EPA Regulation:

Utility MACT Proposal

Jennifer Macedonia

March 24, 2011
What is Utility MACT?

 Proposed EPA regulation for public comment

 Controls power plant smokestack emissions 

 New and existing facilities 

 Coal & oil-fired

 Hazardous air pollutants (HAP)/air toxics:

 metals (e.g., mercury, arsenic, chromium, nickel)

 acid gases (e.g., hydrogen chloride (HCl))

 organic air toxics (dioxin, furans)

 MACT= Maximum Achievable Control Technology

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Why did EPA propose MACT?

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Court-ordered deadlines for Utility MACT 

Proposed Rule: March 16, 2011 Final Rule: November 16, 2011

Thus, Act requires MACT emission limits

First EPA attempt (2005 CAMR) thrown 

out by court in 2008

Court disagreed w/EPA “delisting” power 

sector from toxic provisions

1990 Clean Air Act required EPA study on power plant toxics

determine if “appropriate and 

necessary” to regulate In 2000, EPA determined: yes 
What is required?

 Strict “command & control” MACT emission limits

 Mercury, Particulate Matter (PM), HCl (acid gas)

 Work practice standards (good combustion)

 Dioxin/furans

 Some existing units comply w/current controls

 For some, required installations include:

 Activated Carbon Injection (ACI)

 Upgraded particulate controls

 Scrubber or Dry Sorbent Injection (DSI)

 Some units will retire rather than invest in controls

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HCl: Hydrogen Chloride
MACT Flexibility

 Facility-wide averaging

 Could allow some units to exceed MACT limits

 Weaker limits for 

 Existing units, compared to new

 Lignite, compared to other coal

 Pet coke, compared to oil

 Alternative emission standards (less monitoring)

 Exempt gas units that infrequently burn oil

 4

th compliance year, if needed for controls

subcategories

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Health Based Emission Limits

 Clean Air Act requires MACT for air toxics

 Limit at least as stringent as performance of top 12% 

 EPA discretion for less stringent alternative

 Health Based Emission Limit CAA §112(d)(4)

 Must ensure margin of safety above health standard

 In past, EPA exempted other sectors from HCl MACT

 But EPA did not use health-based limit for utilities

 Power plants are largest human source of many toxics

 Lack of info on respiratory irritant cumulative impacts 

 Environmental effects of acid gases

 Significant health co-benefits of MACT limit

MACT: Maximum Achievable Control Technology

HCl: Hydrogen Chloride

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MACT Costs and Benefits

Costs Health 

Benefits

Benefits are primarily 

from co-benefit particle 

reductions

Source: EPA projected costs and benefits

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Potential Impacts on Jobs

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“EPA finds that more jobs will be created in the air 

pollution control technology production field than may 

be lost as the result of compliance with these proposed 

rules”

 Temporary gains during construction phase

 Long term impacts harder to discern
MACT Emission Reductions

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Hg

• 78% reduction of mercury

HCl

• 91% reduction of acid gas

PM

• 30% reduction of particulate matter

SO2

• 55% reduction of sulfur dioxide

CO2

• 3% reduction of carbon dioxide

EPA projected % reduction from affected units, compared to their baseline reference case
Electric Reliability

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 With proper planning and coordination

 Retirements and retrofits should be manageable

 But poor planning and stacking up retrofits in the last 

year/maintenance season could lead to issues

EPA: “To the extent that isolated issues remain concerning the 

availability of electricity in some more remote parts of the 

country, we believe that EPA has the ability to work with 

companies making good faith efforts to comply with the 

standards so that consumers in those areas are not adversely 

affected.”
MACT Retirement Projections

 EPA: MACT retires <1% national capacity (10 GW)

 On top of 27 GW expected to retire regardless

 Includes Transport Rule in baseline 

 but not future rules for ash, cooling water, NOX, or GHGs

 Other studies

 Assume all units install most expensive technologies

 EPA allows lower cost alternative technologies to comply

 Include worst case estimates of other rules 

 Ash disposal, cooling water, future NOX, and GHGs

 Some studies include baseline retirements projected 

regardless of EPA regulation

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What Replaces Retired Coal?

 Retired: small, inefficient generators that do not 

operate near full capacity

 Extra capacity in existing fleet to take up slack

 Capacity additions, regardless of MACT

 25-36 GW renewables (mostly wind)

 1-3 GW gas

 As a result of MACT, EPA projects:

 83 MW of new renewables built by 2015

 No new gas, nuclear, coal (incremental)

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MACT: Maximum Achievable Control Technology

GW: Gigawatts
Retirements vs. Retrofits

Retirements

Control Installations

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Wet scrubber DSI Baghouse ACI SCR Ash Cooling Tower Alternate 

Water

Relative Capital Cost $/kW

Retrofit Capital Costs

300 MW

500 MW

700 MW

Pollution Control Technologies

Pollutant/Issue Control Technologies

Acid Gases + Sulfur Dioxide (SO2) Wet or dry scrubber 

or Dry Sorbent Injection (DSI) + Particulate Controls

Metallic toxics/Particulate Matter (PM) Baghouse/Fabric Filter or ESP

Mercury Activated Carbon Injection (ACI) + Particulate Controls

or wet scrubber + SCR

NOX Selective Catalytic Reduction (SCR)

or SNCR, low-NOx burners, etc

Coal ash Dry ash handling + ash pond/pit liners, etc

Cooling Water Intake Screens, barrier nets, low velocity caps, etc

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*

* Dry scrubber cost 10-15% less 
Wet scrubber DSI Baghouse ACI SCR Ash Cooling Tower Alternate 

Water

Relative Capital Cost

Retrofit Capital Costs

300 MW

500 MW

700 MW

Relative Costs of Control

MACT Controls

or

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Pollutant/Issue Control Technologies

Acid Gases + Sulfur Dioxide (SO2) Wet or dry scrubber 

or Dry Sorbent Injection (DSI) + Particulate Controls

Metallic toxics/Particulate Matter (PM) Baghouse/Fabric Filter or ESP

Mercury Activated Carbon Injection (ACI) + Particulate Controls

or wet scrubber + SCR

NOX Selective Catalytic Reduction (SCR)

or SNCR, low-NOx burners, etc

Coal ash Dry ash handling + ash pond/pit liners, etc

Cooling Water Intake Screens, barrier nets, low velocity caps, etc

or Cooling Tower
Compliance with Acid Gas Limits

Analysis based on EPA data files from MACT IPM runs

* Particulate control upgrades/retrofits also required with DSI and to comply with MACT PM limit 

MACT 

Retrofits 

GWs Design + 

construction 

time1

DSI 65 12 months

Dry FGD 24 24 months

Wet FGD 4 36 months

Existing 

Scrubbers

Retrofits 

regardless 

of MACT

Add Wet 

Scrubber

Add Dry 

Scrubber Add DSI

Acid Gases

*

EPA Projected Retrofits for Acid 

Gases

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1

Institute of Clean Air Companies, Letter to Senator Carper, November 3, 2010
Annual Control Costs

wet scrubber DSI Baghouse ACI

Relative Levelized Cost

Annualized Costs of Utility MACT Retrofits

300 MW

500 MW

700 MW

 Scrubber investment much higher than DSI

 But on-going cost of DSI brings annual cost closer to scrubber

 DSI best suited for certain fuels & smaller, less frequently run units

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Other Rules For Power Sector

 Air

 Transport Rule: SO2 and NOXcaps

 Transport Rule II: tighter caps

 GHG NSPS

 Water

 Cooling Water Intake 316(b)

 Waste

 Coal Ash – Coal Combustion Residuals

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Power Sector EPA Rules

2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025

AIR

Transport Rule 

Utility MACT 

Transport Rule II

GHG NSPS

WATER

316(b) Intake 

WASTE

Coal waste/ash

Phase I Phase II Caps

National Emission Standards

pending final rule

5 yr phase-in, pending rule 

new units existing units: pending EPA/state rulemakings

Estimated Compliance Dates for Upcoming Regulations

pending revised NAAQS

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Also Proposed: Revised NSPS

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Revised new source emission limits 

• New Source Performance Standards (NSPS)

• For conventional pollutants: PM, SO2, NOX

Responds to past litigation

• EPA sued on 2006 NSPS amendments

• 2009 voluntary remand
21 www.BipartisanPolicy.org

Jennifer Macedonia

jmacedonia@bipartisanpolicy.org