[Federal Register Volume 80, Number 205 (Friday, October 23, 2015)]
[Rules and Regulations]
[Pages 64509-64660]
[FR Doc No: 2015-22837]

Vol. 80

Friday,

No. 205

October 23, 2015

Part II

Environmental Protection Agency

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40 CFR Parts 60, 70, 71, et al.

 Standards of Performance for Greenhouse Gas Emissions From New,
Modified, and Reconstructed Stationary Sources: Electric Utility
Generating Units; Final Rule

Federal Register / Vol. 80 , No. 205 / Friday, October 23, 2015 /
Rules and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60, 70, 71, and 98

[EPA-HQ-OAR-2013-0495; EPA-HQ-OAR-2013-0603; FRL-9930-66-OAR]
RIN 2060-AQ91

Standards of Performance for Greenhouse Gas Emissions From New,
Modified, and Reconstructed Stationary Sources: Electric Utility
Generating Units

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is finalizing new
source performance standards (NSPS) under Clean Air Act (CAA) section
111(b) that, for the first time, will establish standards for emissions
of carbon dioxide (CO2) for newly constructed, modified, and
reconstructed affected fossil fuel-fired electric utility generating
units (EGUs). This action establishes separate standards of performance
for fossil fuel-fired electric utility steam generating units and
fossil fuel-fired stationary combustion turbines. This action also
addresses related permitting and reporting issues. In a separate
action, under CAA section 111(d), the EPA is issuing final emission
guidelines for states to use in developing plans to limit
CO2 emissions from existing fossil fuel-fired EGUs.

DATES: This final rule is effective on October 23, 2015. The
incorporation by reference of certain publications listed in the rule
is approved by the Director of the Federal Register as of October 23,
2015.

ADDRESSES: The EPA has established dockets for this action under Docket
ID No. EPA-HQ-OAR-2013-0495 (Standards of Performance for Greenhouse
Gas Emissions from New Stationary Sources: Electric Utility Generating
Units) and Docket ID No. EPA-HQ-OAR-2013-0603 (Carbon Pollution
Standards for Modified and Reconstructed Stationary Sources: Electric
Utility Generating Units). All documents in the dockets are listed on
the www.regulations.gov Web site. Although listed in the index, some
information is not publicly available, e.g., Confidential Business
Information or other information whose disclosure is restricted by
statute. Certain other material, such as copyrighted material, will be
publicly available only in hard copy. Publicly available docket
materials are available either electronically in www.regulations.gov or
in hard copy at the EPA Docket Center (EPA/DC), Room 3334, EPA WJC West
Building, 1301 Constitution Ave. NW., Washington, DC. The Public
Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through
Friday, excluding legal holidays. The telephone number for the Public
Reading Room is<PHONE_NUMBER>, and the telephone number for the Air
Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Dr. Nick Hutson, Energy Strategies
Group, Sector Policies and Programs Division (D243-01), U.S. EPA,
Research Triangle Park, NC 27711; telephone number<PHONE_NUMBER>,
facsimile number<PHONE_NUMBER>; email address<EMAIL_ADDRESS>or
Mr. Christian Fellner, Energy Strategies Group, Sector Policies and
Programs Division (D243-01), U.S. EPA, Research Triangle Park, NC
27711; telephone number<PHONE_NUMBER>, facsimile number (919) 541-
5450; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Acronyms. A number of acronyms and chemical
symbols are used in this preamble. While this may not be an exhaustive
list, to ease the reading of this preamble and for reference purposes,
the following terms and acronyms are defined as follows:

AB Assembly Bill
AEO Annual Energy Outlook
AEP American Electric Power
ANSI American National Standards Institute
ASME American Society of Mechanical Engineers
BACT Best Available Control Technology
BDT Best Demonstrated Technology
BSER Best System of Emission Reduction
Btu/kWh British Thermal Units per Kilowatt-hour
Btu/lb British Thermal Units per Pound
CAA Clean Air Act
CAIR Clean Air Interstate Rule
CBI Confidential Business Information
CCS Carbon Capture and Storage (or Sequestration)
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CEMS Continuous Emissions Monitoring System
CFB Circulating Fluidized Bed
CH4 Methane
CHP Combined Heat and Power
CO2 Carbon Dioxide
CSAPR Cross-State Air Pollution Rule
DOE Department of Energy
DOT Department of Transportation
ECMPS Emissions Collection and Monitoring Plan System
EERS Energy Efficiency Resource Standards
EGU Electric Generating Unit
EIA Energy Information Administration
EO Executive Order
EOR Enhanced Oil Recovery
EPA Environmental Protection Agency
FB Fluidized Bed
FGD Flue Gas Desulfurization
FOAK First-of-a-kind
FR Federal Register
GHG Greenhouse Gas
GHGRP Greenhouse Gas Reporting Program
GPM Gallons per Minute
GS Geologic Sequestration
GW Gigawatts
H2 Hydrogen Gas
HAP Hazardous Air Pollutant
HFC Hydrofluorocarbon
HRSG Heat Recovery Steam Generator
IGCC Integrated Gasification Combined Cycle
IPCC Intergovernmental Panel on Climate Change
IPM Integrated Planning Model
IRPs Integrated Resource Plans
kg/MWh Kilogram per Megawatt-hour
kJ/kg Kilojoules per Kilogram
kWh Kilowatt-hour
lb CO2/MMBtu Pounds of CO2 per Million British
Thermal Unit
lb CO2/MWh Pounds of CO2 per Megawatt-hour
lb CO2/yr Pounds of CO2 per Year
lb/lb-mole Pounds per Pound-Mole
LCOE Levelized Cost of Electricity
MATS Mercury and Air Toxic Standards
MMBtu/hr Million British Thermal Units per Hour
MRV Monitoring, Reporting, and Verification
MW Megawatt
MWe Megawatt Electrical
MWh Megawatt-hour
MWh-g Megawatt-hour gross
MWh-n Megawatt-hour net
N2O Nitrous Oxide
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NAS National Academy of Sciences
NETL National Energy Technology Laboratory
NGCC Natural Gas Combined Cycle
NOAK n\th\-of-a-kind
NRC National Research Council
NSPS New Source Performance Standards
NSR New Source Review
NTTAA National Technology Transfer and Advancement Act
O2 Oxygen Gas
OMB Office of Management and Budget
PC Pulverized Coal
PFC Perfluorocarbon
PM Particulate Matter
PM2.5 Fine Particulate Matter
PRA Paperwork Reduction Act
PSD Prevention of Significant Deterioration
PUC Public Utilities Commission
RCRA Resource Conservation and Recovery Act
RFA Regulatory Flexibility Act
RGGI Regional Greenhouse Gas Initiative
RIA Regulatory Impact Analysis
RPS Renewable Portfolio Standard
RTC Response to Comments
RTP Response to Petitions
SBA Small Business Administration
SCC Social Cost of Carbon
SCR Selective Catalytic Reduction
SCPC Supercritical Pulverized Coal
SDWA Safe Drinking Water Act
SF6 Sulfur Hexafluoride
SIP State Implementation Plan

SNCR Selective Non-Catalytic Reduction
SO2 Sulfur Dioxide
SSM Startup, Shutdown, and Malfunction
Tg Teragram (one trillion (10\12\) grams)
Tpy Tons per Year
TSD Technical Support Document
TTN Technology Transfer Network
UIC Underground Injection Control
UMRA Unfunded Mandates Reform Act of 1995
U.S. United States
USDW Underground Source of Drinking Water
USGCRP U.S. Global Change Research Program
VCS Voluntary Consensus Standard
WGS Water Gas Shift
WWW World Wide Web

    Organization of This Document. The information presented in this
preamble is organized as follows:

I. General Information
    A. Executive Summary
    B. Does this action apply to me?
    C. Where can I get a copy of this document?
    D. Judicial Review
    E. How is this preamble organized?
II. Background
    A. Climate Change Impacts From GHG Emissions
    B. GHG Emissions From Fossil Fuel-Fired EGUs
    C. The Utility Power Sector
    D. Statutory Background
    E. Regulatory Background
    F. Development of Carbon Pollution Standards for Fossil Fuel-
Fired Electric Utility Generating Units
    G. Stakeholder Engagement and Public Comments on the Proposals
III. Regulatory Authority, Affected EGUs and Their Standards, and
Legal Requirements
    A. Authority To Regulate Carbon Dioxide From Fossil Fuel-Fired
EGUs
    B. Treatment of Categories and Codification in the Code of
Federal Regulations
    C. Affected Units
    D. Units Not Covered by This Final Rule
    E. Coal Refuse
    F. Format of the Output-Based Standard
    G. CO2 Emissions Only
    H. Legal Requirements for Establishing Emission Standards
    I. Severability
    J. Certain Projects Under Development
IV. Summary of Final Standards for Newly Constructed, Modified, and
Reconstructed Fossil Fuel-Fired Electric Utility Steam Generating
Units
    A. Applicability Requirements and Rationale
    B. Best System of Emission Reduction
    C. Final Standards of Performance
V. Rationale for Final Standards for Newly Constructed Fossil Fuel-
Fired Electric Utility Steam Generating Units
    A. Factors Considered in Determining the BSER
    B. Highly Efficient SCPC EGU Implementing Partial CCS as the
BSER for Newly Constructed Steam Generating Units
    C. Rationale for the Final Emission Standards
    D. Post-Combustion Carbon Capture
    E. Pre-Combustion Carbon Capture
    F. Vendor Guarantees, Industry Statements, Academic Literature,
and Commercial Availability
    G. Response to Key Comments on the Adequacy of the Technical
Feasibility Demonstration
    H. Consideration of Costs
    I. Key Comments Regarding the EPA's Consideration of Costs
    J. Achievability of the Final Standards
    K. Emission Reductions Utilizing Partial CCS
    L. Further Development and Deployment of CCS Technology
    M. Technical and Geographic Aspects of Disposition of Captured
CO2
    N. Final Requirements for Disposition of Captured CO2
    O. Non-Air Quality Impacts and Energy Requirements
    P. Options That Were Considered by the EPA But Were Ultimately
Not Determined to Be the BSER
    Q. Summary
VI. Rationale for Final Standards for Modified Fossil Fuel-Fired
Electric Utility Steam Generating Units
    A. Rationale for Final Applicability Criteria for Modified Steam
Generating Units
    B. Identification of the Best System of Emission Reduction
    C. BSER Criteria
VII. Rationale for Final Standards for Reconstructed Fossil Fuel-
Fired Electric Utility Steam Generating Units
    A. Rationale for Final Applicability Criteria for Reconstructed
Sources
    B. Identification of the Best System of Emission Reduction
VIII. Summary of Final Standards for Newly Constructed and
Reconstructed Stationary Combustion Turbines
    A. Applicability Requirements
    B. Best System of Emission Reduction
    C. Final Emission Standards
    D. Significant Differences Between Proposed and Final Combustion
Turbine Provisions
IX. Rationale for Final Standards for Newly Constructed and
Reconstructed Stationary Combustion Turbines
    A. Applicability
    B. Subcategories
    C. Identification of the Best System of Emission Reduction
    D. Achievability of the Final Standards
X. Summary of Other Final Requirements for Newly Constructed,
Modified, and Reconstructed Fossil Fuel-Fired Electric Utility Steam
Generating Units and Stationary Combustion Turbines
    A. Startup, Shutdown, and Malfunction Requirements
    B. Continuous Monitoring Requirements
    C. Emissions Performance Testing Requirements
    D. Continuous Compliance Requirements
    E. Notification, Recordkeeping, and Reporting Requirements
XI. Consistency Between BSER Determinations for This Rule and the
Rule for Existing EGUs
    A. Newly Constructed Steam Generating Units
    B. New Combustion Turbines
    C. Modified and Reconstructed Steam and NGCC Units
XII. Interactions With Other EPA Programs and Rules
    A. Overview
    B. Applicability of Tailoring Rule Thresholds Under the PSD
Program
    C. Implications for BACT Determinations Under PSD
    D. Implications for Title V Program
    E. Implications for Title V Fee Requirements for GHGs
    F. Interactions With Other EPA Rules
XIII. Impacts of This Action
    A. What are the air impacts?
    B. Endangered Species Act
    C. What are the energy impacts?
    D. What are the water and solid waste impacts?
    E. What are the compliance costs?
    F. What are the economic and employment impacts?
    G. What are the benefits of the final standards?
XIV. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act (CRA)
XV. Withdrawal of Proposed Standards for Certain Modified Sources
XVI. Statutory Authority

I. General Information

A. Executive Summary

1. Purpose of the Regulatory Action
    In this final action the EPA is establishing standards that limit
greenhouse gas (GHG) emissions from newly constructed, modified, and
reconstructed fossil fuel-fired electric utility steam generating units
and stationary combustion turbines, following the issuance of proposals
for such standards and an accompanying Notice of Data Availability.
    On June 25, 2013, in conjunction with the announcement of his
Climate Action Plan (CAP), President Obama issued a

Presidential Memorandum directing the EPA to issue a proposal to
address carbon pollution from new power plants by September 30, 2013,
and to issue ``standards, regulations, or guidelines, as appropriate,
which address carbon pollution from modified, reconstructed, and
existing power plants.'' Pursuant to authority in section 111(b) of the
CAA, on September 20, 2013, the EPA issued proposed carbon pollution
standards for newly constructed fossil fuel-fired power plants. The
proposal was published in the Federal Register on January 8, 2014 (79
FR 1430; ``January 2014 proposal'').\1\ In that proposal, the EPA
proposed to limit emissions of CO2 from newly constructed
fossil fuel-fired electric utility steam generating units and newly
constructed natural gas-fired stationary combustion turbines.
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    \1\ The EPA previously proposed performance standards for newly
reconstructed fossil fuel-fired EGUs in April 2012 (77 FR 22392). In
that action, the EPA proposed standards for steam generating units
and natural gas-fired combustion turbines based on a single Best
System of Emission Reduction determination. On January 8, 2014, the
EPA withdrew that proposal (79 FR 1352).
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    The EPA subsequently issued a Notice of Data Availability (NODA) in
which the EPA solicited comment on its initial interpretation of
provisions in the Energy Policy Act of 2005 (EPAct05) and associated
provisions in the Internal Revenue Code (IRC) and also solicited
comment on a companion Technical Support Document (TSD) that addressed
these provisions' relationship to the factual record supporting the
proposed rule. 79 FR 10750 (February 26, 2014).
    On June 2, 2014, the EPA proposed standards of performance, also
pursuant to CAA section 111(b), to limit emissions of CO2
from modified and reconstructed fossil fuel-fired electric utility
steam generating units and natural gas-fired stationary combustion
turbines. 79 FR 34960 (June 18, 2014) (``June 2014 proposal'').
Specifically, the EPA proposed standards of performance for: (1)
Modified fossil fuel-fired steam generating units, (2) modified natural
gas-fired stationary combustion turbines, (3) reconstructed fossil
fuel-fired steam generating units, and (4) reconstructed natural gas-
fired stationary combustion turbines.
    In this action, the EPA is issuing final standards of performance
to limit emissions of GHG pollution manifested as CO2 from
newly constructed, modified, and reconstructed fossil fuel-fired
electric utility steam generating units (i.e., utility boilers and
integrated gasification combined cycle (IGCC) units) and from newly
constructed and reconstructed stationary combustion turbines.
Consistent with the requirements of CAA section 111(b), these standards
reflect the degree of emission limitation achievable through the
application of the best system of emission reduction (BSER) that the
EPA has determined has been adequately demonstrated for each type of
unit. These final standards are codified in 40 CFR part 60, subpart
TTTT, a new subpart specifically created for CAA 111(b) standards of
performance for GHG emissions from fossil fuel-fired EGUs.
    In a separate action that affects the same source category, the EPA
is issuing final emission guidelines under CAA section 111(d) for
states to use in developing plans to limit CO2 emissions
from existing fossil fuel-fired EGUs. Pursuant to those guidelines,
states must submit plans to the EPA following a schedule set by the
guidelines.
    The EPA received numerous comments and conducted extensive outreach
to stakeholders for this rulemaking. After careful consideration of
public comments and input from a variety of stakeholders, the final
standards of performance in this action reflect certain changes from
the proposals. Comments considered include written comments that were
submitted during the public comment period and oral testimony provided
during the public hearing for the proposed standards.
2. Summary of Major Provisions and Changes to the Proposed Standards
    The BSER determinations and final standards of performance for
affected newly constructed, modified, and reconstructed EGUs are
summarized in Table 1 and discussed in more detail below. The final
standards for new, modified, and reconstructed EGUs apply to sources
that commenced construction--or modification or reconstruction, as
appropriate--on or after the date of publication of corresponding
proposed standards.\2\ The final standards for newly constructed fossil
fuel-fired EGUs apply to those sources that commenced construction on
or after the date of publication of the proposed standards, January 8,
2014. The final standards for modified and reconstructed fossil fuel-
fired EGUs apply to those sources that modify or reconstruct on or
after the date of publication of the proposed standards, June 18, 2014.
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    \2\ See CAA section 111(a)(2).

     Table 1--Summary of BSER and Final Standards for Affected EGUs
------------------------------------------------------------------------
                                                      Final standards of
          Affected EGUs                  BSER             performance
------------------------------------------------------------------------
Newly Constructed Fossil Fuel-    Efficient new       1,400 lb CO2/MWh-
 Fired Steam Generating Units.     supercritical       g.
                                   pulverized coal
                                   (SCPC) utility
                                   boiler
                                   implementing
                                   partial carbon
                                   capture and
                                   storage (CCS).
Modified Fossil Fuel-Fired Steam  Most efficient      Sources making
 Generating Units.                 generation at the   modifications
                                   affected EGU        resulting in an
                                   achievable          increase in CO2
                                   through a           hourly emissions
                                   combination of      of more than 10
                                   best operating      percent are
                                   practices and       required to meet
                                   equipment           a unit-specific
                                   upgrades.           emission limit
                                                       determined by the
                                                       unit's best
                                                       historical annual
                                                       CO2 emission rate
                                                       (from 2002 to the
                                                       date of the
                                                       modification);
                                                       the emission
                                                       limit will be no
                                                       more stringent
                                                       than:
                                                      1. 1,800 lb CO2/
                                                       MWh-g for sources
                                                       with heat input
                                                       >2,000 MMBtu/h.
                                                      2. 2,000 lb CO2/
                                                       MWh-g for sources
                                                       with heat input
                                                       <=2,000 MMBtu/h.
Reconstructed Fossil Fuel-Fired   Most efficient      1. Sources with
 Steam Generating Units.           generating          heat input >2,000
                                   technology at the   MMBtu/h are
                                   affected source     required to meet
                                   (supercritical      an emission limit
                                   steam conditions    of 1,800 lb CO2/
                                   for the larger;     MWh-g.
                                   and subcritical    2. Sources with
                                   conditions for      heat input
                                   the smaller).       <=2,000 MMBtu/h
                                                       are required to
                                                       meet an emission
                                                       limit of 2,000 lb
                                                       CO2/MWh-g.

Newly Constructed and             Efficient NGCC      1. 1,000 lb CO2/
 Reconstructed Fossil Fuel-Fired   technology for      MWh-g or 1,030 lb
 Stationary Combustion Turbines.   base load natural   CO2/MWh-n for
                                   gas-fired units     base load natural
                                   and clean fuels     gas-fired units.
                                   for non-base load  2. 120 lb CO2/
                                   and multi-fuel-     MMBtu for non-
                                   fired units.\3\     base load natural
                                                       gas-fired units.
                                                      3. 120 to 160 lb
                                                       CO2/MMBtu for
                                                       multi-fuel-fired
                                                       units.\4\
------------------------------------------------------------------------

a. Fossil Fuel-Fired Electric Utility Steam Generating Units
    This action establishes standards of performance for newly
constructed fossil fuel-fired steam generating units \5\ based on the
performance of a new highly efficient SCPC EGU implementing post-
combustion partial carbon capture and storage (CCS) technology, which
the EPA determines to be the BSER for these sources. After
consideration of a wide range of comments, technical input received on
the availability, technical feasibility, and cost of CCS
implementation, and publicly available information about projects that
are implementing or planning to implement CCS, the EPA confirms its
proposed determination that CCS technology is available and technically
feasible to implement at fossil fuel-fired steam generating units.
However, the EPA's final standard reflects the consideration of
legitimate concerns regarding the cost to implement available CCS
technology on a new steam generating unit. Accordingly, the EPA is
finalizing an emission standard for newly constructed fossil fuel-fired
steam generating units at 1,400 lb CO2/MWh-g, a level that
is less stringent than the proposed limitation of 1,100 lb
CO2/MWh-g. This final standard reflects our identification
of the BSER for such units to be a lower level of partial CCS than we
identified as the basis of the proposed standards--one that we conclude
better represents the requirement that the BSER be implementable at
reasonable cost.
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    \3\ The term ``multi-fuel-fired'' refers to a stationary
combustion turbine that is physically connected to a natural gas
pipeline, but that burns a fuel other than natural gas for 10
percent or more of the unit's heat input capacity during the 12-
operating-month compliance period.
    \4\ The emission standard for combustion turbines co-firing
natural gas with other fuels shall be determined at the end of each
operating month based on the amount of co-fired natural gas. Units
only burning natural gas with other fuels with a relatively
consistent chemical composition and an emission factor of 160 lb
CO2/MMBtu or less (e.g., natural gas, distillate oil,
etc.) only need to maintain records of the fuels burned at the unit
to demonstrate compliance. Units burning fuels with variable
chemical composition or with an emission factor greater than 160 lb
CO2/MMBtu (e.g., residual oil) must conduct periodic fuel
sampling and testing to determine the overall CO2
emission rate.
    \5\ Also referred to as just ``steam generating units'' or as
``utility boilers and IGCC units''. These are units that are covered
under 40 CFR part 60, subpart Da for criteria pollutants.
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    The EPA proposed that the BSER for newly constructed steam
generating EGUs was highly efficient new generating technology (i.e., a
supercritical utility boiler or IGCC unit) implementing partial CCS
technology to achieve CO2 emission reductions resulting in
an emission limit of 1,100 lb CO2/MWh-g.\6\
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    \6\ Using the most recent data on partial capture rates to meet
an emission standard of 1,100 lb CO2/MWh-gross, about 35
percent capture would be required at an SCPC unit and about 22
percent capture would be required at an IGCC unit.
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    The BSER for newly constructed steam generating EGUs in the final
rule is very similar to that in the January 2014 proposal. In this
final action, the EPA finds that a highly efficient new supercritical
pulverized coal (SCPC) utility boiler EGU implementing partial CCS to
the degree necessary to achieve an emission of 1,400 lb CO2/
MWh-g is the BSER. Contrary to the January 2014 proposal, the EPA finds
that IGCC technology--either with natural gas co-firing or implementing
partial CCS--is not part of the BSER, but recognizes that IGCC
technology can serve as an alternative method of compliance.
    The EPA finds that a highly efficient SCPC implementing partial CCS
is the BSER because CCS technology has been demonstrated to be
technically feasible and is in use or under construction in various
industrial sectors, including the power generation sector. For example,
the Boundary Dam Unit #3 CCS project in Saskatchewan, Canada is a full-
scale, fully integrated CCS project that is currently operating and is
designed to capture more than 90 percent of the CO2 from the
lignite-fired boiler. A newly constructed, highly efficient SCPC
utility boiler burning bituminous coal will be able to meet this final
standard of performance by capturing and storing approximately 16
percent of the CO2 produced from the facility. A newly
constructed, highly efficient SCPC utility boiler burning subbituminous
coal or dried lignite \7\ will be able to meet this final standard of
performance by capturing and storing approximately 23 percent of the
CO2 produced from the facility. As an alternative compliance
option, utilities and project developers will also be able to construct
new steam generating units (both utility boilers and IGCC units) that
meet the final standard of performance by co-firing with natural gas.
This final standard of performance for newly constructed fossil fuel-
fired steam generating units provides a clear and achievable path
forward for the construction of such sources while addressing GHG
emissions and supporting technological innovation. The standard of
1,400 lb CO2/MWh-g is achievable by fossil fuel-fired steam
generating units for all fuel types, under a wide range of conditions,
and throughout the United States.
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    \7\ For a summary of lignite drying technologies, see ``Techno-
economics of modern pre-drying technologies for lignite-fired power
plants'' available at www.iea-coal.org.uk/documents/83436/9095/
Techno-economics-of-modern-pre-drying-technologies-for-lignite-
fired-power-plants,-CCC/241; ``Drying the lignite prior to
combustion in the boiler is thus an effective way to increase the
thermal efficiencies and reduce the CO2 emissions from
lignite-fired power plants.''
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    We note that identifying a highly efficient new SCPC EGU
implementing partial CCS as the BSER provides a path forward for new
fossil fuel-fired steam generation in the current market context.
Numerous studies have predicted that few new fossil fuel-fired steam
generating units will be constructed in the future. These analyses
identify a range of factors unrelated to this rulemaking, including low
electricity demand growth, highly competitive natural gas prices, and
increases in the supply of renewable energy. The EPA recognizes that,
in certain circumstances, there may be interest in building fossil
fuel-fired steam generating units despite these market conditions. In
particular, utilities and project developers may build new fossil fuel-
fired steam generating EGUs in order to achieve or maintain fuel
diversity within generating fleets, as a hedge against the possibility
of natural gas prices far exceeding projections, or to co-produce both
power and chemicals, including capturing CO2 for use in
enhanced oil

recovery (EOR) projects.\8\ As regulatory history has shown,
identifying a new highly efficient SCPC EGU implementing partial CCS as
the BSER in this rule is likely to further boost research and
development in CCS technologies, making the implementation even more
efficacious and cost-effective, while providing a competitive, low
emission future for fossil fuel-fired steam generation.
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    \8\ As the EIA has stated: Policy-related factors, such as
environmental regulations and investment or production tax credits
for specified generation sources, can also impact investment
decisions. Finally, although levelized cost calculations are
generally made using an assumed set of capital and operating costs,
the inherent uncertainty about future fuel prices and future
policies may cause plant owners or investors who finance plants to
place a value on portfolio diversification. While EIA considers many
of these factors in its analysis of technology choice in the
electricity sector, these concepts are not included in LCOE or LACE
calculations. http://www.eia.gov/forecasts/aeo/electricity_generation.cfm.
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    The EPA is also issuing final standards for steam generating units
that implement ``large modifications,'' (i.e., modifications resulting
in an increase in hourly CO2 emissions of more than 10
percent when compared to the source's highest hourly emissions in the
previous 5 years).\9\ The EPA is not issuing final standards, at this
time, for steam generating units that implement ``small modifications''
(i.e., modifications resulting in an increase in hourly CO2
emissions of less than or equal to 10 percent when compared to the
source's highest hourly emissions in the previous 5 years).
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    \9\ 40 CFR 60.14(h) provides that no physical change, or change
in the method of operation, at an existing electric utility steam
generating unit will be treated as a modification provided that such
change does not increase the maximum hourly emissions above the
maximum hourly emissions achievable at that unit during the 5 years
prior to the change.
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    The standards of performance for modified steam generating units
that make large modifications are based on each affected unit's own
best potential performance as the BSER. Specifically, such a modified
steam generating unit will be required to meet a unit-specific
CO2 emission limit determined by that unit's best
demonstrated historical performance (in the years from 2002 to the time
of the modification).\10\ The EPA has determined that this standard
based on each unit's own best potential performance can be met through
a combination of best operating practices and equipment upgrades and
that these steps can be implemented cost-effectively at the time when a
source is undertaking a large modification. To account for facilities
that have already implemented best practices and equipment upgrades,
the final rule also specifies that modified facilities will not have to
meet an emission standard more stringent than the corresponding
standard for reconstructed steam generating units (i.e., 1,800 lb
CO2/MWh-g for units with heat input greater than 2,000
MMBtu/h and 2,000 lb CO2/MWh-g for units with heat input
less than or equal to 2,000 MMBtu/h).
---------------------------------------------------------------------------

    \10\ For the 2002 reporting year the EPA introduced new
automated checks in the software that integrated automated quality
assurance (QA) checks on the hourly data. Thus, the EPA believes
that the data from 2002 and forward are of higher quality.
---------------------------------------------------------------------------

    The final standards for steam generating units implementing large
modifications are similar to the proposed standards for such units. In
the proposal, we suggested that the standard should be based on when
the modification is undertaken (i.e., before being subject to
requirements under a CAA section 111(d) state plan or after being
subject to such a plan). We also suggested that for units that
undertake modifications prior to becoming subject to an approved CAA
section 111(d) state plan, the standard should be its best historical
performance plus an additional two percent reduction. In response to
comments on the proposal, we are not finalizing separate standards that
are dependent upon when the modification takes place, nor are we
finalizing the proposed additional two percentage reduction.
    The EPA is not promulgating final standards of performance for, and
is withdrawing the proposed standards for steam generating sources that
make modifications resulting in an increase of hourly CO2
emissions of less than or equal to 10 percent (see Section XV of this
preamble). As we indicated in the proposal, the EPA has been notified
of very few modifications for criteria pollutant emissions from the
power sector to which NSPS requirements have applied. As such, we
expect that there will be few NSPS modifications for GHG emissions as
well. Even so, we also recognize (and we discuss in this preamble) that
the power sector is undergoing significant change and realignment in
response to a variety of influences and incentives in the industry. We
do not have sufficient information at this time, however, to anticipate
the types of modifications, if any, that may result from these changes.
In particular, we do not have sufficient information about the types of
modifications, if any, that would result in increases in CO2
emissions of 10 percent or less, and what the appropriate standard for
such sources would be. Therefore, we conclude that it is prudent to
delay issuing standards for sources that undertake small modifications
(i.e., those resulting in an increase in CO2 emissions of
less than or equal to 10 percent).
    For reconstructed steam generating units, the EPA is finalizing
standards based on the performance of the most efficient generating
technology for these types of units as the BSER (i.e., reconstructing
the boiler if necessary to use steam with higher temperature and
pressure, even if the boiler was not originally designed to do so).\11\
The emission standard for these sources is 1,800 lb CO2/MWh-
g for large sources, (i.e. those with a heat input rating of greater
than 2,000 MMBtu/h) or 2,000 lb CO2/MWh-g for small sources
(i.e., those with a heat input rating of 2,000 MMBtu/h or less). The
difference in the standards for larger and smaller units is based on
greater availability of higher pressure/temperature steam turbines
(e.g., supercritical steam turbines) for larger units. The standards
can also be met through other non-BSER options, such as natural gas co-
firing.
---------------------------------------------------------------------------

    \11\ Steam with higher temperature and pressure has more thermal
energy that can be more efficiently converted to electrical energy.
---------------------------------------------------------------------------

b. Stationary Combustion Turbines
    This action also finalizes standards of performance for newly
constructed and reconstructed stationary combustion turbines. In the
January 2014 proposal for newly constructed EGUs, the EPA proposed that
natural gas-fired stationary combustion turbines (i.e., turbines
combusting over 90 percent natural gas) would be subject to a standard
of performance for CO2 emissions if they are constructed for
the purpose of supplying and actually annually supply to the grid (1)
one-third or more of their potential electric output \12\ and (2) more
than 219,000 MWh,\13\ based on a three-year rolling average. We refer
to units that operate above the electric sales thresholds as ``base
load units,'' and we refer to units that operate below these thresholds
as ``non-base load units.''
---------------------------------------------------------------------------

    \12\ We refer to thresholds related to an EGU's actual annual
electrical sales (as a fraction of potential annual output) as
``percentage electric sales criteria.''
    \13\ We refer to thresholds related to an EGU's actual annual
electrical sales in megawatt-hours as ``total electric sales
criteria.''
---------------------------------------------------------------------------

    In the January 2014 proposal for newly constructed combustion
turbines, the EPA proposed standards for two subcategories of base load
natural gas-fired stationary combustion turbines. The proposed standard
for small combustion turbines (units with base load ratings less than
or equal to 850 MMBtu/h) was 1,100 lb CO2/MWh-g. The
proposed standard for large combustion turbines (units with base

load ratings greater than 850 MMBtu/h) was 1,000 lb CO2/MWh-
g. The EPA did not propose standards for non-base load units.
    In the June 2014 proposal for modified and reconstructed combustion
turbines, the EPA solicited comment on alternative approaches for
establishing applicability and subcategorization criteria, including
(1) eliminating the ``constructed for the purpose of supplying''
qualifier for the total electric sales and percentage electric sales
criteria, (2) eliminating the 219,000 MWh total electric sales
criterion altogether, (3) replacing the fixed percentage electric sales
criterion with a variable percentage electric sales criterion (i.e.,
the sliding-scale approach \14\), and (4) eliminating the proposed
small and large subcategories for base load natural gas-fired
combustion turbines. These proposed applicability requirements were
intended to exclude combustion turbines that are used for the purpose
of meeting peak power demand, as opposed to those that are used to meet
base load power demand.
---------------------------------------------------------------------------

    \14\ The sliding-scale approach determines a unit-specific
percentage electric sales threshold equivalent to a unit's net
design efficiency (the maximum value is capped at 50 percent).
---------------------------------------------------------------------------

    In both proposals, the EPA also solicited comment on a broad
applicability approach that would include non-base load natural gas-
fired units (primarily simple cycle combustion turbines) and multi-
fuel-fired units (primarily distillate oil-fired combustion turbines)
in the general applicability of subpart TTTT. As part of the broad
applicability approach, the EPA solicited comment on imposing ``no
emission standard'' or establishing separate numerical limits for these
two subcategories.
    In this action, the EPA is finalizing a variation of the approaches
put forward in the January 2014 proposal for new sources and the June
2014 proposal for modified and reconstructed sources. Based on our
review of public comments related to the proposed subcategories for
small and large combustion turbines and our additional data analyses,
we have determined that there is no need to set two separate standards
for different sizes of combustion turbines for base load natural gas-
fired combustion turbines. The EPA has determined that all sizes of
affected newly constructed and reconstructed stationary combustion
turbines can achieve the final standards. For newly constructed and
reconstructed base load natural gas-fired stationary combustion
turbines, the EPA is finalizing a standard of 1,000 lb CO2/
MWh-g based on efficient natural gas combined cycled (NGCC) technology
as the BSER. Alternatively, owners and operators of base load natural
gas-fired combustion turbines may elect to comply with a standard based
on net output of 1,030 lb CO2/MWh-n.
    The EPA is eliminating the 219,000 MWh total annual electric sales
criterion for non-CHP units. In addition, the EPA is finalizing the
sliding-scale approach for deriving the unit-specific, percentage
electric sales threshold above which a combustion turbine transitions
from the subcategory for non-base load units to the subcategory for
base load units. For newly constructed and reconstructed non-base load
natural gas-fired stationary combustion turbines, the EPA is finalizing
the combustion of clean fuels (natural gas with a small allowance for
distillate oil) as the BSER with a corresponding heat input-based
standard of 120 lb CO2/MMBtu. This standard of performance
will apply to the vast majority of simple cycle combustion turbines.
The EPA is finalizing a heat input-based clean fuels standard because
we have insufficient information at this time to set a uniform output-
based standard that can be achieved by all new and reconstructed non-
base load units.
    In addition, for newly constructed and reconstructed multi-fuel-
fired stationary combustion turbines, the EPA is finalizing an input-
based standard of 120 to 160 lb CO2/MMBtu based on the
combustion of clean fuels as the BSER.\15\ The EPA has similarly
determined that it has insufficient information at this time to set a
uniform output-based standard for stationary combustion turbines that
operate with significant quantities of a fuel other than natural gas.
---------------------------------------------------------------------------

    \15\ Combustion turbines co-firing natural gas with other fuels
shall determine fuel-based site-specific standards at the end of
each operating month. The site-specific standards depend on the
amount of co-fired natural gas.
---------------------------------------------------------------------------

    We are not promulgating final standards of performance for
stationary combustion turbines that make modifications at this time. We
are simultaneously withdrawing the proposed standards for modifications
(see Section XV of this preamble). As we indicated in the proposal,
sources from the power sector have notified the EPA of very few NSPS
modifications, and we expect that there will be few NSPS modifications
for CO2 emissions as well. Moreover, our decision to
eliminate the subcategories for small and large EGUs and set a single
standard of 1,000 lb CO2/MWh-g has raised questions as to
whether smaller existing combustion turbines that undertake a
modification can meet this standard. As a result, we have concluded
that it is prudent to delay issuing standards for sources that
undertake modifications until we can gather more information.
    A more detailed discussion of the final standards of performance
for stationary combustion turbines, the applicability criteria, and the
comments that influenced the final standards is provided in Sections
VIII and IX of this preamble.
3. Costs and Benefits
    As explained in the regulatory impact analysis (RIA) for this final
rule, available data--including utility announcements and Energy
Information Administration (EIA) modeling--indicate that, even in the
absence of this rule, (i) existing and anticipated economic conditions
are such that few, if any, fossil fuel-fired steam-generating EGUs will
be built in the foreseeable future, and (ii) utilities and project
developers are expected to choose new generation technologies
(primarily NGCC) that would meet the final standards and renewable
generating sources that are not affected by these final standards.
These projections are consistent with utility announcements and EIA
modeling that indicate that new units are likely to be NGCC and that
any coal-fired steam generating units built between now and 2030 would
have CCS, even in the absence of this rule.\16\ Therefore, based on the
analysis presented in Chapter 4 of the RIA, the EPA projects that this
final rule will result in negligible CO2 emission changes,
quantified benefits, and costs by 2022 as a result of the performance
standards for newly constructed EGUs.\17\ However, as noted earlier,
for a variety of reasons, some companies may consider coal-fired steam
generating units that the modeling does not anticipate. Thus, in
Chapter 5 of the RIA, we also present an analysis of the project-level
costs of a newly constructed coal-fired steam generating unit with
partial CCS that meets the requirements of this final rule alongside
the project-level costs of a newly constructed coal-fired unit without
CCS. This analysis indicates that the

quantified benefits of the standards of performance would exceed their
costs under a range of assumptions.
---------------------------------------------------------------------------

    \16\ The EPA's Integrated Planning Model (IPM) projects no new
non-compliant coal (i.e., newly constructed coal-fired plants that
do not meet the final standard of performance) throughout the model
horizon of 2030 (there is a small amount of new coal with CCS that
is hardwired into the modelling, consistent with EIA assumptions to
represent units already under construction or under development).
    \17\ Conditions in the analysis year of 2022 are represented by
a model year of 2020.
---------------------------------------------------------------------------

    As explained in the RIA and further below, the EPA has been
notified of few power sector NSPS modifications or reconstructions.
Based on that experience, the EPA expects that few EGUs will trigger
either the modification or the reconstruction provisions that we are
finalizing in this action. In Chapter 6 of the RIA, we discuss factors
that limit our ability to quantify the costs and benefits of the
standards for modified and reconstructed sources.

B. Does this action apply to me?

    The entities potentially affected by the standards are shown in
Table 2 below.

                Table 2--Potentially Affected Entities a
------------------------------------------------------------------------
                                                 Examples of potentially
            Category               NAICS code       affected entities
------------------------------------------------------------------------
Industry.......................          221112  Fossil fuel electric
                                                  power generating
                                                  units.
Federal Government.............       \b\221112  Fossil fuel electric
                                                  power generating units
                                                  owned by the federal
                                                  government.
State/Local Government.........       \b\221112  Fossil fuel electric
                                                  power generating units
                                                  owned by
                                                  municipalities.
Tribal Government..............          921150  Fossil fuel electric
                                                  power generating units
                                                  in Indian Country.
------------------------------------------------------------------------
\a\ Includes NAICS categories for source categories that own and operate
  electric power generating units (including boilers and stationary
  combined cycle combustion turbines).
\b\ Federal, state, or local government-owned and operated
  establishments are classified according to the activity in which they
  are engaged.

    This table is not intended to be exhaustive, but rather to provide
a guide for readers regarding entities likely to be affected by this
action. To determine whether your facility, company, business,
organization, etc., would be regulated by this action, refer to Section
III of this preamble for more information and examine the applicability
criteria in 40 CFR 60.1 (General Provisions) and Sec.  60.550840 of
subpart TTTT (Standards of Performance for Greenhouse Gas Emissions for
Electric Utility Generating Units). If you have any questions regarding
the applicability of this action to a particular entity, consult either
the air permitting authority for the entity or your EPA regional
representative as listed in 40 CFR 60.4 or 40 CFR 63.13 (General
Provisions).

C. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of
this final action will also be available on the Worldwide Web (WWW).
Following signature, a copy of this final action will be posted at the
following address: http://www2.epa.gov/carbon-pollution-standards.

D. Judicial Review

    Under section 307(b)(1) of the CAA, judicial review of this final
rule is available only by filing a petition for review in the U.S.
Court of Appeals for the District of Columbia Circuit by December 22,
2015. Moreover, under section 307(b)(2) of the CAA, the requirements
established by this final rule may not be challenged separately in any
civil or criminal proceedings brought by the EPA to enforce these
requirements. Section 307(d)(7)(B) of the CAA further provides that
``[o]nly an objection to a rule or procedure which was raised with
reasonable specificity during the period for public comment (including
any public hearing) may be raised during judicial review.'' This
section also provides a mechanism mandating the EPA to convene a
proceeding for reconsideration if the person raising an objection can
demonstrate that it was impracticable to raise such objection within
the period for public comment or if the grounds for such objection
arose after the period for public comment (but within the time
specified for judicial review) and if such objection is of central
relevance to the outcome of the rule. Any person seeking to make such a
demonstration should submit a Petition for Reconsideration to the
Office of the Administrator, U.S. EPA, Room 3000, Ariel Rios Building,
1200 Pennsylvania Ave. NW., Washington, DC 20460, with a copy to both
the person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT
section, and the Associate General Counsel for the Air and Radiation
Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200
Pennsylvania Ave. NW., Washington, DC 20460.

E. How is this preamble organized?

    This action presents the EPA's final standards of performance for
newly constructed, modified, and reconstructed fossil fuel-fired
electric utility steam generating units and newly constructed and
reconstructed stationary combustion turbines. Section II provides
background information on climate change impacts from GHG emissions,
GHG emissions from fossil fuel-fired EGUs, the utility power sector,
the statutory and regulatory background relating to CAA section 111(b),
EPA actions prior to this final action, and public comments regarding
the proposed actions. Section III explains the EPA's authority to
regulate CO2 and EGUs, identifies affected EGUs, and
describes the source categories. Section IV provides a summary of the
final standards for newly constructed, modified, and reconstructed
fossil fuel-fired steam generating units. Sections V through VII
present the rationale for the final standards for newly constructed,
modified, and reconstructed steam generating units, respectively.
Sections VIII and IX provide a summary of the final standards for
stationary combustion turbines and present the rationale for the final
standards for newly constructed and reconstructed combustion turbines,
respectively. Section X provides a summary of other final requirements
for newly constructed, modified, and reconstructed fossil fuel-fired
steam generating units and stationary combustion turbines. Section XI
addresses the consistency of the respective BSER determinations in
these rules and under the emission guidelines issued separately under
CAA section 111(d). Interactions with other EPA programs and rules are
described in Section XII. Projected impacts of the final action are
then described in Section XIII, followed by a discussion of statutory
and executive order reviews in Section XIV. Section XV addresses the
withdrawal of the proposed standards for steam generating EGUs that
make modifications resulting in an increase of hourly CO2
emissions of less than or equal to 10 percent and the proposed
standards for modified stationary combustion turbines. The statutory
authority for this action is provided in Section XVI. We address major
comments throughout this preamble and in greater detail in an
accompanying response-to-comments document located in the docket.

II. Background

    In this section, we discuss climate change impacts from GHG
emissions, both on public health and public welfare. We also present
information about GHG emissions from fossil fuel-fired EGUs and
describe the utility power sector and its changing structure. We then
summarize the statutory and regulatory background relevant to this
final rulemaking. In addition, we provide background information on the
EPA's January 8, 2014 proposed carbon pollution standards for newly
constructed fossil fuel-fired EGUs, the June 18, 2014 proposed carbon
pollution standards for modified and reconstructed EGUs, and other
actions associated with this final rulemaking. We close this section
with a general discussion of comments and stakeholder input that the
EPA received prior to issuing this final rulemaking.

A. Climate Change Impacts From GHG Emissions

    According to the National Research Council, ``Emissions of
CO2 from the burning of fossil fuels have ushered in a new
epoch where human activities will largely determine the evolution of
Earth's climate. Because CO2 in the atmosphere is long
lived, it can effectively lock Earth and future generations into a
range of impacts, some of which could become very severe. Therefore,
emission reduction choices made today matter in determining impacts
experienced not just over the next few decades, but in the coming
centuries and millennia.'' \18\
---------------------------------------------------------------------------

    \18\ National Research Council, Climate Stabilization Targets,
p. 3.
---------------------------------------------------------------------------

    In 2009, based on a large body of robust and compelling scientific
evidence, the EPA Administrator issued the Endangerment Finding under
CAA section 202(a)(1).\19\ In the Endangerment Finding, the
Administrator found that the current, elevated concentrations of GHGs
in the atmosphere--already at levels unprecedented in human history--
may reasonably be anticipated to endanger public health and welfare of
current and future generations in the United States. We summarize these
adverse effects on public health and welfare briefly here.
---------------------------------------------------------------------------

    \19\ ``Endangerment and Cause or Contribute Findings for
Greenhouse Gases Under Section 202(a) of the Clean Air Act,'' 74 FR
66496 (Dec. 15, 2009) (``Endangerment Finding'').
---------------------------------------------------------------------------

1. Public Health Impacts Detailed in the 2009 Endangerment Finding
    Climate change caused by human emissions of GHGs threatens the
health of Americans in multiple ways. By raising average temperatures,
climate change increases the likelihood of heat waves, which are
associated with increased deaths and illnesses. While climate change
also increases the likelihood of reductions in cold-related mortality,
evidence indicates that the increases in heat mortality will be larger
than the decreases in cold mortality in the United States. Compared to
a future without climate change, climate change is expected to increase
ozone pollution over broad areas of the U.S., especially on the highest
ozone days and in the largest metropolitan areas with the worst ozone
problems, and thereby increase the risk of morbidity and mortality.
Climate change is also expected to cause more intense hurricanes and
more frequent and intense storms and heavy precipitation, with impacts
on other areas of public health, such as the potential for increased
deaths, injuries, infectious and waterborne diseases, and stress-
related disorders. Children, the elderly, and the poor are among the
most vulnerable to these climate-related health effects.
2. Public Welfare Impacts Detailed in the 2009 Endangerment Finding
    Climate change impacts touch nearly every aspect of public welfare.
Among the multiple threats caused by human emissions of GHGs, climate
changes are expected to place large areas of the country at serious
risk of reduced water supplies, increased water pollution, and
increased occurrence of extreme events such as floods and droughts.
Coastal areas are expected to face a multitude of increased risks,
particularly from rising sea level and increases in the severity of
storms. These communities face storm and flood damage to property, or
even loss of land due to inundation, erosion, wetland submergence and
habitat loss.
    Impacts of climate change on public welfare also include threats to
social and ecosystem services. Climate change is expected to result in
an increase in peak electricity demand. Extreme weather from climate
change threatens energy, transportation, and water resource
infrastructure. Climate change may also exacerbate ongoing
environmental pressures in certain settlements, particularly in Alaskan
indigenous communities, and is very likely to fundamentally rearrange
U.S. ecosystems over the 21st century. Though some benefits may balance
adverse effects on agriculture and forestry in the next few decades,
the body of evidence points towards increasing risks of net adverse
impacts on U.S. food production, agriculture and forest productivity as
temperature continues to rise. These impacts are global and may
exacerbate problems outside the U.S. that raise humanitarian, trade,
and national security issues for the U.S.
3. New Scientific Assessments and Observations
    Since the administrative record concerning the Endangerment Finding
closed following the EPA's 2010 Reconsideration Denial, the climate has
continued to change, with new records being set for a number of climate
indicators such as global average surface temperatures, Arctic sea ice
retreat, CO2 concentrations, and sea level rise.
Additionally, a number of major scientific assessments have been
released that improve understanding of the climate system and
strengthen the case that GHGs endanger public health and welfare both
for current and future generations. These assessments, from the
Intergovernmental Panel on Climate Change (IPCC), the U.S. Global
Change Research Program (USGCRP), and the National Research Council
(NRC), include: IPCC's 2012 Special Report on Managing the Risks of
Extreme Events and Disasters to Advance Climate Change Adaptation
(SREX) and the 2013-2014 Fifth Assessment Report (AR5), the USGCRP's
2014 National Climate Assessment, Climate Change Impacts in the United
States (NCA3), and the NRC's 2010 Ocean Acidification: A National
Strategy to Meet the Challenges of a Changing Ocean (Ocean
Acidification), 2011 Report on Climate Stabilization Targets:
Emissions, Concentrations, and Impacts over Decades to Millennia
(Climate Stabilization Targets), 2011 National Security Implications
for U.S. Naval Forces (National Security Implications), 2011
Understanding Earth's Deep Past: Lessons for Our Climate Future
(Understanding Earth's Deep Past), 2012 Sea Level Rise for the Coasts
of California, Oregon, and Washington: Past, Present, and Future, 2012
Climate and Social Stress: Implications for Security Analysis (Climate
and Social Stress), and 2013 Abrupt Impacts of Climate Change (Abrupt
Impacts) assessments.
    The EPA has carefully reviewed these recent assessments in keeping
with the same approach outlined in Section III.A of the 2009
Endangerment Finding, which was to rely primarily upon the major
assessments by the USGCRP, the IPCC, and the NRC of the National
Academies to provide the technical and scientific information to inform
the Administrator's judgment regarding the question of whether GHGs
endanger public health and welfare. These

assessments addressed the scientific issues that the EPA was required
to examine, were comprehensive in their coverage of the GHG and climate
change issues, and underwent rigorous and exacting peer review by the
expert community, as well as rigorous levels of U.S. government review.
    The findings of the recent scientific assessments confirm and
strengthen the conclusion that GHGs endanger public health, now and in
the future. The NCA3 indicates that human health in the United States
will be impacted by ``increased extreme weather events, wildfire,
decreased air quality, threats to mental health, and illnesses
transmitted by food, water, and disease-carriers such as mosquitoes and
ticks.'' The most recent assessments now have greater confidence that
climate change will influence production of pollen that exacerbates
asthma and other allergic respiratory diseases such as allergic
rhinitis, as well as effects on conjunctivitis and dermatitis. Both the
NCA3 and the IPCC AR5 found that increasing temperature has lengthened
the allergenic pollen season for ragweed, and that increased
CO2 by itself can elevate production of plant-based
allergens.
    The NCA3 also finds that climate change, in addition to chronic
stresses such as extreme poverty, is negatively affecting indigenous
peoples' health in the United States through impacts such as reduced
access to traditional foods, decreased water quality, and increasing
exposure to health and safety hazards. The IPCC AR5 finds that climate
change-induced warming in the Arctic and resultant changes in
environment (e.g., permafrost thaw, effects on traditional food
sources) have significant impacts, observed now and projected, on the
health and well-being of Arctic residents, especially indigenous
peoples. Small, remote, predominantly-indigenous communities are
especially vulnerable given their ``strong dependence on the
environment for food, culture, and way of life; their political and
economic marginalization; existing social, health, and poverty
disparities; as well as their frequent close proximity to exposed
locations along ocean, lake, or river shorelines.'' \20\ In addition,
increasing temperatures and loss of Arctic sea ice increases the risk
of drowning for those engaged in traditional hunting and fishing.
---------------------------------------------------------------------------

    \20\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part B: Regional Aspects. Contribution of Working
Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D.
Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O.
Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S.
MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge
University Press, Cambridge, p. 1581.
---------------------------------------------------------------------------

    The NCA3 concludes that children's unique physiology and developing
bodies contribute to making them particularly vulnerable to climate
change. Impacts on children are expected from heat waves, air
pollution, infectious and waterborne illnesses, and mental health
effects resulting from extreme weather events. The IPCC AR5 indicates
that children are among those especially susceptible to most allergic
diseases, as well as health effects associated with heat waves, storms,
and floods. The IPCC finds that additional health concerns may arise in
low-income households, especially those with children, if climate
change reduces food availability and increases prices, leading to food
insecurity within households.
    Both the NCA3 and IPCC AR5 conclude that climate change will
increase health risks facing the elderly. Older people are at much
higher risk of mortality during extreme heat events. Pre-existing
health conditions also make older adults susceptible to cardiac and
respiratory impacts of air pollution and to more severe consequences
from infectious and waterborne diseases. Limited mobility among older
adults can also increase health risks associated with extreme weather
and floods.
    The new assessments also confirm and strengthen the conclusion that
GHGs endanger public welfare, and emphasize the urgency of reducing GHG
emissions due to their projections that show GHG concentrations
climbing to ever-increasing levels in the absence of mitigation. The
NRC assessment, Understanding Earth's Deep Past, projected that,
without a reduction in emissions, CO2 concentrations by the
end of the century would increase to levels that the Earth has not
experienced for more than 30 million years.\21\ In fact, that
assessment stated that ``the magnitude and rate of the present
greenhouse gas increase place the climate system in what could be one
of the most severe increases in radiative forcing of the global climate
system in Earth history.'' \22\ Because of these unprecedented changes,
several assessments state that we may be approaching critical, poorly
understood thresholds. As stated in the assessment, ``As Earth
continues to warm, it may be approaching a critical climate threshold
beyond which rapid and potentially permanent--at least on a human
timescale--changes not anticipated by climate models tuned to modern
conditions may occur.'' The NRC Abrupt Impacts report analyzed abrupt
climate change in the physical climate system and abrupt impacts of
ongoing changes that, when thresholds are crossed, can cause abrupt
impacts for society and ecosystems. The report considered
destabilization of the West Antarctic Ice Sheet (which could cause 3-4
m of potential sea level rise) as an abrupt climate impact with unknown
but probably low probability of occurring this century. The report
categorized a decrease in ocean oxygen content (with attendant threats
to aerobic marine life); increase in intensity, frequency, and duration
of heat waves; and increase in frequency and intensity of extreme
precipitation events (droughts, floods, hurricanes, and major storms)
as climate impacts with moderate risk of an abrupt change within this
century. The NRC Abrupt Impacts report also analyzed the threat of
rapid state changes in ecosystems and species extinctions as examples
of irreversible impacts that are expected to be exacerbated by climate
change. Species at most risk include those whose migration potential is
limited, whether because they live on mountaintops or fragmented
habitats with barriers to movement, or because climatic conditions are
changing more rapidly than the species can move or adapt. While the NRC
determined that it is not presently possible to place exact
probabilities on the added contribution of climate change to
extinction, they did find that there was substantial risk that impacts
from climate change could, within a few decades, drop the populations
in many species below sustainable levels, thereby committing the
species to extinction. Species within tropical and subtropical
rainforests such as the Amazon and species living in coral reef
ecosystems were identified by the NRC as being particularly vulnerable
to extinction over the next 30 to 80 years, as were species in high
latitude and high elevation regions. Moreover, due to the time lags
inherent in the Earth's climate, the NRC Climate Stabilization Targets
assessment notes that the full warming from any given concentration of
CO2 reached will not be fully realized for several
centuries, underscoring that emission activities today carry with them
climate commitments far into the future.
---------------------------------------------------------------------------

    \21\ National Research Council, Understanding Earth's Deep Past,
p. 1.
    \22\ Id., p. 138.
---------------------------------------------------------------------------

    Future temperature changes will depend on what emission path the
world follows. In its high emission scenario, the IPCC AR5 projects
that

average global temperatures by the end of the century will likely be
2.6 degrees Celsius ([deg]C) to 4.8 [deg]C (4.7 to 8.6 degrees
Fahrenheit ([deg]F)) warmer than today. Temperatures on land and in
northern latitudes will likely warm even faster than the global
average. However, according to the NCA3, significant reductions in
emissions would lead to noticeably less future warming beyond mid-
century, and therefore less impact to public health and welfare.
    While rainfall may only see small globally and annually averaged
changes, there are expected to be substantial shifts in where and when
that precipitation falls. According to the NCA3, regions closer to the
poles will see more precipitation, while the dry subtropics are
expected to expand (colloquially, this has been summarized as wet areas
getting wetter and dry regions getting drier). In particular, the NCA3
notes that the western U.S., and especially the Southwest, is expected
to become drier. This projection is consistent with the recent observed
drought trend in the West. At the time of publication of the NCA, even
before the last 2 years of extreme drought in California, tree ring
data was already indicating that the region might be experiencing its
driest period in 800 years. Similarly, the NCA3 projects that heavy
downpours are expected to increase in many regions, with precipitation
events in general becoming less frequent but more intense. This trend
has already been observed in regions such as the Midwest, Northeast,
and upper Great Plains. Meanwhile, the NRC Climate Stabilization
Targets assessment found that the area burned by wildfire is expected
to grow by 2 to 4 times for 1 [deg]C (1.8 [deg]F) of warming. For 3
[deg]C of warming, the assessment found that 9 out of 10 summers would
be warmer than all but the 5 percent of warmest summers today, leading
to increased frequency, duration, and intensity of heat waves.
Extrapolations by the NCA also indicate that Arctic sea ice in summer
may essentially disappear by mid-century. Retreating snow and ice, and
emissions of CO2 and methane released from thawing
permafrost, will also amplify future warming.
    Since the 2009 Endangerment Finding, the USGCRP NCA3, and multiple
NRC assessments have projected future rates of sea level rise that are
40 percent larger to more than twice as large as the previous estimates
from the 2007 IPCC 4th Assessment Report due in part to improved
understanding of the future rate of melt of the Antarctic and Greenland
Ice sheets. The NRC Sea Level Rise assessment projects a global sea
level rise of 0.5 to 1.4 meters (1.6 to 4.6 feet) by 2100, the NRC
National Security Implications assessment suggests that ``the
Department of the Navy should expect roughly 0.4 to 2 meters (1.3 to
6.6 feet) global average sea-level rise by 2100,'' \23\ and the NRC
Climate Stabilization Targets assessment states that an increase of 3
[deg]C will lead to a sea level rise of 0.5 to 1 meter (1.6 to 3.3
feet) by 2100. These assessments continue to recognize that there is
uncertainty inherent in accounting for ice sheet processes.
Additionally, local sea level rise can differ from the global total
depending on various factors. The east coast of the U.S. in particular
is expected to see higher rates of sea level rise than the global
average. For comparison, the NCA3 states that ``five million Americans
and hundreds of billions of dollars of property are located in areas
that are less than four feet above the local high-tide level,'' and the
NCA3 finds that ``[c]oastal infrastructure, including roads, rail
lines, energy infrastructure, airports, port facilities, and military
bases, are increasingly at risk from sea level rise and damaging storm
surges.'' \24\ Also, because of the inertia of the oceans, sea level
rise will continue for centuries after GHG concentrations have
stabilized (though more slowly than it would have otherwise).
Additionally, there is a threshold temperature above which the
Greenland ice sheet will be committed to inevitable melting. According
to the NCA, some recent research has suggested that even present day
CO2 levels could be sufficient to exceed that threshold.
---------------------------------------------------------------------------

    \23\ NRC, 2011: National Security Implications of Climate Change
for U.S. Naval Forces. The National Academies Press, p. 28.
    \24\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 9.
---------------------------------------------------------------------------

    In general, climate change impacts are expected to be unevenly
distributed across different regions of the United States and have a
greater impact on certain populations, such as indigenous peoples and
the poor. The NCA3 finds that climate change impacts such as the rapid
pace of temperature rise, coastal erosion and inundation related to sea
level rise and storms, ice and snow melt, and permafrost thaw are
affecting indigenous people in the U.S. Particularly in Alaska,
critical infrastructure and traditional livelihoods are threatened by
climate change and, ``[i]n parts of Alaska, Louisiana, the Pacific
Islands, and other coastal locations, climate change impacts (through
erosion and inundation) are so severe that some communities are already
relocating from historical homelands to which their traditions and
cultural identities are tied.'' \25\ The IPCC AR5 notes, ``Climate-
related hazards exacerbate other stressors, often with negative
outcomes for livelihoods, especially for people living in poverty (high
confidence). Climate-related hazards affect poor people's lives
directly through impacts on livelihoods, reductions in crop yields, or
destruction of homes and indirectly through, for example, increased
food prices and food insecurity.'' \26\
---------------------------------------------------------------------------

    \25\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 17.
    \26\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part A: Global and Sectoral Aspects. Contribution of
Working Group II to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros,
D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee,
K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N.
Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)].
Cambridge University Press, p. 796.
---------------------------------------------------------------------------

    CO2 in particular has unique impacts on ocean
ecosystems. The NRC Climate Stabilization Targets assessment found that
coral bleaching will increase due both to warming and ocean
acidification. Ocean surface waters have already become 30 percent more
acidic over the past 250 years due to absorption of CO2 from
the atmosphere. According to the NCA3, this acidification will reduce
the ability of organisms such as corals, krill, oysters, clams, and
crabs to survive, grow, and reproduce. The NRC Understanding Earth's
Deep Past assessment notes that four of the five major coral reef
crises of the past 500 million years were caused by acidification and
warming that followed GHG increases of similar magnitude to the
emissions increases expected over the next hundred years. The NRC
Abrupt Impacts assessment specifically highlighted similarities between
the projections for future acidification and warming and the extinction
at the end of the Permian which resulted in the loss of an estimated 90
percent of known species. Similarly, the NRC Ocean Acidification
assessment finds that ``[t]he chemistry of the ocean is changing at an
unprecedented rate and magnitude due to anthropogenic CO2
emissions; the rate of change exceeds any known to have occurred for at
least the past

hundreds of thousands of years.'' \27\ The assessment notes that the
full range of consequences is still unknown, but the risks ``threaten
coral reefs, fisheries, protected species, and other natural resources
of value to society.'' \28\
---------------------------------------------------------------------------

    \27\ NRC, 2010: Ocean Acidification: A National Strategy to Meet
the Challenges of a Changing Ocean. The National Academies Press, p.
5.
    \28\ Id.
---------------------------------------------------------------------------

    Events outside the United States, as also pointed out in the 2009
Endangerment Finding, will also have relevant consequences. The NRC
Climate and Social Stress assessment concluded that it is prudent to
expect that some climate events ``will produce consequences that exceed
the capacity of the affected societies or global systems to manage and
that have global security implications serious enough to compel
international response.'' The NRC National Security Implications
assessment recommends preparing for increased needs for humanitarian
aid; responding to the effects of climate change in geopolitical
hotspots, including possible mass migrations; and addressing changing
security needs in the Arctic as sea ice retreats.
    In addition to future impacts, the NCA3 emphasizes that climate
change driven by human emissions of GHGs is already happening now and
it is happening in the United States. According to the IPCC AR5 and the
NCA3, there are a number of climate-related changes that have been
observed recently, and these changes are projected to accelerate in the
future. The planet warmed about 0.85 [deg]C (1.5 [deg]F) from 1880 to
2012. It is extremely likely (>95 percent probability) that human
influence was the dominant cause of the observed warming since the mid-
20th century, and likely (>66 percent probability) that human influence
has more than doubled the probability of occurrence of heat waves in
some locations. In the Northern Hemisphere, the last 30 years were
likely the warmest 30-year period of the last 1400 years. U.S. average
temperatures have similarly increased by 1.3 to 1.9 [deg]F since 1895,
with most of that increase occurring since 1970. Global sea levels rose
0.19 m (7.5 inches) from 1901 to 2010. Contributing to this rise was
the warming of the oceans and melting of land ice. It is likely that
275 gigatons per year of ice have melted from land glaciers (not
including ice sheets) since 1993, and that the rate of loss of ice from
the Greenland and Antarctic ice sheets has increased substantially in
recent years, to 215 gigatons per year and 147 gigatons per year
respectively, since 2002. For context, 360 gigatons of ice melt is
sufficient to cause global sea levels to rise 1 mm. Annual mean Arctic
sea ice has been declining at 3.5 to 4.1 percent per decade, and
Northern Hemisphere snow cover extent has decreased at about 1.6
percent per decade for March and 11.7 percent per decade for June.
Permafrost temperatures have increased in most regions since the 1980s,
by up to 3 [deg]C (5.4 [deg]F) in parts of Northern Alaska. Winter
storm frequency and intensity have both increased in the Northern
Hemisphere. The NCA3 states that the increases in the severity or
frequency of some types of extreme weather and climate events in recent
decades can affect energy production and delivery, causing supply
disruptions, and compromise other essential infrastructure such as
water and transportation systems.
    In addition to the changes documented in the assessment literature,
there have been other climate milestones of note. In 2009, the year of
the Endangerment Finding, the average concentration of CO2
as measured on top of Mauna Loa was 387 parts per million, far above
preindustrial concentrations of about 280 parts per million.\29\ The
average concentration in 2013, the last full year before this rule was
proposed, was 396 parts per million. The average concentration in 2014
was 399 parts per million. And the monthly concentration in April of
2014 was 401 parts per million, the first time a monthly average has
exceeded 400 parts per million since record keeping began at Mauna Loa
in 1958, and for at least the past 800,000 years based on ice core
records.\30\ Arctic sea ice has continued to decline, with September of
2012 marking a new record low in terms of Arctic sea ice extent, 40
percent below the 1979-2000 median. Sea level has continued to rise at
a rate of 3.2 mm per year (1.3 inches/decade) since satellite
observations started in 1993, more than twice the average rate of rise
in the 20th century prior to 1993.\31\ And 2014 was the warmest year
globally in the modern global surface temperature record, going back to
1880; this now means 19 of the 20 warmest years have occurred in the
past 20 years, and except for 1998, the ten warmest years on record
have occurred since 2002.\32\ The first months of 2015 have also been
some of the warmest on record.
---------------------------------------------------------------------------

    \29\ ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_annmean_mlo.txt.
    \30\ http://www.esrl.noaa.gov/gmd/ccgg/trends/.
    \31\ Blunden, J., and D. S. Arndt, Eds., 2014: State of the
Climate in 2013. Bull. Amer. Meteor. Soc., 95 (7), S1-S238.
    \32\ http://www.ncdc.noaa.gov/sotc/global/2014/13.
---------------------------------------------------------------------------

    These assessments and observed changes make it clear that reducing
emissions of GHGs across the globe is necessary in order to avoid the
worst impacts of climate change, and underscore the urgency of reducing
emissions now. The NRC Committee on America's Climate Choices listed a
number of reasons ``why it is imprudent to delay actions that at least
begin the process of substantially reducing emissions.'' \33\ For
example:
---------------------------------------------------------------------------

    \33\ NRC, 2011: America's Climate Choices, The National
Academies Press.
---------------------------------------------------------------------------

     The faster emissions are reduced, the lower the risks
posed by climate change. Delays in reducing emissions could commit the
planet to a wide range of adverse impacts, especially if the
sensitivity of the climate to greenhouse gases is on the higher end of
the estimated range.
     Waiting for unacceptable impacts to occur before taking
action is imprudent because the effects of greenhouse gas emissions do
not fully manifest themselves for decades and, once manifest, many of
these changes will persist for hundreds or even thousands of years.
     In the committee's judgment, the risks associated with
doing business as usual are a much greater concern than the risks
associated with engaging in strong response efforts.
4. Observed and Projected U.S. Regional Changes
    The NCA3 assessed the climate impacts in eight regions of the
United States, noting that changes in physical climate parameters such
as temperatures, precipitation, and sea ice retreat were already having
impacts on forests, water supplies, ecosystems, flooding, heat waves,
and air quality. Moreover, the NCA3 found that future warming is
projected to be much larger than recent observed variations in
temperature, with precipitation likely to increase in the northern
states, decrease in the southern states, and with the heaviest
precipitation events projected to increase everywhere.
    In the Northeast, temperatures increased almost 2 [deg]F from 1895
to 2011, precipitation increased by about 5 inches (10 percent), and
sea level rise of about a foot has led to an increase in coastal
flooding. The 70 percent increase in the amount of rainfall falling in
the 1 percent of the most intense events is a larger increase in
extreme precipitation than experienced in any other U.S. region.
    In the future, if emissions continue increasing, the Northeast is
expected to experience 4.5 to 10 [deg]F of warming by

the 2080s. This will lead to more heat waves, coastal and river
flooding, and intense precipitation events. The southern portion of the
region is projected to see 60 additional days per year above 90 [deg]F
by mid-century. Sea levels in the Northeast are expected to increase
faster than the global average because of subsidence, and changing
ocean currents may further increase the rate of sea level rise.
Specific vulnerabilities highlighted by the NCA include large urban
populations particularly vulnerable to climate-related heat waves and
poor air quality episodes, prevalence of climate sensitive vector-borne
diseases like Lyme and West Nile Virus, usage of combined sewer systems
that may lead to untreated water being released into local water bodies
after climate-related heavy precipitation events, and 1.6 million
people living within the 100-year coastal flood zone who are expected
to experience more frequent floods due to sea level rise and tropical-
storm induced storm-surge. The NCA also highlighted infrastructure
vulnerable to inundation in coastal metropolitan areas, potential
agricultural impacts from increased rain in the spring delaying
planting or damaging crops or increased heat in the summer leading to
decreased yields and increased water demand, and shifts in ecosystems
leading to declines in iconic species in some regions, such as cod and
lobster south of Cape Cod.
    In the Southeast, average annual temperature during the last
century cycled between warm and cool periods. A warm peak occurred
during the 1930s and 1940s, followed by a cool period, and temperatures
then increased again from 1970 to the present by an average of 2
[deg]F. There have been increasing numbers of days above 95 [deg]F and
nights above 75 [deg]F, and decreasing numbers of extremely cold days
since 1970. Daily and five-day rainfall intensities have also
increased, and summers have been either increasingly dry or extremely
wet. Louisiana has already lost 1,880 square miles of land in the last
80 years due to sea level rise and other contributing factors.
    The Southeast is exceptionally vulnerable to sea level rise,
extreme heat events, hurricanes, and decreased water availability.
Major consequences of further warming include significant increases in
the number of hot days (95 [deg]F or above) and decreases in freezing
events, as well as exacerbated ground-level ozone in urban areas.
Although projected warming for some parts of the region by the year
2100 is generally smaller than for other regions of the United States,
projected warming for interior states of the region is larger than
coastal regions by 1 [deg]F to 2 [deg]F. Projections further suggest
that there will be fewer tropical storms globally, but that they will
be more intense, with more Category 4 and 5 storms. The NCA identified
New Orleans, Miami, Tampa, Charleston, and Virginia Beach as being
specific cities that are at risk due to sea level rise, with homes and
infrastructure increasingly prone to flooding. Additional impacts of
sea level rise are expected for coastal highways, wetlands, fresh water
supplies, and energy infrastructure.
    In the Northwest, temperatures increased by about 1.3 [deg]F
between 1895 and 2011. A small average increase in precipitation was
observed over this time period. However, warming temperatures have
caused increased rainfall relative to snowfall, which has altered water
availability from snowpack across parts of the region. Snowpack in the
Northwest is an important freshwater source for the region. More
precipitation falling as rain instead of snow has reduced the snowpack,
and warmer springs have corresponded to earlier snowpack melting and
reduced streamflows during summer months. Drier conditions have
increased the extent of wildfires in the region.
    Average annual temperatures are projected to increase by 3.3 [deg]F
to 9.7 [deg]F by the end of the century (depending on future global GHG
emissions), with the greatest warming expected during the summer.
Continued increases in global GHG emissions are projected to result in
up to a 30 percent decrease in summer precipitation. Earlier snowpack
melt and lower summer stream flows are expected by the end of the
century and will affect drinking water supplies, agriculture,
ecosystems, and hydropower production. Warmer waters are expected to
increase disease and mortality in important fish species, including
Chinook and sockeye salmon. Ocean acidification also threatens species
such as oysters, with the Northwest coastal waters already being some
of the most acidified worldwide due to coastal upwelling and other
local factors. Forest pests are expected to spread and wildfires to
burn larger areas. Other high-elevation ecosystems are projected to be
lost because they can no longer survive the climatic conditions. Low
lying coastal areas, including the cities of Seattle and Olympia, will
experience heightened risks of sea level rise, erosion, seawater
inundation and damage to infrastructure and coastal ecosystems.
    In Alaska, temperatures have changed faster than anywhere else in
the United States. Annual temperatures increased by about
3[emsp14][deg]F in the past 60 years. Warming in the winter has been
even greater, rising by an average of 6[emsp14][deg]F. Arctic sea ice
is thinning and shrinking in area, with the summer minimum ice extent
now covering only half the area it did when satellite records began in
1979. Glaciers in Alaska are melting at some of the fastest rates on
Earth. Permafrost soils are also warming and beginning to thaw. Drier
conditions have contributed to more large wildfires in the last 10
years than in any previous decade since the 1940s, when recordkeeping
began. Climate change impacts are harming the health, safety, and
livelihoods of Native Alaskan communities.
    By the end of this century, continued increases in GHG emissions
are expected to increase temperatures by 10 to 12[emsp14][deg]F in the
northernmost parts of Alaska, by 8 to 10[emsp14][deg]F in the interior,
and by 6 to 8[emsp14][deg]F across the rest of the state. These
increases will exacerbate ongoing arctic sea ice loss, glacial melt,
permafrost thaw and increased wildfire, and threaten humans,
ecosystems, and infrastructure. Precipitation is expected to increase
to varying degrees across the state. However, warmer air temperatures
and a longer growing season are expected to result in drier conditions.
Native Alaskans are expected to experience declines in economically,
nutritionally, and culturally important wildlife and plant species.
Health threats will also increase, including loss of clean water,
saltwater intrusion, sewage contamination from thawing permafrost, and
northward extension of diseases. Wildfires will increasingly pose
threats to human health as a result of smoke and direct contact. Areas
underlain by ice-rich permafrost across the state are likely to
experience ground subsidence and extensive damage to infrastructure as
the permafrost thaws. Important ecosystems will continue to be
affected. Surface waters and wetlands that are drying provide breeding
habitat for millions of waterfowl and shorebirds that winter in the
lower 48 states. Warmer ocean temperatures, acidification, and
declining sea ice will contribute to changes in the location and
availability of commercially and culturally important marine fish.
    In the Southwest, temperatures are now about 2[emsp14][deg]F higher
than the past century, and are already the warmest that region has
experienced in at least 600 years. The NCA notes that there is evidence
that climate change-induced warming on top of recent drought has
influenced tree mortality, wildfire frequency and area, and forest
insect outbreaks. Sea levels have risen about 7

or 8 inches in this region, contributing to inundation of Highway 101
and back up of seawater into sewage systems in the San Francisco area.
    Projections indicate that the Southwest will warm an additional 5.5
to 9.5[emsp14][deg]F over the next century if emissions continue to
increase. Winter snowpack in the Southwest is projected to decline
(consistent with the record lows from this past winter), reducing the
reliability of surface water supplies for cities, agriculture, cooling
for power plants, and ecosystems. Sea level rise along the California
coast will worsen coastal erosion, increase flooding risk for coastal
highways, bridges, and low-lying airports, pose a threat to groundwater
supplies in coastal cities such as Los Angeles, and increase
vulnerability to floods for hundreds of thousands of residents in
coastal areas. Climate change will also have impacts on the high-value
specialty crops grown in the region as a drier climate will increase
demands for irrigation, more frequent heat waves will reduce yields,
and decreased winter chills may impair fruit and nut production for
trees in California. Increased drought, higher temperatures, and bark
beetle outbreaks are likely to contribute to continued increases in
wildfires. The highly urbanized population of the Southwest is
vulnerable to heat waves and water supply disruptions, which can be
exacerbated in cases where high use of air conditioning triggers energy
system failures.
    The rate of warming in the Midwest has markedly accelerated over
the past few decades. Temperatures rose by more than 1.5[emsp14][deg]F
from 1900 to 2010, but between 1980 and 2010, the rate of warming was
three times faster than from 1900 through 2010. Precipitation generally
increased over the last century, with much of the increase driven by
intensification of the heaviest rainfalls. Several types of extreme
weather events in the Midwest (e.g., heat waves and flooding) have
already increased in frequency and/or intensity due to climate change.
    In the future, if emissions continue increasing, the Midwest is
expected to experience 5.6 to 8.5[emsp14][deg]F of warming by the
2080s, leading to more heat waves. Though projections of changes in
total precipitation vary across the regions, more precipitation is
expected to fall in the form of heavy downpours across the entire
region, leading to an increase in flooding. Specific vulnerabilities
highlighted by the NCA include long-term decreases in agricultural
productivity, changes in the composition of the region's forests,
increased public health threats from heat waves and degraded air and
water quality, negative impacts on transportation and other
infrastructure associated with extreme rainfall events and flooding,
and risks to the Great Lakes including shifts in invasive species,
increases in harmful algal blooms, and declining beach health.
    High temperatures (more than 100[emsp14][deg]F in the Southern
Plains and more than 95[emsp14][deg]F in the Northern Plains) are
projected to occur much more frequently by mid-century. Increases in
extreme heat will increase heat stress for residents, energy demand for
air conditioning, and water losses. North Dakota's increase in annual
temperatures over the past 130 years is the fastest in the contiguous
U.S., mainly driven by warming winters. Specific vulnerabilities
highlighted by the NCA include increased demand for water and energy,
changes to crop-growth cycles and agricultural practices, and negative
impacts on local plant and animal species from habitat fragmentation,
wildfires, and changes in the timing of flowering or pest patterns.
Communities that are already the most vulnerable to weather and climate
extremes will be stressed even further by more frequent extreme events
occurring within an already highly variable climate system.
    In Hawaii, other Pacific islands, and the Caribbean, rising air and
ocean temperatures, shifting rainfall patterns, changing frequencies
and intensities of storms and drought, decreasing baseflow in streams,
rising sea levels, and changing ocean chemistry will affect ecosystems
on land and in the oceans, as well as local communities, livelihoods,
and cultures. Low islands are particularly at risk.
    Rising sea levels, coupled with high water levels caused by
tropical and extra-tropical storms, will incrementally increase coastal
flooding and erosion, damaging coastal ecosystems, infrastructure, and
agriculture, and negatively affecting tourism. Ocean temperatures in
the Pacific region exhibit strong year-to-year and decadal
fluctuations, but since the 1950s, they have exhibited a warming trend,
with temperatures from the surface to a depth of 660 feet rising by as
much as 3.6[emsp14][deg]F. As a result of current sea level rise, the
coastline of Puerto Rico around Rinc[oacute]n is being eroded at a rate
of 3.3 feet per year. Freshwater supplies are already constrained and
will become more limited on many islands. Saltwater intrusion
associated with sea level rise will reduce the quantity and quality of
freshwater in coastal aquifers, especially on low islands. In areas
where precipitation does not increase, freshwater supplies will be
adversely affected as air temperature rises.
    Warmer oceans are leading to increased coral bleaching events and
disease outbreaks in coral reefs, as well as changed distribution
patterns of tuna fisheries. Ocean acidification will reduce coral
growth and health. Warming and acidification, combined with existing
stresses, will strongly affect coral-reef fish communities. For Hawaii
and the Pacific islands, future sea surface temperatures are projected
to increase 2.3[emsp14][deg]F by 2055 and 4.7[emsp14][deg]F by 2090
under a scenario that assumes continued increases in emissions. Ocean
acidification is also taking place in the region, which adds to
ecosystem stress from increasing temperatures. Ocean acidity has
increased by about 30 percent since the pre-industrial era and is
projected to further increase by 37 percent to 50 percent from present
levels by 2100.
    The NCA also discussed impacts that occur along the coasts and in
the oceans adjacent to many regions, and noted that other impacts occur
across regions and landscapes in ways that do not follow political
boundaries.

B. GHG Emissions From Fossil Fuel-Fired EGUs

    Fossil fuel-fired EGUs are by far the largest emitters of GHGs
among stationary sources in the U.S., primarily in the form of
CO2. Among fossil fuel-fired EGUs, coal-fired units are by
far the largest emitters. This section describes the amounts of these
emissions and places these amounts in the context of the U.S. Inventory
of Greenhouse Gas Emissions and Sinks \34\ (the U.S. GHG Inventory).
---------------------------------------------------------------------------

    \34\ ``Inventory of U.S. Greenhouse Gas Emissions and Sinks:
1990-2013'', Report EPA 430-R-15-004, United States Environmental
Protection Agency, April 15, 2015. http://epa.gov/climatechange/ghgemissions/usinventoryreport.html.
---------------------------------------------------------------------------

    The EPA implements a separate program under 40 CFR part 98 called
the Greenhouse Gas Reporting Program \35\ (GHGRP) that requires
emitting facilities that emit over certain threshold amounts of GHGs to
report their emissions to the EPA annually. Using data from the GHGRP,
this section also places emissions from fossil fuel-fired EGUs in the
context of the total emissions reported to the GHGRP from facilities in
the other largest-emitting industries.
---------------------------------------------------------------------------

    \35\ U.S. EPA Greenhouse Gas Reporting Program Dataset, see
http://www.epa.gov/ghgreporting/ghgdata/reportingdatasets.html.
---------------------------------------------------------------------------

    The EPA prepares the official U.S. GHG Inventory to comply with
commitments under the United Nations Framework Convention on Climate

Change (UNFCCC). This inventory, which includes recent trends, is
organized by industrial sector. It provides the information in Table 3
below, which presents total U.S. anthropogenic emissions and sinks \36\
of GHGs, including CO2 emissions, for the years 1990, 2005
and 2013.
---------------------------------------------------------------------------

    \36\ Sinks are physical units or processes that store GHGs, such
as forests or underground or deep sea reservoirs of CO2.
    \37\ From Table ES-4 of ``Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2013'', Report EPA 430-R-15-004, United
States Environmental Protection Agency, April 15, 2015. http://epa.gov/climatechange/ghgemissions/usinventoryreport.html.
    \38\ 1 metric ton (tonne) is equivalent to 1,000 kilograms (kg)
and is equivalent to 1.1023 short tons or 2,204.62 pounds (lb).
    \39\ The energy sector includes all greenhouse gases resulting
from stationary and mobile energy activities including fuel
combustion and fugitive fuel emissions.

 Table 3--U.S. GHG Emissions and Sinks by Sector (million metric tons carbon dioxide equivalent (MMT CO2e))\37\
                                                      \38\
----------------------------------------------------------------------------------------------------------------
                         Sector                                 1990               2005               2013
----------------------------------------------------------------------------------------------------------------
Energy\39\.............................................            5,290.5            6,273.6            5,636.6
Industrial Processes and Product Use...................              342.1              367.4              359.1
Agriculture............................................              448.7              494.5              515.7
Land Use, Land-Use Change and Forestry.................               13.8               25.5               23.3
Waste..................................................              206.0              189.2              138.3
                                                        --------------------------------------------------------
    Total Emissions....................................            6,301.1            7,350.2            6,673.0
Land Use, Land-Use Change and Forestry (Sinks).........            (775.8)            (911.9)            (881.7)
                                                        --------------------------------------------------------
    Net Emissions (Sources and Sinks)..................            5,525.2            6,438.3            5,791.2
----------------------------------------------------------------------------------------------------------------

    Total fossil energy-related CO2 emissions (including
both stationary and mobile sources) are the largest contributor to
total U.S. GHG emissions, representing 77.3 percent of total 2013 GHG
emissions.\40\ In 2013, fossil fuel combustion by the utility power
sector--entities that burn fossil fuel and whose primary business is
the generation of electricity--accounted for 38.3 percent of all
energy-related CO2 emissions.\41\ Table 4 below presents
total CO2 emissions from fossil fuel-fired EGUs, for years
1990, 2005, and 2013.
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    \40\ From Table ES-2 ``Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2013'', Report EPA 430-R-15-004, United
States Environmental Protection Agency, April 15, 2015. http://epa.gov/climatechange/ghgemissions/usinventoryreport.html.
    \41\ From Table 3-1 ``Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013'', Report EPA 430-R-15-004, United States
Environmental Protection Agency, April 15, 2015. http://epa.gov/climatechange/ghgemissions/usinventoryreport.html.

    Table 4--U.S. GHG Emissions from Generation of Electricity from Combustion of Fossil Fuels (MMT CO2)\42\
----------------------------------------------------------------------------------------------------------------
                     GHG emissions                              1990               2005               2013
----------------------------------------------------------------------------------------------------------------
Total CO2 from fossil fuel-fired EGUs..................            1,820.8            2,400.9            2,039.8
    --from coal........................................            1,547.6            1,983.8            1,575.0
    --from natural gas.................................              175.3              318.8              441.9
    --from petroleum...................................               97.5               97.9               22.4
----------------------------------------------------------------------------------------------------------------

    In addition to preparing the official U.S. GHG Inventory to present
comprehensive total U.S. GHG emissions and comply with commitments
under the UNFCCC, the EPA collects detailed GHG emissions data from the
largest emitting facilities in the U.S. through its GHGRP. Data
collected by the GHGRP from large stationary sources in the industrial
sector show that the utility power sector emits far greater
CO2 emissions than any other industrial sector. Table 5
below presents total GHG emissions in 2013 for the largest emitting
industrial sectors as reported to the GHGRP. As shown in Table 4 and
Table 5, respectively, CO2 emissions from fossil fuel-fired
EGUs are nearly three times as large as the total reported GHG
emissions from the next ten largest emitting industrial sectors in the
GHGRP database combined.
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    \42\ From Table 3-5 ``Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013'', Report EPA 430-R-15-004, United States
Environmental Protection Agency, April 15 2015. http://epa.gov/climatechange/ghgemissions/usinventoryreport.html.
    \43\ U.S. EPA Greenhouse Gas Reporting Program Dataset as of
August 18, 2014. http://ghgdata.epa.gov/ghgp/main.do.

   Table 5--Direct GHG Emissions Reported to GHGRP by Largest Emitting
                    Industrial Sectors (MMT CO2e)\43\
------------------------------------------------------------------------
                  Industrial sector                           2013
------------------------------------------------------------------------
Fossil Fuel-Fired EGUs...............................            2,039.8
Petroleum Refineries.................................              176.7
Onshore Oil & Gas Production.........................               94.8
Municipal Solid Waste Landfills......................               93.0
Iron & Steel Production..............................               84.2
Cement Production....................................               62.8
Natural Gas Processing Plants........................               59.0
Petrochemical Production.............................               52.7
Hydrogen Production..................................               41.9
Underground Coal Mines...............................               39.8
Food Processing Facilities...........................               30.8
------------------------------------------------------------------------

    It should be noted that the discussion above concerned all fossil
fuel-fired EGUs. Steam generators emitted 1,627 MMT CO2e and
combustion turbines emitted 401 MMT CO2e in 2013.\44\
---------------------------------------------------------------------------

    \44\ These figures are based on data for EGUs in the Acid Rain
Program plus additional ones that report to the EPA under the
Regional Greenhouse Gas Initiative.
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C. The Utility Power Sector

1. Modern Electric System Trends
    The EPA includes a background discussion of the electricity system
in the Clean Power Plan (CPP) rulemaking, which is the companion
rulemaking to this rule that promulgates emission guidelines for states
to use in regulating emissions of CO2 from existing fossil
fuel-fired EGUs. Readers are referred to that rulemaking. The following
discussion of electricity sector trends is of particular relevance for
this rulemaking.
    The electricity sector is undergoing a period of intense change.
Fossil fuels--such as coal, natural gas, and oil--have historically
provided a large percentage of electricity in the U.S., with smaller
amounts being provided by other types of generation, including nuclear
and renewables such as wind, solar, and hydroelectric power. Coal has
historically provided the largest percentage of fossil-fuel
generation.\45\ In recent years, the nation has seen a sizeable
increase in renewable generation such as wind and solar, as well as a
shift from coal to natural gas.\46\ In 2013, fossil fuels supplied 67
percent of U.S. electricity, but renewables made up 38 percent of the
new generation capacity (over 5 GW out of 13.5 GW).\47\ From 2007 to
2014, use of lower- and zero-carbon energy sources has grown, while
other major energy sources such as coal and oil have experienced
declines. Renewable electricity generation, including from large hydro-
electric projects, grew from 8 percent to 13 percent over that time
period.\48\ Between 2000 and 2013, approximately 90 percent of new
power generation capacity built in the U.S. has come in the form of
natural gas or renewable energy facilities.\49\ In 2015, the U.S.
Energy Information Administration (EIA) projected the need for 28.4 GW
of additional base load or intermediate load generation capacity
through 2020, with approximately 0.7 GW of new coal-fired capacity, 5.5
GW of new nuclear capacity, and 14.2 GW of new NGCC capacity already in
development.\50\
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    \45\ U.S. Energy Information Administration, ``Table 7.2b
Electricity Net Generation: Electric Power Sector'' data from April
2014 Monthly Energy Review, release data April 25, 2014, available
at http://www.eia.gov/totalenergy/data/monthly/pdf/sec7_6.pdf.
    \46\ U.S. Energy Information Administration, ``Table 7.2b
Electricity Net Generation: Electric Power Sector'' data from April
2014 Monthly Energy Review, release data April 25, 2014, available
at http://www.eia.gov/totalenergy/data/monthly/pdf/sec7_6.pdf.
    \47\ Based on Table 6.3 (New Utility Scale Generating Units by
Operating Company, Plant, Month, and Year) of the U.S. Energy
Information Administration (EIA) Electric Power Monthly, data for
December 2013, for the following renewable energy sources: Solar,
wind, hydro, geothermal, landfill gas, and biomass. Available at:
http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_6_03.
    \48\ Bloomberg New Energy Finance and the Business Council for
Sustainable Energy, 2015 Factbook: Sustainable Energy in America, at
16 (2015), available at http://www.bcse.org/images/2015%20Sustainable%20Energy%20in%20America%20Factbook.pdf.
    \49\ Energy Information Administration, Electricity: Form EIA-
860 detailed data (Feb. 17, 2015), available at http://www.eia.gov/electricity/data/eia860/.
    \50\ EIA, Annual Energy Outlook for 2015 with Projections to
2040, Final Release, available at http://www.eia.gov/forecasts/AEO/pdf/0383(2015). The AEO numbers include projects that are under
development and model-projected nuclear, coal, and NGCC projects.
---------------------------------------------------------------------------

    The change in the resource mix has accelerated in recent years, but
wind, solar, other renewables, and energy-efficiency resources have
been reliably participating in the electric sector for a number of
years. This rapid development of non-fossil fuel resources is occurring
as much of the existing power generation fleet in the U.S. is aging and
in need of modernization and replacement.\51\ For example, the average
age of U.S. coal steam units in 2015 is 45 years.\52\ In its 2013
Report Card for America's Infrastructure, the American Society for
Civil Engineers noted that ``America relies on an aging electrical grid
and pipeline distribution systems, some of which originated in the
1880s.'' \53\ While there has been an increased investment in electric
transmission infrastructure since 2005, the report also found that
``ongoing permitting issues, weather events, and limited maintenance
have contributed to an increasing number of failures and power
interruptions.''\54\ However, innovative technologies have increasingly
entered the electric energy space, helping to provide new answers to
how to meet the electricity needs of the nation. These new technologies
can enable the nation to answer not just questions as to how to
reliably meet electricity demand, but also how to meet electricity
demand reliably and cost-effectively\55\ with the lowest possible
emissions and the greatest efficiency.
---------------------------------------------------------------------------

    \51\ Quadrennial Energy Review, http://energy.gov/epsa/quadrennial-energy-review-qer.
    \52\ We calculated the average age of coal steam units based on
the NEEDS inventory, and included units with planned retirements in
2015-2016. See http://www.epa.gov/airmarkets/documents/ipm/needs_v514.xlsx.
    \53\ American Society for Civil Engineers, 2013 Report Card for
America's Infrastructure (2013), available at http://www.infrastructurereportcard.org/energy/.
    \54\ American Society for Civil Engineers, 2013 Report Card for
America's Infrastructure (2013), available at http://www.infrastructurereportcard.org/energy/.
    \55\ Business Council for Sustainable Energy Comments in Docket
Id. No. EPA-HQ-OAR-2013-0602 at 2 (Nov. 19, 2014).
---------------------------------------------------------------------------

    Natural gas has a long history of meeting electricity demand in the
U.S. with a rapidly growing role as domestic supplies of natural gas
have dramatically increased. Natural gas net generation increased by
approximately 36 percent between 2004 and 2014.\56\ In 2014, natural
gas accounted for approximately 27 percent of net generation.\57\ The
EIA projects that this demand growth will continue, with its Annual
Energy Outlook 2015 (AEO 2015) reference case forecasting that natural
gas will produce 31 percent of U.S. electric generation in 2040.\58\
---------------------------------------------------------------------------

    \56\ U.S. Energy Information Administration (EIA), Electric
Power Monthly: Table 1.1 Net Generation by Energy Source: Total (All
Sectors), 2004-December 2014 (2015), available at http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_1_1.
    \57\ Id.
    \58\ The AEO 2015 Reference case projection is a business-as-
usual trend estimate, given known technology and technological and
demographic trends. EIA explores the impacts of alternative
assumptions in other cases with different macroeconomic growth
rates, world oil prices, and resource assumptions. U.S. Energy
Information Administration (EIA), Annual Energy Outlook 2015 with
Projections to 2040, at 24-25 (2015), available at http://
www.eia.gov/forecasts/aeo/pdf/0383(2015).pdf.
---------------------------------------------------------------------------

    Renewable sources of electric generation also have a history of
meeting electricity demand in the U.S. and are expected to have an
increasing role going forward. A series of energy crises provided the
impetus for renewable energy development in the early 1970s. The OPEC
oil embargo in 1973 and oil crisis of 1979 caused oil price spikes,
more frequent energy shortages, and significantly affected the national
and global economy. In 1978, partly in response to fuel security
concerns, Congress passed the Public Utilities Regulatory Policies Act
(PURPA) which required local electric utilities to buy power from
qualifying facilities (QFs).\59\ QFs were either cogeneration
facilities \60\ or small

generation resources that use renewables such as wind, solar, biomass,
geothermal, or hydroelectric power as their primary fuels.\61\ Through
PURPA, Congress supported the development of more renewable energy
generation in the U.S. States have taken a significant lead in
requiring the development of renewable resources. In particular, a
number of states have adopted renewable portfolio standards (RPS). As
of 2013, 29 states and the District of Columbia have enforceable RPS or
similar laws.\62\ In its AEO 2015 Reference case, the EIA found that
renewable energy will account for 38 percent of the overall growth in
electricity generation from 2013 to 2040.\63\ The AEO 2015 Reference
case forecasts that the renewables share of U.S. electricity generation
will grow from 13 percent in 2013 to 18 percent in 2040.\64\
---------------------------------------------------------------------------

    \59\ Casazza, J. and Delea, F., Understanding Electric Power
Systems, IEEE Press, at 220-221 (2d ed. 2010).
    \60\ Cogeneration facilities utilize a single source of fuel to
produce both electricity and another form of energy such as heat or
steam. Casazza, J. and Delea, F., Understanding Electric Power
Systems, IEEE Press, at 220-221 (2d ed. 2010).
    \61\ Casazza, J. and Delea, F., Understanding Electric Power
Systems, IEEE Press, at 220-221 (2d ed. 2010).
    \62\ U.S. Energy Information Administration (EIA), Annual Energy
Outlook 2014 with Projections to 2040, at LR-5 (2014).
    \63\ U.S. Energy Information Administration (EIA), Annual Energy
Outlook 2015 with Projections to 2040, at E-12 (2015).
    \64\ U.S. Energy Information Administration (EIA), Annual Energy
Outlook 2015 with Projections to 2040, at 24-25(2015).
---------------------------------------------------------------------------

    Price pressures caused by oil embargoes in the 1970s also brought
the issues of conservation and energy efficiency to the forefront of
U.S. energy policy.\65\ This trend continued in the early 1990s. Some
state regulatory commissions and utilities supported energy efficiency
through least-cost planning, with the National Association of
Regulatory Utility Commissioners (NARUC) ``adopting a resolution that
called for the utility's least cost plan to be the utility's most
profitable plan.'' \66\ Energy efficiency has been utilized to meet
energy demand to varying levels since that time. As of April 2014, 25
states \67\ have ``enacted long-term (3+ years), binding energy savings
targets, or energy efficiency resource standards (EERS).'' \68\ Funding
for energy efficiency programs has grown rapidly in recent years, with
budgets for electric efficiency programs totaling $5.9 billion in
2012.\69\
---------------------------------------------------------------------------

    \65\ Edison Electric Institute, Making a Business of Energy
Efficiency: Sustainable Business Models for Utilities, at 1 (2007).
Congress passed legislation in the 1970s that jumpstarted energy
efficiency in the U.S. For example, President Ford signed the Energy
Policy and Conservation Act (EPCA) of 1975--the first law on the
issue. EPCA authorized the Federal Energy Administration (FEA) to
``develop energy conservation contingency plans, established vehicle
fuel economy standards, and authorized the creation of efficiency
standards for major household appliances.'' Alliance to Save Energy,
History of Energy Efficiency, at 6 (2013) (citing Anders, ``The
Federal Energy Administration,'' 5; Energy Policy and Conservation
Act, S. 622, 94th Cong. (1975-1976)), available at https://www.ase.org/sites/ase.org/files/resources/Media%20browser/ee_commission_history_report_2-1-13.pdf.
    \66\ Edison Electric Institute, Making a Business of Energy
Efficiency: Sustainable Business Models for Utilities, at 1 (2007),
available at http://www.eei.org/whatwedo/PublicPolicyAdvocacy/StateRegulation/Documents/Making_Business_Energy_Efficiency.pdf.
    \67\ American Council for an Energy-Efficient Economy, State
Energy Efficiency Resource Standards (EERS) (2014), available at
http://aceee.org/files/pdf/policy-brief/eers-04-2014.pdf. ACEEE did
not include Indiana (EERS eliminated), Delaware (EERS pending),
Florida (programs funded at levels far below what is necessary to
meet targets), Utah, or Virginia (voluntary standards) in its
calculation.
    \68\ American Council for an Energy-Efficient Economy, State
Energy Efficiency Resource Standards (EERS) (2014), available at
http://aceee.org/files/pdf/policy-brief/eers-04-2014.pdf.
    \69\ American Council for an Energy-Efficient Economy, The 2013
State Energy Efficiency Scorecard, at 17 (Nov. 2013), available at
http://aceee.org/sites/default/files/publications/researchreports/e13k.pdf.
---------------------------------------------------------------------------

    Advancements and innovation in power sector technologies provide
the opportunity to address CO2 emission levels at affected
power plants while at the same time improving the overall power system
in the U.S. by lowering the carbon intensity of power generation, and
ensuring a reliable supply of power at a reasonable cost.
2. Fossil Fuel-Fired EGUs Regulated by this Action, Generally
    Natural gas-fired EGUs typically use one of two technologies: NGCC
or simple cycle combustion turbines. NGCC units first generate power
from a combustion turbine (the combustion cycle). The unused heat from
the combustion turbine is then routed to a heat recovery steam
generator (HRSG) that generates steam, which is then used to produce
power using a steam turbine (the steam cycle). Combining these
generation cycles increases the overall efficiency of the system.
Simple cycle combustion turbines use a single combustion turbine to
produce electricity (i.e., there is no heat recovery or steam cycle).
The power output from these simple cycle combustion turbines can be
easily ramped up and down making them ideal for ``peaking'' operations.
    Coal-fired utility boilers are primarily either pulverized coal
(PC) boilers or fluidized bed (FB) boilers. At a PC boiler, the coal is
crushed (pulverized) into a powder in order to increase its surface
area. The coal powder is then blown into a boiler and burned. In a
coal-fired boiler using FB combustion, the coal is burned in a layer of
heated particles suspended in flowing air.
    Power can also be generated using gasification technology. An IGCC
unit gasifies coal or petroleum coke to form a synthetic gas (or
syngas) composed of carbon monoxide (CO) and hydrogen (H2),
which can be combusted in a combined cycle system to generate power.
3. Technological Developments and Costs
    Natural gas prices have decreased dramatically and generally
stabilized in recent years as new drilling techniques have brought
additional supply to the marketplace and greatly increased the domestic