Is Biopower Carbon Neutral?
Kelsi Bracmort
Specialist in Agricultural Conservation and Natural Resources Policy
February 19September 28, 2015
Congressional Research Service
7-5700
www.crs.gov
R41603
Is Biopower Carbon Neutral?
Summary
To promote energy diversity and improve energy security, Congress has expressed interest in
biopower—electricity generated from biomass. Biopower, a baseload power source, can be
produced from a large range of biomass feedstocks nationwide (e.g., urban, agricultural, and
forestry wastes and residues). The two most common biopower processes are combustion (e.g.,
direct-fired or co-fired) and gasification, with the former being the most widely used. Proponents
sayhave stated that biopower has the potential to strengthen rural economies, enhance energy
security, and
minimize the environmental impacts of energy production. Challenges to biopower production
production include the need for a sufficient feedstock supply, concerns about potential health
impacts to
nearby communities from the combustion of biomass, and its higher generation costs
relative to fossil fuel-based electricity. At
present, biopower generally requires tax incentives to
be competitive with conventional fossil
fuel-fired electric generation.
The legislative record shows minimal debate about the carbon status of biopower. An energy
An energy production activity typically is classified as carbon neutral if it produces no net
increase in
greenhouse gas (GHG) emissions on a life-cycle basis. The legislative record shows
minimal debate about the carbon status of biopower. The argument that biopower is carbon
neutral has come under scrutiny in debate on its potential to help meet U.S. energy demands and
reduce U.S. GHG emissions. Whether biopower is considered carbon neutral depends on many
factors, including the definition of carbon neutrality, feedstock type, technology used, and time
frame examined. Carbon flux (emission and sequestration) varies at each phase of the biopower
pathway, given site- and operation-specific factors. A life-cycle assessment (LCA) is a common
technique to calculate the environmental footprint, including the carbon flux, of a particular
biopower pathway. However, past legislation would not have required a standardized LCA for
biopower.
The carbon-neutral status of biopower may be of concern to stakeholders, especially if Congress
expands support for biopower. Questions such as where the feedstock supply for biopower
originates, if it is managed in a sustainable manner, and whether the associated air-quality impacts
impacts from biopower generation are tolerable are part of the biopower carbon-neutrality debate.
Congress may decide whether the current carbon-neutral designation for biopower is accurate or
approach regarding the carbon status of biopower is
acceptable or whether additional carbon accounting for biopower is warranted and what impact
this accounting
might have on renewable energy, agricultural, and environmental legislative
goals.
Two recent actions by the executive branch—the U.S. Environmental Protection Agency’s
(EPA’s) proposed standards for GHG emissions from existing fossil-fueled power plants (i.e., the
Clean Power Plan)Clean Power Plan (CPP), which addresses carbon dioxide (CO2) emission reductions
from existing fossil fuel-fired electric power plants, and EPA’s proposed framework to account for emissions of biogenic carbon
dioxide (CO2)
for biogenic CO2 emissions from stationary sources—could focus attention on biopower’s carbon
neutrality.
The Clean Power Plan establishes state-specific CO2 emission rate targets, measured in pounds of
CO2 per megawatt-hour of electricity. It uses four building blocks to establish the emission rate
targets, which could include the use of biomass-derived fuels at affected electric generating units.
The CPP requires states to devise a plan that allows them to reach a state-specific CO2
emission reduction goal by 2030, using various options, including renewable energy (e.g.,
biopower). In the CPP final rule, EPA specifies that “qualified biomass” may be included in a
state plan given certain conditions. In November 2014, EPA released its second biogenic
accounting framework. The framework
addresses some of the EPA Science Advisory Board’s
recommendations from the first framework
, released in 2011, including the finding that “carbon
neutrality cannot be assumed for all biomass
energy a priori.” EPA acknowledges that the
framework is an analytical methodology and that
some stakeholders may consider it a precursor toan example
of how EPA may treat biogenic emissions in both
the Clean Power Plan the CPP and the Prevention of Significant
Deterioration program. However, EPA
reports that it “has not yet determined how the framework
might be applied in any particular
regulatory or policy contexts or taken the steps needed for such
implementation.”
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Is Biopower Carbon Neutral?
Contents
Introduction. ..................................................................................................................................... 1
Biomass Carbon Cycle. .................................................................................................................... 2
Greenhouse Gas Emission Accounting for Biopower Production ................................................... 3
Recent Developments Affecting Biopower Assessment .................................................................. 6
6
The Clean Power Plan Proposed Rule ............................................................................................................... 7
Framework for Assessing Biogenic CO2 Emissions from Stationary Sources .......................... 7
Prevention of Significant Deterioration/New Source Review Program and Title V
Greenhouse Gas Permitting Requirements ............................................................................. 9 8
Best Available Control Technologies .................................................................................. 9
Considerations for the Regulation of Biogenic CO2 Emissions ...................................................... 9 10
Is Biopower Carbon Neutral? It Depends ...................................................................................... 10
Legislative Implications ................................................................................................................. 11
Figures
Figure 1. Bioenergy CO2 Balance vs. Fossil Fuel CO2 Balance ...................................................... 4
Figure 2. Biopower and Biofuel Pathways ...................................................................................... 5
Contacts
Author Contact Information. .......................................................................................................... 12
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Is Biopower Carbon Neutral?
Introduction
Biomass energy, or bioenergy, may receive more attention from stakeholders as an alternative to
fossil fuels because of its potential to minimize the environmental impacts of energy production,
provide energy security, and promote economic development. Biomass is organic matter—woody
biomass, agricultural biomass, animal wastes, and aquatic biomass—that can be converted to
energy (e.g., heat, electricity, or liquid transportation fuels).1 Thus far, the federal government has
given legislative support for one form of bioenergy, biopower (electricity generated from
biomass, such as paper mill residue used to generate power),2 without considering its carbon
statusOne form of bioenergy is biopower,
electricity generated from biomass (e.g., paper mill residues). As federal and state governments
and others dedicate more resources to biopower, these
same government agencies, along with
environmentalists, biomass feedstock producers, and
others others, are paying more attention to the
biopower carbon-neutrality issue. The carbon-neutral
designation typically is assigned to an
energy-production activity that essentially produces no net
increase in greenhouse gas (GHG)
emissions on a life-cycle basis (or one that absorbs the amount
of carbon dioxide emitted during
the power-production cycle).32 Where biopower stands among
the other renewable energy sources
with respect to GHG emissions may affect the level of future
legislative support granted to it.
Many views exist about whether biopower is carbon neutral and how its net carbon status is
determined. Some biomass feedstock producers and biopower generators, among other
stakeholders, contend that biopower is carbon neutral because the carbon released during
bioenergy production comes from a carbon-neutral feedstockfeedstock that removed the carbon from the atmosphere as it
was growing—biomass. Some environmentalists,
among others, argue that biopower is not
carbon neutral because the amount of GHG emissions
released per unit of energy during simple
biopower combustion may be higher for certain biomass
fuels than for fossil fuels or because,
even if the GHG emissions from certain biomass fuels are
lower than those from fossil fuels, they
are still not zero. Stakeholders often base their
perspectives on differing assumptions,
technologies, and time frames.
The debate concerning biopower’s designation as carbon neutral may intensify, given possible
congressional and Administration decisions. Congress may consider legislation involving
biopower (e.g., under renewable energy and clean energy assistance, energy efficiency, and GHG
emission reduction policy). and energy efficiency).
Additionally, biopower production may receive increased attention
due to executive branch
actions, such as the U.S. Environmental Protection Agency’s (EPA’s)
proposed standards for GHG emissions from existing fossil-fueled power plants (e.g., the Clean
Power Plan)4 and Clean Power Plan3 and
EPA’s proposed framework to account for emissions of biogenic carbon dioxide
(CO2) from stationary sources.
1
For more information on biomass, see CRS Report R40529, Biomass: Comparison of Definitions in Legislation, by
Kelsi Bracmort.
2
Biopower is a baseload power source offering firm power without the need for power storage. Combustion—the
burning of biomass in a power plant—is the dominant technology used to produce biopower.
3
stationary sources.
This report discusses some factors taken into account when considering whether biopower is
carbon neutral. It does not discuss carbon accounting for other bioenergy pathways.4
1
For more information on biomass, see CRS Report R40529, Biomass: Comparison of Definitions in Legislation, by
Kelsi Bracmort.
2
The life cycle of a bioenergy pathway includes all stages of fuel and feedstock production and distribution, from
feedstock generation or extraction through distribution, delivery, and use of the finished fuel by the ultimate consumer.
The mass values for all greenhouse gases (GHGs) are adjusted to account for their relative global warming potential.
43
For more information, see CRS Report R43572, EPA’s Proposed Greenhouse Gas Regulations for Existing Power
Plants: Frequently Asked Questions.
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This report discusses some factors taken into account when considering whether biopower is
carbon neutral. It does not discuss carbon accounting for other bioenergy pathways.5R44145, EPA’s Clean Power Plan: Highlights of the Final Rule, by Jonathan
L. Ramseur and James E. McCarthy.
4
Congress addressed carbon accounting for another major bioenergy pathway—liquid transportation biofuels—with a
life-cycle emission analysis (a requirement within the Renewable Fuel Standard). For more information, see CRS
Report R40460, Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard (RFS), by Brent
D. Yacobucci and Kelsi Bracmort.
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Biomass Carbon Cycle
The carbon cycle encompasses the many pathways through which carbon is exchanged between
the atmosphere and the land and water.65 Human activities (also called anthropogenic activities)
contribute to the carbon cycle by emitting CO2. The human contribution of CO2 to the carbon
cycle is relatively small compared to other contributions, but CO2 released to the atmosphere
from human activities is taken up by soils, vegetation, and the ocean at a rate that is relatively
slowerslower rate than the rate
at which human activities are emitting CO2. If the excess carbon is not stored
in land and ocean
sinks, the atmospheric concentration of CO2 increases, potentially impacting
the Earth’s climate.
One significant anthropogenic source of CO2 in the carbon cycle is energy production. The net
effect of an energy
activity on the carbon cycle can be classified in one of three ways. A carbonpositivecarbon-positive activity
releases CO2 into the atmosphere. A carbon-negative activity removes more CO2
from the
atmosphere than it emits. A carbon-neutral activity is one in which the CO2 release and
absorption are essentially in balance. No commonly accepted definition for a carbon-neutral
activity exists in
the biopower arena. Those involved with bioenergy have put forth multiple
assertions about
carbon neutrality, including the following:7
•6
Biomass energy is carbon neutral because biomass is naturally carbon neutral.
The premise is that if biomass is carbon neutral, then any product resulting from
its use is also carbon neutral.
•
Biomass energy is carbon neutral if growing the biomass removes as much CO2
as is emitted into the atmosphere from its combustion.
•
Biomass energy is carbon neutral only if the net life-cycle emissions are zero.87
Emissions include the emissions from the cultivation, harvest, and transportation
of the biomass, as well as from its combustion.
•
Biomass energy is carbon neutral if it achieves lower net increases in
atmospheric GHGs when compared to alternative energy activities.
Each assertion raises issues. For instance, declaring that biomass energy is carbon neutral because
biomass is naturally carbon neutral does not account for GHG emissions released due to
management of crops grown for energy production (e.g., fertilizer). In addition, there may need to
5
Congress addressed carbon accounting for another major bioenergy pathway—liquid transportation biofuels—with a
life-cycle emission analysis (a requirement within the Renewable Fuel Standard). For more information, see CRS
Report R40460, Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard (RFS), by Brent
D. Yacobucci and Kelsi Bracmort.
6
be additional plantings of certain biomass feedstocks to remove the CO2 emitted from biomass
cultivated for energy production.
The carbon cycles for a bioenergy system and a fossil fuel system differ in at least two ways: the
carbon source (finite versus renewable) and the atmospheric carbon concentration (potentially
stable versus additional; see Figure 1). Three main factors contribute to the amount of carbon
emitted from biopower generation: feedstock production (cultivation and harvest), feedstock
transport, and the biopower technology type. However, as noted by many sources, feedstock
production also absorbs carbon during growth.
5
Carbon is an elemental building block of molecules that make up all organisms on Earth. Carbon cycling is the
process by which living things absorb carbon from the atmosphere, carbonate rocks and ocean deposits, dead organic
matter in the soil, or food and return it to the atmosphere or soil by respiration, combustion, or decay.
76
R. Miner, “Biomass Carbon Neutrality in the Context of Forest-based Fuels and Products,” U.S. Department of
Agriculture (USDA) Bioelectricty and GHG Workshop, Washington, DC, November 15, 2010. Some of the definitions
are not mutually exclusive.
87
A life-cycle assessment (LCA) accounts for the GHG emissions from bioenergy production. The LCA is further
discussed in “Greenhouse Gas Emission Accounting for Biopower Production,” below.
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be additional plantings of certain biomass feedstocks to remove the CO2 emitted from biomass
cultivated for energy production.
The carbon cycles for a bioenergy system and a fossil fuel system differ in at least two ways: the
carbon source (finite versus renewable) and the atmospheric carbon concentration (potentially
stable versus additional; see Figure 1). Three main factors contribute to the amount of carbon
emitted from biopower generation: feedstock production (cultivation and harvest), feedstock
transport, and the biopower technology type. However, as noted by many sources, feedstock
production also absorbs carbon during growth.
Greenhouse Gas Emission Accounting for
Biopower Production
Whether and how to conduct GHG emission accounting for biopower are issues that have been
under consideration for the last few years. GHG emission accounting can be used to compare the
environmental footprint of a biopower operation with that of a conventional fossil fuel operation
(e.g., electricity from coal or natural gas).98 A life-cycle assessment (LCA) is one method to
calculate the environmental footprint. The LCA is an analytic method for identifying, evaluating,
and comparing the environmental impacts of emissions and the resource depletion associated with
a specific process.109 An LCA generally uses observed data and assumptions to model what GHGs
are being released at each phase of the process. Ideally, an LCA would encompass economic and
social factors for a more comprehensive assessment (e.g., job growth, poverty). However, most
LCAs focus exclusively on emissions and fossil fuel consumption. An LCA can be one element
used in assessing a preferred energy approach, along with cost and performance data. In some
cases, even if LCA results favor a particular approach, an LCA alone might not be the deciding
factor when choosing an energy process; financial objectives, policy goals, and other factors may
influence which approach is selected.
98
For the purposes of this report, greenhouse gas emission accounting refers to methods used to compute the GHGs
emitted from one or more stages of biopower production. Further carbon flux, or GHG flux, refers to the total
greenhouse gas emitted or sequestered at particular stages of the biopower production process.
109
National Renewable Energy Laboratory, Energy Analysis, October 2010, at http://www.nrel.gov/analysis/
tech_bio_analysis.html. For more information on life-cycle assessments, see U.S. Environmental Protection Agency
(EPA), Life Cycle Assessment: Principles and Practice, EPA/600/R-06/060, Cincinnati, OH, May 2006.
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Figure 1. Bioenergy CO2 Balance vs. Fossil Fuel CO2 Balance
Source: International Energy Agency (IEA), IEA Bioenergy Task 38, Greenhouse Gas Balances of Bioenergy and
Bioenergy Systems, 2002. Adapted by the Congressional Research Service (CRS).
Notes: The magnitude of the carbon flows, as indicated by the width of the arrows, is a significant part of the
debate over the carbon neutrality of bioenergy.
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GHG accounting with an LCA can be performed at each phase of the biopower pathway: biomass
cultivation and harvest, biomass transport, electricity generation, electricity transmission and
distribution, and electricity end use (see Figure 2). The first three phases of the biopower
pathway pathway
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(cultivation and harvest, transport, and electricity generation) are where the bulk of
GHG GHG
emissions occur. GHG flux during the first three phases is site and operation specific and
depends depends
on many factors, including the biomass type, management strategies, and biopower
generation generation
technology.
Figure 2. Biopower and Biofuel Pathways
Source: Q. Zhang, K.R. Goldstein, and J.R. Mihelcic, “A Review of Life Cycle Assessment Renewable Energy
Derived from Forest Resources,” in Renewable Energy from Forest Resources in the United States, ed. B. D.
Solomon, C. A. Luzadis (New York: Routledge, 2009). Adapted by CRS.
Published LCAs for biopower are limited and, as noted above, may not be applicable to specific
cases.1110 The LCAs performed often are tailored to one feedstock and one biopower technology
type, and LCA results vary depending on assumptions such as the time frame of the assessment.1211
The LCA time frame can be long (e.g., “cradle to grave”) or relatively short (e.g., “cradle to gate).13
gate”).12 Different LCA time frames can lead to radically different, even contradictory, results. The
The majority of biopower LCAs were completed for two biopower technology types: combustion and
and gasification. Both technologies have strengths and weaknesses.1413 The technology to co-fire
(or
combust) biomass with coal is available at commercial scale and is in use today. Gasification
technology is in the development and demonstration phase.1514
Although biopower LCAs are scarce compared to liquid transportation biofuel LCAs, certain
trends appear in existing assessments. For instance, the National Renewable Energy Laboratory
(NREL) reviewed and analyzed 57 biopower LCAs. The NREL review shows that biopower
11reduces GHG emissions when compared with fossil-based generation of electricity.15 Elsewhere,
some members of the academic community reviewed more than 25 LCAs. They determined that
10
Most LCAs for bioenergy have focused on GHG emissions from biomass used for liquid transportation fuels and its
impact on climate.
1211
For more information on biopower LCAs, see Electric Power Research Institute, Literature Review and Sensitivity
Analysis of Biopower Life-Cycle Assessments and Greenhouse Gas Emission, January 2013.
1312
A cradle-to-grave time frame generally includes all phases from feedstock production to energy end use. A cradle-togate time frame generally includes a fraction of the complete biopower pathway and may include feedstock production,
feedstock cultivation, feedstock transport, and electricity generation.
1413
D. Peterson and S. Haase, Market Assessment of Biomass Gasification and Combustion Technology for Small- and
Medium-Scale Applications, U.S. Department of Energy National Renewable Energy Laboratory (NREL), NREL/TP7A2-46190, July 2009, at http://www.nrel.gov/docs/fy09osti/46190.pdf.
1514
Some gasification plants are starting to come on-line. For example, the PHG Energy waste-to-energy gasification
plant in Tennessee began operating in 2013 and can process up to 12 tons of waste per day.
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reduces GHG emissions when compared with fossil-based generation of electricity.16 Elsewhere,
some members of the academic community reviewed more than 25 LCAs. They determined that
15
The analysis did not consider land use change. NREL, Biopower Greenhouse Gas Emissions in the LCA Literature,
October 5, 2011, at http://lcacenter.org/lcaxi/final/446.pdf.
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biopower is in the top tier of bioenergy pathways that avoid the most GHG emissions and replace
the largest amounts of fossil energy.1716 Approximately 15 of the LCAs reviewed included
electricity as an end product, of which at least 10 had an LCA time frame of when the feedstock
was extracted to when the biopower was produced (e.g., cradle to gate).
There is an ongoing discussion about the foundation and underlying assumptions of LCAs, GHG
modeling, and other methodologies used to evaluate the carbon impact of bioenergy.18 17 Some
members of the academic community assert that the methodologies do not sufficiently address
land use (e.g., land available to satisfy energy, food, and feed needs) and incorrectly account for
biomass (e.g., double counting biomass). They contend that some biofuel systems and fossil fuel
systems may not be compared easily using some of the methodologies that exist, among other
concerns.1918 Others maintain that some of these issues have been addressed, specifically that landuse concerns stem from multiple factors, not just bioenergy, that increased productivity (e.g.,
rising crop yields) must be considered when discussing global food and feed requirements, and
that crops used for bioenergy have the ability to naturally re-sequester carbon.20 under certain
circumstances.19
Recent Developments Affecting
Biopower Assessment
Certain actions have kept the biomass carbon-neutrality issue a concern for the bioenergy and
environmental communities, among others. Most notable are EPA’s proposed standards for
greenhouse gas
emissions from existing fossil-fueled power plants (e.g., the Clean Power Plan),
EPA’s 2014
framework for assessing biogenic CO2 emissions from stationary sources, and EPA’s
permitting permitting
requirements under the Clean Air Act (CAA).21
16
The analysis did not consider land use change. NREL, Biopower Greenhouse Gas Emissions in the LCA Literature,
October 5, 2011, at http://lcacenter.org/lcaxi/final/446.pdf.
17
20
16
Q. Zhang, K. R. Goldstein, and J. R. Mihelcic, “A Review of Life Cycle Assessment Renewable Energy Derived
from Forest Resources,” in Renewable Energy from Forest Resources in the United States, ed. Barry D. Solomon,
Calerie A. Luzadis (New York: Routledge, 2009). Information regarding the feedstocks, conversion processes, end
products, system boundaries, allocation methods, and impact metrics for each LCA is available in Table 8.1.
1817
Although the discussion has primarily centered on biomass used for liquid transportation fuels, these same concerns
are applicable to biomass used for any type of energy production, including biopower.
1918
John De Cicco, “The liquid carbon challenge: evolving views on transportation fuels and climate,” WIREs Energy
and Environment, vol. 4 (2015), pp. 98-114; World Resources Institute, Avoiding Bioenergy Competition for Food
Crops and Land, January 2015.
2019
Renewable Fuels Association, “Debunking Searchinger’s Doomsday Theories ... Again,” press release, January 29,
2015; Global Renewable Fuels Alliance, “World Resources Institute Wrong About Biofuels Impact on Land Use and
the Environment,” press release, January 30, 2015.
21
Many scientists continue to contribute to the discussion by submitting letters to Members of Congress and the EPA.
In 2014, more than 90 scientists submitted a letter to EPA urging the agency to base its regulations for stationary
sources of biogenic emissions (e.g., biopower plants) on sound science “by putting in place a system that links emitter
behavior directly to what’s happening on the landscape and rigorously assesses the incremental carbon emissions
impacts of bioenergy production.” Cary Institute of Ecosystem Studies, “Scientists nationwide call on EPA to create
scientifically strong pollution standards for biomass energy,” press release, June 19, 2014.
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Clean Power Plan Proposed Rule20
Members in both chambers of Congress have submitted letters to the EPA Administrator and the Secretaries of
Agriculture and Energy expressing their support for the carbon neutrality of forest biomass (Senator Susan Collins,
“U.S. Senators Collins (R-ME) and Merkley (D-OR) Urge EPA, DOE, and USDA to Recognize Clear Benefits of
Forest Bioenergy in Federal Policy,” press release, July 1, 2015; U.S. Representative Reid Ribble, “Ribble to EPA:
Don't Punish Sustainable Forestry,” press release, August 3, 2015.). Further, many scientists continue to contribute to
the discussion by submitting letters to Members of Congress and EPA. In 2014, more than 90 scientists submitted a
letter to EPA urging the agency to base its regulations for stationary sources of biogenic emissions (e.g., biopower
plants) on sound science “by putting in place a system that links emitter behavior directly to what’s happening on the
landscape and rigorously assesses the incremental carbon emissions impacts of bioenergy production.” Cary Institute of
Ecosystem Studies, “Scientists nationwide call on EPA to create scientifically strong pollution standards for biomass
energy,” press release, June 19, 2014.
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The Clean Power Plan
In June 2013, President Obama issued a Climate Action Plan. As part of the plan, EPA was
directed to propose standards for “carbon pollution” (i.e., CO2, the principal GHG) from existing
power plants by June 2014 and to finalize the standards by June 2015.22 In June 2014, EPA
released the proposed rule, 21 In August 2015, the EPA
released the final rule for CO2 emission reductions from existing fossil fuel-fired electric power
plants.22 This rule, commonly referred to as the Clean Power Plan (CPP).23 The CPP establishes
, requires states to reach
a state-specific CO2 emission rate targets, -reduction goal (measured in pounds of CO2 emissions per
megawatt-hour
of electricity.24 Under the proposal, states have the flexibility to determine how to reduce their
emission rates, which could include the use of biomass-derived fuels at electric generating units.
EPA reports that it is working to “define a clear path” for states to include biomass. EPA asserts it
will look to its accounting framework for assessing emissions from biogenic sources, once
finalized, as a resource on how to do so.25
EPA completed an evaluation of several GHG abatement measures to determine their national
CO2 reduction potential for the proposed rule, including an analysis for biomass co-firing.26 EPA
concluded that, given the parameters of its analysis, biomass co-firing may result in stack CO2
emission increases and that biomass co-firing for CO2 emission reductions can be relatively costly
when compared with other measures. It is not clear what impact future federal and state policy
and program decisions (e.g., biomass eligibility requirements, tax incentives, clean energy
standards) would have on making biomass co-firing a more economically attractive option for
GHG emission reduction using EPA’s evaluation method of electricity generation) by 2030.23 States are to develop a plan—using guidance
from EPA—that can incorporate renewable energy, including biopower, among other things.24
EPA reports that “qualified biomass”—biomass feedstock that has been demonstrated to be a
method to control increases of CO2 levels in the atmosphere—may be included in a state’s plan.
However, there remains uncertainty about which forms of biomass EPA will deem acceptable.
Further, there are various stipulations associated with the use of biomass to generate electricity
for the CPP. Thus, it is not clear what role biopower will play in the implementation of the CPP.
Framework for Assessing Biogenic CO2 Emissions from
Stationary Sources
EPA released two draft frameworks—the first in 2011 and the second in 2014—that establish a
process to evaluate and account for GHGs associated with the use of biomass to produce energy
at stationary sources (e.g., biopower).2725 The frameworks indicate how EPA may treat bioenergy
for the programs and regulations within its domain. In addition to seeking public comment about
the framework, EPA entrustsentrusted its Science Advisory Board (SAB) with conducting an independent
review of each framework.
The 2014 framework addresses some of the SAB recommendations and stakeholder comments
from the 2011 framework. The framework focuses on carbon flux corresponding to three stages
of bioenergy production: (1) feedstock growth and harvest; (2) processing, transport, storage, and
22use of a biogenic feedstock at the stationary source; and (3) the possible alternative fate of
biogenic feedstock materials if not used for bioenergy. In preparing the 2014 framework, EPA
reports that it considered information that “supports the finding that use of waste-derived
feedstocks and certain forest-derived industrial byproducts are likely to have minimal or no net
atmospheric contributions of biogenic CO2 emissions, or even reduce such impacts, when
compared with an alternate fate of disposal.”26 EPA acknowledges that the 2014 framework is an
analytical methodology and that some stakeholders may consider the framework a precursor to
21
Executive Office of the President, The President’s Climate Action Plan, June 2013. The President’s Climate Action
Plan reiterates the Obama Administration’s focus on reducing carbon pollution from power plants, which has included
and is likely to continue to involve biopower, among other renewable electricity-generation sources.
2322
EPA, “Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units,”
Proposed Rule, 79 Federal Register 34830, June 18, 2014.
24Final Rule, prepublication version, August 3, 2015.
23
For more information on the proposed rule, see CRS Report R43572, EPA’s Proposed Greenhouse Gas Regulations
for Existing Power Plants: Frequently Asked Questions, by James E. McCarthy et al. and CRS Report R43652, State
CO2 Emission Rate Goals in EPA’s Proposed Rule for Existing Power Plants , by Jonathan L. Ramseur.
25
The accounting framework is described in “Framework for Assessing Biogenic CO2 Emissions from
Stationary Sources.”
26
EPA, Clean Power Plan Proposed Rule: GHG Abatement Measures, June 10, 2014.
27R44145, EPA’s Clean Power Plan: Highlights of the
Final Rule, by Jonathan L. Ramseur and James E. McCarthy.
24
For more information, see CRS In Focus IF10280, The Clean Power Plan (CPP): The Treatment of Biomass, by
Kelsi Bracmort.
25
EPA, Accounting Framework for Biogenic CO2 Emissions from Stationary Sources, September 2011; EPA,
Framework for Assessing Biogenic CO2 Emissions from Stationary Sources, November 2014.
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use of a biogenic feedstock at the stationary source; and (3) the possible alternative fate of
biogenic feedstock materials if not used for bioenergy. In preparing the 2014 framework, EPA
reports that it considered information that “supports the finding that use of waste-derived
feedstocks and certain forest-derived industrial byproducts are likely to have minimal or no net
atmospheric contributions of biogenic CO2 emissions, or even reduce such impacts, when
compared with an alternate fate of disposal.”28 EPA acknowledges that the 2014 framework is an
analytical methodology and that some stakeholders may consider the framework a precursor to
26
Letter from EPA, Addressing Biogenic Carbon Dioxide Emissions from Stationary Sources, to Air Division
Directors, November 19, 2014.
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how EPA treats biogenic emissions for both the proposed standards for GHG emissions from
existing existing
fossil-fueled power plants and the Prevention of Significant Deterioration program (see
“Prevention of Significant Deterioration/New Source Review Program and Title V Greenhouse
Gas Permitting Requirements,” below).2927 However, EPA reports that it “has not yet determined
how the framework might be applied in any particular regulatory or policy contexts or taken the
steps needed for such implementation.”3028 EPA has requested that the SAB peer review the 2014
framework.3129
For the 2011 framework, EPA charged the SAB with reviewing and commenting on (1) EPA’s
characterization of the science and technical issues relevant to accounting for biogenic CO2
emissions from stationary sources; (2) EPA’s framework, overall approach, and methodological
choices for accounting for these emissions; and (3) options for improving upon the framework for
accounting for biogenic CO2 emissions, among other issues.3230 The SAB conducted the
independent review of the agency’s 2011 biogenic accounting framework and released its
findings in September 2012. These findings included that “carbon neutrality cannot be assumed
for all biomass energy a priori.”3331 The SAB acknowledged the “daunting task” of assessing the
GHG implications of bioenergy and the “narrow regulatory boundaries” within EPA’s purview
that limit the consideration of GHG flux at various points along the bioenergy pathway. The SAB
identified multiple factors (e.g., time scale, spatial scale, leakage) that require further assessment
by EPA and provided recommendations to revise the biogenic accounting framework. The SAB
“found that quantification of most components of the framework has uncertainties, technical
difficulties, data deficiencies and implementation challenges.” The SAB recommended an
alternative biogenic accounting framework based on feedstock category, region, land
management, and prior land use.
28
Letter from EPA, Addressing Biogenic Carbon Dioxide Emissions from Stationary Sources, to Air Division
Directors, November 19, 2014.
29
For instance, more than 75 scientists submitted a letter to the EPA administratorPrevention of Significant Deterioration/New Source Review
Program and Title V Greenhouse Gas Permitting Requirements
The CAA’s Prevention of Significant Deterioration (PSD)/New Source Review program requires
a “new major stationary source or the major modification of any existing stationary source” to
undergo preconstruction review and permitting, including the installation of Best Available
Control Technology (BACT) to limit emissions.32 Title V of the act requires all new and existing
facilities that have the potential to emit a GHG pollutant in amounts of 100 tons per year or more
to obtain permits.33 In July 2011, EPA decided to defer for a period of three years the application
27
For instance, more than 75 scientists submitted a letter to the EPA Administrator expressing concerns about EPA’s
proposed treatment of emissions from biomass used to produce energy. Cary Institute of Ecosystem Studies, February
9, 2015.
3028
EPA, Framework for Assessing Biogenic CO2 Emissions from Stationary Sources, November 2014.
3129
EPA reports that the specific elements of the 2014 framework that it wants the Science Advisory Board (SAB) to
SAB to review are forthcoming.
Letter from EPA, Request for Review of Additional Scientific Product, to Science Advisory
Board Staff Office,
November 19, 2014.
3230
The agency’s charge for the SAB, review documents (including the accounting framework), and meeting materials
are available at http://yosemite.epa.gov/sab/sabproduct.nsf/0/2f9b572c712ac52e8525783100704886!OpenDocument&
TableRow=2.2#2.
3331
EPA, SAB Review of EPA’s Accounting Framework for Biogenic CO2 Emissions from Stationary Sources, EPASAB-12-011, September 28, 2012.
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Prevention of Significant Deterioration/New Source Review
Program and Title V Greenhouse Gas Permitting Requirements
The CAA’s Prevention of Significant Deterioration (PSD)/New Source Review program requires
new or modified major stationary sources to undergo preconstruction review and permitting,
including the installation of Best Available Control Technology (BACT) to limit emissions. Title
V of the act requires all new and existing facilities that have the potential to emit a GHG pollutant
in amounts of 100 tons per year or more to obtain permits.34 In July 2011, EPA decided to defer
for a period of three years the application
32
42 USC 7475.
33
42 USC 7661. For more information on the Prevention of Significant Deterioration and Title V permits, see CRS
Report R41212, EPA Regulation of Greenhouse Gases: Congressional Responses and Options.
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of PSD and Title V permitting requirements for CO2
emissions from bioenergy and other
biogenic stationary sources.3534 EPA proposed using the threeyearthree-year time period to conduct a detailed
examination of the science associated with biogenic CO2
emissions from stationary sources to
determine how to treat emissions from biomass-fired and
biogenic sources (i.e., charging its Science Advisory Board SAB
with reviewing EPA’s approach to the
assessment of CO2 emissions from biogenic sources). In
2013, a DC circuitDistrict of Columbia Circuit court decision
vacated the deferral rule because the rule
“cannot be justified under any of the administrative law
doctrines [de minimis, one-step-at-a-timeatime, administrative necessity, and absurd results] relied on
by EPA.”36 Following the decision, the DC circuit court granted a series of motions to extend the
deadline for petitioning for rehearing, the last grant extending the deadline to 30 days after the
court issues its mandate in a related case now before the court.37 These extensions, however, did
not extend the original July 2014 expiration for the deferral period. The practical applications of
the court changing its 2013 ruling at this point, well after the deferral period has expired, are
unclear and beyond the scope of this report. The court’s opinion on the deferral rule “leaves for
another day the question whether the agency has authority under the Clean Air Act to
permanently exempt biogenic carbon dioxide sources from the PSD permitting program.”38
Best Available Control Technologies
EPA noted in the PSD and Title V Permitting Guidance for Greenhouse Gases that it may
consider certain types of biomass a best available control technology (BACT)39 after taking into
account environmental, energy, and economic considerations and state and federal policies that
promote biomass for energy-independence and environmental reasons.40 EPA provided specific
34
For more information on the Prevention of Significant Deterioration and Title V permits, see CRS Report R41212,
EPA Regulation of Greenhouse Gases: Congressional Responses and Options, by James E. McCarthy.
35
by EPA.”35 The court issued its
mandate on August 10, 2015.
Best Available Control Technologies
EPA noted in the PSD and Title V Permitting Guidance for Greenhouse Gases that it may
consider certain types of biomass a best available control technology (BACT)36 after taking into
account environmental, energy, and economic considerations and state and federal policies that
promote biomass for energy-independence and environmental reasons.37 EPA provided specific
guidance on how to consider the unique GHG attributes of biomass as fuel in the BACT selection
process.38 PSD permits require that facilities apply the BACT, but individual states, with EPA
guidance, determine BACT on a case-by-case basis.
Considerations for the Regulation of Biogenic
CO2 Emissions
There are some key points to consider about the regulation of biogenic CO2 sources. First, EPA is
in the process of comprehensively assessing the GHG classification for biogenic CO2 sources
(which it is doing with the release of the second framework for assessing biogenic CO2
emissions). Stakeholders likely will contest in the courts any decision the agency makes regarding
these sources, although there is little to no precedent for the courts to follow. Second, EPA, thus
far, has received no guidance from the courts (or the SAB) about how to exempt biogenic CO2
sources from PSD requirements. The court stopped current practices without offering alternatives.
Third, the legal and regulatory struggles over biogenic CO2 sources reflect a larger issue:
Congress’s bioenergy policy typically has not included carbon accounting for bioenergy, with an
exception for the Renewable Fuel Standard.39 Thus, it is not clear if Congress would treat
34
EPA, “Deferral for CO2 Emissions From Bioenergy and Other Biogenic Sources Under the Prevention of Significant
Deterioration (PSD) and Title V Programs: Final Rule,” 76 Federal Register 43490, July 20, 2011. Biogenic includes
facilities that emit CO2 from sources originating via biological processes, such as landfills.
3635
Center for Biological Diversity v. Environmental Protection Agency, 722 F. 3d 401, 412 (DC Cir. 2013).
37
The last grant was on September 19, 2014. The related case now before the court is Coalition for Responsible
Regulation v. EPA. This case was first decided by the DC circuit in 2012, 684 F.3d 102, then reversed in part by the
Supreme Court in 2014 under the name Utility Air Regulatory Group v. EPA. The case is now back before the DC
circuit, under the original case name, to decide the remaining issues.
38
Ibid.
3936
A Best Available Control Technology (BACT) is a pollution control standard mandated by the Clean Air Act in PSD
areas.
4037
EPA, PSD and Title V Permitting Guidance for Greenhouse Gases, EPA-457/B-11-001, March 2011. The Supreme
Court’s 2014 decision for the Utility Air Regulatory Group v. EPA, 134 S. Ct. 2427 (2014) case exempted biogenic
CO2 sources along with all
other CO2 sources, unless the source is covered by the PSD program due to its emissions of
non-GHG emissions,
otherwise known as anyway sources. The court decision significantly reduces the number of
facilities applying for such
permits and, thus, possibly in need of a BACT.
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guidance on how to consider the unique GHG attributes of biomass as fuel in the BACT selection
process.41 PSD permits require that facilities apply the BACT, but individual states, with EPA
guidance, determine BACT on a case-by-case basis.
Considerations for the Regulation of Biogenic
CO2 Emissions
There are some key points to consider about the regulation of biogenic CO2 sources. First, EPA is
in the process of comprehensively assessing the GHG classification for biogenic CO2 sources
(which it is doing with the release of the second framework for assessing biogenic CO2
emissions). Stakeholders likely will contest in the courts any decision the agency makes regarding
these sources, although there is little to no precedent to follow. Second, EPA, thus far, has
received no guidance from the courts (or the SAB) about how to proceed regarding whether to
exempt biogenic CO2 sources from PSD requirements or, if so, how to complete such an
assessment. The court stopped current practices without offering alternatives. Third, the legal and
regulatory struggles over biogenic CO2 sources reflect a larger issue: Congress’s bioenergy policy
typically has not included carbon accounting for bioenergy, with an exception for the Renewable
Fuel Standard. Thus, it is not clear if Congress would treat biopower differently from other types
of power generated from conventional energy and renewable energy sources. Congress’s
permits and, thus, possibly in need of a BACT.
38
EPA, Guidance for Determining Best Available Control Technology for Reducing Carbon Dioxide Emissions from
Bioenergy Production, Washington, DC, March 2011, at http://www.epa.gov/NSR/ghgdocs/bioenergyguidance.pdf.
39
Congress’s approach thus far has tended at times to focus singularly on a particular bioenergy source (e.g.,
ethanol),
or a biomass feedstock (e.g., cellulosic), or bioenergy conversion technology (e.g., anaerobic
digestion), as opposed to an end result that is desired from a policy standpoint (e.g., the most
most efficient use of biomass for energy production with the least environmental effects).
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biopower differently from other types of power generated from conventional energy and
renewable energy sources. If EPA is to If EPA is to
carry out the bioenergy legal requirements in a timely
fashion, it may need better and more
explicit direction from Congress. Such direction might
include providing EPA with a
predetermined amount of time—free of legal intrusions—to resolve
issues with stakeholder and
public input.
Is Biopower Carbon Neutral? It Depends
Carbon neutrality for biopower is calculated most accurately based on the carbon flux (i.e., GHG
emission or sequestration) of several parameters over a specified time period. These parameters
include at least the following: (1) the feedstock type; (2) the management and procurement of the
energy source (in the case of biomass, how the feedstock is managed and harvested); (3) the
feedstock transportation method; (4) the energy generation technology; and (5) the time frame to
replenish the feedstock. Carbon flux attributed to the management and procurement of biomass
feedstock deviates according to the type or mixture of feedstock used. For instance, agricultural
biomass entails a different nutrient management plan than woody biomass. GHG emissions may
be higher for agricultural biomass due to fertilizer treatments (e.g., emissions from the GHG
nitrous oxide emissions from
from biofuel-dedicated crops).4240 Carbon flux also will vary given how the biomass
feedstock is
harvested. For example, removal of woody biomass (e.g., thinnings) in large quantities may
41
EPA, Guidance for Determining Best Available Control Technology for Reducing Carbon Dioxide Emissions from
Bioenergy Production, Washington, DC, March 2011, at http://www.epa.gov/NSR/ghgdocs/bioenergyguidance.pdf.
42
When agricultural waste is the biomass used for biopower production, some GHG emissions may be attributed to
crop cultivation whereby the crop is used for other feed, fiber, and fuel purposes.
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quantities may reduce carbon, and some methane, emissions on a CO2-equivalent basis that
would have been
released if the woody biomass remained in the forest to decompose. Biomass-feedstockBiomassfeedstock transport
emits differing amounts of GHGs depending on how far one transports the
feedstock and on fossil
fuel usage.4341 The carbon flux of the biopower generation technology will
depend on the type of
technology and any emission capture or sequestration.4442 In addition, the
time frame (e.g., 40
years, 100 years) assigned for biomass feedstock replenishment will
determine CO2 sequestration
rates to balance out the GHGs emitted during biomass combustion,
particularly for woody
biomass, as growth periods (rotation ages for the trees) are often measured
in decades.4543
It could be argued that only an LCA for each biopower operation can accurately determine
whether biopower generation is carbon neutral. Such an LCA would measure carbon flux for each
phase of the biopower pathway and incorporate biomass feedstock replenishment. A standard
approach to performperforming a biopower LCA could ensure uniformity in GHG accounting across the
biopower sector. However, multiple LCAs can be expensive and time-consuming to complete.
Biopower’s carbon neutrality is a contentious aspect of the bioenergy debate. One reason the
topic is so controversial is concern about unsustainable harvests of biomass feedstocks. Some
environmentalists, among others, contend that if biopower proceeds with no carbon balance
restrictions, it could lead to, for example, large amounts of woody biomass removal for energy
production. Another reason for controversy is concern about the air quality of areas surrounding
biopower plants. These two concerns—sustainability and air quality—can be, and in some cases
already are, addressed through other avenues (e.g., sustainability requirements, air-quality
regulations) at the federal and state levels.
Legislative Implications
Legislation with the goals of providing energy independence and security include biopower
without considering its carbon status. Recent developments may prompt Congress to further
analyze this premise. Carbon neutrality depends in part on the feedstock type, the technology, and
the time frame for feedstock replenishment. Biopower can be produced using multiple biomass
feedstocks and technologies. Each feedstock and technology has its own environmental footprint.
The time frame to analyze carbon neutrality is relevant because it incorporates feedstock
replenishment, and thus CO2 removal rates, and considers technology developments.
To the extent carbon neutrality continues to be a legislative concern, Congress could examine
whether the current carbon-neutral assumption for biopower is adequate. Congress may consider
if additional carbon accounting for biopower is warranted and what impact this accounting might
have on renewable energy, agricultural, and environmental legislative goals. A key contributor to
this discussion may be whether decisions concerning biopower made by the executive branch
contradict legislative goals set by Congress. A scientific assessment of whether a biopower plant
43
Some stakeholders make the case that feedstock transportation could involve the use of fuels (e.g., ethanol) other
than fossil fuels (e.g., diesel or gasoline).
44
No commercial carbon capture and sequestration (CCS) projects currently operate. Therefore, CCS is not likely to
impact carbon flux at the biopower generation stage in the near term.
45
For more information on carbon sequestration in trees, see CRS Report R40562, U.S. Tree Planting for Carbon
Sequestration, by Ross W. Gorte.
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is carbon positive, carbon negative, or carbon neutral may require an analysis, such as an LCA.
There are time and economic constraints in conducting an LCA for each biopower operation40
When agricultural waste is the biomass used for biopower production, some GHG emissions may be attributed to
crop cultivation whereby the crop is used for other feed, fiber, and fuel purposes.
41
Some stakeholders make the case that feedstock transportation could involve the use of fuels (e.g., ethanol) other
than fossil fuels (e.g., diesel or gasoline).
42
No commercial carbon capture and sequestration (CCS) projects currently operate in the United States. Therefore,
CCS is not likely to impact carbon flux at the biopower generation stage in the near term.
43
For more information on carbon sequestration in trees, see James E. Smith, Linda S. Heath, and Kenneth E. Skog,
Methods for Calculating Forest Ecosystem and Harvested Carbon with Standard Estimates for Forest Types of the
United States, U.S. Forest Service, GTR-NE-343, April 2006.
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production. Another reason for controversy is concern about the air quality of areas surrounding
biopower plants, especially if particulate matter and select compounds from a plant exceed certain
limits. These two concerns—sustainability and air quality—can be, and in some cases already are,
addressed through other avenues (e.g., sustainability requirements, air-quality regulations) at the
federal and state levels.
Legislative Implications
Congress may be prompted to further analyze the carbon status of biopower with congressional
oversight or review due to recent and forthcoming developments (e.g., EPA’s decisions regarding
“qualified biomass” for the CPP and the framework to account for emissions of biogenic CO2
from stationary sources). Biopower can be produced using multiple biomass feedstocks and
technologies. Each feedstock and technology has its own environmental footprint. The time frame
to analyze carbon neutrality is relevant because such an analysis would incorporate feedstock
replenishment, and thus CO2 removal rates, and consider technology developments.
Congress could decide to use existing legislative authorities to address carbon accounting for
biopower. Federal environmental regulatory controls exist for the three chief environmental
concerns associated with a biopower plant—air quality, use of public land, and water discharges.
GHG emissions may be accounted for with federal regulations regarding air quality. In addition, a
biopower plant also has to meet state regulatory standards, which in some cases may be stricter
than the federal regulatory controls.
To the extent carbon neutrality continues to be a legislative concern, Congress could examine
whether the current carbon-neutral assumption for biopower is adequate. Congress may consider
if additional carbon accounting for biopower is warranted and what impact this accounting might
have on renewable energy, agricultural, and environmental legislative goals. A key contributor to
this discussion may be whether decisions concerning biopower made by the executive branch
contradict legislative goals set by Congress. A full carbon accounting for biopower could result in
A full carbon accounting for biopower could result in slowing the achievement of multiple
renewable energy, agricultural, and environmental goals.
Alternatively, the carbon-neutrality
debate for biopower may lead to requests for carbon
accounting of some or all energy ventures—
renewable and conventional. Lastly, an ill-defined
carbon accounting assessment for biopower
may limit public and private investment, feedstock
production, and more. Scientists, investors,
biomass producers, and others may hesitate to expend
time and money on expanding biopower
efforts if they are not certain about the future
contribution of biopower to U.S. energy and
environmental goals.
If Congress chooses to address energy security and GHG emission increases, some stakeholders
have argued that these goals could be met through the creation of a national renewable electricity
standard (RES) or a clean electricity standard (CES). The mandate of a potential national RES or
CES may require substantial quantities of baseload power, which some policymakers and others
see as being achieved by using biopower. If biopower is a part of an RES or CES, the carbonneutrality designation of biopower may need to be reconsideredconsidered in response to environmental and
sustainability concerns.
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Author Contact Information
Kelsi Bracmort
Specialist in Agricultural Conservation and Natural
Resources Policy
kbracmort@crs.loc.gov, 7-7283
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