1. Best available control technology (BACT) requirements
Roland C. Hea, P.E.
Colorado Air Pollution Control Division

2. Main PSD Program Requirements
Install Best Available Control Technology (BACT)
Perform air quality analysis to assess impacts on air quality (NAAQS and PSD increments)
Perform Class I Area analysis to assess impacts on national parks and wilderness areas or other Class I Areas
Perform additional impacts analysis
Provide opportunities for public involvement

3. BACT – Major Topics When does BACT apply
Steps in the “Top Down” BACT analysis
What does a BACT determination and limit look like
Greenhouse gas (GHG) BACT issues
State (Colorado) perspectives

4. Best Achievable Control Technology (BACT) Overview
Pollutant specific emissions limit, case-by-case
Takes into account energy, environmental, or economic impacts
Limit must be at least as stringent as applicable
New Source Performance Standard (NSPS) and/or
National Emission Standard for Hazardous Air Pollutants (NESHAP)
Selected by “Top Down” BACT analysis
Identify all available control technologies
Eliminate technically infeasible control options
Rank remaining control technologies by its effectiveness (considering economic, energy and environmental impacts)
Evaluate most effective controls and document results
Select BACT

5. BACT Applicability Identify emissions units that are subject to BACT
Applies to each individual new or modified affected emissions unit or activity at which a net emissions increase would occur
Perform BACT analysis at each of the applicable emissions units for each regulated pollutant subject to PSD review 5

6. BACT Analysis Step 1
Identify all available air pollution control technologies, regardless of cost
Information sources
Review RACT/BACT/LAER Clearing House
Look at BACT and LAER
Control technology vendors
Federal/state/local NSR permits
Environmental consultants
Technical journals (e.g., Journal of Air and Waste Management Association) and air pollution conferences
EPA’s Draft October 1990 NSR Workshop Manual

7. BACT Analysis Step 1 (cont.)
Include technologies used outside the U.S.
Include controls applied to similar categories and gas streams
Review applicable NSPS and NESHAP (including MACT), which define minimal “floor” for BACT
Consider
Inherently lower-emitting processes/practices
Add-on controls (e.g., scrubbers, fabric filters)
Combination of inherently lower-emitting processes/practices and add-on controls

8. BACT Analysis Step 1 (cont.)
EPA has not considered BACT requirement as a means to redefine design of a source when considering available control technology
For example, EPA does not require coal-fired electric generators to consider gas-fired electric turbines
Colorado takes the same position on this issue

9. BACT Analysis Step 2 Eliminate technically infeasible control options
Source must demonstrate technical infeasibility, based on physical, chemical, and engineering principles
If someone has issued a permit requiring a certain technology or emission limit, assumption is that the technology or limit is technically feasible (Colorado uses its permitting discretion to assess this aspect)

10. BACT Analysis Step 2 (cont.)
Where control technology has not been installed and operated successfully on the type of source under review, feasibility is determined based on
Availability (i.e., product has reached licensing and commercial sales stage of development)
Applicability
Control alternative has or will be deployed on same or similar source type, or
Could be used on source based on physical and chemical characteristics of pollutant-bearing gas stream

11. BACT Analysis Step 2 (cont.)
Applicant may show technical infeasibility through an unresolvable technical difficulty with applying the control (e.g., size of unit, location of proposed site, operating problems related to specific circumstances of source)
Applicant may not use cost to demonstrate infeasibility, but may be considered in economic impacts portion of BACT analysis

12. Class exercise
Please see handout

13. BACT Analysis Step 3
Rank remaining control technologies according to control effectiveness. For each pollutant, list includes
Control efficiency (percent of pollutant removed)
Expected emissions reduction (tons/year)
Economic Impacts
Environmental Impacts (e.g., significant impact on surface water)
Energy Impacts

14. BACT Analysis Step 3 -Control Efficiency
Two key questions
How to compare apples to apples (deciding common unit for comparing the emissions of each option)
How to analyze control techniques that can operate over a wide range of emission performance levels
Tips: what to watch for
Observations: major issues in this area

15. BACT Analysis Step 3 - Expected Emissions Reductions (tons/year)
Calculate annual emission projections for each option using standard PTE approach
Options ranked with top spot going to control technology option that achieves lowest emissions level, in descending order of emissions control effectiveness

16. BACT Analysis Step 3 – Economic and Other Impacts
Applicant prepares list to display top-down ranking, and for each alternative includes data on
Economic impacts
Environmental impacts (i.e., non-air quality impacts)
Energy impacts

17. BACT Analysis Step 3 – Economic Impacts
Economic impacts include
Average cost effectiveness (dollars per ton of emissions reduced) based on data from similar sources
Incremental cost effectiveness
Affordability to source is not as relevant as average and incremental cost-effectiveness
Where control technology has been successful for similar sources, applicant need to document significant cost differences for its source to eliminate control alternative

18. BACT Analysis Step 3 – Economic Impacts (cont.)
Key issues for cost effectiveness
Ensure that design parameters used in cost estimates are consistent with emissions estimates used in other portions of PSD application (e.g., dispersion modeling inputs and permit emission limits)
Ask for more detailed cost data if cost projections appear excessive in light of recent cost data
Provide example
Where would a reviewer find this information for comparison

19. BACT Analysis Step 3 – Economic Impacts (cont.)
Average cost effectiveness
Total annualized costs of control, divided by
Annual emission reductions (the difference between the baseline emission rate and the controlled emission rate)
Major issues
Underestimation of PTE
Overestimation of annualized costs
Inclusion of indirect costs that should not be considered in a BACT analysis (see EPA control cost manual)

20. BACT Analysis Step 3 – Economic Impacts (cont.)
Incremental cost effectiveness compares costs and emissions performance level of a control option to the next most stringent option
Calculation
Total annualized cost of option 1 minus total annualized cost of option 2 (less stringent option), divided by
Option 2 emission rate minus option 1 emission rate

21. BACT Analysis Step 3 – Environmental Impacts
Environmental impacts should include
any significant or unusual other media impacts (e.g., water or solid waste)
Usually limited to discharges with potential for causing adverse environmental effects
Quantify mass and composition of discharges and consequences of release
Impacts on ground water and local surface water; whether applicable water quality standards will be met; availability/effectiveness of mitigation techniques
Quality and quantity of solid waste to be stored, disposed of or recycled (including permeability, water retention, leachability, hazardous characteristics, etc.)
Irreversible or irretrievable commitment of resources (e.g., scarce water resources)
Significant differences in noise levels, radiant heat, dissipated static electrical energy and greenhouse gas emissions

22. BACT Analysis Step 3 – Environmental Impacts (cont.)
Environmental impacts should include the relative ability of each control alternative to control emission of HAPs and visibility impacts
Examples where environmental factors have made a difference in a BACT analysis
Aqueous versus anhydrous ammonia
Dry vs. wet scrubbing for a coal-fired power plant
Local water table low, thus dry cooling better option
Environmental concerns become important when site- specific receptors exist
Application to tribal issues – discuss with class

23. BACT Analysis Step 3 – Energy Impacts
Generally consider only direct energy consumption of alternative control technologies
Quantify any benefits or penalties
Typically can monetize these impacts and factor them into the economic impacts analysis

24. BACT Analysis Step 4
Evaluate most effective controls based on all the factors in Step 3
Document results

25. Sample Top-Down BACT Determination
Small group exercise: Each group makes a recommendation on BACT
Discuss results

26. BACT Analysis Step 5
Ultimate BACT decision is made by permitting agency after public review
BACT is based on most effective control option for which adequate justification for rejection not provided
Public gets at least 30 days to review draft permit
Practical advice for reviewers
Public comment hearing provisions
Permitting agency will consider any new information revealed during comment period, including recent permit decisions

27. Implementing BACT BACT is an emission limit that
Is needed for each emission unit at a source, subject to PSD for each pollutant subject to review that is emitted by source
Must be met continually at all levels of operation
Alternate BACT limits may be needed for other operational scenarios (e.g., startup/shutdown)
Must protect short-term ambient standards (limits and averaging times)
Specifies a control technology or practice, numerical limit and averaging time

28. Implementing BACT (cont.)
Incentive to operate efficiently
BACT can be made more stringent if initial BACT emission levels would result in a NAAQS or a PSD increment to be exceeded
Proposed source or modification still has to demonstrate compliance with other standards included in the PSD analysis
Must be enforceable as a practical matter
Monitoring considerations for demonstrating on-going compliance

29. Greenhouse Gas Considerations
Relatively new, agencies have less experience implementing
Energy efficiency
Setting numerical limits and averaging times
Carbon capture and sequestration
See

30. Summary
Major stationary sources and major modifications that are subject to PSD must conduct a BACT analysis
Each BACT analysis is case-by-case and is based on evaluation of all available control technologies
Alternatives are ranked in descending order of control effectiveness
The most stringent or top alternative is BACT unless the applicant demonstrates that technical considerations or energy, environmental or economic impacts justify the elimination of the control option