FACTORS AFFECTING 

THE RELATIVE SUCCESS OF EPA'S

NOx CAP-AND-TRADE PROGRAM

June 1998

PREFACE

The Environmental Protection Agency (EPA) has proposed a rule for limiting

emissions of nitrogen oxides (NOx) in 22 eastern states and the District of Columbia.

That rule includes a voluntary program for trading emission allowances among

certain NOx sources in those jurisdictions. EPA estimates that a trading program will

save the electric power industry about $800 million a year compared with a more

traditional approach that imposes a specific limit on emissions from each source. At

the request of the Ranking Minority Member of the House Committee on Commerce,

the Congressional Budget Office (CBO) has examined the factors that could affect

the relative success of the NOx trading program in achieving those savings.

Terry Dinan and Natalie Tawil of CBO's Natural Resources and Commerce

Division wrote the paper under the supervision of Jan Paul Acton and Roger

Hitchner. CBO analysts Kim Cawley, Pam Greene, and Diane Rogers made valuable

comments. In addition, several staff members of EPA's Office of Air Quality

Planning and Standards provided useful information.

Sherry Snyder and Christian Spoor edited the manuscript, and Melissa

Burman proofread it. Rae Wiseman prepared the paper for publication. Laurie

Brown and Martina Wojak-Piotrow prepared the electronic version for CBO's World

Wide Web site (www.cbo.gov). 

June E. O'Neill

Director

June 1998

CONTENTS

SUMMARY vii

I THE PROPOSED NOx CAP-AND-TRADE PROGRAM

AND EPA'S ESTIMATE OF ITS COST 1

Curbing NOx Emissions 3

EPA’s Estimate of Savings Under the 

NOx Trading Program 8

Experiences of Previous Trading Programs 9

II FACTORS AFFECTING THE SUCCESS OF A NOx

CAP-AND-TRADE PROGRAM 15

A Competitive Market for Allowances 15

Minimal Institutional Constraints 16

Low Transaction Costs 18

Allowance Auctions 21

Flexibility in the Timing of Emission Reductions 23

Could Trading Make Some Areas Less Likely

to Achieve the Ozone Standard? 28

Conclusion: How the NOx Program Ranks According

to These Factors 29

APPENDIX Geographic Targeting of Trades 31
vi EPA'S NOX CAP-AND-TRADE PROGRAM June 1998

TABLES

1. Proposed Seasonal Budgets of NOx Emissions for States 

Covered by the Ozone Transport Rule 6

FIGURES

1. The Region Affected by EPA’s Proposed Rule 

for Reducing NOx Emissions 2

2. Sources of NOx Emissions in the Eastern United States 

on an Average Summer Day 4

BOXES

1. An Existing Effort to Control Ozone Transport:

The Ozone Transport Commission 10

2. Flow-Control Banking 27
SUMMARY

The Environmental Protection Agency (EPA) has proposed a rule that requires 22

eastern states and the District of Columbia to reduce their emissions of nitrogen

oxides (NOx), the principal component of smog. The aim of that rule—sometimes

referred to as the Ozone Transport Rule—is to help areas meet the Clean Air Act's

National Ambient Air Quality Standard for ground-level ozone in a cost-effective

way. Wind patterns frequently carry ozone and its precursor chemicals (including

NOx) long distances, a process called ozone transport. Thus, reductions in NOx

emissions throughout the multistate region could help reduce ozone concentrations

in many counties and metropolitan areas that violate the standard.

EPA estimates that the proposed Ozone Transport Rule will cost sources of

NOx emissions approximately $1.8 billion a year. The electric power industry is

expected to bear 75 percent of that cost and other stationary sources the remaining

25 percent. The estimated cost to the electric power industry assumes that the

required cuts in NOx emissions are made through a regionwide program in which

states distribute emission allowances to sources of NOx emissions, and those sources

can buy, sell, or trade the allowances among themselves. The total number of

allowances is subject to a limit, or cap. States decide whether to participate in the

program and also select the NOx sources they want to include in it. 

THE NOX PROGRAM AND EPA'S ESTIMATE OF ITS COST

Under the cap-and-trade program envisioned by EPA, each participating state would

allocate a pool of emission allowances among the sources that it deemed eligible.

One allowance would permit the release of one ton of NOx. Other than shutting

down or decreasing their production, individual sources would then have two options

for complying with the level of emissions that their allowances represented: they

could install pollution-control technology to reduce their emissions and then sell their

unneeded allowances to other sources in the region; or they could forgo investing in

such technology and buy emission allowances from sources that choose the first

option. 

EPA does not have the authority to establish a federal emission trading

program for NOx under the Clean Air Act. Instead, individual states that choose to

participate in the regional trading program will be responsible for establishing a

framework for the program in their jurisdiction. To facilitate trading throughout the

region, state programs will have to be consistent in such critical elements as their

requirements for monitoring and reporting NOx emissions.
viii EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

The cap-and-trade program can potentially reduce NOx emissions at a lower

total cost than a "command-and-control" approach, in which each source is required

to make a specific emission reduction. The reason is that trading encourages those

sources with the lowest pollution-control costs to make the emission cuts. Under a

mandated reduction, every source would have to reduce NOx emissions to a

comparable level, regardless of their cost of doing so.

EPA estimates that trading will reduce the electric power industry's cost of

complying with the Ozone Transport Rule by 36 percent—or $800 million

—compared with a command-and-control approach. That estimate is optimistic,

however, because it assumes that the trading program will realize all possible cost

savings. In reality, no trading program is likely to accomplish that, because markets

rarely, if ever, function flawlessly.

FACTORS AFFECTING THE SUCCESS

OF A NOX CAP-AND-TRADE PROGRAM

Economists have encouraged the use of trading programs for three decades. Such

programs have been employed to address a variety of environmental concerns and

have had varying degrees of success. For example, the acid rain trading program,

which began in 1995, was designed to cut utilities' emissions of sulfur dioxide (SO2).

Assessing the first year of that program, researchers estimate that participants failed

to realize all of the possible cost savings. Compliance costs in 1995 were about 50

percent higher than they would have been if the allowance market had been

functioning flawlessly. 

The experience of the SO2 and other trading programs indicates that several

factors influence the extent to which participants are able to reduce their compliance

costs. Those factors include a competitive market for allowances, minimal

institutional constraints, low transaction costs, the allocation of at least some

allowances through an auction, and the ability of participants to save up, or "bank,"

allowances for future use. The proposed NOx trading program ranks favorably

according to the first two criteria, but the other factors could pose problems.

A Competitive Market for Allowances

If an individual participant, or small group of participants, in a trading program has

the potential to influence prices, the development of a competitive market can be

jeopardized. That generally occurs when the number of buyers and sellers is small,

or when a few participants control a large share of the market. Neither of those

outcomes is likely in the NOx trading program, however, assuming that states allocate

emission allowances among sources in the way that EPA envisions.
SUMMARY ix

EPA expects states to distribute allowances to individual electricity

generators according to a measure related to the amount of electricity they produce

from fossil fuels. The region covered by the Ozone Transport Rule contains 133

different utilities (based on ownership) that use nonrenewable energy sources. Even

the largest of those utilities produces only a small share of the region's electricity

generation; in fact, less than half the allowances allocated to utilities would be

distributed among the 10 largest producers of electricity in the region. In addition,

states would allocate allowances to some combustion devices (or units) that do not

belong to utilities, further alleviating concerns about concentration in the allowance

market.

Minimal Institutional Constraints

For the trading program to be successful, participating sources must act to lower their

compliance costs. But state and federal regulations can reduce their incentives to do

that. For example, the rules that govern state public utilities frequently allow utilities

to depreciate investments in pollution-control technology at a rate that exceeds its

physical rate of deterioration. Emission allowances, by contrast, do not qualify for

depreciation. Thus, a utility may receive a higher rate of return from installing

pollution-control equipment than from purchasing allowances, even though the

allowances are cheaper. Other regulations and tax laws can also make more

expensive compliance options look cheaper from the utility's point of view. 

Recently, however, many states have begun deregulating the electricitygenerating segment of the power industry. By encouraging competition in that sector,

the movement toward deregulation will give utilities greater incentive to reduce their

costs, including the cost of complying with limits on NOx emissions.

Low Transaction Costs

Low transaction costs are an important characteristic of successful trading programs.

Transaction costs include the cost of identifying potential trading partners and

negotiating trades and the cost of obtaining any necessary regulatory approval for

those trades. EPA expects that both types of transaction costs will be low for the

NOx program. First, the private sector can play an important role in reducing the cost

of identifying partners and negotiating a trade—for example, by providing brokerage

services, as it does in the market for SO2 allowances. Second, the monitoring and

reporting responsibilities that EPA expects states to include in their programs will

minimize the need for regulatory oversight to ensure that trades involve legitimate

allowances. Sources would measure their NOx emissions using sophisticated

monitoring systems (which the affected utilities already have in place) and would

report the outcome to regulators at the end of each compliance period. The regulators
x EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

would then deduct the total number of tons emitted by each source from the

allowances contained in its account. If the source's emissions exceeded the number

of allowances in its account, regulators could impose penalties.

As noted above, however, EPA does not have federal authority to establish

a NOx trading program that would apply to all states affected by the Ozone Transport

Rule. Thus, each jurisdiction covered by the rule that chooses to participate in the

program will have to establish its own programmatic details. Small differences in

language among state rules could lead to different interpretations, create uncertainty,

and raise transactions costs. (Such consistency problems have already arisen in an

ongoing attempt to establish a NOx trading program for 12 northeastern states and the

District of Columbia.) EPA hopes that a model trading rule it has proposed for state

programs will encourage uniformity, but how effective that approach will be is not

clear.

Allowance Auctions

Using a regional auction to allocate a share of the NOx allowances may be helpful in

establishing a competitive allowance market. Newly established markets sometimes

have few transactions because participants do not have enough information about

prices to determine their willingness to buy or sell. Auctions can provide price

information that can stimulate direct trades between individual sources.

However, because the Clean Air Act does not give EPA the authority to

compel states to participate in the trading program or to control the initial allocation

of allowances, the agency cannot set aside a share of allowances for a regionwide

auction. For their part, states are very unlikely to volunteer some of their allowances

for a regional auction without a mechanism to guarantee that all states do so. If they

did, they would be forfeiting their ability to provide those allowances at no cost to

sources within their jurisdiction. 

Flexibility in the Timing of Emission Reductions 

Under the cap-and-trade program, sources could vary the timing of their emission

reductions in two ways. The program might permit them to generate allowances by

making early reductions (cutting emissions before the cap takes effect). It might also

allow sources to bank allowances they do not use in a given compliance period once

the cap is in place. In either case, sources could use the banked allowances to cover

future NOx emissions. That practice has several potential advantages.

Sources can help lower total compliance costs by generating allowances

through early reductions, when the marginal cost of such reductions is lower, and
SUMMARY xi

using them once the cap is in place, when the marginal cost is higher. In addition,

early reductions can help sources plan for the relatively short transition to the NOx

cap. A given source might make cuts early at some units and delay them at others in

order to have more time to explore its compliance options. That might allow sources

to capitalize on cost-saving opportunities. Furthermore, early reductions in NOx

emissions could have health and environmental benefits.

Allowing banking once the cap is in place assures NOx sources that their

investments in pollution control will generate allowances that they can use or sell in

the future. Banking can also protect utilities against variations in the availability of

power-generating facilities and in the demand for electricity—both of which can lead

to variations in their need for NOx allowances. Finally, banking can protect against

both a sharp change in allowance prices and a dramatic increase in emissions at the

end of each year's compliance period.

Despite the potential advantages, allowing sources to vary the timing of their

emission reductions does raise an important concern. If sources used a large number

of banked allowances in a given year, the corresponding increase in NOx emissions

could have an important effect on whether areas met the ozone standard.

EPA has not yet proposed what—if any—form of banking it will include in

its model trading rule. It is seeking comment on alternative banking options. 

Conclusion

The presence of a competitive, unconcentrated market for emission allowances and

the deregulation of part of the electric power industry should increase the likelihood

that participants in the market for NOx allowances will capitalize on their

opportunities to make cost-saving trades. However, two other factors—the difficulty

of ensuring low transaction costs and the absence of auctions to allocate some

allowances—will decrease that likelihood. Both of those factors result because EPA

must rely on states to set up comparable NOx trading programs rather than

establishing a uniform, regionwide program itself. 

In addition, savings from the NOx program will be limited if states or EPA

restrict participants' ability to bank allowances out of concern that the practice could

contribute to violations of the ozone standard. Preventing sources from banking

allowances generated by early reductions could make it even more difficult for them

to plan for the short transition to the NOx cap. Finally, any of the 23 jurisdictions

covered by the proposed Ozone Transport Rule could choose not to allow its sources

to participate in the trading program. Such nonparticipation would further reduce

savings.

CHAPTER I

THE PROPOSED NOX CAP-AND-TRADE PROGRAM

AND EPA'S ESTIMATE OF ITS COST

The Environmental Protection Agency (EPA) has proposed a rule that would require

22 eastern states and the District of Columbia to reduce their emissions of nitrogen

oxides, or NOx (see Figure 1). The proposed rule is based on EPA's conclusion that

NOx emissions from those jurisdictions contribute significantly to violations of the

National Ambient Air Quality Standard for ozone in downwind areas. 

Ground-level ozone—the principal component of smog—results when NOx

and volatile organic compounds react chemically in the presence of sunlight. High

ambient concentrations of ground-level ozone typically occur during the summer

months: May 1 through September 30 is the ozone season. Wind patterns carry

ozone and its chemical precursors long distances, particularly in the eastern United

States. Thus, for many counties and metropolitan areas in that region, controlling

emissions in their immediate vicinity may not be enough to attain the ozone standard.

EPA's proposed rule requires states to cut their NOx emissions as a means of

achieving regionwide reductions.

Under the proposal, sometimes referred to as the Ozone Transport Rule, EPA

would give each of the 23 jurisdictions a limit, or "budget," of permitted NOx

emissions. Within that overall budget, states could distribute tradable pollution

rights, known as emission allowances, to eligible sources of NOx pollution.

Emissions from those sources would be limited, or "capped," to the amount

determined by the sum of all states' allocations. Each participating source would then

be able to trade, buy, or sell those emission allowances, depending on whether its

emissions were above or below the level it was entitled to by its initial allocation of

allowances.

Such a cap-and-trade program can lower the total cost of complying with the

Ozone Transport Rule. The reason is that, under such a program, cuts in emissions

can be made by the sources that can do so most cheaply. Those sources will have

allowances left over after they reduce their emissions, and they can sell those

allowances to sources that would find cutting their NOx emissions more expensive.

EPA expects that the electric power industry will have to make most of the

emission reductions under the Ozone Transport Rule. Thus, it will bear the highest

compliance costs. Assuming that states allocate emission allowances in the manner

it recommends, EPA estimates that a trading program will save the electric power

industry $800 million compared with a rule that mandates a specific emission level

for each source—a so-called command-and-control approach. 
2 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

FIGURE 1. THE REGION AFFECTED BY EPA’S PROPOSED RULE

FOR REDUCING NOX EMISSIONS

SOURCE: Congressional Budget Office using information from the Environmental Protection Agency.

NOTE: NOX = nitrogen oxides.
CHAPTER I THE PROGRAM AND EPA'S ESTIMATE OF ITS COST 3

1. EPA projects that in 2007, emission sources included in trading will be responsible for 80 percent of NOx emissions

from point sources. See Environmental Protection Agency, Model NOx Cap and Trade Program, Second Draft

Working Paper: Applicability and Monitoring, December 7, 1997 (available at http://www.epa.gov/acidrain/

modlrule/applic.html).

The Congressional Budget Office (CBO) has reviewed the proposed Ozone

Transport Rule and assessed the likelihood that the trading program envisioned by

EPA will actually save the electric power industry $800 million. This paper

discusses that assessment. Drawing on the experience of previous trading programs,

it also identifies factors that could influence whether a successful trading program for

NOx emissions will develop.

CURBING NOX EMISSIONS

On an average summer day in the eastern United States, large stationary sources such

as power plants and factories—called point sources—are responsible for about 49

percent of all NOx emissions. Of those point sources, electric utilities release about

34 percent of average summer-day emissions, making them the largest single source

of nitrogen oxides (see Figure 2). Nonutility point sources release about 15 percent.

The emission sources that EPA expects states to include in the NOx trading program

are contained in those two categories.1

 

Motor vehicles are an important nonpoint source of NOx, contributing about

25 percent of average summer-day emissions. The proposed Ozone Transport Rule

requires states to follow the current and planned emission controls that other

regulations have established for motor vehicles, but it does not incorporate additional

restrictions on those emissions. EPA does not expect states to include motor vehicles

in the trading program, because accurately monitoring and reporting NOx emissions

from mobile sources presents a host of practical challenges. Those challenges aside,

however, if motor vehicles can reduce NOx emissions more cost-effectively than

some of the sources that are included in the program, then restricting their

participation will reduce the potential savings from trading.

Area sources—including small stationary sources and engines not used for

road transportation (such as engines in construction equipment)—discharge about 15

percent of average summer-day NOx emissions. Living organisms account for the

remaining 11 percent. Like mobile sources, EPA does not envision that states will

include either of those categories in the trading program.
4 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

Living Organisms

(11)

Motor Vehicles

(25)

Electric Utility 

Point Sources

(34)

Nonutility 

Point Sources

(15)

Area Sources

(15)

a

FIGURE 2. SOURCES OF NOX EMISSIONS IN THE EASTERN UNITED STATES ON AN

AVERAGE SUMMER DAY (In percent)

SOURCE: Congressional Budget Office based on Environmental Protection Agency, Ozone Transport Assessment Group,

Final Report (1997), Chapter 3, Table 3-23 (available at http://www.epa.gov/ttn/otag/finalrpt/chp3/toc.htm).

NOTE: NOx = nitrogen oxides.

a. Small stationary sources and engines not used for road transportation. 
CHAPTER I THE PROGRAM AND EPA'S ESTIMATE OF ITS COST 5

2. Projected emission levels reflect measures that states have included in their state implementation plans for the CAA

but have not yet put into effect.

3. Note that for electricity generators, the emission rate assumed by EPA in the proposed rule (0.15 pounds of NOx

per million British thermal units) represents an 85 percent reduction from the emission rate in 1990. See

Environmental Protection Agency, Fact Sheet: Proposed Rule for Reducing Regional Transport of Ground-Level

Ozone (Smog), October 11, 1997 (available at http://www.epa.gov/ttn/oarpg/otag/otagfs.html).

EPA's Ozone Transport Rule

In its Ozone Transport Rule, EPA is proposing a seasonal budget for total NOx

emissions for each of the 23 jurisdictions. The budget for each state is based on

specific control measures that EPA considers cost-effective for that state. The

proposed rule requires each state to submit a plan for meeting its NOx budget, but it

gives states leeway about how to reduce their emissions. Meeting those budgets

would reduce total regional NOx emissions during the ozone season by almost 1.6

million tons in 2007, EPA reports. As a result, emissions would be 35 percent lower

than the level projected for 2007 if those jurisdictions simply complied with the

Clean Air Act (CAA) and its amendments (see Table 1).2

EPA expects the electric power industry to reduce NOx emissions during the

ozone season by 1 million tons in 2007—a 64 percent decrease from the industry's

projected emission levels for 2007 under existing CAA requirements.3

 The second

largest source of cuts in emissions will be point sources that do not generate

electricity. Those sources include businesses and other institutions that have

industrial boilers, process heaters, stationary gas turbines, stationary internal

combustion engines, or other industrial processes that emit nitrogen oxides. EPA

assumes that such sources will reduce their emissions during the ozone season by

322,685 tons in 2007—a 45 percent decrease from their projected level for 2007

under current CAA requirements.

The NOx Cap-and-Trade Program

EPA's estimate of the cost that the Ozone Transport Rule would impose on the

electric power industry assumes that the industry achieves its emission reductions

through a trading program that includes all 23 jurisdictions affected by the rule. EPA

expects some point sources that do not generate electricity to participate in the

program as well. However, the agency did not estimate the extent to which trading

would reduce costs for those sources.

States will distribute allowances to eligible sources within their borders.

They have some leeway in determining which sources are eligible, but EPA envisions

that the trading program will include two types of sources that use fossil fuel: those
6 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

TABLE 1. PROPOSED SEASONAL BUDGETS OF NOX EMISSIONS FOR STATES

COVERED BY THE OZONE TRANSPORT RULE

Nox Emissions in 2007 (Tons)

Under the

Clean 

Air Act

(Projected)a

Under the

Ozone 

Transport Rule

(Proposed)

Percentage

Reduction Under

the Ozone

Transport Rule

Alabama 241,564 155,617 36

Connecticut 52,014 39,909 23

Delaware 30,568 21,010 31

District of Columbia 7,978 7,000 12

Georgia 246,243 159,013 35

Illinois 350,154 218,679 38

Indiana 340,084 200,345 41

Kentucky 263,855 158,360 40

Maryland 118,065 73,628 39

Massachusetts 103,445 73,575 29

Michigan 283,821 199,238 30

Missouri 185,104 116,246 38

New Jersey 132,032 93,464 29

New York 230,310 185,537 19

North Carolina 234,300 153,106 35

Ohio 391,012 236,443 40

Pennsylvania 328,433 207,250 37

Rhode Island 12,175 10,132 17

South Carolina 169,572 109,267 36

Tennessee 291,225 187,250 36

Virginia 219,835 162,375 26

West Virginia 158,240 81,701 48

Wisconsin 142,759 95,902 33

Total 4,532,790 2,945,046 35

SOURCE: Congressional Budget Office based on Environmental Protection Agency, Supplemental Notice for the Finding

of Significant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group

Region for the Purposes of Reducing Regional Transport of Ozone (April 28, 1998), Table III-7 (available at

http://www.epa.gov/ttn/oarpg/otagsip.html).

NOTE: NOx = nitrogen oxides.

a. Based on the measures included in states' implementation plans for the Clean Air Act and its amendments.
CHAPTER I THE PROGRAM AND EPA'S ESTIMATE OF ITS COST 7

4. See Environmental Protection Agency, Supplemental Notice for the Finding of Significant Contribution and

Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing

Regional Transport of Ozone, April 28, 1998 (available at http://www.epa.gov/ttn/oarpg/otagsip.html). In

calculating the state-specific emission budgets, EPA based them on a 0.15 lb/mmBtu emission rate for electricity

generators and a 70 percent reduction in emissions from uncontrolled levels for other large stationary sources.

Unless otherwise stated, CBO assumes that states allocate emission allowances to existing sources using the same

formula that EPA used in setting the state-specific emission budgets.

5. EPA assumes that an emissions cap is set for the electric power industry during the summer months based on

projections of expected emissions in 2007 given an emission rate of 0.15 lb/mmBtu. Btu is a measure related to

the fuel input used by a facility. Based on EPA's assumptions, the industry would be allowed 564,784 tons of NOx

emissions. The actual level of the cap would vary based on the number of non-electricity-generating sources that

were included and states' decisions about which sources could participate. The proposed rule requires that sources

meet the cap by 2003.

that serve an electricity generator and have a capacity greater than 25 megawatts, and

those that do not generate electricity and have a capacity greater than 250 million

British thermal units (mmBtu) per hour.4

 Each allowance will entitle the source

holding it to emit one ton of NOx during the ozone season. 

Sources will be free to trade, buy, or sell allowances among themselves

throughout the region. Trading provides an economic incentive for sources that can

reduce NOx emissions at low cost to exceed their required reduction and sell their

excess allowances. Those sources can make a profit as long as their cost of

"producing" the excess allowances (that is, reducing their emissions by more than the

required amount) is less than the price at which they can sell them. Conversely,

sources that have high abatement costs for NOx have an economic incentive to buy

allowances: it is cheaper for them to do so than to reduce their emissions.

How would trading work for sources in the electric power industry? EPA

assumes that states will give enough allowances to each eligible combustion device

(or unit) in the electric power industry to let it release NOx at a rate of 0.15 pounds

per million British thermal units.5 Each unit can meet the limit in one of two ways:

by reducing its emissions to that level, or by obtaining allowances from other units

that reduce their emissions below that level and thus generate excess allowances.

Electricity generators may transfer allowances among units they own. Alternatively,

they can buy them from, or sell them to, other participants in the trading program.

The total cost of reducing emissions (that is, of achieving the NOx cap) is

minimized when the cost of further reductions—referred to as the marginal cost—is

the same for all units. In that case, no further cost-saving trades can be made. The

more the marginal cost of cutting emissions varies among sources, the more trading

is necessary to lower the cost of achieving the cap. For example, the cost of reducing

NOx emissions varies among units in the electric power industry depending on

characteristics such as age and size. Based on its analysis of the Ozone Transport

Rule as proposed in October 1997, EPA estimates that 47 percent of the coal-fired

electricity-generating capacity in the region would have to obtain additional
8 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

6. That figure comes from subtracting the amount of coal-fired electricity generation that would install selective

catalytic reduction (SCR) under the trading program from the amount that would install SCR if all units were

required to meet a 0.15 lb/mmBtu emission rate. That difference indicates the amount of generation that would

depend on obtaining additional allowances under the program. EPA's analysis of the proposed Ozone Transport

Rule, as revised in April 1998, does not allow for a similar calculation. See Environmental Protection Agency,

Proposed Ozone Transport Rulemaking Regulatory Analysis, Appendix A, January 1998 (available at

www.epa.gov/capi/capi/reganal2.html). 

7. As modeled by EPA, total emissions are the same under a trading program and a command-and-control approach.

In reality, the uniform emission rate under the latter could result in more variation in emissions, stemming from

variations in either electricity demand or the availability of different types of electricity-generating capacity. For

example, yearly variation in the amount of nuclear capacity has been shown to result in significant differences in

the level of NOx emissions under a requirement for a uniform emission. See Electric Power Research Institute, The

Timing of NOx Emissions and Emission Trading in the Ozone Transport Region, EPRI TR-107186 3835-02 (Palo

Alto, Calif.: EPRI, December 1996).

allowances to meet an emission rate of 0.15 lb/mmBtu.6 EPA's estimate of the cost

to the industry from the Ozone Transport Rule therefore requires an active,

competitive market for trading emission allowances.

Because the Clean Air Act does not give EPA the authority to establish a

federal trading program for NOx emissions, each state will need to establish its own

program. To facilitate trading throughout the region, those programs will have to

be consistent in such critical elements as requirements for monitoring and reporting

NOx emissions. With input from the affected states, EPA is developing a model

trading rule that states can use in developing their programs. EPA hopes that the

model rule will create enough uniformity among state programs for the regionwide

trading program to succeed. How effective that approach will be is not yet clear.

EPA'S ESTIMATE OF SAVINGS UNDER THE NOX TRADING PROGRAM

EPA proposed the Ozone Transport Rule in October 1997 and estimated that it would

cost the electric power industry $1.7 billion a year. The agency compared that

estimate with the $2.2 billion annual cost that it believes a command-and-control

approach would impose on the industry. Under a command-and-control approach,

all electricity-generating units would be required to meet an emission limit of 0.15

lb/mmBtu during the ozone season. The industry's total NOx emissions would be the

same as under a trading approach, but individual units would not have the option of

trading emission allowances.7

 Based on the assumptions and data used in EPA's

original Ozone Transport Rule, the agency expected a NOx trading program to reduce

the costs imposed on the electric power industry by $500 million, or 23 percent. 

On April 28, 1998, EPA published a supplemental notice that modified the

proposed rule and also revised the estimate of annual costs downward—to $1.4

billion. The lower estimate reflects the addition of lower-emitting NOx sources

expected to be built in the future (which had been inadvertantly omitted from the

October 1997 cost estimate), revisions in state-specific growth rates for electricity
CHAPTER I THE PROGRAM AND EPA'S ESTIMATE OF ITS COST 9

8. See Environmental Protection Agency, Supplemental Ozone Transport Rulemaking Regulatory Analysis, April 7,

1998 (available at http://www.epa.gov/capi/ipm/npr.htm).

9. Personal communication with Robert LaCount, Environmental Protection Agency, April 1998.

10. See J.H. Dales, Pollution, Property and Prices (Toronto: University of Toronto Press, 1968).

demand, and changes in the structure of EPA's cost model. It also reflects the

industry's costs in 2007, whereas the earlier estimate reflected costs for 2005.8

The current cost estimate of $1.4 billion is based on specific assumptions

about existing NOx controls in 12 northeastern states and the District of Columbia

(see Box 1). Like the earlier cost estimate, the current estimate assumes that the

electric power industry will achieve its emission reductions through a trading

program and will realize all possible savings that might be obtained from trading.

However, EPA did not reestimate the industry's compliance costs under a commandand-control approach using its revised data, assumptions, and model structure. It

therefore did not update its estimate of how much money could be saved through

trading. 

Discussions with EPA staff suggest that the $2.2 billion estimate of

compliance costs under a command-and-control program is still a valid point of

comparison.9

 Thus, compliance costs for the electric power industry under such a

program would be $800 million more than under a flawlessly operating trading

market. In other words, trading NOx emission allowances could reduce the electric

power industry's compliance costs by as much as 36 percent.

EPA's assumption that participants in the trading program will realize all

possible savings is very optimistic. In reality, that is unlikely to occur because

markets rarely, if ever, function flawlessly. Other trading programs, such as one

designed to reduce acid rain, have captured only a portion of the possible cost savings

to date. Nonetheless, as sources develop confidence in the allowance market, they

will probably hone their compliance strategies to capture more of the potential

savings.

EXPERIENCES OF PREVIOUS TRADING PROGRAMS

The concept of distributing tradable pollution rights—what this paper refers to as

emission allowances—first appeared in the academic literature in 1968.10 Trading

programs can be attractive alternatives to more traditional approaches that mandate

specific pollution limits for all sources. A primary advantage of trading programs is
10 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

BOX 1.

AN EXISTING EFFORT TO CONTROL OZONE TRANSPORT:

 THE OZONE TRANSPORT COMMISSION

The proposed Ozone Transport Rule builds on an existing effort to reduce the movement of

ground-level ozone and its chemical precursors. The 1990 Clean Air Act Amendments

created the Ozone Transport Commission, made up of representatives from 12 northeastern

states plus the District of Columbia. The commission has the authority, upon majority vote,

to recommend strategies to the Environmental Protection Agency (EPA) for addressing

violations of the ozone standard in the 13 jurisdictions.1

 

If EPA approves the majority's recommendations, each jurisdiction—whether or

not it was part of the majority—must "include the approved additional control measures" in

a revised state implementation plan.2

 For example, the Ozone Transport Commission

recommended, and EPA approved, adopting California's Low-Emission Vehicle program.

In addition, member states have agreed to work within their individual regulatory processes

to establish limits on emissions of nitrogen oxides (NOx) for power plants and other large

boilers. They are working to implement those controls through a cap-and-trade program,

with the cap taking effect in 1999. A task force of state representatives developed a model

rule that member states are using to formulate their own programs: the rule defines numerous details of the program, including provisions for trading allowances, monitoring and

reporting emissions, and banking allowances. 

The proposed Ozone Transport Rule affects a larger area than that represented by

the Ozone Transport Commission and builds on the commission's efforts to reduce NOx

emissions. The estimate of what the new rule will cost electricity generators depends on

assumptions about which commission requirements will already be in place. EPA estimates

that the proposed rule will cost the electric power industry $1.4 billion per year, assuming

that electricity generators in the 13 jurisdictions represented by the Ozone Transport Commission install "reasonable available control technologies." That estimate falls to $1.25

billion per year if the commission's NOx trading program is already operating. 

1. For more information on the Ozone Transport Commission and its agreements, see Congressional Budget

Office, Federalism and Environmental Protection: Case Studies for Drinking Water and Ground-Level

Ozone (November 1997).

2. Title I, subpart 2 of the Clean Air Act Amendments of 1990, 42 U.S.C. 7511c(c)(5), 104 Stat. 2450.
CHAPTER I THE PROGRAM AND EPA'S ESTIMATE OF ITS COST 11

11. See David W. Montgomery, "Markets in Licenses and Efficient Pollution Control Programs," Journal of Economic

Theory, vol. 5 (1972); and Tom H. Tietenberg, Emissions Trading: An Exercise in Reforming Pollution Policy

(Washington, D.C.: Resources for the Future, 1985). Trading programs may offer other advantages as well. They

may increase the certainty of achieving an environmental goal (compared with imposing taxes), and they may

maintain environmental standards in the face of inflation and economic growth. See Robert W. Hahn and Roger

G. Noll, "Designing a Market for Tradable Emissions Permits," in Wesley Magat, ed., Reform of Environmental

Regulation (Cambridge, Mass.: Ballinger Publishing Company, 1982).

12. See Robert W. Hahn, "Environmental Markets in the Year 2000," Journal of Risk and Uncertainty, vol. 3 (1990).

13. See Robert C. Anderson, Lisa A. Hofmann, and Michael Rusin, The Use of Economic Incentive Mechanisms in

Environmental Management (Washington, D.C.: American Petroleum Institute, August 1989).

14. Dallas Burtraw, "The SO2 Emissions Trading Program: Cost Saving Without Allowance Trades," Contemporary

Economic Policy, vol. 14 (April 1996), p. 80.

that they can lower the cost of achieving a given environmental goal by giving

participants some flexibility.11 Trading programs have been used for various purposes in the United States, such as to gradually reduce the amount of lead in gasoline.12 Trading programs have also been used to reduce discharges into both Wisconsin's Fox River and Colorado's Dillon Reservoir.13 

The most relevant comparison for the NOx trading program is the program

used to reduce the discharge of sulfur dioxide (SO2). That trading program was

established several years ago to limit the environmental damage resulting from acid

rain. 

The SO2 Trading Program

Title IV of the 1990 Clean Air Act Amendments authorized the first large-scale use

of tradable emission allowances. In 1995, all major electricity-generating units with

relatively high SO2 emissions received an allocation of tradable allowances, each

one permitting the discharge of one ton of SO2. Taken together, the allowances

correspond to a specified reduction in total SO2 emissions during the 1995-1999

period. In 2000, all electricity-generating units will receive tradable allowances that

further limit national SO2 emissions—to roughly 50 percent of 1980 levels. 

To date, utilities have reduced their SO2 emissions at significantly lower

costs than analysts had expected. Not all of those savings stem from allowance

trading, however; changes in the price of rail transport for low-sulfur coal and other

unanticipated factors have also been instrumental in lowering abatement costs.14

To what extent have utilities realized the potential gains from trading allowances? According to a recent unpublished study, the electric power industry could

have complied with title IV for $552 million in 1995, but it actually spent $832
12 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

15. The $552 million figure represents a 30 percent savings from the cost of complying with a uniform SO2 emission

standard for all units. See Curtis Carlson and others, "SO2 Control by Electric Utilities: What Are the Gains from

Trade?" (draft, Resources for the Future, Washington, D.C., December 1997).

16. A. Denny Ellerman and others, Emissions Trading Under the U.S. Acid Rain Program: Evaluation of Compliance

Costs and Allowance Market Performance (Cambridge, Mass.: MIT Center for Energy and Environmental Policy

Research, October 1997).

17. Douglas R. Bohi and Dallas Burtraw, "SO2 Allowance Trading: How Do Expectations and Experience Measure

Up?" Electricity Journal (August/September 1997), pp. 67-75.

18. Another indication of improved performance is that the industry increased SO2 emissions slightly in 1996 compared

with 1995, reflecting more cost-effective use of allowances to cover present releases. In 1995, utilities banked too

much because they were reluctant to rely on the allowance market to ensure compliance. It would have been less

expensive for them to use allowances to cover greater releases that year and incur future costs of compliance

without relying on banked allowances. That is demonstrated by the fact that the weighted marginal cost of

compliance in 1995 was greater than the present discounted value of future marginal compliance costs. See Dallas

Burtraw, "Cost Savings, Market Performance and Economic Benefits of the U.S. Acid Rain Program" (draft,

Resources for the Future, Washington, D.C., January 26, 1998). 

million to do so.15 The reason, observers say, is that participants were reluctant to

fully embrace the new trading program. Utilities wanted to be sure that they could

use independent strategies (such as “banking,” or reducing more than required in

early years in order to have higher emissions in later years) to achieve compliance

rather than relying on the allowance market. As a result, their costs exceeded what

a perfectly operating market could have achieved by $280 million, or about 50

percent. 

The use of SO2 allowances for compliance in 1995 gives an idea of how

actively utilities pursued cost savings from trading. Of the 8.69 million allowances

issued for that year, sources used about 55 percent to cover emissions equal to or

less than their original allocation, banked 39 percent to reduce their expected future

costs of compliance, and acquired the remaining 6 percent to cover emissions that

exceeded their original allocation.16 Trades within utilities represented about twothirds of the trading activity, and trades between utilities (primarily involving six

utilities) accounted for about one-third.17

It would be premature to pass judgment on the long-run prospects for the

SO2 allowance market based solely on its first year of operation. There are indications that the electric power industry is adjusting to take better advantage of the

program. For example, the number of trades virtually doubled in 1996 and again in

1997.18 Furthermore, the introduction of competition in the electric power industry

through deregulation is putting pressure on companies to capture all of the potential

gains from trading emission allowances.
CHAPTER I THE PROGRAM AND EPA'S ESTIMATE OF ITS COST 13

19. Clean Air Act Amendments of 1990, 42 U.S.C. 7651b(d)(1), 104 Stat. 2591.

The Relevance of the SO2 Trading Program to the NOx Program

Both the SO2 and NOx trading programs address electric utilities' contributions to

interstate environmental problems caused by pollutants released into the air. Thus,

experience with SO2 emission trading can provide valuable lessons about the extent

to which participants in a NOx trading program could be expected to realize potential savings. Nevertheless, it is also critical to recognize two principal differences

between the programs. 

First, the proposed NOx trading program lacks the SO2 program's extensive

federal legislative authority. The CAA Amendments established the two fundamental components of the SO2 trading program: they identified participating emission sources, and they specified how many allowances each source would receive.

The amendments also gave EPA authority to establish "a system for issuing, recording and tracking allowances, which shall specify all necessary procedures and requirements for an orderly and competitive functioning of the allowance system."19

Interstate NOx trading, by contrast, would operate on a foundation of 23 individual

programs—one established by each of the jurisdictions covered by the Ozone

Transport Rule. 

Second, the environmental problems that the two programs combat are

slightly different. The proposed NOx trading program addresses a recurring, seasonal problem with air quality: violations of the National Ambient Air Quality

Standard for ground-level ozone. The SO2 trading program addresses the cumulative impact of acid deposition on the environment. 

CHAPTER II

FACTORS AFFECTING THE SUCCESS OF

A NOx CAP-AND-TRADE PROGRAM

Will the proposed cap-and-trade program for emissions of nitrogen oxides fulfill its

potential to lower the cost of complying with the Ozone Transport Rule?

Specifically, will the trading program cost the electric power industry $800 million

less than requiring all electricity generators to meet the same emission rate, as the

Environmental Protection Agency asserts? Based on the experience of previous

trading programs, several factors will influence whether the answer is yes. Those

factors include:

o Having a competitive market for emission allowances,

o Ensuring minimal institutional constraints,

o Keeping transaction costs low,

o Allocating a share of allowances through an auction, and 

o Allowing participants to "bank" allowances for future use.

A COMPETITIVE MARKET FOR ALLOWANCES

To be effective in lowering the cost of cutting regional NOx emissions, the market

for allowance trading must be a competitive one. Concerns about market

concentration arise when the actions of one participant in the market have the

potential to influence the price of emission allowances. That would occur if the

number of buyers and sellers were small, or if a few participants controlled a large

share of the market. But if states allocate NOx allowances along the lines envisioned

by EPA, neither of those scenarios is likely.

Under EPA's plan, the market for NOx allowances will have many

participants. EPA envisions that states will allocate allowances to an electricity

generator based on a measure related to the amount of electricity it generates from

fossil fuels. One group that would receive allowances is electricity-generating boilers

with a capacity of 25 megawatts or more. Such boilers are responsible for most of

the electricity generated from fossil fuels in the region subject to the proposed Ozone
16 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

1. That includes utilities that rely on fossil-fuel and nuclear generation; it excludes utilities that produce less than 0.01

percent of net generation in the region and those that generate electricity wholly from renewable energy sources.

See Department of Energy, Energy Information Administration, Electric Power Annual, 1995, vol. 1, DOE/EIA0348(95)/1 (July 1996); and personal communication with staff members of the Federal Energy Regulatory

Commission.

2. Ibid.

Transport Rule. That region contains 133 different utilities (based on ownership),

which account for 96 percent of the electricity generated there.1

 

Because the electricity-generating market is not highly concentrated, there is

little potential for a few participants to control a large share of the market for

allowances. The Congressional Budget Office examined the percentage of regional

electricity generation attributable to each of the 133 utilities in the area. The utility

responsible for the largest share produces just 8 percent of the regional total, and the

next two largest account for only 7 percent and 6 percent, respectively. In all, the top

10 utilities produce less than 45 percent of the region's total electricity generation.2

That implies that less than half of the allowances that states would allocate to utilities

would be distributed among the 10 largest electricity producers in the region.

Looking beyond utilities, there is even less cause for concern that a few

participants will control much of the allowance market. EPA anticipates that states

will also give allowances to some electricity-generating units that do not belong to

utilities as well as to combustion devices with a capacity greater than 250 million

British thermal units per hour that do not generate electricity. 

MINIMAL INSTITUTIONAL CONSTRAINTS

The rules established by state and federal institutions can affect the incentives that

NOx sources have to buy or sell emission allowances. Those rules include ones made

by state public utility commissions and the federal Internal Revenue Service (IRS).

For participants in the program to realize the potential cost savings from trading,

institutional impediments to trading must be kept to a minimum.

Rules for State Public Utilities

At least two conditions are necessary (although not by themselves sufficient) for

trading to achieve compliance with the NOx cap at the lowest possible cost. First,

participants must minimize the cost of reducing their NOx emissions. Second, the
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 17

3. For a discussion of this issue in the context of utilities' decisions about sulfur dioxide, see Douglas R. Bohi,

"Utilities and State Regulators Are Failing to Take Advantage of Emission Allowance Trading," Electricity Journal

(March 1994).

4. For a more complete discussion of this issue, see Douglas R. Bohi and Dallas Burtraw, "Avoiding Regulatory

Gridlock in the Acid Rain Program," Journal of Policy Analysis and Management, vol. 10, no. 4 (1991).

5. A review of the policies of 11 states that received 85 percent of the allowances issued during phase I of the SO2

program revealed that six states actively promoted pollution-control equipment through favorable cost-recovery

rules. See Bohi, "Utilities and State Regulators Are Failing to Take Advantage of Emission Allowance Trading."

6. One researcher identifies nine public utility commissions that developed guidelines or generic rules on how

allowance transactions should affect the rate-making process. Only one of those states, Connecticut, allows utilities

to retain the profits from the sale of allowances originally allocated to them. See Elizabeth Bailey, Allowance

Trading Activity and State Regulatory Rulings: Evidence from the U.S. Acid Rain Program, Working Paper No.

MIT-CEEPR 96-002 WP (Cambridge, Mass.: MIT Center for Energy and Environmental Policy Research, March

1996).

7. See Bohi, "Utilities and State Regulators Are Failing to Take Advantage of Emission Allowance Trading," p. 678.

8. That occurs when regulators allow utilities to pass the cost of pollution-control equipment on to customers. See

Don Fullerton, Shaun P. McDermott, and Jonathan P. Caulkins, "Sulfur Dioxide Compliance of a Regulated

Utility," Journal of Environmental Economics and Management, vol. 24, no.1 (September 1997).

costs that they perceive for various compliance options must reflect the actual costs.3

Because electricity generation is currently regulated in most states, those conditions

may not hold. 

The rules that regulators establish can distort the relative marginal cost of

investments in pollution-control technology and in allowances. In other words, they

can make more expensive compliance options look cheaper to a utility. Thus,

options that minimize a utility's costs may not minimize costs to its customers.4

 For

example, companies can often depreciate investments in pollution control technology

at a rate that exceeds the physical rate of deterioration. Emission allowances,

however, do not qualify for depreciation. As a result, utilities could receive a higher

rate of return from installing pollution-control equipment than from purchasing

allowances, even though allowances cost less.5

Further, most states require utilities to pass all profits from the sale of

allowances on to their customers.6 Some analysts argue that this requirement

inappropriately discourages utilities from selling their allowances.7 Other analysts

say, however, that letting utilities keep a share of the profits from selling allowances

can give them an incentive to reduce emissions more than is optimal for society.8

Recommending how to design public utility regulations so that utilities have

appropriate incentives is beyond the scope of this paper. However, it is clear that

some of the rules established by state regulators can determine whether utilities face

incentives to reduce their NOx emissions at the lowest cost. Ensuring that they do

will require modifying the historical practices of state regulators.
18 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

9. The Natural Resources Defense Council argues that one limitation of the Ozone Transport Rule is that utilities

might shift power generation to facilities in states not covered by the rule. That would lead to higher emission

levels in those states. See "Northeast Senators Call on Administration to Address Pollution in Restructuring Bill,"

BNA Environment Reporter, vol. 28, no. 39 (February 6, 1998), p. 2009.

10. See Kenneth Rose, "Implementing an Emissions Trading Program in an Economically Regulated Industry: Lessons

from the SO2 Trading Program," in Richard F. Kosobud and Jennifer M. Zimmerman, eds., Market Based

Approaches to Environmental Policy: Regulatory Innovations to the Fore (New York: Van Nostrand Reinhold,

1997).

11. For example, researchers found that low transaction costs help explain the success of the trading program designed

to reduce the lead content of gasoline. By contrast, they found that high transaction costs had a detrimental effect

on emissions trading in the early 1980s and on the trading program designed to reduce discharges into Wisconsin's

Many states have started deregulating the sector of the electric industry that

generates power (a process referred to as restructuring the industry), although they

continue to regulate the distribution and transmission of electricity. Currently, nine

of the 23 jurisdictions covered by the Ozone Transport Rule have either begun such

restructuring or have definite dates to do so. All of the other jurisdictions are

studying the issue, considering legislation to initiate restructuring, or both. In

addition, the federal government is considering legislation to require such

restructuring throughout the country. By increasing competition in the electric power

industry, deregulation should put pressure on utilities to minimize their costs

—including the cost of complying with limits on NOx emissions.9

Tax Disincentives

Some people argue that current IRS rules could discourage the sale of NOx emission

allowances, as may have occurred with SO2 allowances. Specifically, the IRS

assesses the value of SO2 allowances on a historical-cost basis. Since most of the

allowances were distributed to utilities at no charge, their historical cost is zero. (The

cost basis for purchased allowances is the purchase price.) Thus, when utilities sell

freely obtained allowances, they realize a gain that is taxed at the same rate as

corporate income. Allowances that are not sold, however, avoid taxation. That tax

treatment may create an incentive for utilities to hold onto SO2 allowances and could

affect the market for NOx allowances as well.10 However, no empirical evidence

exists about whether the tax treatment of allowances has impeded SO2 trading. Thus,

it is difficult to determine whether those rules would have a significant impact on the

market for NOx allowances. 

LOW TRANSACTION COSTS

Transaction costs—the costs that participants incur to complete a trade of

allowances—can play an important role in determining how well trading programs

perform.11 Transaction costs have two main components: the cost of identifying
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 19

Fox River. See Robert W. Hahn and Gordon L. Hester, "Marketable Permits: Lessons for Theory and Practice,"

Ecology Law Quarterly, vol. 16, no. 2 (1989).

12. See Robert N. Stavins, "What Can We Learn from the Grand Policy Experiment? Lessons from SO2 Allowance

Trading," Journal of Economic Perspectives (forthcoming).

13. Environmental Protection Agency, Model NOx Cap and Trade Program, Draft Working Paper: Elements of Model

NOx Cap and Trade Rule, December 7, 1997 (available at http://www.epa.gov/acidrain/modlrule/element.html).

trading partners (including the cost of negotiating the trade), and the cost of obtaining

regulatory approval for the trade. EPA expects both types of costs to be low for the

NOx trading program. But that expectation will be fulfilled only if participating

states incorporate certain key requirements into their trading programs and establish

programs that are sufficiently compatible with one another. Lack of federal authority

to establish a NOx trading program could lead to transaction costs that are higher than

EPA anticipates. Those costs in turn could limit the realization of potential savings.

The market for SO2 allowances helped demonstrate that the private sector can

play an important role in minimizing the first component, the cost of identifying

partners and negotiating a trade. "Entrepreneurs have stepped in to make available

a variety of services, including private brokerage, electronic bid/ask bulletin boards,

and allowance price forecasts."12 The private sector could play a similar role in the

NOx trading market. 

High regulatory transaction costs typically result from the need to ensure that

trading programs actually achieve the desired environmental goal. For example, the

regulator will want to make sure that the party selling an allowance actually

decreased its emissions by the amount necessary to generate that allowance. The

allowance trading market cannot function well when the process of obtaining

regulatory approval is costly or time consuming.

As envisioned by EPA, the regulatory costs of trading NOx allowances will

be minimal. The agency proposes using a process similar to that used to approve

trades of SO2 allowances—a process that generally takes only 24 hours. Participants

would complete trades by submitting a form to EPA that requires only the signature

of the selling party.13

Monitoring and Reporting Requirements 

In the SO2 trading program, monitoring and reporting requirements are the factors

that keep transaction costs low while still ensuring the integrity of the program.

Sources use continuous monitoring systems for emissions and report those emissions

quarterly to EPA. The agency then deducts the tons of SO2 emitted by each boiler
20 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

14. Those penalties are $2,000 per excess ton of emissions (indexed to inflation) and an automatic assessment of one

allowance per excess ton. See Renee Rico, "The U.S. Allowance Trading System for Sulfur Dioxide: An Update

on Market Experience," Environmental and Resource Economics, vol. 5 (1995), p. 117.

15. See Environmental Protection Agency, Model NOx Cap and Trade Program, Draft Working Paper: Elements of

Model NOx Cap and Trade Rule.

16. See Environmental Protection Agency, Supplemental Notice for the Finding of Significant Contribution and

Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing

Regional Transport of Ozone, April 28, 1998, p. 239 (available at http://www.epa.gov/ttn/oarpg/otagsip.html).

from the allowances in that boiler's account. If the boiler's SO2 emissions exceed the

allowances in its account, the government imposes statutory penalties.14

That system of tracking SO2 emissions and allowances lets program

participants make individual trades with minimal regulatory costs. Any failure to buy

the appropriate number of allowances, or any attempt to sell allowances not

associated with actual cuts in emissions, is detected during the tallying-up process at

the end of the year. Automatic penalties discourage violations. 

EPA expects that states will require NOx sources in the trading program to

comply with similar monitoring and reporting requirements. In fact, title IV of the

Clean Air Act already requires many of the sources that are expected to be part of a

NOx trading program to collect, ensure the quality of, and report the necessary NOx

data. 

To ensure the integrity of the NOx program, EPA wants all of the sources

included to have monitoring and reporting requirements that are as rigorous as those

used in SO2 trading.15 As indicated above, however, states will have some leeway in

determining which sources are included in the trading program. 

State-Established Programs 

Because EPA does not have the authority to set up a federal NOx trading program,

the agency will have less control over the elements of the program—including those

elements that affect transaction costs—than it does over the SO2 trading program.

Each state will need to establish its own trading program, although it can choose not

to. 

In EPA's view, a successful trading market requires "a belief that all of the

sources included in the program are following the same set of rules, and a belief that

trades can be made easily, quickly and with a great deal of confidence that they will

not be altered or denied."16 Achieving that goal for the NOx trading program will

require uniform rules for each state program that are consistently implemented and

enforced. Small differences in language among state rules could lead to different
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 21

17. The possibility of alternative interpretations in different states could also lead to numerous legal challenges, with

resulting delays and uncertainty.

18. For example, Massachusetts will issue allowances for four years at one time, whereas New Jersey will issue them

annually. Personal communication with Nancy Seidman, Massachusetts Department of Environmental Protection;

and New Jersey Department of Environmental Protection, “Policy and Planning/Air Quality Management: NOx

Budget Program,” New Jersey Register, September 15, 1997, 29 N.J.R. 3934.

interpretations and create uncertainty and higher transaction costs than EPA

anticipates.17 For example, the Ozone Transport Commission has encountered

problems with consistency in its attempt to establish a NOx trading program for 12

northeastern states and the District of Columbia. States have chosen different

allocation schemes—some issuing allowances for one year at a time and others for

several years at a time.18 Those differences could increase the transaction costs

associated with negotiating trades and limit the potential for trading between NOx

sources in different states.

To help ensure uniformity among state programs, EPA has developed a model

trading rule; it lists elements that the agency believes state programs must include in

order for a regionwide trading program to succeed. If states establish programs with

those key elements, EPA will administer the system that tracks the emissions and

allowances of sources in those states. That arrangement gives states the opportunity

to reduce their administrative costs by setting up a program that conforms with the

model rule. 

How successful EPA's approach will be is unclear. Although the model rule

will help promote consistency among state programs, it is not likely to result in as

much uniformity as a single, federally established trading program. Further, EPA

cannot compel all states affected by the Ozone Transport Rule to participate in a

trading program. If some states refuse to participate, the potential cost savings from

trading will diminish.

ALLOWANCE AUCTIONS

In theory, the method used to allocate allowances—and the pattern of the initial

allocation—should not affect the cost of achieving the emissions cap. The reason is

that the trading that follows the initial allocation is what minimizes the cost of

achieving the cap (assuming that transaction costs are minimal and that a competitive

market for allowances exists). 

In reality, however, some researchers argue that using auctions as a way to

allocate at least some of the allowances can help in reducing transaction costs and
22 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

19. For example, Ellerman and colleagues state that "the SO2 auctions' most important role may have been to establish

visible market values." See A. Denny Ellerman and others, Emissions Trading Under the U.S. Acid Rain Program:

Evaluation of Compliance Costs and Allowance Market Performance (Cambridge, Mass.: MIT Center for Energy

and Environmental Policy Research, October 1997), p. 33.

20. For a discussion of the role that auctions were expected to play in the SO2 market, see Karl Hausker, "Coping with

the Cap: How Auctions Can Help the Allowance Market Work," Public Utilities Fortnightly (May 24, 1990). 

21. Different methods of allocating allowances will result in different income distributions. For example, program

participants would have less income if the government chose to auction allowances than if it freely distributed

them. Furthermore, workers and owners of capital would benefit if the government chose to offset auction revenues

by lowering existing taxes on labor and capital.

22. Robert N. Stavins, "What Can We Learn from the Grand Policy Experiment?" 

23. See Lawrence H. Goulder, Ian W.H. Parry, and Dallas Burtraw, "Revenue-Raising Versus Other Approaches to

Environmental Protection: The Critical Significance of Preexisting Tax Distortions," RAND Journal of Economics,

vol. 28, no. 4 (Winter 1997).

establishing a competitive allowance market.19 The trading program assumed in

EPA's cost estimate for the Ozone Transport Rule represents a new market for NOx

allowances. The initial number of buyers and sellers in that market is uncertain.

Markets that are "thin" (that is, that have few transactions) have trouble reaching a

stable price, because participants have too little information to use in deciding to buy

or sell. In that case, auctioning a share of allowances can help provide price

information, which can then stimulate direct trades between program participants.

In the acid rain program, the Congress mandated that a share of SO2 allowances be

auctioned, in part to prompt early trades and serve that price-signaling function.20

The government could choose to allocate all allowances through an auction

rather than giving some away. On the one hand, that approach would increase the

costs incurred by program participants. For example, units serving electricity

generators would have to buy allowances for all of their NOx emissions, not just

those over 0.15 lb/mmBtu. On the other hand, research indicates that gains in

efficiency could result if the government kept the revenue from the auction and used

it to lower taxes, such as those on labor and capital, without affecting the balance of

the federal budget.21 Lowering taxes on labor and capital could enhance economic

efficiency by increasing people's incentives to work and save. Such "revenue

recycling" can lower the net cost to society of achieving the emissions cap.22 For

example, some researchers estimate that the cost of the SO2 trading program would

be 25 percent less if allowances were auctioned rather than freely allocated and the

revenues were used to reduce certain taxes.23

Because of EPA's lack of authority over the NOx program, however, it cannot

set aside a share of NOx allowances for auction. States could voluntarily offer some

of their NOx allowances for a regionwide auction, but they would be very unlikely to

do so. If one state did that and all other affected states did not, that state would be

unilaterally reducing its emissions budget. States affected by the Ozone Transport
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 23

24. States are required to submit state implementation plans, indicating how they will meet their emission budgets, in

September 1999. Controls must be in place by September 2002. See Environmental Protection Agency, Fact

Sheet: Proposed Rule for Reducing Regional Transport of Ground-Level Ozone (Smog), October 10, 1997

(available at http://www.epa.gov/ttn/oarpg/otag/otagfs.html). 

Rule might benefit if all of them agreed to offer a share of their allowances for a

regionwide auction. But without a mechanism to ensure such an agreement, no

individual state has an incentive to do so.

Of course, states could decide to allocate allowances to sources within their

borders through an auction. But such limited auctions would not provide useful price

signals for the regionwide market. An auction will provide appropriate price signals

only if it is open to all potential buyers and sellers. Because the market for NOx

allowances will cover the 23 jurisdictions assigned emission budgets under the

Ozone Transport Rule, an appropriate price-signaling auction would need to be open

to buyers and sellers throughout that region. 

FLEXIBILITY IN THE TIMING OF EMISSION REDUCTIONS

Cap-and-trade programs can allow participants to vary the timing of their emission

cuts in two ways. First, programs can let participants generate allowances by

reducing their emissions before the cap goes into effect. The participant can then

bank those allowances to use later when the cap is operating. Second, once the cap

is in place, programs can allow participants to bank unused allowances for future use.

For example, unused allowances in a source's account at the end of 2005 could be

used in 2006. 

Both forms of banking can play an important role in reducing the cost of

meeting the NOx cap and may offer other benefits as well. However, banking also

has disadvantages. EPA has not yet proposed what, if any, type of banking it will

include in its model trading rule. 

The Advantages of Banking Early Reductions 

Allowing participants to generate allowances by cutting emissions before the cap

takes effect has at least three advantages. First, it can help sources plan for the

transition to the cap. For example, if a utility makes early reductions at some of its

units, it can delay controlling emissions from other units once the cap is in place.

That gives the utility more time to explore various compliance options. That

advantage can be particularly important when sources have a relatively short period

in which to plan before the cap takes effect, as is the case with the Ozone Transport

Rule.24 A utility's decision about how to comply depends on the price of allowances,
24 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

25. Robert W. Hahn and Roger G. Noll, "Environmental Markets in the Year 2000," Journal of Risk and Uncertainty,

vol. 3 (1990), p. 353. 

26. Ellerman and others, Emissions Trading Under the U.S. Acid Rain Program, pp. 28-29.

which is affected by other participants' decisions. By delaying compliance at some

of its units, a utility can get preliminary information about allowance prices and thus

be better able to reduce total compliance costs. That same benefit could also be

obtained by phasing in the cap. 

Second, letting participants bank allowances generated by early reductions

gives them an economic incentive to cut their emissions before they are required to

do so. By making early reductions, participants can save allowances for use when

restrictions on NOx emissions are tighter and the marginal cost of control is higher.

Those early reductions can lower total compliance costs. 

Third, early reductions mean that areas obtain the health and environmental

benefits of lower NOx emissions sooner than they would otherwise. Later on,

however, emissions could be higher than they would have been if participants had not

generated allowances through early reductions. In some cases, though, early cuts in

nitrogen oxides, which occur when total emissions are high, could create larger

health and environmental benefits than later reductions, which occur when total

emissions are lower. That would be the case if the incremental damage from NOx

emissions increased as the total level of emissions rose.

The Advantages of Banking Once the Cap Is in Place 

Allowing participants to save up unused allowances after the cap is in place could

also have several benefits. For one thing, banking can facilitate trading. Pollutioncontrol strategies for nitrogen oxides generally involve investment decisions that

affect emissions for many years. Without banking, participants may be reluctant to

make investments that would reduce their emissions beyond the required amount

without knowing for sure that someone else will be able to purchase their

allowances.25 Banking assures participants that those investments will generate

allowances that can be used or sold at a future date. That facilitates the development

of a futures market for allowances, as has occurred with SO2 allowances.26

For another thing, banked allowances can protect utilities against variations

in the availability of power-generating facilities and swings in the demand for
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 25

27. See Laurel J. Carlson, NESCAUM/MARAMA NOx Budget Model Rule (prepared for the Northeast States for

Coordinated Air Use Management (NESCAUM) and the Mid-Atlantic Regional Air Management Association

(MARAMA) NOx Budget Task Force’s NESCAUM/MARAMA NOx Budget Ad Hoc Committee and the Ozone

Transport Commission’s Stationary and Area Source Committee by Environmental Science Services, Providence,

R.I., May 1, 1996), p. 19.

28. That can occur if sources turn off NOx controls that have relatively high operating costs. See Electric Power

Research Institute, The Timing of NOx Emissions and Emission Trading in the Ozone Transport Region, EPRI TR107186 3835-02 (Washington, D.C.: EPRI, December 1996), p. 5-5. The report was prepared by National

Economic Research Associates of Cambridge, Massachusetts.

electricity.27 For example, generating power from nuclear facilities does not create

NOx emissions. Thus, variation in the amount of nuclear capacity available can lead

to variation in a utility's need for NOx allowances. In the SO2 program, utilities

initially tried to avoid relying on the allowance market to provide for unexpected

future needs, preferring instead to bank their allowances to ensure future compliance.

In addition, like generating allowances through early reductions, having the

ability to bank once the cap is in place gives sources an incentive to decrease their

emissions earlier than might otherwise be the case. Those early decreases can result

in benefits to human health and the environment. 

Finally, banking can protect against instability in the price of allowances and

spikes in emissions. Without banking, the price of allowances could change sharply

at the end of each compliance period. If sources had saved extra allowances to

provide for unexpected requirements throughout the compliance period, they would

want to sell them at the end of that period. At that point, the price of allowances

could fall sharply as many participants attempted to sell them before they expired.

Emissions, in turn, could spike as sources used up the excess allowances.28

Conversely, the price of allowances could increase sharply if unusual circumstances

created a shortage at the end of a trading period.

The Potential Disadvantages of Banking 

Despite its potential advantages, the use of banking in a NOx trading program could

lead to problems as well. If a large number of banked allowances were used in a

given ozone season, the emissions cap for that season would be exceeded, which

could contribute to violations of the ozone standard. 

Banking has played an important role in the SO2 trading program. Unlike the

NOx trading program, however, the SO2 program addresses a problem that stems

from the cumulative impact of a pollutant. Because of that difference, the use of

banked SO2 allowances does not raise the same concerns as the use of banked NOx

allowances.
26 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

29. Ibid, pp. 5-8 and 5-9.

30. Environmental Protection Agency, Proposed Ozone Transport Rulemaking Regulatory Analysis, January 1998,

p. A3-29 (available at http://www.epa.gov/capi/capi/reganal2.html).

A report by National Economic Research Associates (NERA) examined

whether banking in the Ozone Transport Commission's cap-and-trade program (see

Box 1 in Chapter I) would be likely to lead to significant breaches of that program's

cap. NERA concluded that "excessive" banking would be discouraged in at least two

ways.29 First, banking entails an opportunity cost, since banked allowances cannot

earn interest, so sources will be willing to do it only if they expect the price of

allowances to increase by more than the interest rate. Second, market forces should

prevent excessive banking. As more sources choose to bank allowances, the

expected price of allowances sold in the future will fall. Furthermore, the current

price of allowances will rise as banking reduces the current supply. Those forces

should have a moderating effect on the amount of banking that will occur. However,

further analysis is necessary to better understand how much EPA's proposed cap

might be exceeded under various banking provisions. 

EPA did allow for banking (after the cap was in place) when it estimated the

cost that the NOx trading program would impose on electricity generators. The

agency predicted that no banking would occur, however, because the cap is constant

throughout the time period examined in its cost model and because EPA expects

control costs to be constant or to decrease in real terms (that is, after accounting for

inflation).30 Thus, banking cannot reduce power generators' compliance costs.

However, EPA's model did not account for important factors that could lead to

banking. As described above, those factors include uncertainty about the future

availability of power-generating facilities and swings in the demand for electricity.

EPA is seeking comment on what form of banking, if any, it should include

in its model trading rule. One option under consideration is "flow-control" banking,

which is part of the model trading rule developed by the Ozone Transport

Commission. Flow control seeks to capture some of the advantages of banking while

limiting the potential disadvantages. For a detailed explanation of how flow control

would work, see Box 2. 
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 27

BOX 2.

FLOW-CONTROL BANKING

Under the flow-control version of banking, trading participants may bank as many emission

allowances as they want. If the total number banked in a given year is less than a specified

percentage of the regional cap on allowances for that year (the Ozone Transport Commission's trading program uses 10 percent), then banked allowances can be used in the upcoming

year at full value. In that case, participants can emit one ton of nitrogen oxides (NOx) for

each banked allowance they use. If, by contrast, the number of banked allowances exceeds

the specified percentage, then some of the banked allowances will be subject to a discount.

In that case, participants may need to use more than one banked allowance for some of the

tons of NOx that they emit. The share of banked allowances that is subject to that discount

in a particular year depends on the extent to which the number of allowances banked in the

previous year exceeds the specified percentage of the cap. 

The Ozone Transport Commission's flow-control banking provides an example of

this concept in operation.1

 In 1999, the NOx cap for the commission's 13-jurisdiction region

will be 219,005 tons. If sources of NOx emissions in those jurisdictions hold 29,200 banked

allowances in 1999, they will exceed 10 percent of the NOx cap for that year. Therefore,

some of the banked allowances will be subject to a discount the following year (2000). The

exact number subject to a discount in 2000 depends on how much the actual number of

banked allowances in 1999 exceeds 10 percent of that year's NOx cap: 

 0.10 x NOx cap in 1999 = 21,901 = 0.75

# of allowances in the bank in 1999 29,200

That ratio is applied to each source's account to identify the number of banked allowances

that can be used on a one-for-one basis in 2000 and the number of allowances that can be

used on a two-for-one basis. For example, if a source has 1,000 allowances in the bank, it

may use 750 on a one-for-one basis and the remaining 250 on a two-for-one basis.

1. See Laurel J. Carlson, NESCAUM/MARAMA NOx Budget Model Rule (prepared for the Northeast States

for Coordinated Air Use Management (NESCAUM) and the Mid-Atlantic Regional Air Management

Association (MARAMA) NOx Budget Task Force's NESCAUM/MARAMA NOx Budget Ad Hoc

Committee and the Ozone Transport Commission's Stationary and Area Source Committee by

Environmental Science Services, Providence, R.I., May 1, 1996), pp. 21-22.
28 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

31. All estimates are based on predicted emissions in 2007. See Environmental Protection Agency, Supplemental

Ozone Transport Rulemaking Regulatory Analysis, April 7, 1998, Appendix D, Table D-1 (available at

http://www.epa.gov/capi/ipm/npr.htm).

32. Ibid. Other states with higher estimated NOx emissions from electricity-generating sources under trading are New

Jersey and Maryland (7 percent), North Carolina (6 percent), Illinois (4 percent), and Pennsylvania (less than 1

percent).

COULD TRADING MAKE SOME AREAS LESS LIKELY 

TO ACHIEVE THE OZONE STANDARD?

Another concern besides whether the trading program will achieve its potential cost

savings is whether trading could make some areas less likely to meet the ozone

standard. EPA's Ozone Transport Rule calls for significant reductions in NOx

emissions throughout the multistate region. Those reductions will be instrumental

in reducing ozone concentrations and bringing many counties and metropolitan areas

into compliance with the standard.

Although introducing allowance trading does not alter the magnitude of the

regional abatement effort, it is likely to alter how that effort is distributed among the

23 jurisdictions covered by the rule. With trading, EPA estimates, NOx emissions in

14 of those jurisdictions would be reduced by more than the amount specified in the

Ozone Transport Rule. On the whole, electricity-generating sources in each of those

14 jurisdictions would be net sellers of emission allowances.31

The nine other jurisdictions, the agency estimates, would experience smaller

cuts in NOx emissions with trading than those specified in the Ozone Transport Rule.

Thus, sources in each of those jurisdictions would, on the whole, be net buyers of

emission allowances. For example, EPA estimates that annual NOx emissions from

electricity-generating sources in four states would be more than 15 percent higher

with the introduction of a regionwide trading program than without it. Specifically,

West Virginia’s annual emissions from those sources would be 94 percent higher

with trading than without it; Alabama’s would be 22 percent higher; Michigan’s

would be 19 percent higher; and Georgia’s would be 16 percent higher. 32

Some states worry that the distribution of NOx emissions under regionwide

allowance trading will worsen air-quality problems, leading to violations of the ozone

standard that would not have occurred under a requirement for a uniform emissions

rate. A trading program in which all emissions are treated identically, regardless of

the location of their source, is particularly problematic when the emissions from a

source with relatively high abatement costs contribute relatively more to violations

of the standard. In such cases, health and environmental considerations call for

reducing emissions from that source, but cost considerations encourage that source

to buy allowances instead of cutting emissions. In effect, the sale of allowances by
CHAPTER II FACTORS AFFECTING THE SUCCESS OF THE PROGRAM 29

33. For example, suppose that reducing NOx emissions at three North Carolina sources west and northwest of Charlotte

turned out to be the only way for the city to achieve compliance with the ozone standard. Suppose further that

those sources' relative marginal costs of abatement prompted them to buy allowances instead of cutting their

emissions. Although reduced emissions elsewhere would make the allowances available, those abatement efforts

would have no impact on whether Charlotte met the standard.

low-cost, low-damage sources promotes an increase in emissions at high-cost, highdamage sources on a ton-for-ton basis.

EPA's proposed trading program does not prevent states from imposing

control requirements on specific emission sources within their borders. States may

choose to do that to prevent excessive releases from sources that have a particularly

potent effect on ozone concentrations in areas in the state that are violating the

standard. Such requirements would reduce the potential cost savings from trading

by limiting participation in the allowance market, but they would be appropriate if

they reflected the most cost-effective way to bring an area into compliance with the

standard.33

Similarly, it might also be appropriate for states to prevent excessive releases

from emitters in their jurisdiction that have an especially great impact on ozone

concentrations in out-of-state areas that violate the standard. However, states are

unlikely to choose to do that. Thus, federal authority would be necessary for the

trading program to comprehensively address the location-based differences in effects

that NOx emissions have on air quality in areas violating the ozone standard

throughout the multistate region. For a detailed discussion of how such geographic

targeting might operate, see the appendix. 

CONCLUSION: HOW THE NOX PROGRAM 

RANKS ACCORDING TO THESE FACTORS 

Trading programs are most likely to operate successfully when the market for

allowances is competitive, when there are minimal institutional constraints and low

transaction costs, when some allowances are allocated through an auction, and when

participants can bank allowances for future use. How does the proposed NOx trading

program rank in terms of those factors?

By the first two criteria, the program ranks favorably. The market for NOx

allowances is likely to be competitive. Given the sources that EPA expects states to

include in the trading program and the allocation procedures it expects states to

follow, it is unlikely that any individual source or group of sources would be able to

influence the price of allowances. In addition, existing institutional constraints

should be reduced by the move toward deregulation of the electric utility sector.

Deregulation should give utilities an incentive to engage in allowance trading when

doing so can minimize their cost of reducing emissions. 
30 EPA'S NOx CAP-AND-TRADE PROGRAM June 1998

By the other factors, the program does not rank as favorably. In many

instances, that is because EPA does not have authority to establish a regionwide NOx

trading program. For example, although EPA expects transaction costs to be low, its

ability to ensure that they are is limited. In each of the jurisdictions covered by the

proposed rule, participation in the trading program is contingent on state-level

regulatory action. Differences in state rules could lead to delays, uncertainty, and

higher transaction costs than EPA envisions. The agency has proposed a model rule

that it hopes will encourage enough uniformity among state programs to minimize

those problems, but how successful that strategy will be is unclear.

EPA's lack of authority to establish a regionwide program also precludes it

from setting aside a share of allowances for a regional auction. Auctions can be

useful in providing price information to participants in newly established markets,

such as the NOx allowance market. In the absence of such price information, markets

can have trouble reaching a stable price, which discourages trading. Further, EPA

does not have authority to compel states to participate in the trading program. If

some states choose not to participate, the potential savings from trading will decrease

and the cost of achieving the NOx cap will rise.

EPA has not yet determined whether it will allow NOx sources to bank

allowances. Restricting sources' ability to bank allowances for future use can

discourage trading and limit the potential savings from the program. Such

restrictions might be justified, however, if the use of banked allowances would

contribute to violations of the ozone standard. Further analysis is needed to

determine whether restrictions on banking are warranted.
1. Note that from the perspective of economic efficiency, the appropriate ambient trading program for NOx would define

emission allowances in terms of the damage attributable to NOx emissions (through ambient ozone concentrations and

otherwise) in areas throughout the region.

APPENDIX 

GEOGRAPHIC TARGETING OF TRADES

The Clean Air Act requires all areas to comply with the National Ambient Air

Quality Standard for ground-level ozone. The trading program for emissions of

nitrogen oxides (NOx) would be one way to help achieve that goal. As the

Environmental Protection Agency (EPA) currently envisions the program, any

participating source would have to use one allowance—obtained either through its

initial allocation or through trading with other sources—for each ton of NOx it

emitted. Compared with an approach that required all sources to meet a uniform

level of emissions, trading would lower the cost of achieving the regional NOx cap

by allowing cuts to be made by those sources that can do so most cheaply. A key

question, however, is whether that is analogous to reducing the cost of bringing the

multistate region into compliance with the ozone standard.

The answer to that question depends primarily on atmospheric science. If

regional concentrations of ambient ozone respond similarly to cuts in NOx emissions

regardless of where those cuts occur, the answer is unequivocally yes. However,

atmospheric modeling has shown that the impact of NOx emissions on ambient ozone

varies with the location and timing of emissions. Further, the effects of location and

timing interact: emissions may have an impact on local concentrations of ozone

fairly quickly but on distant concentrations with a significant lag.

AN AMBIENT TRADING PROGRAM

In theory, when transported pollutants have a critical effect on compliance with an

air-quality standard, the most cost-effective way for a region to meet that standard is

through an ambient trading program. Such programs are based on the concept of

geographic targeting. For example, each area violating the NOx standard could have

a unique allowance market. The allowances traded in that market would give sources

throughout the region permission to affect that area's ambient ozone concentration

by so many parts per billion through their NOx releases.1

 Thus, if nitrogen oxides

from a given source altered the ambient ozone concentrations in five different areas,

that source would have to deal in five different allowance markets. In EPA's

proposed NOx trading program, by contrast, sources are not subject to geographic
32 EPA'S NOX CAP-AND-TRADE PROGRAM June 1998

2. In its October 1997 notice of proposed rulemaking, EPA solicited comments on approaches that factor in the differential

effects of emissions from varying locations on air quality in areas throughout the 23-jurisdiction region that violate the

ozone standard. The agency’s April 28, 1998, supplemental notice of proposed rulemaking states, “If after review of

alternative approaches (including sub-regional modeling analyses submitted by states and other commenters) EPA

concludes that a new approach is appropriate, EPA will issue a S(upplemental) N(otice) of P(roposed) R(ulemaking).”

See Environmental Protection Agency, Supplemental Notice for the Finding of Significant Contribution and

Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing Regional

Transport of Ozone, April 28, 1998 (available at http://www.epa.gov/ttn/oarpg/otagsip.html).

3. Taking both the location and timing of emissions into account would further increase the number of relevant markets.

In addition, allowance prices would probably take time to stabilize in those very interdependent markets. Moreover,

ambient ozone concentrations depend on NOx emissions from all sources, not just those in the program, and on

emissions of volatile organic compounds and meteorological conditions in different locations at different times.

targeting. Instead, they can trade allowances regardless of the resulting impact of

their emissions on concentrations of ambient ozone throughout the region.2

In practice, an ambient trading program is very ambitious because it requires

detailed information about the effect of every source's NOx emissions on every area's

ozone concentration. Scientists do not yet understand the formation and transport of

ozone thoroughly enough to provide that information. In addition, such a program

would entail large transaction costs because sources might have to participate in

allowance markets for many different areas.3 Those high transaction costs could

overwhelm the potential savings from trading.

EPA could incorporate a less ambitious version of geographic targeting into

its proposed NOx trading program, which could reduce the cost of achieving

compliance with the ozone standard. Compared with a "pure" ambient trading

program, a modified version would require less detailed knowledge of how ozone is

formed and transported and would entail lower transaction costs.

LESS AMBITIOUS GEOGRAPHIC TARGETING PROGRAMS

EPA could use two basic approaches to incorporate geographic targeting into its NOx

program: the trading-zone approach, and the location-weighted emissions approach.

Both approaches require information about the geographic relationship between

sources of NOx emissions and area-specific concentrations of ozone. Unlike an

ambient trading program, however, they can use more general information about that

relationship.

Under the trading-zone approach, the region covered by the Ozone Transport

Rule would be divided into separate zones, each with its own emissions cap and

market. Zones could vary in size and might contain all or part of one or more states.

Sources would be able to trade emission allowances only within their zone, and in

each zone one allowance would be worth one ton of NOx emissions. 
APPENDIX GEOGRAPHIC TARGETING OF TRADES 33

4. This location-weighted emissions approach is analogous (subject to appropriate initial allocations) to establishing

different trading ratios based on the location of the trading parties. Under a trading-ratio approach, sources do not

trade allowances on a one-for-one basis. Instead, a ton of emissions reduced at one source trades for "x" tons of

emissions released at another source. The value of "x" reflects the sources' marginal impact on areas' compliance with

the ozone standard. The advantage of the location-weighted emissions approach is that it avoids the high transaction

costs associated with the trading-ratio approach. Sources simply need an appropriate number of one-ton allowances

to cover their emissions. A source determines that number by multiplying its emissions by the number of allowances

required per ton released at its location.

5. Allowing one-way trades across appropriate boundaries could ease, but not eliminate, that problem. For example,

California's South Coast Air Quality Management District established two zones for its NOx and SO2 (sulfur dioxide)

trading program. Although sources in the coastal zone generally cannot use allowances from the inland zone, any

source can use coastal zone allowances regardless of its location. That feature allows shifts in emissions away from

zones subject to more stringent levels of control. In theory, such trades should be unlikely because marginal costs of

abatement should be higher in those zones. Nevertheless, if the cost difference is reversed (because of the

characteristics of certain sources), allowing one-way trades makes both economic and environmental sense.

6. The costs of notifying sources and monitoring their compliance are relatively minor. EPA notes, however, that

substantial resources could be required to defend decisions that impose different compliance burdens on different

sources (personal communication with Brian McLean, Director, Acid Rain Division, Environmental Protection

The location-weighted emissions approach would maintain a regionwide

market for allowances, but the number required for each ton of NOx emissions would

vary according to the location of the source.4 For example, sources close to urban

areas that violate the ozone standard might need two allowances for every ton of NOx

they release.

COST AND FLEXIBILITY OF THE LESS AMBITIOUS PROGRAMS

A decision about whether to use either of the less ambitious approaches to geographic

targeting should consider the net effect of two factors: the increased costs associated

with greater complexity, and the potential for reducing the cost of meeting the ozone

standard. Even if the advantages outweigh the disadvantages under both approaches,

the difference is likely to be greater with location-weighted emissions trading.

In principle, the trading-zone approach can reduce the opportunities for costsaving trades because it includes multiple (and therefore small) allowance markets

compared with EPA's proposed single market. Sources that can reduce NOx

emissions at lower marginal costs will have fewer potential buyers for the allowances

they make available.5 In addition, with fewer participants than a regionwide market,

the market in each zone could be less competitive. Further, that approach would

carry higher costs because of the need to administer a separate cap-and-trade program

for each zone.

The location-weighted emissions approach would also involve higher

administrative costs than the type of trading program that EPA now envisions.

Program officials would have to specify the required number of allowances per ton

of NOx emitted from different sources.6 In addition, to capture the cost savings
34 EPA'S NOX CAP-AND-TRADE PROGRAM June 1998

Agency). For example, it is not true that the acid rain damage from a ton of SO2 emissions is the same regardless of

the source's location. Like ground-level ozone, acid rain varies considerably by area, in part because of long-range

transport, but the impact of emissions tends to be greatest in areas where they are released. Since ecosystems also differ

in their sensitivity to acid rain, the marginal damage caused by a ton of emissions varies widely. Although it is

scientifically inaccurate to say that the location of SO2 emissions does not affect the level of damages from acid rain,

this regulatory fiction has proved to be very useful. It has made the goal of the acid rain program a reduction in overall

emissions, thus avoiding the need to identify damages and specify responsible parties.

7. The location-weighted emissions approach requires more than one allowance per ton of NOx emitted from sources that

contribute significantly to violations of the ozone standard in the region. To preserve the incentive for greater

reductions at those sources, officials would not want to give them the additional allowances created under the increased

emissions cap. Instead, they would want to allocate those allowances among other sources.

8. Nonetheless, the prospects for geographic targeting merit some consideration. For example, state officials have

expressed concern that compliance with the ozone standard could depend on what pattern of emissions results from the

trading program that EPA envisions. Under the location-weighted emissions approach, officials could simply weight

emissions from different sources more or less heavily—requiring a higher or lower number of allowances per ton of

NOx released—according to the sources' relative impact on areas' compliance with the standard. EPA expects to

complete a modeling analysis over the next few months that will show predicted changes in ambient concentrations of

ground-level ozone under its proposed trading program (personal communication with Norm Possiel of EPA, March

12, 1998). The agency's April 28, 1998, supplemental notice of proposed rulemaking reports the results of a modeling

analysis that shows predicted changes in ozone concentrations throughout the region if each state meets its own NOx

emission budget without trading. See Environmental Protection Agency, Supplemental Notice for the Finding of

Significant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group Region for

Purposes of Reducing Regional Transport of Ozone, April 28, 1998 (available at http://www.epa.gov/ttn/

oarpg/otagsip.html).

9. Officials would also have the opportunity to address changes in the electric power industry that influenced emission

patterns and thus areas' status with respect to the ozone standard. Any advisable changes in the value of weights would

require recalculating states' emissions budgets to correspond to changes in the overall cap.

associated with that approach, officials would have to recalculate the states' emission

budgets to correspond to a higher overall cap.7

However, the location-weighted emissions approach would avoid the limits

on trading associated with the zone approach. Because all potential participants

would be in the same market, they could fully capitalize on opportunities for costsaving trades.

The other important advantage of the location-weighted emissions approach (compared with the trading-zone approach) is its flexibility. Assessing the

extent to which the available scientific evidence can justify geographic targeting is

beyond the scope of this paper.8

 At best, current understanding of ozone formation

and variable patterns of ozone transport may only support modest implementation of

geographic targeting. The location-weighted emissions approach provides a more

adaptable mechanism through which to incorporate evolving scientific understanding

about sources' relative contributions to violations of the standard. Initially, program

officials could start with a trading program like the one envisioned by EPA by simply

requiring one allowance for each ton of NOx emitted, regardless of the location of its

source. At predetermined intervals, program officials could change that requirement,

making broad or fine distinctions between geographic areas, if the available scientific

evidence supported that.9