Part IV — Implications Of Regulating CO2 as an NSR Pollutant
The Environmental Protection Agency (EPA) is currently deliberating over an endangerment finding and associated rulemakings that may subject certain stationary sources, such as coal-fired power plants, to the requirement for Best Available Control Technology (BACT) for CO2 emissions under the Clean Air Act. This requirement promises to be highly controversial and burdensome and has the potential to be enormously expensive for the regulated community. There are numerous technical and policy issues associated with the application of BACT for CO2 emissions, but three of these issues stand out-
a. Whether and to what extent the permitting authority can and should dictate alternative production processes in its BACT determination;
b. Whether and to what extent decreases in CO2 emissions should be required at the expense of increases in emissions of conventional air pollutants; and
c. What is the economic value of avoided CO2 emissions from a proposed stationary source in the United States?
Each of these considerations arises under the statutory definition of BACT, which is as follows:
“[BACT] means an emission limitation based on the maximum degree of reduction of each pollutant subject to regulation under this Act emitted from or which results from any major emitting facility, which the permitting authority, on a case-by-case basis, taking into account energy, environmental, and economic impacts and other costs, determines is achievable for such facility through application of production processes and available methods, systems, and techniques, including fuel cleaning or treatment, clean fuels, or innovative fuel combustion techniques for control of each such pollutant. In no event shall application of [BACT] result in emission of any pollutants which will exceed the emissions allowed by any applicable standard established pursuant to section 111 or 112 of this Act.”
BACT analyses are generally performed on a source-by-source and pollutant-by-pollutant basis using five key steps:
Step 1. Identify all control technologies.
In a BACT analysis, “available” control options are those technologies or techniques with a practical potential for application to the subject emission units and pollutants. All potential options are listed in this step; those that are technically infeasible or have unacceptable energy, economic or environmental impacts are eliminated in subsequent steps.
Step 2. Eliminate technically infeasible options.
In the second step, the technical feasibility of each identified control option is evaluated with respect to source specific factors. Demonstrations of technical infeasibility must show, based on physical, chemical and engineering principles, that technical difficulties would preclude the control option from being employed successfully on the subject emissions unit.
Step 3. Rank remaining control technologies by control effectiveness.
In the third step, all remaining control alternatives not eliminated in Step 2 are ranked in order of overall control effectiveness for the pollutant under review. For each option, estimated control efficiency and overall emissions reduction must be documented.
Step 4. Evaluate most effective controls and document results.
In the fourth step, beneficial and adverse energy, environmental and economic impacts of each remaining control option are listed and considered. If the best option (i.e., the option with the highest control effectiveness as ranked in step 3) is rejected as BACT due to unacceptable energy, environmental or economic impacts, the rationale must be documented for the public record, and the next best control option subjected to the same evaluation.
Step 5. Select BACT.
Finally, the most effective control technology not eliminated in the previous step is proposed as the technological basis for BACT and an emission limit representing BACT is proposed in the draft permit.
The first of the three main issues identified above reflects a tension created by the definition of BACT - the agency is required by the statute to determine BACT for the facility for which the applicant has submitted a permit application, and also is required to consider “production processes,” “clean fuels” and “innovative fuel combustion techniques” as control options. This leaves the permitting authority considerable discretion in defining how broadly or narrowly to construe the facility proposed by the applicant. The position advocated by the Sierra Club and other environmental groups would require a very broad construct and would mandate consideration of alternative process technologies, such as integrated gasification combined cycle (IGCC) in place of proposed pulverized coal-fired boilers, in the Step 1 analysis outlined above. One court, in Georgia, has ruled that the permitting authority must include in the analysis any method of producing the desired product from the desired raw material, regardless of any process equipment changes necessitated by the decision.
On the other hand, EPA, most other permitting authorities, and the 7th Circuit Court of Appeals (in Prairie State) have concluded that the BACT determination should not require substantial addition or redesign of process equipment. Under this approach, the BACT analysis considers in Step 1 only air pollution control technologies or minor equipment alterations that can be applied to the process technology proposed by the permit applicant. This is consistent with how most permitting authorities have historically performed BACT analyses for conventional air pollutants.
The remaining two of the three main issues that will arise in BACT determinations for CO2 emissions are specific to the Step 4 impacts analysis. These issues are in many ways similar to the policy issues that have long arisen in BACT analyses for conventional air pollutants, but will require that permitting authorities apply a new set of metrics. These issues will be discussed in the fifth and final installment of this series on ClimateIntel.