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Center for Biological Diversity * Clean Air Task Force * Clean Wisconsin * Kentucky

Environmental Foundation * Minnesota Center for Environmental Advocacy *  Natural

Resources Defense Council * Sierra Club

October 28, 2010

Hon. Lisa P. Jackson, Administrator

United States Environmental Protection Agency

Ariel Rios Building

1200 Pennsylvania Avenue, NW, Mail Code 1101A

Washington, DC 20460

Email: Jackson.Lisap@epa.gov

Petition for Rulemaking  

To

Correct Emissions Factors in the Mandatory Greenhouse Gas Reporting Rule

Dear Administrator Jackson:

The Sierra Club, the Center for Biological Diversity, Clean Air Task Force, Clean

Wisconsin, the Kentucky Environmental Foundation, the Minnesota Center for

Environmental Advocacy, and the Natural Resources Defense Council hereby petition

EPA, pursuant to 5 U.S.C. § 553(e), to use its authority under the Clean Air Act and other

relevant statutes to initiate rulemaking to correct erroneous emissions factors within

the Mandatory Greenhouse Gas Reporting Rule, 40 C.F.R. Pt. 98.  The final rule

unfortunately uses an emissions factor for nitrous oxide (N2O) emissions which is

substantially too low when applied to fluidized bed boilers, a common power plant

design, and does not include emissions factors based upon waste coal, a common

fluidized bed boiler fuel.  EPA should correct these errors to protect the accuracy of the

reporting rule and ensure equitable treatment in the utility sector.

I. Petitioner

The Sierra Club is the nation’s oldest and largest grassroots environmental organization.

Its mission is to explore, enjoy, and protect the planet.  The Sierra Club’s staff and

volunteers are working to combat climate change throughout the country, including

through its successful Beyond Coal Campaign, which focuses on reducing greenhouse

gas and other pollutant emissions from electrical generating stations. Because accurate

and timely facility‐specific data is essential to this effort, and to safeguard public health

and the environment, the Sierra Club has participated extensively in the development of

the reporting rule, submitting comments on every proposed rulemaking associated with

the rule. Sierra Club’s members benefit directly from the reporting rule and the data it

produces and are harmed when this data is compromised.
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Sierra Club’s national headquarters are at 85 Second St., Second Floor, San Francisco,

CA, 94105.  Its campaign offices are at 408 C St. NE, Washington, DC.  Its phone number

is 202‐548‐4597, and its fax number is 202‐547‐6009.

The Center for Biological Diversity is a nonprofit environmental organization dedicated

to the protection of imperiled species and their habitats through science, education,

policy, and environmental law. The Center has approximately 43,000 members

throughout the United States. The goal of the Center’s Climate Law Institute is to reduce

U.S. greenhouse gas emissions and other air pollution to protect biological diversity, the

environment, and public health.  Specific objectives include securing protections for

species threatened by the impacts of global warming, ensuring compliance with

applicable law in order to reduce greenhouse gas emissions and other air pollution, and

educating and mobilizing the public on global warming and air quality issues. Its

headquarters mailing address is P.O. Box 710, Tucson, AZ, 85702‐0710 and its phone

number is 520‐623‐5252.

The Clean Air Task Force ("CATF") is a nonprofit organization dedicated to reducing

atmospheric pollution through research, advocacy, and private sector collaboration.  

CATF works closely with the Administration to develop climate policies and regulations

grounded in science, technology, and the law.  CATF has participated extensively in

EPA's development of greenhouse gas regulations.  Accurate and timely facility‐specific

data is essential to developing effective climate change policies, and to safeguard public

health and the environment, and inaccurate data will hamper CATF's efforts in working

to develop policies that will reduce harmful greenhouse gas pollution.  CATF’s address is

18 Tremont St., Suite 530 Boston, MA, 02108 and its phone number is 617‐624‐0234.

Clean Wisconsin advocates for clean water and air, and for transition to a clean energy

economy on behalf of its 10,000 members. It does this by holding Wisconsin politicians,

polluters, and regulatory agencies accountable, and educating Wisconsin residents,

media, and government policy makers. Clean Wisconsin is recognized statewide as a

major force in enhancing Wisconsin’s water and air quality and strengthening

Wisconsin’s reputation as a leader for environmental stewardship and environmental

protection.    Clean Wisconsin’s address is 122 State Street, Suite 200, Madison, WI,

53703 and its phone number is (608)251‐7020.

The Kentucky Environmental Foundation is a 20‐year old non‐profit organization

dedicated to securing solutions to environmental problems in a manner that safeguards

human health, promotes environmental justice, preserves ecological systems and

encourages sustainability.  KEF is based in Berea, Kentucky and serves the health

interests of communities in Kentucky and elsewhere in the U.S.  Its mailing address is PO

Box 467, Berea, KY, 40403 and its phone number is 859‐986‐0868.

The Minnesota Center for Environmental Advocacy (“MCEA”) is a Minnesota‐based non‐

profit environmental organization whose mission is to use law, science, and research to
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preserve and protect Minnesota’s natural resources, wildlife, and the health of its

people.  MCEA has state‐wide membership, and is headquartered in St. Paul, Minnesota.  

Reduction in greenhouse gases is a goal in many of the areas of MCEA’s work, including

clean energy, air quality, public health, and protection of natural resources. MCEA’s

mailing address is 26 E. Exchange Street, Suite 206, St Paul, MN, 55101 and its phone

number is 651‐223‐5969.

The Natural Resources Defense Council (“NRDC”) is a national nonprofit environmental

organization with approximately 400,820 members nationwide. NRDC uses law, science,

and the support of its members to ensure a safe and healthy environment for all living

things. One of NRDC’s top priorities is to reduce emission of the air pollutants that are

causing global warming. NRDC’s DC address is 1200 New York Ave., NW, Suite 400

Washington, DC 20005, and its phone number is  202‐289‐6868.

II.  N2O and Climate Change

Climate change is rapidly destabilizing ecosystems and economies around the world.  As

EPA has recognized, global warming is driven by rising atmospheric concentrations of a

host of greenhouse gases emitted by stationary and mobile sources in the United States

and elsewhere.1  EPA summarized some of the damage climate change is causing,

concluding that greenhouse gases endanger public health and welfare:

The Administrator has considered how elevated concentrations of the well mixed

greenhouse gases and associated climate change affect public health by evaluating

the risks associated with changes in air quality, increases in

          temperatures, changes in extreme weather events, increases in food‐ and

water‐borne pathogens, and changes in aeroallergens. The evidence concerning

adverse air quality impacts provides strong and clear support for an

endangerment finding. Increases in ambient ozone are expected to occur

over broad areas of the country, and they are expected to increase serious adverse

health effects in large population areas that are and may continue to be in

nonattainment. The evaluation of the potential risks associated with increases in

ozone in attainment areas also supports such a finding.  

The impact on mortality and morbidity associated with increases in average

temperatures, which increase the likelihood of heat waves, also provides support

for a public health endangerment finding. There are uncertainties over the net

health impacts of a temperature increase due to decreases in cold‐related

mortality, but some recent evidence suggests that the net impact on mortality is

 

1 See, e.g., Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of

the Clean Air Act; Final Rule, 74 Fed. Reg. 66,496 (Dec. 15, 2009), attached as Ex 1.  Please note that all

exhibits have been saved to CD and attached as pdfs.  Please contact us if paper copies would be helpful.
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more likely to be adverse, in a context where heat is already the leading cause of

weather related deaths in the United States

...

Strong support for an endangerment finding is also found in the evidence

concerning energy, infrastructure, and  settlements, as well ecosystems and

wildlife. While the impacts on net energy demand may be viewed as generally

neutral for purposes of making an endangerment determination, climate change is

expected to result in an increase in electricity production, especially supply for

peak demand. This may be exacerbated by the potential for adverse impacts from

climate change on hydropower resources as well as the potential risk of serious

adverse effects on energy infrastructure from extreme events. Changes in extreme

weather events threaten energy, transportation, and water resource

infrastructure. Vulnerabilities of industry, infrastructure, and settlements to

climate change are generally greater in high‐risk locations, particularly coastal and

riverine areas, and areas whose economies are closely linked with climate‐

sensitive resources. Climate change will likely interact with and possibly

exacerbate ongoing environmental change and environmental pressures in

settlements, particularly in Alaska where indigenous communities are facing major

environmental and cultural impacts on their historic lifestyles. Over the 21st

century, changes in climate will cause some species to shift north and to higher

elevations and fundamentally rearrange U.S. ecosystems. Differential capacities

for range shifts and constraints from development, habitat fragmentation, invasive

species, and broken ecological connections will likely alter ecosystem structure,

function, and services, leading to predominantly negative consequences for

biodiversity and the provision of ecosystem goods and services.2

EPA has, correctly, characterized the science supporting these conclusions as “robust,

voluminous, and compelling.”3  The evidence that climate change is being driven by

anthropogenic emissions, and is causing increasing harm around the world, rests upon

thousands of scientific studies.  The work of the Intergovernmental Panel on Climate

Change (“IPCC”) and the U.S. Global Change Research Program, amongst other scientific

bodies, synthesizes many of these studies; recent reports from such organizations are

attached to this petition.4

 

2 Ex 1, 75 Fed. Reg. at 66,497‐98. 3 EPA’s Denial of the Petitions To Reconsider the Endangerment and Cause or Contribute Findings for

Greenhouse Gases Under Section 202(a) of the Clean Air Act; Final Rule, 75 Fed. Reg. 49,556, 49,556,

attached as Ex 2. 4 See, IPCC, Bernstein et al., CLIMATE CHANGE 2007: SYNTHESIS REPORT (2007), attached as Ex 3; IPCC, Forster

et al., Changes in Atmospheric Constituents and in Radiative Forcing, in CLIMATE CHANGE 2007: THE PHYSICAL

SCIENCE BASIS (2007), attached as Ex 4; U.S. Climate Change Science Program, THE EFFECTS OF CLIMATE CHANGE

ON AGRICULTURE, LAND RESOURCES, WATER RESOURCES, AND BIODIVERSITY IN THE UNITED STATES (2008), attached as

Ex 5; T. Karl et al. (eds), GLOBAL CLIMATE CHANGE IMPACTS IN THE UNITED STATES (2009), attached as Ex 6; The
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The nub of the problem is that concentrations of greenhouse gases in the atmosphere

have risen, at an increasing rate due to uncontrolled emissions from artificial sources, as

Figure 1 demonstrates. 

Figure 1: Rising Concentrations of Greenhouse Gases5

Although carbon dioxide is the best known of these greenhouse gases, it is not the most

potent on a molecule‐by‐molecule basis.  Each of these gases traps heat differently

because of differences in its molecular structure.  Nitrous oxide is significantly more

efficient at trapping heat than carbon dioxide.6  This difference is expressed as N2O’s

“global warming potential” or “GWP.”  Because gases are removed from the

atmosphere at different rates, and influence warming on different time frames, a GWP

is always expressed over a period of time.  Over 100 years, N2O has a GWP 298 times

greater than carbon dioxide’s.7

  As such, it is an extremely potent greenhouse gas. 8  

Troublingly, N2O emissions have been steeply climbing.  Before humans began emitting

large amounts of N2O, the gas stayed at a stable atmospheric concentration of roughly

 

Lancet Commissions, Anthony Costello et al., Managing the health effects of climate change,  373 THE

LANCET 1693 (2009), attached as Ex 7. 5 Ex 4 at 135. 6 See id.  at 210‐14. 7 Id. at 212.  The EPA still generally uses a GWP of 310 for N2O, as published by the IPCC in its Second

Assessment Report, rather than the more recent figure. 8 Although this petition focuses upon N2O’s climate effects, N2O is also a powerful ozone‐depleting gas,

providing yet another reason to accurately track N2O emissions.
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270 ppb.9 Global concentrations have since increased about 18 percent above pre‐

industrial levels.10 EPA attributes this increase “primarily to anthropogenic emissions,”11

and describes itself as “very interested in obtaining better data on N2O emissions.”12  As

of 1998, N2O had reached a concentration of 314 ppb, and is now climbing past 320 ppb,

increasing 0.2‐0.3% each year.13 Figure 2 charts this steep increase over the past few

decades.   

Figure 2: Observed Increases in N2O Atmospheric Concentrations14

The EPA’s most recent national Inventory of U.S. Greenhouse Gas Emissions and Sinks

confirms that this trend generally holds true in the United States, albeit with some

recent reductions driven by improved control technologies.15  The EPA's most recent

national inventory of U.S. Greenhouse Gas Emissions and Sinks provides information on

U.S. emissions of N2O:16

Table 1: U.S. Emissions of N2O

 

9 Id. at 143. 10 EPA, INVENTORY OF U.S. GREENHOUSE GAS EMISSIONS AND SINKS: 1990‐2008 (Apr. 1, 2010) at ES‐10, attached as

Ex 8. 11 Ex 1, 75 Fed Reg. at 66,517. 12 75 Fed. Reg. 48,744, 48,767 (Aug. 11, 2010). 13 Id. at 143‐44. 14 Ex 4 at 143. 15 See, e.g., J. Perez‐Ramirez et al., Formation and control of N2O in nitric acid production: Where do we

stand today?, 44 Environmental Chemistry 117 (2003) (detailing control technologies), attached as Ex. 9. 16 Ex 8 at ES‐5.
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1990 1995 2000 2005 2006 2007 2008

Total N2O  (Tg CO2e) 322.3 342.5 345.5 328.3 329.5 327.7 318.2

Agricultural Soil Management   203.5   205.9   210.1   215.8   211.2   211.0   215.9

Mobile Combustion   43.9   54.0   53.2   36.9   33.6   30.3   26.1

Nitric Acid Production   18.9   21.0   20.7   17.6   17.2   20.5   19.0

Manure Management   14.4   15.5   16.7   16.6   17.3   17.3   17.1

Stationary Combustion   12.8   13.3   14.5   14.7   14.5   14.6   14.2

Forest Land Remaining Forest  

Land   2.7   3.7   12.1   8.4   18.0   16.7   10.1

Wastewater Treatment   3.7   4.0   4.5   4.7   4.8   4.9   4.9

N2O from Product Uses   4.4   4.6   4.9   4.4   4.4   4.4   4.4

Adipic Acid Production   15.8   17.6   5.5   5.0   4.3   3.7   2.0

Composting   0.4   0.8   1.4   1.7   1.8   1.8   1.8

Settlements Remaining  

Settlements   1.0   1.2   1.1   1.5   1.5   1.6   1.6

Field Burning of Agricultural  

Residues   0.4   0.4   0.5   0.5   0.5   0.5   0.5

Incineration of Waste   0.5   0.5   0.4   0.4   0.4   0.4   0.4

As these figures suggest, U.S. emissions, though high, have tailed downwards in recent

years, largely thanks to improvements in N2O controls  for mobile combustion and

adipic acid production.  As these sectors have declined, stationary combustion has

become a relatively more important source, as emissions have increased relative to

1990, hovering around 14 Tg CO2e annually.

Within the stationary combustion category, coal‐fired power plants are, far and away,

the dominant source of N2O emissions, as Table 2 demonstrates.17 Moreover, because

EPA used an unduly conservative emissions factor to determine coal power plant

emissions, as we discuss below, these emissions likely significantly larger than reported

in the inventory.  Even using EPA’s figures, however, emissions from this dominant

source have increased substantially over the lifetime of the inventory.

Table 2: Domestic N2O Emissions from Stationary Combustion

1990 1995 2000 2005 2006 2007 2008

Sector/Fuel

Type

       

Electricity

Generation

8.1 8.6 10.0 10.3 10.1 10.2 10.1

Coal 7.6 8.1 9.4 9.7 9.5 9.7 9.6

Fuel Oil 0.2 0.1 0.2 0.2 0.1 0.1 0.1

Natural Gas 0.2 0.1 0.2 0.2 0.2 0.2 0.2

 

17 From Ex 8 at 3‐9.
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Wood 0.2 0.1 0.2 0.2 0.2 0.2 0.2

Industrial 3.2 3.3 3.2 3.0 3.2 3.0 2.8

Coal 0.8 0.7 0.6 0.6 0.6 0.5 0.5

Fuel Oil 0.5 0.4 0.4 0.5 0.6 0.6 0.6

Natural Gas 0.2 0.3 0.3 0.2 0.2 0.2 0.2

Wood 1.7 1.9 1.9 1.7 1.8 1.7 1.5

Commercial 0.4 0.4 0.3 0.3 0.3 0.3 0.3

Coal 0.1 0.1 >0.05 >0.05 >0.05 >0.05 >0.05

Fuel Oil 0.2 0.1 0.1 0.1 0.1 0.1 0.1

Natural Gas 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Wood 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Residential 1.1 1.0 0.9 0.9 0.8 0.9 0.9

Coal >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05

Fuel Oil 0.3 0.2 0.3 0.3 0.2 0.2 0.2

Natural Gas 0.1 0.1 0.2 0.1 0.1 0.1 0.1

Wood 0.7 0.6 0.5 0.5 0.5 0.5 0.6

U.S.

Territories

0.1 0.1 0.1 0.1 0.1 0.1 0.1

Coal >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05

Fuel Oil 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Natural Gas >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05

Wood >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05

Total   12.8 13.3 14.5 14.7 14.5 14.6 14.2

The high N2O emissions from the coal‐fired power sector are not evenly distributed

across all types of power plants.  Because “N2O emissions from stationary combustion

are closely related to air‐fuel mixes and combustion temperatures, as well as the

characteristics of any pollution control equipment that is employed,” plant design

differences mean that some boilers produce far more N2O than others.18 As we next

discuss, fluidized bed boilers stand out as top N2O emitters.

III. Fluidized Bed Boilers and N2O

Fluidized bed boilers provide a flexible way to burn a wide range of fuel types, including

waste coals.  There has been long‐term interest in this boiler design and a substantial

number of fluidized boilers are in service, or proposed, in the U.S.19  This design,

however, inherently emits more N2O than conventional coal plant designs.  As a result,

fluidized bed boilers have a disproportionate greenhouse gas impact.

 

18 See Ex 8. at 3‐7 – 3‐8. 19 See generally S. Bañales‐Lopez & v. Norberg‐Bohm, Public policy for energy technology innovation: A

historical analysis of fluidized bed combustion development in the USA, 30 ENERGY POLICY 1173 (2002),

attached as Ex. 10.
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A. Fluidized Bed Boilers In the Domestic Power Market

Most existing domestic fluidized bed boilers were installed in the late 1980s and early

1990s thanks to incentives created by the Public Utilities Regulatory Policy Act, which

encouraged non‐utilities to enter the electricity market.  At the peak of the boom, over

600 MW of fluidized bed capacity was being installed annually, as Figure 3 shows.

Figure 3: Non‐Utility Fluidized Bed Capacity Installed20

Fluidized bed boilers work by passing a high velocity air stream through a “bed”

composed of a mixture of inert particles and fuel.  As air speed increases, the bed

particles begin to drift in slip stream, effectively behaving like a fluid.  This burner design

allows the boiler to burn the fuel evenly, and to burn many types of fuel.   

At lower velocities, the bed “bubbles” as gas moves through the burning fuel bed; at

higher velocities, the bed material itself rises and moves as a fluid.  Larger boilers take

advantage of the rising bed by including a “backpass” system, which channels the

burning fuel and bed material through a downward shaft, recirculating it back into the

main boiler.  These “circulating fluidized bed” boilers, or “CFBs” are the more popular

design for power producers.21  Figure 4 is a schematic of such a boiler.

 

20 Id. at 1175. 21 Id. at 1175‐76.
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Figure 4: A Circulating Fluidized Bed Boiler22

As the Electric Power Research Institute (“EPRI”) explains:

 

22From Ex 18, infra.
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[CFB] combustion is now well established as a mature power generation

technology.  There are over 370 units worldwide [as of December 2003] in the

size range 20 to 320 MW burning a wide range of fuels covering bituminous and

sub‐bituminous coal, coal waste, lignite, petroleum coke, biomass, and a variety

of waste fuels.  In many instances units are designed to fire several fuels

emphasizing one of the major advantages of the technology.23

EPRI reported in 2002 that 5,778 MW of CFB capacity had been installed in the

Americas, with most of that capacity going to the United States.24  Interest in CFBs

continued throughout the last decade, with several utility‐scale CFB projects coming

online, including the 521 MW Seward station in Pennsylvania and the approximately 260

MW Spurlock  3 and  4 stations in Kentucky.25

EPA’s CEMS database for 2009 contains 64 plants which self‐reported to EPA that they

are CFBs.  Of those plants, 25 also appear in EPA’s separate power plant database, which

includes capacity figures.  Those plants have a combined capacity of 2,685 MW.  As the

remaining 39 have boiler heat capacities essentially identical to the 25 listed plants, if

they have the same ratio of MW capacity to boiler capacity they would add roughly

another 2,685 MW, confirming EPRI’s estimate of between 5,000 and 6,000 MW of

installed CFB capacity in the U.S.

Although rising awareness of the dire environmental consequences of all coal‐fired

power plants, including CFBs, has slowed CFB construction, projects are still moving

forward across the country.  These include the 1200 MW Las Brisas, 1320 MW White

Stallion, and 303 MW NuCoastal CFBs in Texas, the 585 MW Wise County CFB in Virginia,

the 580 MW Wellington CFB in Pennsylvania, the 278 MW Smith, 660 MW Black Stallion,

and 110 MW Estill County CFBs in Kentucky, the 660 MW Rodemacher CFB in Louisiana,

the 112 MW Spiritwood CFB in North Dakota, the 43 MW Jamestown CFB in New York,

and the 50 MW Purdue CFB in Indiana.  Thus, although many of these projects may not

be completed, there is still some prospect of increased CFB capacity in the United

States.

These new plants, along with the existing CFBs, are significant sources of N2O, as we

next discuss.

B. N2O and CFBs

Coal, like most all organic fuels, contains nitrogen.  As coal is combusted, some fraction

of this nitrogen, along with nitrogen from the atmosphere in the boiler, is oxidized into

 

23 J. Wheeldon, Electric Power Research Institute, EVALUATION OF PROCESSES FOR POST‐COMBUSTION CONTROL OF

EMISSIONS FROM CIRCULATING FLUIDIZED‐BED POWER PLANTS at ix (2003), attached as Ex 11. 24 J. Wheeldon, Electric Power Research Institute, ATMOSPHERIC FLUIDIZED‐BED COMBUSTION GUIDEBOOK – 2002

UPDATE (2002), Table 1‐2, attached as Ex 12. 25 Steve Blankinship, CFB: Technology of the Future?, POWER ENGINEERING (Feb. 2008), attached as Ex. 13.
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several different possible forms, some of it coming directly from the combusting coal

and some arising from chemical reactions in the remaining char.  Under continuing

combustion, these oxides convert into one another, meaning that the final oxides

emitted differ depending on combustion temperature, boiler design, fuel type, and

other factors.

Figure 5: Formation and Fate of NO and N2O During Coal Combustion26

In fluidized bed boilers, the fuel itself, rather than char, is the dominant nitrogen source

and the two competing nitrogen oxide species are NO and N2O.27  At lower

temperatures – those at which CFBs and other fluidized bed boilers operate ‐‐ N2O is the

dominant gas, while NO (and NOx generally) formation is suppressed.28  At higher

temperatures – those at which essentially all other forms of coal boilers operate – the

inverse is true, and NOx is almost entirely dominant.  This effect occurs because the

chemical reactions which remove N2O, converting it into other forms of nitrogen, do not

operate quickly enough at the temperatures at which CFBs operate, but do operate

efficiently at higher temperatures.29  Unfortunately, the CFB temperature range,

between roughly 800 and 900 degrees Celsius, appears to be optimal for N2O formation.

 

26 M.A. Wójtowicz et al., Combustion of coal as a source of N2O emission, 34 Fuel Processing Technology 1,

13‐19 (1993), attached as Ex. 14. 27 Id. at 14. 28 Id.  at 43‐44. 29 Id.
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High coal ranks likewise tend to contain more nitrogen (anthracite surpasses bituminous

coal, and so on), meaning that production of all N species tends to be highest with high

rank coal.   

The combined relationship, then, is as expressed in Figure 6.

Figure 6: Effect of Temperature and Fuel Rank on N2O Formation30

As Figure 6 suggests, N2O formation is fairly high for all fuel ranks at the temperatures at

which CFBs operate.  The emissions gap between CFBs and other boilers, as a result, is

quite large.  Although estimates vary somewhat, N2O in the flue gas of pulverized coal

plants generally hovers around  1‐20 ppm and ; in CFBs, it can approach 250 ppm, an

order of magnitude higher.31

This distinction, and the underlying N2O/temperature relationship, is very well

established.  Experimental trials have demonstrated as much for years.  Tests on a

bituminous coal boiler, for instance, showed peak N2O emissions of above 150 ppm at

850 °C, plummeting to well below 50 ppm above 920 °C.

 

30 Id. at 45. 31 Id. at 2.
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Figure 7: Experimental Relationships Between N2O and Temperature32

Similarly, test in a large experimental CFB, designed to replicate conditions in utility

boilers, showed N2O emissions falling sharply as thermal input rose, and NOx emissions

climbing in tandem:

 

32 A. Lyngfelt et al., Methods for Reducing the Emission of Nitrous Oxide from Fluidized Bed Combustion,

37 ENERGY CONSERVATION MANAGEMENT 1297, 1299 (1996), attached as Ex. 15.
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Figure 8: Relationship Between NOx and N2O33

The highest documented N2O emissions of which we are aware soared to an astonishing

400 ppm.34   

In short, these high emissions of a particularly potent greenhouse gas have not escaped

the notice of the scientific community.  N2O emissions from CFBs are well‐documented

in a host of peer‐reviewed papers, textbooks, and manuals.  We have attached a

sampling to this petition, but EPA will readily be able to identify further sources in the

literature.35   

 

33 H. Liu & B.M. Gibbs, Reduction of N2O emissions from a coal‐fired circulating fluidised bed combustor by

afterburning, 77 FUEL 1579, 1582 (1998), attached as Ex 16. 34 B.X. Shen et al., N2O emission under fluidized bed combustion condition, 84 FUEL PROCESSING Technology

13, 13 (2003), attached as Ex. 17. 35 See E. Tsupari, Estimation of annual CH4 and N2O emissions from fluidised bed combustion: an advanced

measurement‐based method and its application to Finland (2007), attached as Ex 18; S. Korhonen et al.,

Methane and Nitrous Oxide Emissions in the Finnish Energy Production, Fortum (2001), attached as Ex 19;
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The IPCC has also addressed this issue in its 2006 IPCC Guidelines for National

Greenhouse Gas Inventories.  In the “Stationary Combustion” section of those

guidelines,36 the IPCC recognizes the high emissions associated with fluidized bed

boilers.  While it provides default emissions factors of between 0.5 and 1.6 kg/TJ for

other coal‐fired boilers, it sets emissions factors of 61‐71 kg/TJ for fluidized bed

boilers.37

These IPCC figures are particularly significant because EPA bases its own national

inventory figures on IPCC emissions figures.38  The national inventory, however, is based

upon the lowest resolution emissions factors that the IPCC provides.  These “Tier 1”

factors set N2O emissions from coal generally at 1.5 kg/TJ.39  The IPCC makes clear,

however, that this generic factor “assume[s] effective combustion in high temperature”

settings, not the low temperatures in fluidized bed boilers.40  The IPCC emphasizes that

“in reality,” N2O emissions depend upon the “combustion technology” used and its

“operating conditions.”41  The IPCC takes these conditions into account in its more

accurate “Tier 3” emissions factors, cited above, which demonstrate that N2O emissions

for fluidized bed boilers are an order of magnitude or more higher than for other

boilers.  As a result, the national inventory, which already shows high N2O emissions

from coal‐fired boilers generally, is undercounting emissions from fluidized bed boilers,

and by a significant margin.

Indeed, EPA‘s own publications and reports recognize the risk of high N2O emissions

from CFBs.  As EPA writes in its Compilation of Air Pollutant Emissions Factors (generally

referred to as “AP‐42”):

Formation of N2O during the combustion process is governed by a complex series

of reactions and its formation is dependent upon many factors.  Formation of N2O

is minimized when combustion temperatures are kept high (above 1575 °F [857 °C]

) and excess air is kept to a minimum (less than 1 percent).  N2O emissions for coal

 

K. Svoboda & M.Pohorely, Influence of operating conditions and coal properties on NOx and N2O emissions

in pressurized fluidized bed combustion of subbituminous coals, 83 FUEL 1095 (2003), attached as Ex 20;

L.Armesto et al., N2O emissions from fluidised bed combustion.  The effect of fuel characteristics and

operating conditions, 82 FUEL 1845 (2003), attached as Ex 21; Simeon N. Oka, FLUIDIZED BED COMBUSTION

(2004), attached as Ex 22; E.J. Anthony & F. Preto, Pressurized Combustion in FBC Systems, in PRESSURIZED

FLUIDIZED BED COMBUSTION, M. Alvarez‐Cuenca & E.J. Anthony, eds. (1995), attached as Ex 23; W.F. Podolski

et al., Air emissions from pressurized fluidized bed combustors, in PRESSURIZED FLUIDIZED BED COMBUSTION, M.

Alvarez‐Cuenca & E.J. Anthony, eds. (1995), attached as Ex 24; Prabir Basu, COMBUSTION AND GASIFICATION IN

FLUIDIZED BEDS (2006), attached as Ex 25; B. Leckner, Emissions of nitrous oxide from large combustion

plants, Presentation to the Second European Climate Change Programme, Topic Group “Other

Greenhouse Gases” (Jan. 1, 2006), attached as Ex 26. 36 Attached as Ex 27. 37 See id., Table 2.6. 38 See Ex 8, Annex 3.1 at A‐105. 39 Ex 27 at Table 2.2. 40 Id. at 2.14 (emphasis added). 41 Id. at 2.12.
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combustion are not significant except for fluidized bed combustion (FBC), where

the emissions are typically two orders of magnitude higher than all other types of

coal firing due to areas of low temperature combustion in the fuel bed.42

For this reason, AP‐42 distinguishes CFBs from all other coal boilers.  Although it sets

emissions factors for N2O from coal fuels of between 0.03‐0.09 lb/tons for all other

boilers, it provides an emission factor of 3.5 lb/ton for both CFBs and bubbling fluidized

bed boilers.43

EPA reached its conclusions in AP‐42 on the basis of several EPA‐funded studies in the

mid 1990s, as well as through the larger scientific consensus.  First, an extensive

literature review by L.P. Nelson et al. surveyed results from 96 coal‐fired boilers,

concluding that “[f]luidized bed combustors showed significantly higher emissions, as

illustrated by the reported average of 123.5 ppm [N2O across 18 reactors].”44  A few

years later, R.L. Peer et al. conducted an extensive review, concluding that “at low

temperatures similar to those used with [fluidized bed boilers], significant levels of N2O

remain after combustion” and assigning CFBs an average emission factor of 57.395 g/GJ,

compared to just an emission factor of between 1‐4 g/GJ for all other coal‐fired

boilers.45

Putting these factors, and others from the literature, into shared unit yields fairly

consistent results, all of them far higher than N2O emissions for any other boiler type:

Table 2: N2O Emission Factor Coal/Coke Fired Combustion Units (10‐3 kg/mmBtu)

Source Average Range Combustion Unit Fuel

AP‐4246 67.3    BFB/CFB Bit coal

AP‐42 92.0    BFB/CFB SB coal

Oka 200447 71.2 27‐188 BFB/CFB Coal & mixes48

 

42 AP‐42, Bituminous and Subbituminous Coal Combustion at 1.1‐5 – 1.1‐6, attached as Ex 28 (emphasis

added).

43 Id. at Table 1.1.‐19. 44 L.P. Nelson et al., Global Combustion Sources of Nitrous Oxide Emissions at 3‐6 (Aug. 1991), attached as

Ex 29 45 R.L. Peer et al., Characterization of Nitrous Oxide Emission Sources (July 1995), attached as Ex 30 46 See Ex 27  The AP‐42 emission factor is reported as 3.5 lb N2O per ton of coal.  This was converted to

kg/mmBtu as follows: (3.5 lb/ton)(0.4536 kg/lb)/24.93 mmBtu/ton) = 0.0637 kg/mmBtu = 67.3 x 10‐3

kg/mmBtu.  The higher heat value of the coal is taken from 40 CFR 98, Subpart C, Table C‐1 and is 24.93

mmBtu/short ton for bituminous coal and 17.25 mmBtu/short ton for subbituminous coal. 47 Ex 22 Table 7.7.  All concentrations reported in ppm in Table 7.7 were converted to kg/mmBtu, based

on 3% oxygen, an F factor of 9780 dscf/mmBtu, and a specific molar volume of 386.8 ft3

/lb‐mole at 70 F.  

The average is the average of the median of nine separate studies (103, 77, 219, 193, 373, 68, 54, 116, 65

ppm at 3% O2). 48 Fuel types include low and high volatile bituminous coals with and without limestone (CaCO3) and

mixtures of coal and industrial waste.
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Finland49 31.7 28.5‐41.1 BFB/CFB Coal, peat, wood

C. N2O Control Strategies

Importantly, although high N2O emissions are inherent to fluidized bed boilers, control

strategies are available which may significantly reduce these emissions.  These include

“after‐burning,” in which fuel burners are placed in the back‐cycle of the CFB to oxidize

N2O without disrupting the low temperature main boiler, and changes to the air ratio of

the boiler which reduces N2O formation.50 After‐burning has been shown to reduce N2O

emissions by as much as 80% and air ratio changes (also called “air staging”) by 75%.51  

Because these techniques may increase emissions of other compounds, including sulfur

oxides and NOx,they are best employed as part of a comprehensive emission control

strategy.

This hopeful note comes, however, with a major caveat:  Because, until very recently,

EPA was not moving forward to require stationary combustion sources to use

greenhouse gas controls, few, if any, domestic operators appear to be controlling their

N2O emissions in this way, or are subject to permit requirements to do so.  Even with

emissions control regulations in progress, CFB operators may not use appropriate

control technology if their emissions are estimated without taking their unique N2O

emissions into account. In short, without clear measurement of N2O, and appropriate

regulatory action, CFBs will continue to emit without constraint.

D. CFBs and Waste Coal Burning

One more aspect of CFB operation is worth noting.  CFBs, as noted, are able to burn a

wider range of fuels than most other coal‐fired boilers.  This has made them particularly

attractive as “waste coal” burners, as they can be used to burn the gob and boney

(bituminous waste) and culm (anthracite waste) left behind by coal mining.52

Waste coal‐fired CFBs are prominent in the U.S.  Reliant Energy’s Seward station, for

instance, has two 260 MW units and is designed to burn almost exclusively coal waste.53  

One comprehensive reference reports that “[w]ith the advent of CFB technology and its

application to this fuel, there has been a significant increase in the use of anthracite

culm and bituminous gob within the USA,” charting an increase from just 1.3‐1.4 million

 

49 Ex 19 Tables 2 and 3.  This factor is likely somewhat lower because of the admixture of biomass, which

can produce less N2O. 50 See, e.g., Ex. 26 Ex. 15 51 Ex 15at 1300‐01 & Ex. 16at 1586; see also U.S. Patent No. 5133950, Reducing N2O emissions when

burning nitrogen‐containing fuels in fluidized bed reactors, (2003), attached as Ex 31 52 See generally Ex 13 53 D.A. Tillman & N. S. Harding, FUELS OF OPPORTUNITY (2004) at 115‐22, attached as Ex 32
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tons used in 1989 to 8.9‐9.3 million tons burned in 2001.54 This increase is attributable,

almost entirely, to CFBs.

Indeed, according to EPA, there are currently 18 plants burning waste coal as a primary

fuel, and 13 plants using waste coal as a secondary fuel.55  EPA records 17 additional

plants that have been proposed and are in some phase of project development.  

According to EPA, every one of these plants uses CFB technology.56

The upshot is that, as these waste coal burners operate, and come online, it becomes

increasingly important both to monitor and control their N2O emissions to understand

any unique factors associated with using waste coal as a fuel.  Because waste coal is

often of lower fuel rank, it is possible that some CFBs burning waste coal have

somewhat lower N2O emissions, for instance, or, for that matter, different carbon

dioxide or methane emissions.

III. The Reporting Rule

Despite broad scientific consensus, the reporting rule does not contain emissions factors

recognizing the important differences between fluidized bed boilers and other coal‐fired

reactors.  Instead, it uses an emissions factor of just 1.6 g/mmBtu for all coal‐fired

boilers.57  This factor is an order of magnitude below the emissions factors in AP‐42 and

all scientifically credible sources.  It will lead to serious undercounting of fluidized bed

boiler emissions, so EPA should correct it.

A. Petitioners Raised This Issue In Comments But EPA Did Not Address Them

Petitioners pointed out this problem to EPA in their initial comments on the proposed

reporting rule.  Those comments stated:

Accurately characterizing N2O emissions will be particularly important for fluidized

bed coal plants.  As EPA explains in AP‐42:  

Formation of N2O during the combustion process is governed by a complex

series of reactions and its formation is dependent upon many factors.

Formation of N2O is minimized when combustion temperatures are kept high

(above 1575oF) and excess air is kept to a minimum (less than 1 percent). N2O

 

54 Id. 55 EPA, Materials Characterization Paper In Support of the

Proposed Rulemaking – Identification of Nonhazardous Secondary Materials That Are Solid Waste Coal

Refuse at 3‐4 (Mar. 18, 2010), attached as Ex 33 see also J.A. Fuller et al., Atmospheric Fluidized Bed

Combustion (AFBC) Plants: An Operations and Maintenance Study, 128 JOURNAL OF ENERGY RESOURCES

TECHNOLOGY 150 (2006), attached as Ex 34(describing 11 U.S. fluidized bed boilers burning gob or culm). 56 Id. 57 See 40 C.F.R. § 98, Subpt. C, Table C‐2.
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emissions for coal combustion are not significant except for fluidized bed

combustion (FBC), where the emissions are typically two orders of magnitude

higher than all other types of coal firing due to areas of low temperature

combustion in the fuel bed.

The National Coal Council has similarly explained:

N2O has a GWP 296 times that of CO2. Because of its long lifetime (about 120

years) it can reach the upper atmosphere, depleting the concentration of

stratospheric ozone, an important filter of UV radiation. N2O is emitted from

fluidized bed coal combustion; global emissions from FBC units are 0.2 Mt/year,

representing approximately 2% of total known sources. N2O emissions from

[pulverized coal] units are much lower. Typical N2O emissions from FBC units

are in the range of 40‐70 ppm (at 3% O2). This is significant because at 60 ppm,

the N2O emission from the FBC is equivalent to 1.8% CO2, an increase of about

15% in CO2 emissions for an FBC boiler. Several techniques have been proposed

to control N2O emissions from FBC boilers, but additional research is necessary

to develop economically and commercially attractive systems

In light of these unusually high emissions, we recommend that EPA require CEMS

for plants of this type.  If it does not, it should at least apply facility‐specific

emissions factors.58

The North Carolina Division of Air Quality similarly pointed out that “bituminous

fluidized bed combustors . . . have significantly higher N2O emission factors; due to the

large global warming potential of this GHG, this can make a significant difference in total

GHG emissions for some facilities.”59  It recommended that EPA develop distinct

emissions factors for the technology.

EPA’s response to these comments did not satisfactorily explain why EPA did not include

a fluidized bed‐specific N2O emissions factor.

In response to Sierra Club, EPA stated only that it believed that continuous emissions

monitoring was not warranted and that it could use “fuel‐specific default emissions

factors,” consistent with “methods used in other programs” to “provide[] data of

sufficient accuracy.”60  The question, however, was not just whether EPA should have

used fuel‐specific default factors at all but whether, if it used such factors, it should

include a separate set for CFBs, which have markedly different emissions characteristics.  

EPA’s response did not satisfactorily explain why it did not do so, as other programs –

 

58 Comments of Sierra Club et al. on the Proposed Mandatory Greenhouse Gas Reporting Rule (June 19,

2009), attached as Ex 35(internal citations omitted; emphasis added). 59 EPA, Mandatory Greenhouse Gas Reporting Rule: EPA’s Response to Public Comments, Volume No: 14,

Subpart C – General Stationary Fuel Combustion Sources at 239 (Sept. 2009), attached as Ex 36 60 Id. at 228.
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including, as noted above, the IPCC’s national guidelines and EPA’s own AP‐42 – actually

do include such factors.

Similarly, EPA replied to North Carolina that it believed its approach to “N2O emissions

factors is consistent with the IPCC Guidelines” and that its factors “come from the IPCC

Guidelines.”61 EPA also suggested that less accurate measurement of stationary sources

could be appropriate because, compared to mobile sources, they were not “key

sources”– a term EPA did not define.62 But, again, EPA was wrong:  In fact, the IPCC

guidelines recommend using distinct emissions factors for fluidized bed boilers that will

accurately capture their high N2O emissions.  And stationary source combustion simply

is not a minor N2O source.  Mobile sources, according to EPA’s own figures, account for

about 8% of national N2O emissions; stationary sources account for 4%.  Further, as

discussed above, these figures are too low, as they also do not recognize the high N2O

emissions associated with fluidized bed boilers.  If EPA recognized these differences,

stationary source emissions would be even more dominant.  In short,  that stationary

source emissions are simply not so small as to be worth discounting – and particularly

not so when N2O emissions have such a great influence on climate change, on a pound‐

for‐pound basis, relative to carbon dioxide.

Nonetheless, EPA finalized the rule without addressing the problem.  At present, 40

C.F.R § 98.33(c) directs all covered stationary combustion sources to calculate their N2O

emissions using emission factors drawn from Table C‐2 of Subpart C, which, as

previously noted, contains an emissions factor that is at least an order of magnitude too

low for fluidized bed boilers.  Electric generators covered by Subpart D are likewise told

to calculate their N2O emissions “by following the applicable method specified in §

98.33(c)” – that is, using the erroneous emission factor.

Notably, Table C‐2, in addition to containing the wrong emission factor for N2O, contains

no fuel‐specific emissions factor for waste coals like gob or culm for either N2O or

methane.  Nor, for that matter, does Table C‐1, which contains default emissions factors

for calculating carbon dioxide emissions.  The result is that fluidized bed boilers – and

CFBs in particular – are inaccurately reflected in the reporting rule.

B. EPA Must Correct the Rule

Congress ordered EPA to promulgate the reporting rule to “require mandatory reporting

of greenhouse gas emissions above appropriate thresholds in all sectors of the economy

of the United States, as required by Public Law 110‐161.”63  This charge necessarily

requires EPA to require accurate and comprehensive data.  The flawed N2O emissions

 

61 Id. at 240. 62 See id.

63 Appropriations Act of 2009, Pub. L. No. 111‐8, 123 Stat. 524, 729 (March 11, 2009) (citing Fiscal Year

2008 Consolidated Appropriations Act, Pub. L. No.110‐161, 121 Stat. 1844, 2128 (Dec. 26, 2007).
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factor, and the rule’s omission of emissions factor specific to waste coal, defeat this

charge.  EPA’s emissions estimates for CFBs will be off by a factor of ten, or even of a

hundred.  This failure does not comport with EPA’s mandate.

Nor is it consistent with Section 114 of the Clean Air Act.  EPA has information collection

authority in order to aid in the development and enforcement of emissions standards

and plans.  See 42 U.S.C. § 7414(a)(i)‐(ii); see also id. § (a)(1) (focusing on information

collection for the “purposes set forth in this subsection”).  EPA cannot readily base

sound plans, policy, and enforcement actions upon faulty data about a large swath of

the U.S. fleet of coal power plants.  Although EPA certainly has authority to collect data

under its current emissions factors, it ill serves the purposes of the statute to collect

significantly inaccurate data.

Moreover, these inaccuracies will do real harm.  They will undercount the emissions of

CFBs and make it difficult to assess the real greenhouse gas costs of waste coal burning.  

As such, they will skew policy choices inordinately towards these technologies.  They will

also make it exceedingly difficult for responsible CFB owners to benefit from installing

and documenting control technology for N2O, as they will not be able to show emissions

reductions, or even document their originally high emissions, under the reporting rule.  

Too, as preconstruction permitting requirements begin to control greenhouse gases,

CFBs may escape some of these requirements because their reported emissions will be

falsely lowered by the emissions factor error.

These harms are not theoretical.  The East Kentucky Power Cooperative (“EKPC”) and

the U.S. Army Corps of Engineers recently completed an environmental impact

statement (“EIS”) for EKPC’s 278 MW Smith station, which is a CFB, using the reporting

rule’s emissions factors.64  With the Table C‐2 factor, the Corps calculated that Smith

would emit only 31 tons of N2O annually.  Had it applied even the AP‐42 factor,

however, it would have come up with an amount at least 60 times greater.

These errors are likely to propagate through EISs and other environmental analyses as

the reporting rule is used as an authoritative source for emissions factors.  It behooves

EPA to correct its error swiftly, before it compromises the reporting rule’s database and

analyses across the country.

IV. Petitioned Action

EPA should correct its errors as quickly as possible.  It should strive to do so within the

next year, so as to ensure that at least the 2012 reporting year’s data is not

compromised.   Because the science supporting our requests is clear, and has long been

known to EPA, and because EPA has already established usable emissions factors in AP‐

 

64 Draft Supplemental Environmental Impact Statement: Section 10/404 Permit for Proposed Baseload

Power Plant East Kentucky Power Cooperative, 3‐29 (Apr 2010), attached as Ex 37
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42, we believe EPA can make these changes quickly.  We therefore petition EPA to take

the following action:

(1) As soon as possible, and before March, 2011, initiate a rulemaking by publishing

in the Federal Register a proposed rule establishing, in Table C‐2 of 40 C.F.R. Part

98, Subpt. C, an emissions factor for N2O emissions from coal burned by fluidized

bed boilers of at least the 67.3 g/mmBtu figure contained in AP‐42.

(2) As soon as possible, and before March, 2011, initiate a rulemaking by publishing

in the Federal Register a proposed rule amending Tables C‐1 and C‐2 of 40 C.F.R.

Part 98, Subpt. C establishing emissions factors for N2O, methane, and carbon

dioxide emissions from waste coal, including gob and culm, and including distinct

factors for fluidized bed boilers.

(3) As soon as possible, and before March, 2011, initiate a rulemaking by publishing

in the Federal Register a proposed rule to amend 40 C.F.R. Part 98, Subpts. C and D

to specify that any covered facility that is a fluidized bed boiler must use the

emissions factors established by the proposed rules referred to in paragraphs (1)

and (2) above to calculate its emissions.

(4) After the notice and comment period closes on these rules, as soon as possible,

and not later than August 2012, publish a final rule in the Federal Register finalizing

each of the proposed rules listed in paragraphs (1)‐(3) above.

We respectfully request that EPA respond to this petition no later than 90 days from the

date it is received.

V. Conclusion

Thank you for addressing these concerns.  We look forward to working with EPA to

continue to build a strong and comprehensive national reporting system for greenhouse

gases.

                  Respectfully Submitted,

       Craig Holt Segall

Sierra Club Environmental Law Program

408 C St NE

Washington, DC, 20002

(202)‐548‐4597

(202)‐547‐6009 (Fax)

Craig.Segall@sierraclub.org
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