assuming same as sorbent costs.

Cost is $1.4 million more than

estimated by EPA.

Incremental Mercury Control

O&M cost

$2,412,000

This is the cost in excess of the

current O&M costs. This

estimate is based on current

compliance of approximately

$1.9 million.

Total MRY 2 Costs

$8,919,500

Per MW (440MW) = $18,978

MRY 1 Projected Costs

$4,880,000

MRY has 235 MW. Based on the

cost per MW from itemized

costs for MRY 2

Total for MRY 1 and MRY 2

$13,799,500

Capital & O&M Costs:

Table B: MRY 2 fPM Compliance Costs

Activity

Cost

Notes

fPM Feasibility Study

$175,000

Based on roughly budgetary

estimates from Southern

Environmental , Inc.

Low cost: MRY 2 ESP

Rebuild Capital Cost

$36,326,000

Based on S&L's conceptual

cost estimates and inputs

from Southern

Environmental, Inc.

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Activity

Cost

Notes

Low cost: MRY 2 ESP

Rebuild Incremental O&M

Cost

$530,000

Incremental costs accounts

for costs incurred above

what is currently paid for by

station for existing PM

compliance (i.e. ESP power

consumption, fly ash

disposal, etc.)

Low cost: MRY 2 ESP

Rebuild Outage Cost

$1,421,000

High cost: New MRY 2

Baghouse

$242,083,000

Low cost: MRY 2 Baghouse

Incremental O&M Cost

$4,047,000

Low cost: MRY 2 Baghouse

Outage Cost

$507,000

Total fPM Cost Range:

Based on S&L's conceptual

cost estimating

Incremental costs accounts

for costs incurred above

what is currently paid for by

station for existing PM

compliance (i.e. ESP power

consumption, fly ash

disposal, etc.)

High – $246,812,000

Low – $38,452,000

Table C: Minnkota’s Total MRY Mercury and fPM Compliance Costs

Activity

Cost

Notes

MRY Total Mercury Costs

for MRY 1 and MRY 2

$13,799,500

From Table above, O&M

based on 1 year

MRY Total fPM Costs for

MRY 2

High – $246,812,000

Low – $38,452,000

From Table above, O&M

based on 1 year

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Activity

Cost

Total Compliance Cost to

MRY

High – $260,611,500

Low – $52,251,500



Filed: 06/07/2024

Page 39 of 204

Notes



























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ATTACHMENT A

(Page 167 of Total)

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Minnkota Power Cooperative, Inc.

Milton R. Young Station Units 1 and 2

Mercury Testing Results for the

MATS Residual Risk and

Technology Review

Rev. 1

May 22, 2023

Project No.: A14559.013

S&L Nuclear QA Program Applicable:

 Yes

 No

55 East Monroe Street

Chicago, IL 60603-5780 USA

312-269-2000

www.sargentlundy.com

(Page 168 of Total)

352a

Minnkota Power Cooperative, Inc.

USCA

Case #24-1119

Document #2058570

Milton R. Young Station Units 1 and 2

Filed: 06/07/2024

Page 43 of

204

Rev.

May 22, 2023

A14559.013

1.INTRODUCTION

1.1. PURPOSE

Sargent

& Lundy (S&L) was retained by Minnkota Power Cooperative, Inc. (Minnkota) to support the evaluation

of mercury (Hg) emissions reductions in response to the pre-published rule to amend the National Emission

Standards for Hazardous Air Pollutants (NESHAP) for Coal-and Oil-Fired Electric Utility Steam Generating

Units (EGUs), commonly known as Mercury and Air Toxics Standards (MATS) published on April 24, 2023

that would require additional Hg emissions reductions on the Milton R. Young (MRY) Station Units 1 and 2. As

part of this evaluation, S&L assisted Minnkota in the coordination of a Hg control test campaign to determine

if it is feasible to achieve incremental Hg emission reduction on a lignite-fired unit without a fabric filter that is

sufficient to meet a 1.2 lb/TBtu Hg emission rate on a continuous basis.

1.2. FACILITY BACKGROUND

The MRY station is located approximately seven (7) miles southeast of Center, North Dakota or forty (40)

miles northwest of Bismarck, North Dakota on ND Highway 25 at 3401 24th Street SW, Center, North Dakota

58530. MRY station provides energy to the Midcontinent Independent System Operator (MISO) system. MRY

station consists of two (2) units. Both MRY units are lignite-fired Babcock and Wilcox (B&W) cyclone boilers.

Both boilers fire North Dakota lignite coal supplied from BNI Coal, Ltd.’s Center Mine located in close proximity

to the plant. The MRY Unit 1 single wall cyclone boiler (Caroline type, radiant natural circulation) was placed

into service in 1970 and has a typical output capacity rating of 257 MWg (gross). The MRY Unit 2 opposed

wall cyclone boiler (Carolina type, radiant pump assisted natural circulation) was placed into service in 1977

and has a typical output capacity rating of 470 MWg (gross). Both units utilize selective non-catalytic reduction

(SNCR) and separated overfire air (SOFA) systems for NOx control, fuel additive (or halide) injection system

and non-halogenated (or non-brominated) powdered activated carbon (PAC) for Hg control, dry electrostatic

precipitators (ESP) for PM emissions control, and wet flue gas desulfurization (WFGD) systems for sulfur

dioxide (SO2) control.

1.2.1.Current Hg Control System Specifications

The existing Hg control system is designed to control Hg emissions below 4.0 lb/TBtu using a combination of

M-Prove halide injection and non-halogenated PAC. The M-Prove is directly applied on the coal belt prior to

reaching coal silos, whereas the non-halogenated PAC is injected into the duct downstream of the air preheater (APH). Additional information on the design of the existing fuel additive and PAC injection systems for

MRY Units 1 and 2 are summarized below:

•

MRY Common Non-brominated PAC Storage Silo:

o PAC Utilized: Cabot DARCO® Hg-H non-halogenated PAC

o Single storage silo with three (3) outlet cones or discharge connections. Each cone is

connected to a feeder train (A, B, and C).

o Feeder Train A is dedicated to MRY Unit 1

o Feeder Trains B and C are dedicated to MRY Unit 2

o Storage Volume: 4,200 cu.ft. (Nominal)

o Capacity: 105,000 lbs. (based on PAC density of 25 lbs/cu.ft.)

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Storage duration: Approximately 18 days based on silo capacity of 105,000 lbs. and total

combined PAC consumption rate of 244 lb/hr (MRY Unit 1 at 86 lb/hr and MRY Unit 2 at 158

lb/hr)

•

MRY Unit 1 (257 MWg)

o Fuel Additive: ARQ (formerly ADA) M-Prove

 Average M-Prove application rate: 6.0 ppm

 Maximum M-Prove dosage pump rate: 18.0 ppm

o Non-brominated PAC Injection:

 Maximum Train A PAC injection at 100% feeder rate: 1.43 lb/min (approximately 86

lb/hr or 1.06 lb/MMacf)

 Transport piping limited to 192 lb/hr (2.37 lb/MMacf) to avoid pluggage issues

 PAC injected into flue gas using eight (8) lances located across the APH outlet duct.

 The lance depths vary from 18” – 54” to provide even distribution of PAC into the flue

gas stream

•

MRY Unit 2 (470 MWg)

o Fuel Additive: ARQ (formerly ADA) M-Prove

 Average M-Prove application rate: 8.0 ppm

 Maximum M-Prove dosage pump rate: 18.0 ppm

o Non-brominated PAC Injection:

 Maximum Train B and C PAC injection at 100% feeder rate: 2.64 lb/min

(approximately 158 lb/hr or 1.12 lb/MMacf)

 PAC injected into flue gas using eight (8) lances located across each of the North and

South APH outlet ducts for a total of sixteen (16) lances.

 The lance depths vary from 15” – 78” to provide even distribution of PAC into the flue

gas stream

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2.TEST CAMPAIGN SUMMARY

The MRY Units 1 and 2 test campaign was completed in phases to control testing variables and to

accommodate vendor availability, and scheduled outages. Testing included:

• November 23

23, 2023 to November 24, 2023: Maximizing MRY Unit 1 capabilities of the existing MProve fuel additive system and non-halogenated PAC injection (at 100% feeder rate) to evaluate if the

current system can meet 1.2 lb/TBtu.

•

December 19, 2023 to December 20, 2023: Maximizing MRY Unit 2 capabilities of the existing MProve fuel additive system and non-halogenated PAC injection (at 100% feeder rate) to evaluate if the

current system can meet 1.2 lb/TBtu.

•

March 19, 2024 to March 23, 2024: Utilizing a rental bulk bag unloading (BBU) system provided by

Motus Group tied into the existing MRY Unit 1 PAC conveying lines and injection lances to inject

brominated PAC (or BPAC), ARQ’s FastPAC Platinum®, at varied injection rates ranging from 100

lb/hr (or 1.23 lb/MMacf) to a maximum of 185 lb/hr (2.28 lb/MMacf) to stay below the transport piping

pluggage limit. The majority of this testing also included maximizing MRY Unit 1 capabilities of the

existing M-Prove fuel additive system; however, test runs on March 22 and March 23 included BPAC

injection with no fuel additive usage. Individual coal samples were taken and analyzed by a 3rd party

lab for determination of inlet Hg coal content.

•

March 28, 2024 to April 1, 2024: Individual coal samples were taken and analyzed by a 3rd party lab

for determination of inlet Hg coal content.

This testing was not able to be completed during the proposed rule’s short comment period of only 60 days.

Due to timing of boiler cleaning outages, time required to develop a test protocol and schedule, and

coordination with multiple vendors, rental equipment availability, various site activities, and unplanned unit

upsets/outages, a much longer duration was needed.

2.1. INCREMENTAL HG REMOVAL TEST RESULTS

The Hg emissions achievable based on maximizing current design capabilities using non-brominated PAC

and M-Prove without any modifications is summarized below for both MRY Units 1 and 2.

Table 2-1 — MRY Units 1 and 2 Existing System Capabilities

MRY Unit 1

MRY Unit 2

18 ppm M-Prove and

100% Non-brominated PAC

MWg

242

469

PAC Injection Rate

lb/MM

MMacf

1.06

1.12

Avg. Sorbent Trap Hg Emissions

lb/TBtu

2.17

1.61

Parameter

Unit Load during testing

Units

Based on maximizing injection capabilities of the existing systems (without any modifications), the test results

show that MRY Unit 1 and MRY Unit 2 cannot achieve the proposed MATS limit of 1.2 lb/TBtu.

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2.2. BROMINATED PAC PERFORMANCE

The proposed rule assumes a 90% Hg removal efficiency is feasible from all lignite units, even those equipped

with an ESP.

• In the Beyond-the-Floor memo (Docket ID No. EPA-HQ

HQ-OAR-2009-0234), it states that “[g]reater than

90 percent control can be achieved at lignite-fired units at a 2.0 lb/MMacf injection rate for units with

installed fabric filter and using treated (i.e., brominated) activated carbon or at an injection rate of 3.0

lb/MMacf for units using treated activated carbon with installed ESPs.”

•

According to the proposed MATS rule, EPA reiterates that “[i]n the beyond-the-floor analysis in the

final MATS rule, we noted that the results from various demonstration projects suggest that greater

than 90 percent Hg control can be achieved at lignite-fifired units using brominated activated carbon

sorbent at an injection rate of 2.0 lb/MMacf for units with installed FFs for PM control and at an injection

rate of 3.0 lb/MMacf for units with installed ESPs for PM control.”

The Final Rule relies on the same assumption. In EPA’s 2024 Technology Memorandum, EPA finds, “In the

beyond-the-floor analysis in the final MATS rule, we noted that the results from various demonstration projects

suggest that greater than 90 percent Hg control can be achieved at lignite- fired units using brominated

activated carbon sorbent at an injection rate of 2.0 lb/MMacf for units with installed Faric Fililters for PM control

and at an injection rate of 3.0 lb/MMacf for units with installed ESPs for PM control. . . all units (in 2022) would

have needed to control their Hg emissions to less than 95 percent to meet an emission standard of 1.2 lb/TBtu.

Based on this, we expect that the units could meet the proposed, more stringent, emission standard of 1.2

lb/TBtu by utilizing brominated activated carbon at the injection rates suggested in the beyond-the-floor

memorandum from the final MATS rule.”

During the MRY Unit 1 March testing, MRY secured a temporary rental injection skid. The materials of

construction of the existing PAC silo (common to MRY Units 1 and 2) is not currently compatible to store

halogenated PAC. The silo would require an internal coating to prevent corrosion (but could otherwise be

reused). The temporary rental injection skid avoided

ed corrosion to the existing silo, but also allowed for

decoupling MRY Unit 1 from the common PAC storage silo to prevent interfering with MRY Unit 2 Hg control

operation.

To achieve a dosage rate of 3.0 lb/MM

MMacf, an injection rate of 245 lb/hr would be required which would exceed

the existing MRY Unit 1 Train A PAC injection/transport system limit of 192 lb/hr (2.37 lb/MMacf). The

maximum BPAC injection rate tested was limited to 185 lb/hr (2.28 lb/MMacf) to avoid line pluggage.

The Hg emissions reductions achievable based on maximizing the use of BPAC (without any fuel additives)

supplied via a temporary rental injection system tied into the existing transport piping/lances is summarized

below for MRY Unit 1. A higher PAC injection rate was not possible due to maximum capability of the existing

transport piping while preventing pluggage.

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Table 2-2 — MRY Unit 1 Existing System Capabilities using Brominated PAC

Parameter

Units

Unit Load during testing

MRY Unit 1

185 lb/hr BPAC

MWg

257.1

PAC Injection Rate

lb/MM

MMacf

2.28

Avg. Sorbent Trap Hg Emissions

lb/TBtu

2.57

At the current injection capabilities of the existing system (i.e. requiring minimal modifications/retrofit of the

existing equipment), BPAC cannot be applied to reduce Hg emissions to 1.2 lb/TBtu.

2.3. MRY MERCURY REMOVAL EFFICIENCY

2.3.1.Lignite Coal Mercury Content

To calculate an overall mercury removal efficiency needed to control to 1.2 lb/TBtu, the coal Hg inlet must be

defined.

•

EPA reported the “Hg Inlet” level based on the maximum Hg content of the range of feedstock coals

that the EPA assumes is available to each of the plants in the Integrated Planning Model (IPM).

o With respect to MRY, EPA reported “Hg inlet”:

 MRY Units 1 and 2: 7.81 lb/TBtu

•

According to the proposed rule, EPA estimated the 2021 Hg inlet concentration from actual 2021 fuel

usage and 2021 Hg emissions reported to the EPA. However, based on the 2024 Technical Memo,

EPA updated the information based on 2022 information.

o With respect to MRY, EPA “Estimated Hg inlet” content documented in 2023 and 2024

Technical Memo is summarized in the table below:

Table 2-3 — EPA Estimated North Dakota Lignite Coal Hg Inlet

•

2023 Technical

Memo

2024 Technical

Memo

(Estimated 2021

Hg Inlet)

(Estimated 2022

Hg Inlet)

Parameter

Units

MRY Unit 1

lb/TBtu

7.78

9.70

MRY Unit 2

lb/TBtu

7.79

9.70

However, recent test information and other resources for the North Dakota lignite fired at MRY has

indicated that significantly higher inlet Hg is experienced at MRY:

o Within the BNI Coal, Ltd.’s Center Mine, the Kinneman Creek (KC) and Hagel (HA) beds are

targeted for the coal supply for MRY. Based on the 2021 BNI coal data (constructed from

Carlson reports), the avg. coal Hg content is approximately 16 lb/TBtu for KC and 15 lb/TBtu

for HA

HA.

o The variability of the projected lignite coal quality received from the Center Mine from 2025

through 2036 is shown in the following table.

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Table 2-4 — Forecasted 2025 – 2036 Center Mine Ultimate Coal Analyses (As-Received)

Fuel Parameter

Units

Average

Minimum

Maximum

Mercury Content

ppm

0.091

0.053

0.184

Higher Heating Value (HHV)

Btu/lb

6,625

6,489

6,739

Estimated Hg Emission

lb/TBtu

8.41

4.79

17.42

Industry experience has shown that lignite coal deposits vary significantly in quality, including

fuel combustion performance, mineral content, and Hg content, resulting in a coal that can

change on a day-to

to-day basis depending on the coal seam being mined at the time. This

variability was demonstrated by the range of coal analyses from MRY Unit 1 recent short-term

testing in 2024 (average = 10.1 lb/TBtu, with individual results ranging from 4.9 – 18.6 lb/TBtu

over the course of five (5) days of testing). Individual coal samples and how they varied across

coal feeders, per day are shown in following table.

Table 2-5 — MRY Unit 1 Coal Sampling Analysis

Coal Hg Inlet (lb/TBtu)

Date

19-Mar-24

20-Mar-24

21-Mar-24

22-Mar-24

23-Mar-24

28-Mar-24

1-Apr-24

Sample

Feeder #1

Feeder #3

Feeder #4

Feeder #5

Feeder #7

#1@ 0730 hrs

14.5

13.0

#2@ 1600 hrs

11.1

8.2

8.0

#3@ 0100 hrs

12.5

10.5

#1@ 0730 hrs

6.2

7.9

#2@ 1600 hrs

7.2

10.1

18.5

#3@ 0100 hrs

10.9

8.1

#1@ 0730 hrs

14.1

7.9

#2@ 1600 hrs

18.6

4.9

7.1

#3@ 0100 hrs

7.2

7.1

#1@ 0700 hrs

10.4

13.4

#2@ 1600 hrs

6.9

11.0

11.4

#3@ 0100 hrs

9.2

7.8

#1@ 1030 hrs

10.2

8.3

#2@ 1500 hrs

14.9

11.9

9.5

#1@ 0930 hrs

16.3

8.0

#2@ 1300 hrs

6.0

12.1

12.3

#3@ 1500 hrs

10.2

6.9

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2.3.2.Required Mercury Removal Based on Lignite Coal Mercury Content

Based on the recent Hg fuel analyses, Hg control higher than 90% would actually be required based on the

range of inlet coal Hg content expected to control to 1.2 lb/TBtu (i.e. keeping the outlet value calculated by the

EPA constant). Note that control to this value does not offer any operating margin for potential exceedances

that may occur due to response delays associated with coal variability. The following table identifies the

required Hg control needed based on several different coal Hg content references. Based on these

estimations, any Hg control approach would need to be able to accommodate a wide range of inlet Hg in order

to optimize operating costs long-term.

Table 2-6 — Hypothetical Hg Emissions and Control Performance Based on Coal

Analyses

Est. Hg Control at

4.0 lb/TBtu

Est. Hg Control at

1.2 lb/TBtu

(%)

7.81

48.8

84.6

9.70

58.6

87.6

Average

10.1

60.4

88.1

Maximum

18.6

78.5

93.5

Minimum

4.9

18.4

75.5

Average

8.41

52.4

85.7

Maximum

17.42

77.0

93.1

Minimum

4.79

16.5

75.0

Fuel Hg Content Reference

Coal Hg Inlet

(lb/TBtu)

EPA Technical Memo

2023 Table 11

Docket ID. No: EPA-HQ

HQ-OAR-2018-0794 1

2024 Table 10

Docket ID. No: EPA-HQ

HQ-OAR-2018-0794 2

2024 MRY Unit 1 Test Campaign

Center Mine Forecast

2.3.3.Projected Mercury Removal Based 3.0 lb/MMacf BPAC

Based on the maximum BPAC rate that MRY Unit 1 was able to test due to current system limitations (1

(185

lb/hr or 2.28 lb/MMacf), the figure below plots the estimated percent removal at the higher injection rate of 3.0

lb/MMacf BPAC using all measurements from the MRY Unit 1 March testing (with and without fuel additive

usage). The plotted values demonstrate a trend line in which BPAC cannot even achieve 80% Hg removal

efficiency.

Benish S. et al.

l. (January 2023). 2023 Technology Review for the Coal- and Oil-Fired EGU Source Category.

Environmental Protection Agency.

Benish S. et al. (January 2024). 2024 Update to the 2023 Proposed Technology Review for the Coal- and Oil-Fired

EGU Source Category. Environmental Protection Agency.

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Figure 2-1 — MRY Unit 1 Existing System Mercury Removal Performance

Capabilities using Brominated PAC

This result is contrary to EPA’s assumption that BPAC at a rate of 3.0 lb/MM

MMacf can be used to result in a 90%

removal efficiency. The plotted curve shown in the figure shows a leveling off such that increasing the amount

of sorbent results in diminishing improvement in Hg control. The projected curve based on the test campaign

results shows this leveling off taking place somewhere less than 80% capture.

Although the plotted values do not support a conclusion that the new Hg 1.2 lb/TBtu limit can be met, further

investigation into other Hg control options in combination with upgrading/optimizing existing Hg control

equipment would be required to determine the lowest mercury emission rate in lb/TBtu that can be achieved

on a long-term basis, considering the range of fuel Hg variability and other technological challenges inherent

in capturing Hg resulting from lignite that have

ve been documented to occur. Some proposed options for

additional Hg control include:

•

Increased fuel additive rate

•

Improved reliability of fuel additive concentration in relation to real-time coal firing rates

•

Implementation of inlet Hg monitor for improved feedback control of Hg control systems

•

Improved lance design to achieve ideal distribution of PAC at all typical unit operating conditions

•

Application of WFGD re-emission control additive

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Further analysis, engineering, testing and equipment modifications would be necessary to determine if these

options would improve Hg control. However, it is clear that adding more brominated PAC, as was assumed in

the Final Rule, is not adequate, given the properties of lignite, compliance margin necessary, and limitation of

mine mouth facilities in regards to fuel staging (i.e. must use coal received from mine; unable to fire only certain

coals that have a more ideal or predictable range of Hg content during a 30-day rolling average).

It should be noted that the achievable Hg emission rate should not be construed to represent an enforceable

regulatory or proposed permit limit. Corresponding permit limits must consider normal operating fluctuations

and coal variability and take into account a minimum additional 20% margin for these fluctuations. Since a

combination of new and/or upgraded control systems would be expected to be required, obtaining a guarantee

from a single vendor to ensure that the unit achieves compliance below the permit limit will be challenging.

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3.EPA COST VALIDITY

3.1.1.Current Hg Compliance Cost Effectiveness (4.0 lb/TBtu)

With respect to MRY, EPA estimated the cost effectiveness for current 2021 Hg emissions is shown below in

an excerpt from Table 12 in 2023 Technology Review for the Coal- and Oil-Fired EGU Source Category

(Docket ID. No: EPA-HQ

HQ-OAR-2018-0794).

Response: Flaws in EPA’s cost analysis for current compliance:

• Est. Hg In (lb) & Hg Out (lb)

o Table 12 would appear to have flipped MRY Unit 1 and Unit 2 in the table, utilizing the higher

MRY Unit 2 operating conditions (heat input, hg loading, etc.) for the smaller sized Unit 1 and

vice versa.

•

PAC Injection Rate:

o Table 12 Avg. Sorbent (lb/hr) – EPA noted MRY Unit 1: 19.0 lb/hr and MRY Unit 2: 43.0 lb/hr

to achieve controlled Hg rate of 3.2 lb/TBtu.

o Minnkota PAC sorbent injection rates to achieve controlled Hg rate of 3.85 lb/TBtu for MRY

Unit 1 is expected to be 86 lb/hr and for MRY Unit 2 is 158 lb/hr

hr.

•

Cost of PAC:

o Table 12 non-brominated PAC sorbent cost – EPA assumed a cost of $0.83/lb.

o In the 2024 Technical Memo, EPA adjusted this cost down to $0.80/lb.

o Based on MRY operational costs for 2023, non-brominated PAC sorbent cost is $0.86/lb.

o Based on MRY operational costs for 2023, actual non-brominated PAC costs for achieving

current compliance with 4.0 lb/TBtu indicated MRY Unit 1: $119,813 and MRY Unit 2:

$329,328

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Cost of Fuel Additive:

o Table 12 Est. 2021 Additive Cost – EPA noted that "Additive costs are unknown. For this

analysis, the EPA assumed the additive costs are the same, annually, as the sorbent costs.”

And lists costs as MRY Unit 1: $227,410 and MRY Unit 2: $147,267

o Based on MRY operational costs for 2023, actual fuel additive costs for achieving current

compliance with 4.0 lb/TBtu indicated MRY Unit 1 $715,157 and MRY Unit 2: $1,574,793.

o Based on the actual 2023 fuel additive usage rates and costs, EPA’s underestimate results in

$487,747 and $1,347,383 that should have been included in the cost analysis for MRY Units

1 and 2, respectively.

3.1.2.Future Hg Compliance Cost Effectiveness (1.2 lb/TBtu)

EPA calculated unit-level cost-effectiveness to meet the proposed, more stringent, emissions standard using

brominated activated carbon at an injection rate of 5.0 lb/MMacf for units with an ESP for PM control or at an

injection rate of 2.5 lb/MMacf for units with fabric filter for PM control.

With respect to MRY, the EPA estimated the cost effectiveness (assuming 2021 operational characteristics)

is shown below in an excerpt from Table 13 in 2023 Technology Review for the Coal- and Oil-Fired EGU

Source Category (Docket ID. No: EPA-HQ

HQ-OAR-2018-0794):

EPA’s incremental cost-effectiveness per the 2024 Update to the 2023 Proposed Technology Review for the

Coal- and Oil-Fired EGU Source Category (Docket ID. No: EPA-HQ

HQ-OAR-2018-0794) is based on a model

800 MW Gulf Coast lignite-fired EGU with a heat rate of 11,000 Btu/kWh operating at an 80% capacity factor

and a Hg concentration of 25.0 lb/TBtu, resulting in an incremental cost-effectiveness of $28,176 per pound

of Hg controlled. It assumes that the unit currently meets a Hg emission standard of 4.0 lb/TBtu using an

injection rate of 2.5 lb/MMacf of non-brominated activated carbon at a sorbent cost of $0.80/lb and that the

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unit can meet a Hg emission standard of 1.2 lb/TBtu using an injection rate of 5.0 lb/MMacf of brominated

activated carbon at a sorbent cost of $1.15/lb.

•

Note that the example does not include fuel additives or any equipment upgrade costs.

EPA made following changes to the calculations between 2023 and 2024 Technical Memo’s:

o EPA updated the Gulf Coast Hg concentration from 14.9 lb/TBtu (2023) to 25.0 lb/TBtu (2024).

This resulted in the baseline annual uncontrolled Hg emissions to change from 919 lb Hg to

1,542 lb Hg.

o EPA corrected the formula for conversion of sorbent injection rate from lb/MMacf to lb/hr by

adjusting the conversion factor from (520 R / 785 R) to (785 R / 520 R). The conversion factor

was applied incorrectly in 2023 Technical Memo.

o EPA added an additional factor to update the formula for conversion of sorbent injection rate

from lb/MMacf to lb/hr which was not previously accounted for in 2023 Technical Memo.

For comparison with the values calculated by the EPA in Table 13, it should be noted that the 2024

calculated cost effectiveness of the 800 MW example used by the EPA to meet 1.2 lb/TBtu, without

fuel additives, is $5,083 per pound of Hg controlled.

Response: Flaws in EPA’s cost analysis for future compliance with 1.2 lb/TBtu:

• Est. Hg In (lb) & Hg Out (lb)

o See previous responses on Table 12 for flipped MRY Unit 1 and MRY Unit 2 unit

information/sizing and cost of fuel additive.

•

BPAC Injection Rate:

o EPA’s cost analysis assumes lignite units with an ESP can achieve 1.2 lb/TBtu, which has not

been demonstrated. The injection level has a direct bearing on the operational costs because

it dictates the amount of BPAC necessary to reduce Hg emissions. Therefore, cost

calculations are hypothetical because no project data demonstrates what the injection level

would be, if 1.2 lb/TBtu is feasible.

o Although the overall feasibility of complying with the proposed Hg limit is undetermined, the

testing confirms that based on maximizing injection capabilities of the existing systems, MRY's

current equipment configuration cannot achieve 1.2 lb/TBtu.

•

Cost of BPAC:

o Table 13 brominated PAC sorbent cost – EPA assumed of $1.15/lb.

o MRY Unit 1 test campaign brominated PAC cost = $1.25/lb.

•

Missing capital costs:

o Irrespective of feasibility, EPA calculated cost-effectiveness shown in Table 13 does not

include capital costs for modifying, upgrading and/or adding new equipment that would be

necessary for the MRY Station due to limitations of existing equipment.

o Modification to the existing PAC injection system, would include,

e, but not be limited to, the

following:

 The materials of construction of the existing PAC silo (common to MRY Units 1 and

2) is not currently compatible to store halogenated PAC. The silo would require an

internal coating to prevent corrosion in order to store brominated PAC.

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Document #2058570

Milton R. Young Station Units 1 and 2

A14559.013

Filed: 06/07/2024

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Rev.

May 22, 2023

New feeding equipment, transport piping and injection lances would be required to

accommodate a higher injection rate.

 As the existing PAC storage silo is shared by MRY Units 1 and 2, the higher injection

rate required for achieving 3.0 lb/MMacf for both units would reduce the total storage

duration to less than seven (7) days of storage. Due to the weather experienced at

the site and the remote location, seven (7) days of storage is recommended for each

unit. Improved equipment redundancy would also likely be required to accommodate

the range of coal Hg expected to be experienced in the future. Therefore, it is likely

that the existing equipment would be dedicated to MRY Unit 1, and a separate silo

would be required for MRY Unit 2 to ensure adequate supply, turndown flexibility, and

reliability is achieved to maintain compliance with a defined Hg emission limit.

As such, a new MRY Unit 2 system would be required to achieve higher injection rates of

PAC. An analogous project to install Hg control equipment at a 500 MW coal-fired unit in 2021

costs roughly $5.0 million dollars, based on S&

S&L internal mercury control database, actual

project costs from recent relevant projects, and adjusted for MRY specific design.



Overall, the cost-effectiveness calculated is still a substantial under-estimation for the incremental Hg control

on MRY Units 1 and 2.

• To provide an example, hypothetical MRY Unit 2 costs are summarized in the following table to

underscore the magnitude of dollars that EPA failed to include in its calculations and that must be

expended by Minnkota.

• Note the table below does not include or account for any costs associated with MRY Unit 1 system

upgrades.

Mercury Testing Results for the MATS Residual Risk and Technology

Review

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Case #24-1119

Document #2058570

Milton R. Young Station Units 1 and 2

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204

Rev.

May 22, 2023

A14559.013

Table 3-1 — Example MRY Unit 2 Cost Underestimations Summary

EPA Example

Hypothetical

800 MW

EPA Assumed

MRY U2 Co

Costs

447

47 MW

Est. Actual

MRY U2 Costs

447

47 MW

Current Hg Compliance (4.0 lb/TBtu) Cost 1

$2.6 M

$0.3 M

$1.

1.9 M

Current Hg Removed

1,295 lb

77 lb

149 lb

Current C/E ($ per lb Hg Removed)

2,004

3,845

12,754

Not included

$472k 2

$7.5 M

$0.6 M

$1.3 M 3

Not included

$0.2 M

$1.6 M 4

Future Hg Compliance (@ 5 lb/MMacf) Cost

$7.5 M

$0.8 M

$3.4 M

Future Hg Removed

(EPA Assumed @ 1.2 lb/TBtu)

1,447 lb 5

110 lb

216 lb

5,083

7,040

15,678

Parameter

Hg Control System Annualized Capital Cost

BPAC Cost @ 5 lb/MMacf

M-Prove Cost

Future C/E ($ per lb Hg Removed)

22,217

28,176

14,360

Incremental C/E ($ per lb Hg Removed)

Note 1 – EPA example only based on sorbent. EPA assumed current compliance cost includes sorbent and chemical

fuel additive. Est. actual cost based on 2023 MRY Unit 2 usage rate & pricing for both sorbent and chemical additive.

Note 2 – Cost of $5.0 million dollars from S&L project database was annualized using a capital recovery factor

calculated based on annual interest rate of 7% (pre-tax marginal rate of return on private investment, EPA Cost

Manual Section 5) and 20 year evaluation period (EPA Cost Manual Section 6).

Note 3 – Cost based on EPA assumed rate but using 2023 MRY BPAC pricing.

Note 4 – Cost based on 2023 MRY Unit 2 usage rate & pricing instead of assuming same as sorbent costs.

Note 5 – Based on calculated value for EPA example inlet Hg of 1,542 lbs (current Hg coal content) – 95 lbs (future

emitted amount). However, the EPA example identifies 1,468 lb for the incremental cost effectiveness calculation.

Mercury Testing Results for the MATS Residual Risk and Technology

Review

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ATTACHMENT B

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Technical Comments on

National Emission Standards for Hazardous Air Pollutants: Coal- and Oil-fired

Electric Utility Steam Generating Units Review of Residual Risk and Technology

Prepared by

J. Edward Cichanowicz

Consultant

Saratoga, CA

James Marchetti

Consultant

Washington, DC

Michael C. Hein

Hein Analytics, LLC

Whitefish, MT

Prepared for the

National Rural Electric Cooperative Association

American Public Power Association

America’s Power

Midwest Ozone Group

NAACO

National Mining Association

Power Generators Air Coalition

June 19, 2023

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Summary of Flaws in EPA’s Approach ............................................................................. 1

Introduction.................................................................................................................... 3

Description of EPA Reference PM Database .................................................................... 5

3.1

Coal Fleet Inventory ............................................................................................................. 5

3.2

Database Characteristics ...................................................................................................... 6

3.2.1 Selection of Sample Year, Quarter.......................................................................................... 6

3.2.2 Number of Samples ................................................................................................................ 7

3.2.3 PM Data Selection and Analysis.............................................................................................. 8

3.2.4 Example Cases ........................................................................................................................ 9

3.3

Conclusions ........................................................................................................................ 10

Coal Fleet PM Emissions Characteristics .........................................................................12

4.1.1

4.1.2

4.1.3

PM Rate of 0.015 lbs/MBtu .................................................................................................. 13

PM Rate of 0.010 lbs/MBtu .................................................................................................. 13

PM Rate of 0.006 lbs/MBtu .................................................................................................. 13

CRITIQUE OF COST-EFFECTIVENESS CALCULATIONS ........................................................14

5.1

EPA Evaluation ................................................................................................................... 14

5.1.1 EPA Study Inputs ................................................................................................................... 14

5.1.2 EPA Results ........................................................................................................................... 16

5.2

Industry Study.................................................................................................................... 17

5.2.1 Revised Cost Inputs .............................................................................................................. 17

5.2.2 Cost Effectiveness Results .................................................................................................... 19

5.3

Conclusions ........................................................................................................................ 21

Mercury Emissions: Lignite Coals ...................................................................................22

6.1

North Dakota Mines and Generating Units ......................................................................... 22

6.2

Texas Gulf Coast Mines and Generating Units .................................................................... 27

6.3

Role of Flue Gas SO3 .......................................................................................................... 30

6.3.1 EIA Hg, Sulfur Relationship ................................................................................................... 30

6.3.2 SO3: Inhibitor to Hg Removal ................................................................................................ 31

6.4

EPA Cost Calculations Ignore FGD ....................................................................................... 32

6.5

Conclusions ........................................................................................................................ 33

Mercury Emissions: Non-Low Rank Fuels .......................................................................34

7.1

Hg Removal ........................................................................................................................ 34

7.2

Role of Fuel Composition and Process Conditions .............................................................. 36

7.2.1 Coal Variability ...................................................................................................................... 36

7.2.2 Process Conditions................................................................................................................ 37

7.3

Conclusions: Mercury Emissions - Non-Low Rank Coals ...................................................... 38

EPA IPM RESULTS: EVALUATION AND CRITIQUE .............................................................39

8.1

IPM 2030 Post-IRA 2022 Reference Case: A Flawed Baseline .............................................. 39

8.1.1 Analytical Approach .............................................................................................................. 39

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8.1.2 Coal Retirements .................................................................................................................. 40

8.1.3 Coal CCS ................................................................................................................................ 44

8.1.4 Coal to Gas Conversions (C2G) ............................................................................................. 44

8.2

Summary ........................................................................................................................... 44

Appendix A: Additional Cost Study Data ................................................................................45

Appendix B: Example Data Chart ...........................................................................................48

*****************************************

List of Tables

Table 5-1. Summary of EPA Results ............................................................................................ 16

Table 5-2. ESP Rebuild Costs: Four Documented Cases ............................................................ 18

Table 5-3. Summary of Results: Industry Study........................................................................... 20

Table 6-1. Hg Variability for Select North Dakota Reference Stations ....................................... 26

Table 6-2. Hg Variability for Select Texas Reference Stations .................................................... 29

Table 8-1. Coal Retirement Errors ................................................................................................ 40

Table 8-2. IPM Coal Retirement Errors: 2028 Post-IRA 2022 Reference Case Run .................. 41

Table 8-3. IPM Coal Retirement Errors: 2030 Post IRA 2022 Reference Case Modeling Run... 42

Table 8-4 Units in the NEEDS to Be Operating in 2028 .............................................................. 42

Table 8-5 Units IPM Predicts CCS By 2030 ............................................................................... 43

Table 8-6 Units IPM Erroneously Predicts Switch to Natural Gas ............................................. 43

Table A-1. Technology Assignment for 0.010 lbs/MBtu PM Rate: Industry Study .................... 46

Table A-2 Technology Assignment for 0.006 lbs/MBtu PM Rate: Industry Study .................... 47

*****************************************

List of Figures

Figure 3-1. Inventory of EPA-Project 2028 Fleet by Control Technology Suite .......................... 6

Figure 3-2. Numbers of Quarters Sampled by EPA for Use in PM Database ................................ 7

Figure 3-3. Coronado Generating Station: 20 Operating Quarters ............................................... 10

Figure 4-1. Fraction of Units Exceeding Three PM Rates: By Control Technology .................. 12

Figure 6-1. Mercury Content Variability for Eight North Dakota Lignite Mines ........................ 23

Figure 6-2. Fuel Sulfur Content Variability for Eight North Dakota Lignite Mines .................... 23

Figure 6-3. Fuel Alkalinity/Sulfur Ratio for Eight North Dakota Mines ..................................... 24

Figure 6-4. Spatial Variation of Hg in a Lignite Mine ................................................................. 25

Figure 6-5. Mercury Variability for Two Gulf Coast Sources: Mississippi, Texas...................... 27

Figure 6-6. Sulfur Variability for Mississippi, Texas Lignite Mines19.1 .................................... 28

Figure 6-7. Fuel Alkalinity/Sulfur Ratio for Mississippi, Texas Lignite Mines........................... 28

Figure 6-8. Lignite Hg and Sulfur Content Variability: 2021 EIA Submission ........................... 30

Figure 6-9. Sorbent Hg Removal in ESP in Lignite-Fired Unit: Effect of Injection Location ..... 32

Figure 7-1. Mean, Standard Deviation of Annual Hg Emissions: 2018 ....................................... 35

Figure 7-2. Mean, Standard Deviation of Annual Hg Emissions: 2018 ....................................... 35

Figure 7-3. Annual Average of Fuel Hg, Sulfur Content in Coal ................................................. 36

Figure A-1. Unit ESP Investment (per EPA’s Cost Assumptions): PM of 0.010 lbs/MBtu ....... 45

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Summary: Flaws in EPA’s Approach

1. Summary of Flaws in EPA’s Approach

The following is a summary of flaws in EPA’s analysis, further described in detail in this report.

Particulate Matter (PM) Database

EPA’s database of PM emissions is inadequate. EPA attempts to capture typical PM emissions

by acquiring samples from 3 years – 2017, 2019, and 2021. For the vast majority of the units –

80% - EPA uses only 2 of the potentially available 12 quarters (in those 3 years; up to 20

quarters from 2017 to 2021) of data to construct the PM database. Further, of these limited

samples. EPA cites the lowest to reflect a target PM emissions rate. EPA cites the use of the

“99th percentile” PM rate in lieu of the average compensates for variability; but this approach

accounts for variability within a single (“the lowest”) quarter. It fails to account for long-term

variability, which is affected by changes in fuel and process conditions, among others.

Lack of Design and Compliance Margin

EPA recognizes the need for margin in both design and operation (for compliance) of

environmental control equipment, but ignores this concept in developing this proposed rule. The

need for design margin is recognized in a 2012 OAQPS memo 1 addressing the initial

developments of this very same rule, while margin for operation is considered in evaluating

CEMS calibration2 for this proposed rule. Neither design nor operating margin is considered in

setting target PM standards, resulting in underestimation of number of units affected and total

costs to deploy control technology. For some owners of fabric filter-equipped units, the revised

rate of 0.010 lbs/MBtu eliminates any operating margin.

Inadequate Cost for ESP Rebuild

Of three categories of ESP upgrades considered by EPA, the cost for the most extensive – a

complete rebuild to add collecting plate area – is inadequate. Four such major ESP rebuild

projects have been implemented for which costs are reported in the public domain – and not

acknowledged by EPA. Incorporating these results elevates the range of cost from EPA’s

estimate of $75-100/kW to $57-213/kW. Consequently, the “average” cost for this action used

in the cost per ton ($/ton) evaluation increases from $87/kW to $133/kW.

Hutson, N., National Emission Standards for Hazardous Air Pollutants (NESHAP) Analysis

of Control Technology Needs for Revised Proposed Emission Standards for New

Source Coal-fired Electric Utility Steam Generating Units, Memo to Docket No. EPA-HQ-OAR—20090234, November 16, 2012. Hereafter Hutson 2012.

Parker, B., PM CEMS Random Error Contribution by Emission Limit, Memo to Docket ID No. EPAHQ-OAR-2018-0794, March 22, 2023. Hereafter Parker 2023.

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Summary: Flaws in EPA’s Approach

Inadequate $/ton Removal Cost

As a consequence of under-predicting capital required for ESP “rebuild,” and not recognizing the

need for a design and operating margin, EPA under-predicts the number of units requiring

retrofit and incurred cost. As a result, in contrast to the annual cost of $169.7 M projected by the

Industry Study described in this report, EPA estimates a range from $77.3 to $93.2 M. Further,

the Industry Study estimates the cost per ton ($/ton) of fPM to be $67,400, 50% more than the

maximum cost estimated by EPA - $44,900 /ton.

Faulty Lignite Hg Rate Revision

EPA’s proposal to lower the Hg emission rate for lignite-fired units to 1.2 lbs/TBtu is based on

improper interpretation of Hg emissions data – both in terms of the mean rate and variability.

EPA’s projection that 85 and 90% Hg removal would be required for the proposed rate is

incorrect, with up to 95% Hg removal required for some units – a level of Hg reduction not

feasible in commercial systems. In addition to the variability of Hg content in lignite, EPA

ignores the deleterious role of flue gas SO 3 in lignite-fired units, which compromises sorbent

performance and effectiveness – even though this latter barrier is recognized and cited by EPA’s

contractor for the IPM model.3

Faults in IPM Modeling

IPM creates a flawed Baseline scenario that does not adequately measure the impacts of the

proposed rule. Most notably, IPM err in the number of coal units that would be retired in both

2028 and 2030; as a consequence, EPA underestimates the number of units subject to the

proposed rule. Also, IPM unrealistically retrofitted 27 coal units with carbon capture and storage

(CCS) in 2030. Consequently, IPM modeling results of the Baseline likely understate the

compliance impacts of the proposed rule.

IPM Model – Updates to Cost and Performance for APC Technologies: Mercury Control Cost

Development Methodology, Prepared by Sargent & Lundy, Project 12847-002, March 2013.

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Introduction

The Environmental Protection Agency (EPA) is proposing to amend the National Emissions

Standards for Hazardous Air Pollutants (NESHAP) for Coal- and Oil-fired Electric Utility Steam

Generating Units (EGUs), otherwise known as the Mercury and Air Toxics Standards (MATS).

The specific emissions limits being revised address the filterable particulate matter (fPM)

standard (which is the surrogate standard for non-mercury (Hg) metal HAPs); the Hg standard

for lignite-fired units; fPM measurement methods for compliance; and the definition of startup.

This report provides a review and evaluation of EPA’s approach to selecting the revised fPM

standard, the capital and annual costs for achieving the proposed revised standard, and the cost

per ton ($/ton) to control non-Hg metal HAPs; and a critique of EPA’s basis for proposing an Hg

limit of 1.2 lbs/TBtu for lignite-fired units. This document also provides information supporting

EPA’s decision to retain the present Hg limit for bituminous and subbituminous coal.

The proposal to lower fPM and Hg limits is premised on EPA’s interpretation of data related to

the cost and capabilities of PM and Hg emission control technologies. EPA reports to have

conducted realistic assessments of PM and Hg emissions and control technology capabilities in

support of their analysis. EPA’s assumptions are reported in the

MATS_RTR_Proposal_Technology Review Memo4 where EPA describes the PM database they

developed, the cost and control capabilities of upgrades to electrostatic precipitators (ESPs) and

fabric filters, and their understanding of the key factors that affect Hg emissions in bituminous,

subbituminous, and lignite coal - and how the latter are alike or differ.

Many of EPA’s assumptions are contrary to data in their possession or strategies previously

adopted by EPA, but not considered. EGUs have been reporting fPM compliance data to EPA

since MATS became applicable to them – i.e., for the vast majority of EGU, April 2015 or April

2016 for units that obtained a one-year extension. However, EPA’s effort to “mine” fPM

emissions data from prior years provides a sparse, inadequate database that does not reflect

operating duty nor account for inevitable variability; further EPA misinterprets this information.

No design or operating margins are considered in setting fPM (the same is true for lignite Hg

emission rates). The cost to upgrade ESPs to meet the proposed limits is inadequate for the most

significant modification EPA envisions – the complete ESP Rebuild. The cost to deploy

enhanced operating and maintenance (O&M) actions on existing fabric filers is inadequate.

Regarding revised Hg limits for lignite coal, EPA does not recognize the differences in lignite

versus Powder River Basin (PRB) subbituminous coal that effect Hg control. EPA draws an

incorrect analogy between PRB and lignite, improperly assuming the Hg removal by carbon

sorbent observed with PRB can be replicated on lignite.

Benish, S. et. al., 2023 Technology Review for the Coal- and Oil-Fired EGU Source Category,

Memo to Docket ID No. EPA-HQ-OAR-2018-0794. January 2023. Hereafter RTR Tech Memo.

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Introduction

The remaining sections of this report detail the findings summarized in Section 1, and are as

follows:

•

Section 3 describes EPA’s approach to assembling their fPM database, and the flaws and

weaknesses in their approach.

Section 4 evaluates the fPM rates assigned by the database for the EPA analysis.

Section 5 evaluates EPA’s cost bases for the proposed fPM revised standard, and

compares these to the realistic assumptions used in the Industry Study described in the

paper.

Section 6 addresses EPA’s proposal to lower Hg from lignite-fired units to 1.2 lbs/TBtu,

delineating the shortcomings in EPA’s approach and assumptions.

Section 7 provides historical data for Hg emission from non-low rank fuels, showcasing

the inherent variability in the 30-day rolling average.

Section 8 reviews the IPM modeling analysis conducted by EPA to support this rule.

Appendix B presents examples of PM emission timelines for a limited number of units 5

that show how EPA’s sparse database does not capture the authentic “PM signature” of

the units.

We reviewed data for a limited number of units because the comment period was very short and did not

allow adequate time to undertake a more thorough review. EPA has all the data and in our opinion should

have conducted such an analysis for every unit at issue.

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Description of EPA Reference PM Database

Section 3 describes the PM database assembled by EPA which serves as the basis for the

proposed NESHAP rule. Section 3 first describes the coal fleet inventory reflected, and then

identifies shortcomings of this database concerning (a) selection of the sample year and quarter,

(b) number of samples considered, and (c) data analysis.

3.1 Coal Fleet Inventory

EPA projects that a total of 275 generating units will be operating at the compliance date of

January 1, 2028, representing a reduction from the present (2023) operating inventory of

approximately 450 units. EPA identified the 275 units based on their estimate of unit retirements

and units planning to switch to natural gas by the compliance date. EPA accounted for these

assets not as individual units, but in terms of the number of reporting monitors to the Clean Air

Markets Division. As 27 units employ common stack reporting, the data presented by EPA in the

draft rule and RTR Tech Memo consider 248 discrete data points that reflect the 275 units. This

analysis will adopt the same reporting methodology.

EPA’s selection of 275 units contains 22 units that have publicly disclosed plans to retire or

switch to natural gas by the compliance date of January 1, 2028. For the purposes of this

analysis, these units are retained in the database so the results can be more readily compared.

Figure 3-1 depicts the installed inventory projected by EPA, presented according to the suite of

control technology. The first two bars (from the left) report units equipped with ESPs as the

primary PM control device in the following configurations: a total of 54,116 MW for an ESP

followed by a wet FGD; and a total of 16,346 MW with an ESP only. The next 3 bars describe

the total inventory equipped with a fabric filter in the following three configurations: 12,194

MW with the fabric filer as the sole device; 20,206 MW with a fabric filter followed by a wet

FGD, and 19,995 MW where the fabric filter is preceded by a dry FGD process. Consequently,

the bulk of the inventory (70,462 MW) will employ an ESP as part of the control scheme, with

52,395 MW employing a fabric filter for PM. Given the role of wet FGD in PM emissions – in

most cases such devices will reduce PM by approximately 50% - more than half (74,322 MW)

employ wet FGD as the last control step.

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Description of EPA Reference PM Database

60,000

Bituminous

Subbituminous

Lignite

Waste Coal

Environmental Control Inventory

50,000

40,000

30,000

20,000

10,000

ESP/Wet FGD

ESP Only

FF Only

FF/Wet FGD

FF/Dry FGD

Wet ESP

Figure 3-1. In

Inventory of EPA-Project 2028 Fleet by Control Technology Suite

3.2 Database Characteristics

Several characteristics of EPA’s database severely compromise the quality of the analysis. These

are the (a) selection of sampling year and quarter and (b) number of samples used.

3.2.1 Selection of Sample Year and Quarter

EPA does not describe the rationale for the limited data selected. The selection of three reference

years (2017, 2019, and 2021) from at least 5-6 years of data readily available to EPA, and the

sampling periods within each year (typically the 1 st or the 3rd quarter even though all quarters are

generally available) are not discussed. EPA extracts data from the year 2021 using a different

approach from the years 2019 and 2017 without explanation. EPA states for 2021 that 2 quarters

of data are utilized (always the 1st and the 3rd). For 2019, EPA reports utilizing data from

“quarters three and occasionally four” while for 2017 EPA reports data acquired from “variable

quarters.”6

The rationale for the irregular selection of quarters is not stated. For 2021, the first and third

quarters are selected with no technical basis. For 2019, the selection of quarters three and

“occasionally” four does not replicate the time periods selected for 2021. For 2017, there is no

description of the quarters or selection criteria.

EPA ignores a rich field of data that could support a much more robust and reasonable analysis.

RTR Tech Memo, page 2.

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Description of EPA Reference PM Database

3.2.2 Number of Samples

The number of discrete data points in EPA’s Reference Database – defined by the number of

operating quarters – is extremely limited. EPA’s description of the sampling approach7 is as

follows:

Quarterly data from 2017 (variable quarters) and 2019 (quarters three and occasionally four)

were first reviewed because data for all affected EGUs subject to numeric emission limits had

been previously extracted from CEDRI. In addition, the EPA obtained first and third quarter

data for calendar year 2021 for a subset of EGUs with larger fPM rates (generally greater than

1.0E-02 lb/MMBtu for either 2017 or 2019).

Figure 3-2 shows most monitor locations — 193 of the 245 — are characterized by only 2

quarters of data, which is inadequate compared to the 16 or 20 EPA has access to. The

distribution of quarters selected by EPA according to either CEMS or stack test measurement for

all 245 locations is shown. The second largest category is 33 units characterized by 4 quarters.

Figure 3-2. Numbers of Quarters Sampled by EPA for Use in PM Database

RTR Tech Memo, page 2.

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Description of EPA Reference PM Database

Additional depictions of the data (not shown) reveal that only nine units are described by data in

2017, and 187 units by data from 2019. Only 41 units are described by data in 2021; the lack of

data in 2021 was intentional as EPA considered this year only if data from 2017 or 2019 showed

the unit exceeding the 0.010 lbs/MBtu proposed limit. 8 In other words, EPA looked at 2021 only

when it was trying to find an emission rate less than 0.010 lbs/MBtu for a unit.

3.2.3 PM Data Selection and Analysis

EPA does not explain the methodology chosen to reflect each quarters’ emission rate, using at

least two methods, depending on the year. EPA followed a four-step process to construct its

database to select the “base rate” for each unit. The process is described as follows:

Step 1: Quarter Selection. EPA looked at 2-4 (usually 2) quarters for each unit. EPA states:

“Quarterly data from 2017 (variable quarters) and 2019 (quarters three and occasionally four)

were first reviewed …. In addition, the EPA obtained first and third quarter data for calendar

year 2021 for a subset of EGUs with larger fPM rates (generally greater than 1.0E-02 lb/MMBtu

for either 2017 or 2019).”9

As noted previously, EPA considered Q1 and Q3 2021 data solely to find a PM rate lower than

0.010 lb/MMBtu, and further explained: “The quarterly 2021 data summarizes recent emissions

and also reflect the time of year where electricity demand is typically higher and when EGUs

tend to operate more and with higher loads.”10

Step 2. Select Single Quarter. From the candidate quarters identified in Step 1, EPA selected a

single value, using criteria specific for each tests methodology:

•

PM CEMS: for quarters in 2017 and 2019, EPA selected the 30-day average observed on

the last day of the quarter; for quarters in 2021, EPA determined the average of the 30day rolling averages observed in that quarter.

Stack Tests: EPA took the average of the multiple (usually 3) test runs.

Step 3. Select Lowest Quarter. EPA selected the “lowest quarter” PM rate from the quarters

selected in Step 2.

Step 4. Determine PM of 99th Percentile. For this lowest quarter per Step 3, EPA calculated the

statistical percentile values as observed over the entire quarter. The methodology varied on

whether PM CEMS or stack test data was provided. For PM CEMS, the percentiles were

calculated for all 30-day rolling averages in the quarter. For stack tests, the percentiles were

calculated for the typically 3 test runs.

Personal communication: Sarah Benish to Liz Williams, April 28, 2023. “Data for 2021 was mined

only for the EGUs that showed 2017 or 2019 fPM data above 1.0E-02 lb/MMBtu. We did not mine 2021

PM data for EGUs not expected to be impacted by the proposed fPM limit.”

RTR Memo, page 2.

Ibid.

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Description of EPA Reference PM Database

The results are reported in Appendix B of the Technology Review Memo. The 99 th percentile

rate was chosen as the “base rate,” supposedly to account for variability within the “lowest

quarter.”

EPA does not describe why data selected was restricted to the years 2017, 2019, and 2021. EPA

does not explain why 2021 data was limited to the 1 st and 3rd quarters, 2019 data was limited to

the 3rd and occasionally the 4th quarter, while 2017 data from variable quarters could be utilized.

Of concern is the limited subset of data used for this analysis – Figure 3-2 showed that for 80%

of the units the lowest is selected from only two samples. EPA states “By using the lowest

quarter’s 99th percentile as the baseline, the analyses account for actions individual EGUs have

already taken to improve and maintain PM emissions.” 11 EPA states employing the PM rate at

the 99th percentile –reflecting approximately the highest data within that quarter – remedies any

bias.12

There is no basis for this statement. EPA is assuming that because a unit emitted fPM during a

single quarter at a particular level, the lowest such level must necessarily reflect “actions

individual EGUs have already taken to improve and maintain PM emissions,” and therefore each

EGU must be able to replicate that rate in every quarter going forward, indefinitely. Also, EPA

ignores the unavoidable variability in emission rates: the “actions individual EGUs have already

taken to improve and maintain PM emissions” are not the only factor that determines fPM

emissions rate. The factors that affect fPM rates are numerous and include but are not limited to

the following: coal quality (e.g., chemical composition and ash content) which varies within a

single mine; variation in temperature within an ESP; content of SO 3 and trace constituents that

determine ash electrical resistivity; physical conditions (spacing) of collecting plates and

emitting electrodes; effectiveness of the rapping “hammers” that dislodge collected ash from the

collecting plates; and physical properties of the collected ash layer that define ash reentrainment. Further, boiler operation will influence ESP performance, most notably unit duty

(i.e., relatively stable operating level for a “baseload” unit versus more load changes for an

intermediate unit or a unit operating in peaking mode), operating level, and load “ramp” rate.

Achieving the “least emission” rate observed during a quarter that EPA selected is not

necessarily feasible at other times and under other conditions.

3.2.4 Example Cases

Figure 3-3 presents an example that demonstrate the shortcomings of EPA’s approach. Figure 33 presents PM data from Coronado Generating Station Units 1 and 2 reflecting all operating

quarters from 2017 through 2021. Both the average PM rate and the 99 th percentile from each

quarter are presented for 20 quarters of operation over the 4-year period. Figure 3-3 also

identifies the two samples EPA selected from 2017 Q3 and 2019 Q3 as representative of low

fPM rate, with the latter as the “least” – and the 99th-percentile reporting 0.0086 lbs/MBtu.

Figure 3-3 shows EPA’s two samples do not capture the full character of Coronado operating

duty (with the red dotted line denoting the PM rate selected as representative of the units’

RTR Tech Memo, page 4.

Ibid.

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Description of EPA Reference PM Database

capabilities to control PM). These quarters as selected by EPA are far from representative of unit

operations or capabilities: among 20 quarters for which data are available, the units’ 90th

percentile fPM rates exceed the 0.0086

86 lbs/MBtu rate EPA selected for 16 quarters. Ten out of

20 quarters showed 90 percentile fPM rates exceeded the proposed standard of 0.010 lb/MBtu.

0.025

Mean PM Rate

99th Percentile Rate

PM Emission Rate (lbs/MBtu)

0.020

0.015

EPA Reference

Quarter

EPA Reference

Quarter

0.010

0.005

0.000

17Q1 17Q2 17Q3 17Q4 18Q1 18Q2 18Q3 18Q4 19Q1 19Q2 19Q3 19Q4 20Q1 20Q2 20Q3 20Q4 21Q1 21Q2 21Q3 21Q4

2017

2018

2019

2020

2021

Figure 3-3. Coronado Generating Station: 20 Operating Quarters

Coronado Units 1/2 show how selecting the least PM rate of any quarter, and adopting the 99 th

percentile PM rate within that quarter, does not capture the variability in fP

fPM emission rates,

which are affected by the variability of coal and operating conditions, among others. These

examples demonstrate that EPA used best-case fPM data from both compliance measures

(continuous monitor and performance test data).

Additional examples are presented in the Appendix B to this report.

3.3

Conclusions

•

EPA’s database is sparse and does not fully capture operating duty. Of the 275 units and

approximately 250 monitoring locations, the vast majority – 80

80% - are characterized by

only two samples.

•

Selecting the lowest quarter - “one” of what in most cases are “two” samples - fails to

capture the operating profile of the unit, and presents a serious deficiency in representing

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operations. EPA’s approach of considering the 99th percentile within a quarter is

inadequate to assess variability, particularly that induced by fuel composition, as such

fuel changes are observed over a characteristic time of years and not several months.

•

The use of statistical means within one quarter does not capture the multi-month

variances in coal composition, seasonal load, and process conditions that are not

constrained to 3-month events.

•

An improved, robust database would allow observing variation between– as opposed to

within – operating quarters, to better reflect variations and uncertainties in operating duty

and fuel supply.

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Coal Fleet PM Emissions

4. Coal Fleet PM Emissions Characteristics

Section 4 characterizes

es the coal-fired fleet selected to represent the PM emissions

The emission control technologies on the 275 units projected by EPA to be operating in 2028

present a variety of approaches to lower fPM emission limits – with implications for upgrades

and actions that would be required to meet a revised standard for fPM. This subsection presents

the distribution of control technology by ability to operate below the revised PM limits for the

units in EPA’s database. By necessity, this analysis uses EPA’s database (both for a discussion

of expected or achievable fPM emission rates and the units projected to operate in 2028 and

later), and such use does not represent an endorsement or acceptance of EPA’s approach. As

discussed above, EPA’s analysis of expected/achievable fPM emission rates is inadequate. And

as discussed later in this report, EPA’s selection of units that would continue to operate after

2028 is flawed: it contains multiple errors; and EPA’s post-IRA IPM analysis is inaccurate.

Figure 4-1 is used to present our analysis.

Figure 4-1. Fraction of Units Exceeding Three PM Rates: By Control Technology

Figure 4-1 presents for five control technology configurations the percentage of units that emit

(according to EPA’s chosen “base rate”) above the following PM emission limits: 0.015

lbs/MBtu, 0.010 lbs/MBtu, and 0.006 lbs/MBtu. The control technologies are (a) dry FGD with a

fabric filter, (b) ESP followed

ed by a wet FGD, (c) fabric filter alone (employing low sulfur coal or

multi-unit station-averaging to meet an SO2 limit), (d) wet ESP as the last control device, (e) ESP

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Coal Fleet PM Emissions

alone (employing low sulfur coal or multi-unit station-averaging to meet an SO 2 limit), and (f)

fabric filter followed by a wet FGD.

In Figure 4-1, the proportion of units in the inventory that exceed the contemplated fPM rate is

proportional to the height of the bar; a higher bar implies a greater fraction of units in the

inventory exceed the contemplated fPM rate. Thus:

4.1.1 PM Rate of 0.015 lbs/MBtu

Units in three categories exceed this highest contemplated rate – those with an ESP alone, a dry

FGD followed by a fabric filter, and an ESP followed by a wet FGD. The latter category of

ESP/wet FGD benefits in that actions within the absorber tower – although not designed to

removed fPM – can under some conditions remove fPM. Data describing PM removal via wet

FGD is sparse but suggests 50% removal can be observed.

4.1.2 PM Rate of 0.010 lbs/MBtu

The number of units in each of the three preceding categories exceeding this rate increases –

there is no change for the category of ESP-alone, but the number of units exceeding this rate

more than triple for dry FGD/fabric filter and ESP/wet FGD. No units with fabric filter/wet FGD

or a wet ESP emit at greater than this rate.

4.1.3 PM Rate of 0.006 lbs/MBtu

The number of units exceeding a rate of 0.006 lbs/MBtu increases with this most stringent

contemplated rate. More than 1/3 of the units with ESP/wet FGD and ¼ of ESP- only cannot

meet this rate, with fabric filters either operating with dry FGD (20%) or alone (16%) not

achieving this target. Almost 20% of those with fabric filter/wet FGD units emit greater than this

value.

In conclusion, within six major categories of control technology, units equipped with fabric

filters achieve the lowest PM rates. Units with ESPs – either operating alone or with a wet FGDrepresent the highest fraction of their population that exceed the strictest contemplated rate.

Units with fabric filters – operating alone, or as part of a wet or dry FGD arrangement – are

among the lowest exceeding the strictest contemplated PM rate. As noted previously, this

analysis used EPA’s database (as reflected in Appendix B of the RTR Tech Memo) out of

necessity, and such use does not represent an endorsement or acceptance of EPA’s approach.

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5. CRITIQUE OF COST-EFFECTIVENESS CALCULATIONS

Section 5 addresses the cost effectiveness ($/ton basis) estimated to reduce the PM emission rate

to EPA’s proposed limit of 0.010 lbs/MBtu, and the alternative limit of 0.006 lbs/MBtu. EPA

has conducted this calculation with inputs based on analysis by Sargent & Lundy (S&L) 13 and

Andover Technology Partners (ATP).14 EPA’s results are presented in both Table 3 of the

proposed rule and in Table 7 of the RTR Tech Memo.

This section reviews EPA’s calculation methodology, critiques inputs of the EPA Study, and

presents results of an Industry Study that utilizes realistic costs. Results from EPA’s evaluation

and the Industry Study addressing the 0.010 lbs/MBtu and 0.006 lbs/MBtu PM rates are

compared.

5.1 EPA Evaluation

5.1.1 EPA Study Inputs

The EPA study used both the PM database described in Section 3 and cost and technology

assumptions derived by the above-mentioned S&L and ATP references. As noted in Section 2,

EPA’s sparsely-populated database is inadequate from which to base a revised PM rate that

represents a significant reduction in PM emissions but is achievable in long-term duty.

The analyses by S&L and ATP provide capital cost for three categories of ESP upgrades,

improvements to fabric filter operating and maintenance (O&M) and associated costs, capital

requirement for fabric filter retrofit and associated O&M cost. Most of the analysis is premised

on the costs and PM removal performance of ESP upgrades as defined by S&L. It should be

noted S&L did not provide specific projects with publicly available data as the basis of their

assumptions.

The most significant shortcoming of EPA’s assumptions is low capital estimates for the most

significant ESP upgrade - the “ESP Rebuild” scenario. In contrast to the generalizations of the

S&L memo, Table 5-2 reports publicly documented costs incurred for “ESP Rebuild.” Equally

significant, EPA ignores the inherent variability of fPM and FGD process equipment by not

utilizing a design or operating margin in selecting the value of fPM rates that would require

operator action. This is counter to EPA’s prior acknowledgement of the use of margin in the

initial rulemaking for MATS15 and recent observations as to CEMS calibration. 16 It is also

contrary to basic operation goals: no source operates at the applicable standard; a compliance

PM Incremental Improvement Memo, Project 13527-002, Prepared by Sargent & Lundy, March 2023.

Hereafter S&L PM Improvement Memo.

Analysis of PM Emission Control Costs and Capabilities, Memo from Jim Staudt (Andover

Technology Partners) to Erich Eschmann, March 22, 2023. Hereafter ATP 2023.

Hutson 2012.

Parker 2023.

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margin is always necessary, at least to account for unavoidable variability of performance in the

real world. By ignoring the need for margin, EPA’s evaluation under-predicts the number of

units that would be retrofit with new or upgraded control technology to meet the target rate.

These and other critiques of EPA’s approach are discussed subsequently.

Shortcomings in EPA inputs compromise the results of their analysis. These shortcomings, as

well as other observations, are summarized as follows:

ESP Upgrade. Three categories of ESP upgrade are proposed by EPA. The most significant

shortcoming relates to the “ESP Rebuild” category in which - as described by S&L – additional

plate area is added to the ESP. The addition of collecting surface area will require major changes

to – or demolition and complete rebuilding of – the gas flow confinement that houses the existing

collecting plates. Also, these process changes require specialized labor for fabrication and

installation that may be limited in availability. The costs suggested by S&L (without citation of

references) - $75-100/kW –are low when compared to publicly disclosed costs from similar

projects.

Fabric Filter O&M. Fabric-filter-equipped units that emit greater than 0.010 lbs/MBtu are

assumed to adopt enhanced O&M practices. These enhanced practices consist of (a) upgrading

filter material to higher quality fabrics, such PTFE, and (b) increasing the replacement frequency

so that filters are replaced on a 3-year basis. The cost premium for this action, based on analysis

by ATP, does not consider the additional manpower costs for the more frequent replacement.

Fabric Filter Construction. EPA’s range of capital cost for retrofit of fabric filter technology is

consistent with industry experience.

Design/Compliance Margin. A premise of environmental control system design is accounting for

variability due to many factors, including, for example, variations in fuel composition, operating

load, and process conditions. Such variability is generally addressed by a design/compliance

margin – selecting a target emission rate less than mandated by a standard. The concept of

design/compliance margin is broadly applied in the industry, and was acknowledged in a 2012

EPA memo summarizing the range of margin adopted by various process suppliers, with a

minimum cited as 20-30%.17 EPA did not adopt a design/compliance or operating margin in

selecting fPM emission rates for a revised fPM standard in this evaluation, despite the fact that

elsewhere in the record of this proposal EPA acknowledges a typical “operational target” of 50%

of the limit.18 Because of its assumption of no design/compliance margin whatsoever, EPA

presumes that units that report an operating fPM of 0.010 lbs/MBtu – based on EPA’s sparse

database - require no investment to meet the proposed standard of 0.010 lb/MBtu.

Hutson, N., National Emission Standards for Hazardous Air Pollutants (NESHAP) Analysis

of Control Technology Needs for Revised Proposed Emission Standards for New

Source Coal-fired Electric Utility Steam Generating Units, Memo to Docket No. EPA-HQ-OAR—20090234, November 16, 2012.

Parker 2023.

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Separate from the preceding issues, EPA did not disclose the capacity factors assumed in the

analysis. The capacity factor can be inferred from the tons of PM removed as reported in

Appendix B of the RTR Tech Memo; this requires acquiring heat input and net plant heat rate

from AMPD and EIA data.

5.1.2 EPA Results

Table 5-1 presents results of EPA’s evaluation.

Table 5-1. Summary of EPA Results

EPA Study

Annual Cost $/ton

($M/y)

fPM

(average)

Non-Hg

metallic HAPS

Removed

(tons)

$/ton

non-Hg metallic

HAP

($000s)

Target: 0.010 lbs/MBtu

2,074

77.3-93.2

37,30044,900

6.34

12,200-14,700

Target: 0.006 lbs/MBtu

6,163

633

103

24.7

25,600

Unit

Affected

Tons fPM

Removed

Proposed Limit: 0.010 lbs/MBtu. EPA estimates 20 units in the entire inventory are required to

retrofit some form of ESP upgrade. The number of units with existing fabric filters required to

enhance O&M is not identified, nor is their cost. EPA estimates a range in annual cost to

implement the ESP and fabric filter O&M enhancement of $77.3 to 93.2 M/yr, with the range

determined by the range in cost and performance of each option as described by S&L. 19 This

total annualized cost translates into an average fPM removal cost effectiveness of $37,300 $44,900 per ton of fPM and $12.2M -$14.7 M per ton of total non-Hg metallic HAPs. These

steps remove a total of 2,074 tons of fPM (6.34 tons of total non-Hg metallic HAPs) annually.

EPA did not consider in its analysis the potential impact of the capital cost of major controls

construction or upgrades (i.e., ESP rebuilds for most of the 20 units; new Fabric Filters for the

two Colstrip units) on the viability of the units at which such rebuilds would occur. Appendix

Figure A-1 presents the capital required for each unit as designated by EPA for upgrade –

requiring an investment likely prohibitive for continued operation.

Potential Limit: 0.006 lbs/MBtu. EPA estimates 65 units in the entire inventory are required to

retrofit a fabric filter or deploy enhanced O&M to an existing fabric filter. EPA estimate an

annual cost of $633 M/yr will be incurred, at an average cost effectiveness of $103,000 per ton

S&L PM Improvement Memo.

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of fPM and $25.6 M per ton of total non-Hg metallic HAPs. These steps remove a total of 6,163

tons of fPM (24.7 tons of total non-Hg metallic HAPs) annually.

5.2 Industry Study

The Industry Study alters several assumptions to reflect actual, documented cost data and the

necessity of a design/compliance margin. Table 5-2 presents these results.

5.2.1 Revised Cost Inputs

The modified cost inputs necessary to reflect authentic conditions ESP upgrade and fabric filter

operation are discussed as follows.

ESP Upgrades. The three categories of ESP upgrades are assessed as follows.

Minor Upgrades (Low Cost). Both the cost range and PM removal efficiency for this activity as

estimated by S&L are adopted for this analysis. ESPs requiring Minor Upgrade are assigned a

$17/kW cost to derive an average of 7.5% removal of fPM.

Typical Upgrades (Average Cost). Both the cost range and PM removal efficiency for this

activity as estimated by S&L are adopted for this analysis. ESPs requiring Typical Upgrade are

assigned a $55/kW cost to derive an average of 15% fPM removal.

ESP Rebuild (High Cost). The cost range for this activity as estimated by S&L does not reflect

that reported publicly for four projects that represent the “ESP Rebuild” category. Two projects

were completed at the AES Petersburg station – the complete renovation of the ESPs on Units 1

and 420 for which S&L provided engineering services. The cost for this work has been publicly

reported in 2016-dollar basis. Two additional major ESP upgrades were implemented by

Ameren at the Labadie station unit in 2014 – with costs publicly reported. 21

Table 5-2 summarizes the cost incurred for the four major ESP retrofits, including costs in the

year incurred and escalated (using the Chemical Engineering Process Cost Index) 22 to 2021.

Table 5-1 shows a cost range of $57-209/kW, with 3 of the 4 units incurring a cost exceeding

$100/kW. These costs significantly exceed EPA’s maximum for this range.

State of Indiana – Indian Public Utility Commission, Cause No. 44242, August 14, 2013. See

Appendix, electronic page 50 of 51.

Ameren Missouri Installs Clean Air Equipment at its Labadie Energy Center;

https://ameren.mediaroom.com/news-releases?item=1351

https://www.chemengonline.com/pcihome#:~:text=Since%20its%20introduction%20in%201963,from%20one%20period%20to%20another.

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Table 5-2. ESP Rebuild Costs: Four Documented Cases

Owner/Station

AES/Petersburg

Ameren Labadie

Unit

Basis Year

2016

2014

2021 ($/kW)

117

192

209

Consequently, the range of ESP rebuild costs is adjusted to $57-209/kW, and the mean value of

$133/kW (2021 basis) selected to represent this category of upgrade. 23

FF O&M. A fabric filter O&M cost was derived for existing units, based on the assumption by

S&L that filter material will be upgraded, as well as the frequency of filter replacement. An

increase in cost – reflected as fixed O&M – of $515,000 is estimated for a 500 MW unit. This

cost premium is comprised of higher material cost of $425,000 to upgrade filter material to PTFE

fabric and an additional $90,000 for installation labor. This cost premium as is assigned to

existing units based on generating capacity, and using a conventional “6/10 th” power law.

The revised Industry Study costs are based on (a) gas flow volume treated, (b) surface area of

filter required based on the unit design, (c) unit cost of filter (e.g. $ per ft 2 of cleaning surface),

and (d) replacement rate of filter material. Gas flow treated for each unit was determined using

the quantitative relationships derived by S&L for fabric filter cost evaluation developed for the

IPM model.24 Filter surface area was not defined for each unit as dependent on the specific

air/cloth ratio; rather a fleet air/cloth ratio of 5 – a mean value between conventional and pulsejet design concepts – is selected. The unit cost for fabric was selected (at $4.00/ft 2) per ATP

analysis. Per S&L’s IPM fabric filter costing procedure25 and the EPA-sponsored review of filter

material cost,26 the increase in cost for enhanced O&M is derived. The cost to upgrade material,

accelerate filter replacement (from 5 to 3 years) and supporting cages (from 9 to 6 year) intervals

is estimated as $425K per year for a reference 500 MW unit.

Fabric Filter Capital Cost. EPA proposed a capital cost to retrofit a fabric filter as $150$360/kW. The cost range offered by EPA is consistent with industry experience and is used in

this study.

EPA did not share the incremental operating cost incurred by the retrofit fabric filters. The

Industry Study adopted fixed and variable operating costs from the previously cited S&L fabric

filter cost estimating procedure. For the assigned inputs, the S&L evaluation projects a fixed

Colstrip Units 3 and 4 are equipped with legacy FGD that combine removal of SO2 and PM in a wet

venturi; there is not an ESP option to upgrade. Fabric filer retrofit is the only option; as Colstrip

represents an atypical case the costs are reported in the category of Major ESP upgrade.

IPM Model – Updates to Cost and Performance for APC Technologies: Particulate Control Cost

Development Methodology, Project 13527-001, Sargent & Lundy, April 2017. Hereafter S&L Fabric

Filter 2017.

Ibid.

ATP report.

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O&M of $0.27/kW-yr and a variable operating cost of 0.48 $/MWh. The variable O&M cost is

mostly comprised of filter replacement at the accelerated rate described, and auxiliary power.

Design/Compliance Margin. EPA in two public documents address – and apparently recognize –

the need for design/compliance margin. 27 The use of design/compliance margin was

acknowledged in a 2012 EPA memo summarizing the range adopted by various suppliers, citing

a minimum of 20-30%.28 For the proposed limit of 0.010 lbs/MBtu, the minimum of 20% is

used as a design target for ESP upgrades. Thus, the Industry Study applied ESP upgrade and

fabric filter O&M enhancements to attain 0.008 lbs/MBtu, in lieu of EPA’s target of 0.010

lbs/MBtu. It should be noted this 20% margin is the least of those considered; if the highest

operating margin of 50% suggested by EPA in the record of this rule was used the units requiring

upgrade and the cost would have been even higher.

As noted by EPA, the sole reliable compliance means for a 0.006 lbs/MBtu PM rate is a fabric

filter. Fabric filters historically exhibit low variability due to their inherent design; thus, the

operating margin is slightly relaxed to 0.005 lbs/MBtu. Consequently, the Industry Study

assumed ESP-equipped units emitting greater than 0.005 lbs/MBtu will retrofit a fabric filter to

insure 0.006 lbs/MBtu is attained. Units with existing fabric filters operating at greater than

0.005 lbs/MBtu will adopt improved operation and maintenance, as previously described.

5.2.2 Cost Effectiveness Results

Revised costs from the Industry Study are projected for the proposed fPM limit of 0.010

lbs/MBtu, and the alternative rate of 0.006 lbs/MBtu. Table 5-4 presents these results.

Proposed Limit: 0.010 lbs/MBtu. Results derived in the Industry Study are reported for all three

categories of ESP upgrade in Table 5-1. A total of 26 units are required to upgrade ESPs – 11

deploying Minor, 7 deploying Typical, and 8 deploying Major upgrades. 29 In addition, 11 units

equipped with fabric filters are required to enhance O&M activities. The totality of these actions

each year incur an operating cost of $169.7 M/yr, and remove 2,523 tons of PM.

Hutson, 2012 and Parker, 2023.

Hutson, N., National Emission Standards for Hazardous Air Pollutants (NESHAP) Analysis

of Control Technology Needs for Revised Proposed Emission Standards for New

Source Coal-fired Electric Utility Steam Generating Units, Memo to Docket No. EPA-HQ-OAR—20090234, November 16, 2012. at 1 (discussing mercury); 2 (discussing PM).

The two Colstrip units are equipped with an early generation FGD process which does not include an

ESP, thus the concept of an ESP upgrade is irrelevant. Consistent with EPA’s assumption, the Colstrip

units are assumed to retrofit a fabric filter as the only option to meet a limit of 0.010 lbs/MBtu.

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Table 5-3. Summary of Results: Industry Study

Non-Hg

$/ton

Technology Annual Tons

metallic HAPS

fPM

Cost

(Units

($M/y) Removed average Removed (tons)

Affected)

$/ton

non-Hg metallic HAP

($000s)

Target: 0.010 lbs/MBtu

ESP Minor 20.9

100

(11)

ESP

34.7

282

Typical (7)

ESP Major 113.6

1,665

†

(8)

FF O&M

0.4

475

(11)

Total or

169.7

2,523

Average

Target: 0.006 lbs/MBtu

FF O&M

1.23

652

(23)

FF Retrofit 1,955.4 6,269

(52)

Total or

1,956.6 6,921

Average

209,340

0.31

67,470

122,926

0.86

40,216

68,228

5.1

21,662

869

1.45

284

67.3

7.71

22,000

1,887

2.61

617

311,900

25.13

102,000

282,715

27.74

92,470

† Includes 2 fabric filters retrofit to Colstrip Units 3 and 4. See footnote #23.

The incurred cost per ton varies significantly by ESP upgrade category. For the ESP Minor

upgrade, the average cost effectiveness is approximately $67,470,000 per ton of non-Hg metal

HAP for 0.31 of tons removed ($209,340 per ton of fPM for 100 tons of fPM removed). The

cost-effectiveness cost effectiveness for the ESP Typical upgrade average $40,216,000 per ton of

non-Hg metal HAP for 0.86 tons removed ($122,956 tons of fPM for 282 tons of fPM removed).

The Major upgrade removes the most non-Hg metal HAP – 5.1 tons – (1,665 tons of fPM) for an

average cost effectiveness of $21,662,000 per ton of non-Hg metal HAP ($68,228 per ton of

fPM). The most cost-effective control evaluated is enhanced fabric filter O&M, which removes

1.45 tons of non-Hg metal HAP at a cost-effectiveness of $284,230/ton (475 tons of fPM at a

cost-effectiveness of $869/ton).

These actions cumulatively remove a total of 2,523 tons of PM for an average cost effectiveness

of 22,000,000 per ton of non-Hg metal HAP ($67,262 per ton of fPM) removed, a 50% increase

compared to the cost estimated by EPA.

Appendix Table A-1 reports the units to which the Industry Study assigned ESP upgrades, and

defines the category of upgrade to meet the proposed fPM limit of 0.010 lbs/MBtu.

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Possible Lower Limit: 0.006 lbs/MBtu. The Industry Study projects 52 ESP-equipped units

would be required to retrofit a fabric filter, removing 25.13 tons of non-Hg metal HAP (6,269

tons of fPM) for an average cost effectiveness of $102,000,000 per ton of non-Hg metal HAP

($311,900 per ton of fPM). In addition, 23 existing units equipped with fabric filters would have

to adopt enhanced O&M, removing an additional 2.61 tons of non-Hg metal HAP (652 tons of

fPM) for an average of cost of $617,195/ton of non-Hg metal HAP ($1,887/ton of fPM). These

actions cumulatively remove a total of 27.74 tons of non-Hg metal HAP (6,921 tons of fPM) for

an average cost effectiveness of $92,470,000/ton non-Hg metal HAP ($282,715/ton of fPM)

removed. These costs are a factor of almost three times that projected by EPA.

Appendix Table A-2 reports the units to which the Industry Study assigned fabric filter retrofits

and enhancements of operating and maintenance procedures, to meet the alternative fPM limit of

0.006 lbs/MBtu.

5.3 Conclusions

•

EPA’s cost study is deficient in terms of the number of ESP-equipped units required to

retrofit improvements, the capital cost assigned for the most significant Major ESP

improvement, and estimates of $/ton cost-effectiveness incurred. EPA, by ignoring the

need for a design and operating margin cited in at least two of their publications (Hutson,

2012 and Parker, 2023) under-predicts the number of units that would require retrofits.

•

This study – using the minimum margin cited by EPA in previous publications – projects

a much higher annual cost for capital equipment to meet the proposed 0.010 lbs/MBtu $169.7 M versus EPA’s maximum estimate of $93.3 M. To meet the alternative PM rate

of 0.006 lbs/MBtu, this study projects 50% more units (87 versus 65) must be retrofit

with fabric filters or implement enhanced O&M to an existing fabric filter, incurring an

annual cost of $1.96 B versus EPA’s estimate of 633 M/yr – a three-fold increase.

•

As a consequence, this study predicts the cost effectiveness to meet 0.010 lbs/MBtu will

average $22,000,000 per ton of non-Hg metal HAP removed ($67,262 per ton of fPM), a

50% premium to EPA’s estimate of $12,200,000 - $14,700,000/ton of non-Hg metal HAP

($37,300 – $44,900/ton of fPM) removed. This study projects the cost to meet the

alternative rate of 0.006 lbs/MBtu will average $92,470,000/ton non-Hg metal HAP

($282,715/ton fPM) removed, almost a factor of three higher than EPA’s estimate of

$103,000/ton.

(Page 207 of Total)

391a

USCA Case #24-1119

Document #2058570

Filed: 06/07/2024

Page 82 of 204

Mercury Emissions: Lignite Coals

Section 6 addresses EPA’s proposed action to reduce the limit for Hg for lignite-fired units to 1.2

lbs/TBtu. (the following Section 7 addresses EPA’s proposal to retain the present emission limit

of 1.2 lbs/TBtu for units firing bituminous and subbituminous coals (i.e., non-low rank fuels).)

This section critiques EPA’s basis for proposing the lignite Hg emission rate of 1.2 lbs/MBtu,

while supporting the proposal to retain the existing rate for non-low rank coals.

EPA states the following in support of their proposal regarding lignite:

“…..ash from lignite and subbituminous coals tends to be more alkaline (relative to that from

bituminous coal) due to the lower amounts of sulfur and halogen and the presence of a more

alkaline and reactive (non-glassy) form of calcium in the ash. The natural alkalinity of the

subbituminous and lignite fly ash can effectively neutralize the limited free halogen in the flue

gas and prevent oxidation of the Hg0.

Both lignite and subbituminous coal do contain less sulfur than bituminous coal, but other major

differences in composition exist that EPA does not recognize. These are Hg content and its

variability, the sulfur content, and the alkalinity of inorganic matter. EPA’s failure to recognize

these differences manifests itself as (a) assuming activated carbon sorbent effectiveness observed

on subbituminous coal (specifically PRB) extends to lignite, and (b) ignoring variability in Hg

content, as well as the role of sulfur trioxide (SO3), which compromises achieving 90%+ Hg

removal as required to attain 1.2 lbs/TBtu.

Fuel properties are described separately for the North Dakota and Gulf Coast (Texas and

Mississippi) lignite mines.

6.1 North Dakota Mines and Generating Units

Figures 6-1 to 6-4 present data provided by lignite suppliers from North Dakota mines that

describe the variability for Hg and other constituents key to Hg removal. These figures present

data as a “box and whisker” plot, which portrays the mean value, the 25 th and 75th percentile of

the observed data, and the near-minimum (5%) and near-maximum (95%) extremities. Figure 61 shows the variability of Hg and Figure 6-2 the variability of sulfur content. Figure 6-3 shows

variability of fuel alkalinity compared to sulfur content – specifically, the ratio of calcium (Ca)

and sodium (Na) to sulfur – i.e., the (Ca + Na)/S metric.

(Page 208 of Total)

392a

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