GHG BACT Examples

1. GHG BACT Examples • Next several sections walk through BACT reviews for GHGs for a number of source categories. • They are designed to demonstrate the kinds of technical and policy issues that can arise and how they can be addressed. • These examples do not represent guidance on what an actual BACT review must address and they do not represent any guidance on what constitutes BACT for similar sources that undergo an actual determination. DRAFT

2. GHG BACT Example:Municipal Solid Waste Landfill

3. BACT Example: MSW Landfill Project: New, large municipal solid waste landfill. Step 1: Identifying all available controls • For capture of the landfill gas, the application proposes use of an active capture system that will be in compliance with the NSPS that applies to the NMOC emissions • For control, the following NSPS compliant options are examined: • Flaring of the gas • Using gas in on-site internal combustion engines to generate electricity for sale • Treating gas for delivery to a natural gas pipeline DRAFT

4. BACT Example: MSW Landfill (cont’d) Step 1 (cont’d) • The permitting authority asked the applicant to review two additional control measures: • Collect and control landfill gas earlier in the life of the landfill than is specified in the NSPS • A gas turbine to generate power rather than internal combustion engines • At this stage, there are two options for gas capture : • NSPS compliant active capture system • That system, with earlier initiation of gas collection DRAFT

5. BACT Example: MSW Landfill (cont’d) Step 1 (cont’d) • There are four options for the control of the landfill gas: • Flaring, • Fueling engines, • Fueling a gas turbine, and • Treatment and routing of the gas to a pipeline DRAFT

6. BACT Example: MSW Landfill (cont’d) Step 2: Elimination of technically infeasible options • Applicant demonstrated that the volume of gas would be inadequate to fuel a commercially available gas turbine • Permitting authority reviewed the record • Accepted elimination of that option from further consideration DRAFT

7. BACT Example: MSW Landfill (cont’d) Step 3: Evaluation and ranking of controls by their effectiveness • Applicant used CO2e emissions over the life of the landfill, as the effectiveness indicator • Considered combinations of capture systems and controls for overall effectiveness • Early capture of gas and conversion of the gas to pipeline quality for export is the most effective combination, from a PSD perspective: • Maximum amount of gas would be captured • Most of the gas would not be combusted on site • Flaring and the use of engines are similar in their control • Reducing methane emissions significantly • Generating relatively small on-site CO2 emissions DRAFT

8. BACT Example: MSW Landfill (cont’d) Step 4: Evaluating the most effective controls • Analysis of the cost effectiveness, expressed as $/ton of CO2e reduced over the life of the landfill. • Applicant found conversion of gas to pipeline quality was not cost effective. Would more than double the overall cost of the project since the landfill was far from an existing pipeline. • NSPS compliant control system with early collection was cost effective for either the flare or the engines case. • The flare was more cost effective because revenue from the sale of power from use of engines would not offset the added cost of the engines and a power transmission line. DRAFT

9. BACT Example: MSW Landfill (cont’d) Step 4 (cont’d) Any significant energy and environmental impacts to be considered: • The application noted a positive environmental impact from the use of a flare because NOX emissions for a flare would be lower than those for the engines. • Public comment identified positive energy and environmental offsite impacts arising from using landfill gas to generate electricity which displaces offsite energy generation and associated emissions. • Permitting authority determined that this benefit outweighed the lower NOx emissions and better cost effectiveness of a flare. DRAFT

10. BACT Example: MSW Landfill (cont’d) Step 5: Selecting BACT Permitting authority determined BACT to be: • NSPS compliant active collection system with early installation/operation • Landfill gas routed to engines and used to generate electricity DRAFT

11. BACT Example: MSW Landfill(cont’d) Step 5 (cont’d) Permit conditions are: • CO2e limit on engine emissions, expressed in lbs per kWh, to be demonstrated in a stack test annually. • Compliance with the landfill NSPS design, operating and recordkeeping requirements • Earlier trigger for gas capture and use • Requirement to operate engines under a written O&M plan to assure combustion efficiency DRAFT

12. GHG BACT Example:Natural Gas Fired Boiler

13. BACT Example: Gas Boiler Project Scope: • Existing major source • New 250 MMBtu/hour natural gas-fired boiler DRAFT

14. BACT Example: Gas Boiler (cont’d) Step 1: Identifying all available controls Permit application lists the following four controls: • Oxygen Trim Control: • Inlet air flow adjusted for optimal thermal efficiency • Economizer: • Increases thermal efficiency by preheating feedwater • Blowdown Heat Recovery: • A heat exchanger transfers some of the heat in the blowdown water to feedwater for deaeration or preheating • Increases the boiler’s thermal efficiency DRAFT

15. BACT Example: Gas Boiler (cont’d) Step 1 (cont’d) • Condensate Recovery: • When hot condensate is returned to the boiler as feedwater, the thermal efficiency increases Permitting Authority asks for inclusion of air preheater DRAFT

16. BACT Example: Gas Boiler (cont’d) Step 1 (cont’d) • Public comment asks for consideration of a combined cycle natural gas-fired turbine • Applicatant explains that a boiler is necessary for business purposes: • Providing process steam (and not electricity) and • Varying steam demand • Permitting authority rejects a combined cycle natural gas-fired turbine for consideration on grounds it would “redefine the source.” DRAFT

17. BACT Example: Gas Boiler (cont’d) Step 2: Eliminating technically infeasible options • Permitting authority determines that the six controls are technically feasible; demonstrated or available and applicable to this type of source Step 3: Evaluation and ranking of controls by their effectiveness • Applicant ranked control measures for the boiler based on their impact on the thermal efficiency of the boiler (Could also be based on emissions per unit of steam produced) DRAFT

18. BACT Example: Gas Boiler (cont’d) Step 3 (cont’d) The permit applicant completed the control effectiveness analysis and found: • Most effective single measure is oxygen trim control • Air preheater is no more effective than an economizer in recovering exhaust heat • The most effective combination of measures is: oxygen trim control, an economizer, condensate recovery, and blowdown heat recovery . DRAFT

19. BACT Example: Gas Boiler (cont’d) Step 4: Evaluating the most effective controls • Permit applicant completed an analysis of the cost effectiveness: • Considered both measures and combinations of measures, • Expressed as $/ton of CO2e reduced • Given the size and layout of the facility, boiler blowdown heat recovery was not cost effective • Next most effective combination of measures was: • the use of oxygen trim control • an economizer • condensate recovery DRAFT

20. BACT Example: Gas Boiler (cont’d) Step 4: (cont’d) • Any significant energy and environmental impacts to be considered in this step. • Application identifies recovery and reuse of condensate: • Reduces the use of feedwater treatment chemicals • Reduces generation of related waste • Reduces the amount of water going to wastewater treatment at the site DRAFT

21. BACT Example: Gas Boiler (cont’d) Step 5: Selecting BACT Permitting authority determined, and the record showed, that BACT was the combination of: • Oxygen trim control, • An economizer, and • Condensate recovery DRAFT

22. BACT Example: Gas Boiler (cont’d) Step 5: (cont’d) Permit conditions included: • Emission limit: lbs of CO2e per pound of steam produced, 30-day rolling monthly average • CO2e emissions determined from natural gas use and standard emission factors • Steam production determined from a gauge • Installation of boiler as described in the application, as a design standard • Preventive maintenance program for the air to fuel ratio controller • Periodic calibration of gas meter and steam flow analyzer DRAFT

23. GHG BACT Example:Petroleum Refinery Hydrogen Plant Addition

24. BACT Example: Petroleum Refinery Hydrogen Plant Project Scope: • Expand the hydrogen production and hydrotreating capacity of an existing major source refinery • For simplicity, analysis addresses the GHG BACT for the new hydrogen plant that is being added in the context of a larger project DRAFT

25. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) DRAFT

26. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Project Scope (cont’d): • Proposed project producing hydrogen via the steam methane reforming (SMR) process. In SMR, methane and steam are reacted via a catalyst to produce hydrogen and CO. The reaction is endothermic and the necessary heat is provided in a gas-fired reformer furnace. The CO reacts further with the steam to generate hydrogen and CO2. CH4 + H2O = CO + 3H2 CO + H2O = CO2 + H2 • The hydrogen is then separated from the CO2 and other impurities. The application shows that the purification is done using a Pressure Swing Adsorption Unit. The permit applicant proposes to use the off gas from that step (containing some hydrogen, CO2, and other gases) as part of the fuel for the reformer furnace. DRAFT

27. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 1: Identifying all available controls • Permit application lists the following control options for GHG emissions: • Furnace Air/Fuel Control – An oxygen sensor in the furnace exhaust is to be used to control the air and fuel ratio for optimal efficiency • Waste Heat Recovery – The overall thermal efficiency is to be optimized through the recovery of heat from both the furnace exhaust and the process streams to preheat the furnace combustion air, to preheat the feed to the furnace and to produce steam for use in the process and elsewhere in the refinery. • CO2 Capture and Storage – Capture and compression, transport, and geologic storage of the CO2. (Some refineries isolate hydrogen reformer CO2 for sale but that is not a part of this example project.) • The permitting authority did not require the applicant to consider any additional control options beyond those in the application, and none were suggested in public comments. DRAFT

28. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 2: Eliminating the technically infeasible options • In this example, the permitting record shows that all three controls are technically feasible because there is no evidence that any of these options are not demonstrated or available to this type of source. DRAFT

29. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 3: Evaluation and ranking of controls by their effectiveness • The applicant ranked control measures for the hydrogen plant based on the CO2e emissions per unit of hydrogen produced. • An output-based indicator is a good way to capture the overall effect of multiple energy efficiency measures used in the design of a complex process such as this. • The permit applicant effectiveness analysis included benchmarking data on the energy efficiency and GHG emissions of recently installed hydrogen plants. • Benchmarking data showed that this hydrogen plant would be a lower emitter (on an output basis) than similar new plants, and the permitting authority concurred in that determination. • The applicant determined that the most effective control combination was one in which all three options (furnace control, heat recovery and CCS) were included. DRAFT

30. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 4: Evaluating the most effective controls • Applicant analysis of the cost effectiveness of measures and combinations of measures was expressed as $/ton of CO2e reduced. The applicant also determined the incremental cost effectiveness. • The information supplied by the applicant demonstrated that the transport and sequestration of CO2 would not be cost effective because the nearest prospective location for sequestration was more than 500 miles away and there was not an existing pipeline suitable for CO2 transport between the refinery and the sequestration location. DRAFT

31. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 4 (cont’d) • The cost of transport was significant in comparison to the amount of CO2 to be sequestered and the cost of the project overall. • In responding to public comments on the issue, the permitting authority noted that in circumstances in which a refinery was located near an oil field that used CO2 injection for enhanced recovery, the cost calculations for transport and sequestration would likely be in a range that would not exclude CCS. • Other significant energy and environmental impacts are also considered in this step. In this case, none were presented in the application, and the only significant public comment on the issue was addressed by the permitting authority as noted above. DRAFT

32. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 5: Selecting BACT • With the analysis and record complete, the permitting authority determined that BACT was a combination of furnace combustion control and integrated waste heat recovery. DRAFT

33. BACT Example: Petroleum Refinery Hydrogen Plant (cont’d) Step 5 (cont’d) BACT Permit Limits: • Emission limit in pounds of CO2e emitted per pound of hydrogen produced, averaged over rolling 30 day periods. • CO2e emissions would be determined by metering natural gas sent to the hydrogen plant. There may need to be an adjustment for excess fuel gas sent to other parts of the refinery on a periodic basis. A separate meter and fuel analysis would be needed to get that credit. • Hydrogen production would be metered. • The plant would need to be installed as described in the application. • There would need to be a program for calibration and maintenance of meters and the oxygen trim system. DRAFT

34. GHG BACT Example:Coal-Fired Electric Generating Unit

35. BACT Example: Coal EGU Project: New greenfield sub-bituminous pulverized coal-fired boiler and steam turbine electricity generating facility. DRAFT

36. Coal EGU – Boiler and Steam Turbine DRAFT

37. BACT Example: Coal EGU (cont’d) Step 1: Identifying all available controls Applicant’s BACT analysis had two elements: • Efficiency measures, including the design of the boiler and turbine: • Super critical boiler and turbine design • Coal drying • Optimized combustion with continuous control • CO2 control through CCS. State requests that the BACT analysis also include: • Ultra-super critical design • Integrated Gasification Combined Cycle (IGCC) • Motor efficiency improvements (to increase net output of electricity and thereby fuel use) DRAFT

38. IGCC DRAFT

39. IGCC with Pre-Combustion CO2 Capture Step 1 (cont’d) • Pre-combustion capture of CO2 is an option with coal gasification. In the gasifier, the coal decomposes in the presence of oxygen to syngas, a mixture of H2 and carbon monoxide (CO), along with minor other constituents. • To enable pre-combustion capture, the syngas is further processed to convert CO into CO2 while producing additional H2. A solvent absorption system can then be used to separate the CO2 from the H2. DRAFT

40. IGCC with Pre-Combustion CO2 Capture (continued) Step 1 (cont’d) • After CO2 removal, the H2 can be used as a fuel in the combustion turbine. • Pre-combustion CO2 capture is less expensive than post-combustion capture. The advantages of this type of system are the higher CO2 concentration and the lower volume of syngas to be handled, which result in smaller equipment sizes and lower capital costs. DRAFT

41. BACT Example: Coal EGU (cont’d) • Public comment calls for use of natural gas instead of coal. While this happened after the BACT determination and draft permit were out for comment, it relates to the control measures considered in Step 1 of the analysis. • The permitting agency determines this is outside the scope of BACT, representing a change in basic design and business purpose. DRAFT

42. BACT Example: Coal EGU (cont’d) Step 2: Elimination of technically infeasible options • All options are considered by the permitting authority to be available and technically feasible: • Ultra-supercritical boiler and turbine design • Integrated Gasification Combined Cycle • Coal drying • Combustion control • Variable speed motors • CCS DRAFT

43. BACT Example: Coal EGU (cont’d) Step 3: Evaluation and ranking of controls by their effectiveness • Applicant proposes to rank measures based on emissions per unit of fuel used • State requires that options be ranked by CO2 emissions on a “net” output basis. • Most effective combination is either ultra-supercritial with CCS or IGCC with CCS. Coal drying and efficient motors included in both instances. DRAFT

44. BACT Example: Coal EGU (cont’d) Step 4: Evaluating the most effective controls • CCS dismissed for both designs based on excessive costs, siting issues, and parasitic electricity load • In the absence of CCS, IGCC shown to not superior to ultra-supercritical design • Ultra-supercritical chosen as BACT: cost-effective, no adverse collateral impacts • All energy efficiency measure also required • Permitting agency documents conclusion with supporting documentation for the record DRAFT

45. BACT Example: Coal EGU (cont’d) Step 5: Selecting BACT BACT is determined to be: • A ultra-supercritical boiler design w/ high efficiency steam turbine, • Control of boiler air fuel ratio, • Coal drier using low grade/waste heat • High efficiency variable speed motors for electric drives DRAFT

46. BACT Example: Coal EGU (cont’d) Step 5 (cont’d) Enforceable permit conditions are: • Annual limit in tons of CO2 per net MWh; rolling 12 month totals • O&M plan addressing combustion controls, steam turbine efficiency and electrical motors DRAFT

47. GHG BACT Example:Cement Plant

48. BACT Example: Cement Plant Project Scope: • A new cement kiln is proposed. The product is finished cement for local markets. Cement is produced from raw materials such as limestone, chalk, shale, clay, and sands which are quarried, crushed, ground, and blended to the correct chemical composition. • The raw material is fed into a large rotary kiln (cylindrical furnace) which rotates while the contents are heated to extremely high temperatures. The high temperature causes the raw material to react and form a hard nodular material called “clinker”. Clinker is cooled and ground with gypsum and other additives to produce portland cement. • CO2 is emitted due to both the decomposition of the limestone and the combustion of fuel in the kiln. DRAFT

49. BACT Example: Cement Plant (cont’d) DRAFT

50. BACT Example: Cement Plant (cont’d) Step 1: Identify all available controls • This BACT analysis has four elements: process technology/energy efficiency, fuel choice, product specification and CO2 removal and storage. Process Technology/Energy Efficiency • Applicant proposes to use a preheater/precalciner design, which is more efficient that older designs that have less heat recovery. DRAFT