STATEMENT OF BASIS. Air Quality Emissions and Impact. Milbank Community Foundation dba Midwest Dairy Institute. Milbank, South Dakota

Transcription

1 STATEMENT OF BASIS Air Quality Emissions and Impact Milbank Community Foundation dba Midwest Dairy Institute Milbank, South Dakota South Dakota Department of Environment and Natural Resources May 2005

2 TABLE OF CONTENTS 1.0 BACKGROUND/OPERATIONS EMISSION FACTORS Unit 1 Boiler 1 Digester gas and Propane Unit 2 Generator 1 Digester gas Unit 3 Generator 2 Distillate oil Unit 4 Flare Digester gas POTENTIAL EMISSIONS PERMIT REQUIREMENTS New Source Review Prevention of Significant Deterioration New Source Performance Standards 5 Page ARSD 74:36:07:05 40 CFR, Part 60, Subpart Dc, Standards of Performance for Small Industrial-Commercial-Institutional Steam Generating Units National Emission Standards for Hazardous Air Pollutants Maximum Achievable Control Technology Standards ARSD 74:36:08:03 40 CFR, Part 63, Subpart DDDDD, National Emission Standards for Hazardous Air Pollutants for Commercial, and Institutional Boilers and Process Heaters State Requirements Particulate and Sulfur Dioxide Emission Limits Summary of Applicable Requirements RECOMENDATION 7 ii

3 1.0 BACKGROUND/OPERATIONS On December 21, 2004, the Milbank Community Foundation dba Midwest Dairy Institute submitted a minor permit application for the operation of a steam generating boilers and two electrical generators in Milbank, South Dakota. Based on a review of the application and discussions with Carole Boos, the listed facility contact, it was determined that the equipment forms in the application were incomplete and that the facility would require a Title V permit based on potential emissions. On March 01, 2005, Midwest Dairy Institute submitted a Title V permit application. In April 2005, the Department of Environment and Natural Resources (DENR) was notified that changes were made to one of the generators to be installed at the facility. The biogas generator would be equipped with an electronic combustion control system to reduce nitrogen oxide emissions. Midwest Dairy Institute is a training facility for the dairy industry. The Institute plans to milk 2000 cows and dispose of the manure in an anaerobic digester. The methane produced by the digester will be burned to produce heat and electricity for the facility. The following units were included in the facility s application and in this statement of basis. Unit 1 Unit 2 Unit 3 Unit 4 Boiler Hurst steam boiler, model S1-GG , rated at 4.4 million British thermal units per hour (MMBtu/hr) heat input. This unit is fired with digester gas and propane; Generator Caterpillar internal combustion generator, model 3412C LE, rated at 350 kw of heat output. This unit is fired with digester gas and is equipped with an electronic combustion control system to reduce nitrogen oxide emissions; Generator Caterpillar internal combustion generator, model 3456, rated at 450 kw of heat output. This unit is fired with distillate oil; and Digester Gas Flare 2005 Varec, model 244W waste gas burner, capable of handling 51,000 ft 3 per hour. 2.0 EMISSION FACTORS 2.1 Unit 1 Boiler 1 Digester gas and Propane (Liquefied Petroleum Gas LPG) Based on its heat input rating, AP-42 classifies Unit 1 as a commercial boiler. EPA estimated emission factors for the combustion of digester gas are not currently available. Typical anaerobic digester gas consists of methane (50%-80%) and carbon dioxide (20%-50%), with trace levels of other gases such as hydrogen, carbon monoxide, nitrogen, and hydrogen sulfide. The relative percentage of these constituents depends on the feed material and management of the process. Processed natural gas is generally percent methane, 2 5 percent ethane, butane and other light hydrocarbons and also contains traces of carbon dioxide, and nitrogen. Most hydrogen sulfide is removed during processing. With the exception of sulfur dioxide, DENR based the emission factors for digester gas combustion on AP-42 s emission factors for natural gas combustion (Fifth Edition, Table 1.4.1, Table 1.4.2, and Table 1.4.2, 7/98). The emission factors developed can be seen in Table 1. Per AP-42 instructions for adjusting emission factors to fuels of different heat contents, DENR converted the AP-42 emission factors from [lbs/mmcf] to [lbs/mmbtu] using the heat content of the digester gas listed in the Draft 1

4 application (750 [MMBtus/MMcf]). Sulfur dioxide emissions from digester gas combustion depend on the sulfur content of the fuel. This facility is under construction, so site-specific digester gas samples are not available for testing. However, Dakota Value Capture, a permitted facility in the Pierre region proposed using cow manure digester gas as fuel and submitted test results on the hydrogen sulfide content (2000 [ppm]). DENR assumes, based on the similarity of the digester input, that the digester output will be similar. DENR used Equation 1 and the Dakota Value Capture test results to develop a sulfur dioxide emission factor based on the application of the ideal gas law under standard conditions and the assumption that any sulfur in the digester gas is in the form of hydrogen sulfide and that 100 percent of that sulfur converts to SO2 during combustion. Equation 1 sulfur dioxide emission factor lbs SO EF 2 SO = FH S CFAP42 WFS/H S WF 2 2 S/SO MMBtu 2 input Where: 2 FH 2 S HC Biogas = the hydrogen sulfide content of the fuel = 2000 [ppm] CF AP42 = AP-42 conversion factor [ppm] to [lbs / MMft 3 ] = (mol weight of H 2 S) / derived from ideal gas STP WF = weight fraction of sulfur in hydrogen sulfide = [lb S / lb H 2 S] S / H 2S WF S / SO 2 = weight fraction of sulfur in sulfur dioxide = [lb S / lb SO 2 ] HC Biogas = heat content of digester gas = 630 [MMBtus / MMft 3 ] Result: EF SO = lbs SO2 MMBtu input DENR derived the emission factors for firing the boiler with propane, also shown in Table 1, based on EPA s factors for propane fired commercial boilers ( AP-42 Table 1.5-1, page 1.5-3, 10/96), a propane heat content of 2515 MMBtus/MMcf, and an assumed sulfur content of 0.2 grains per 100 cubic feet. The emission factors for each fuel type are compared in Table 1. In this case the firing of digester gas has the potential to produce the greatest emissions for all criteria pollutants. 2.2 Unit 2 Generator 1 Digester gas AP-42 does not list emission factors for reciprocating internal combustion generators burning digester gas. With the exception of sulfur dioxide and nitrogen oxides, DENR used emission factors for natural gas burning units of similar design (AP-42 Table 3.2-2, 7/00), adjusted for the lower heat content of biogas, to derive emission factors for Unit 2 burning digester gas. The NOx emission factor was derived from manufacturer data on the unit burning natural gas. DENR assumes, as in the case of the Draft 2

5 boiler, that any sulfur in the digester gas is in the form of hydrogen sulfide and that 100 percent of that sulfur converts to SO2 during combustion. Therefore, DENR will use the sulfur dioxide emission factor developed for the boiler to estimate potential emissions from this unit. The emission factors for this unit are shown in Table Unit 3 Generator 2 Distillate oil The renewal application states the unit has a maximum capacity of 612 horsepower. AP-42 classifies diesel powered generators over 600 horsepower as large internal-combustion engines. Emission factors for this unit are derived from AP-42 Air Pollutant Emission Factors (Tables 3.4-1, 3.4-2, 3.4-3, /96) and are shown in Table Unit 4 Flare Digester gas AP-42 does not list emission factors for flares burning biogas or natural gas. DENR used the emission factors developed for the boiler burning biogas to estimate potential emissions from the flare. Table 1 Emission Factor Summary and Comparison by Fuel Type for Unit 1 Species Emission Factor [lbs pollutant/mmbtus of heat input] Unit ID Fuel Type TSP a PM10 SO 2 NOx VOC HAP CO Unit 1 Digester gas Propane c Unit 2 Digester gas b 0.91 d Unit 3 Distillate oil e Unit 4 Digester gas a The particulate emitted by these units is typically less than 0.1 microns in diameter; therefore, the emission factor for PM10 is equivalent to TSP. b Manufacturer data from 2002 Dakota Value Capture Cooperative SOB c The ratio of HAPs to VOC was assumed identical to that ratio for natural gas. d manufacturer data by ratio heat contents of (natural gas / biogas) e - based on a distillate oil sulfur content of 0.5 percent by weight 3.0 POTENTIAL EMISSIONS Potential emissions of each pollutant are calculated assuming the units operate every hour of every day of the year (8,760 hours per year) at the maximum design capacity listed in the application. The application listed the maximum design output capacities of the generators in terms of kilowatts. Equation 2 converts the maximum design operating rate from kilowatts (heat output) to million Btus (MMBtu) per hour (heat input) using an assumed efficiency of 33%. Draft 3

6 Equation 2 Converting from heat output to heat input MMBtus MCheat input = MCheat output efficiency hr CF Where: MC heat output = the maximum design capacity of the unit [kw] efficiency = assumed ratio of heat input to energy output at full capacity = 0.33 CF = conversion factor = x MMBtu hr kw Result: MC heat input = Unit = Unit MMBtu hr MMBtu hr The manufacturer lists the maximum capacity of the flare as 51,000 ft 3 per hour. The worst case scenario for emissions from the flare would be if the generator and the boiler were unavailable for and all the gas produced was routed to the flare. The maximum production capacity of the digester is 15,000 ft 3 per hour (9.45 MMBtus per hour) based on the 2400 dairy cows producing 150 ft 3 of gas per day. DENR will use the digester capacity to calculate the potential emissions from this unit. DENR used Equation 3 to estimate the potential emissions from each unit. Equation 3 Potential emissions tons Potential = MC yr MMBtus hr lbs hr x emission factor 8760 MMBtu yr heat input 2000 The results of the potential emission calculations are shown in Table 2. Table 2 Potential Emissions Unit Potential Emissions [tons per year] TSP PM-10 SO 2 NO x VOCs HAPs CO Totals lb ton Draft 4

7 4.0 PERMIT REQUIREMENTS 4.1 New Source Review ARSD 74:36:10:01 states that New Source Review (NSR) regulations apply to areas of the state that are designated as nonattainment pursuant to the Clean Air Act for any pollutant regulated under the Clean Air Act. The facility is located near Milbank, South Dakota, which is in attainment for all the pollutants regulated under the Clean Air Act. Therefore, this facility is not subject to NSR review. 4.2 Prevention of Significant Deterioration (PSD) Any stationary source which emits or has the potential to emit 250 tons per year or more of any air pollutant is considered a major source and subject to prevention of significant deterioration (PSD) requirements (ARSD 74:36:09 40 C.F.R. Part 52.21(b)(1)). Any stationary source which emits, or has the potential to emit, 100 tons per year or more of any air pollutant and is subject to one of the 28 named PSD source categories is subject to PSD requirements (ARSD 74:36:09 40 C.F.R. Part 52.21(b)(1)). This facility does not meet the 250 tons per year threshold and is not one of the 28 named PSD source categories. Therefore, the facility is considered a minor source under the PSD program and is not subject to PSD requirements. 4.3 New Source Performance Standards (NSPS) DENR reviewed the New Source Performance Standards and determined that the following may be applicable to Midwest Dairy Institute ARSD 74:36:07:05-40 C.F.R., Part 60, Subpart Dc - Standards of Performance for Small Industrial, Commercial, and Institutional Steam Generating Units This standard applies if the steam generating unit has a maximum design heat input capacity equal to or greater than 10 million Btus per hour but less than or equal to 100 million Btus per hour. Unit 1 does not fall under this new source performance standard because it has a heat input capacity less than 10 million Btu per hour. 4.4 National Emission Standards for Hazardous Air Pollutants (NESHAP Part 61) Presently, there are no finalized or promulgated National Emissions Standards for Hazardous Air Pollutants standards for the type of operations used at this facility. 4.5 Maximum Achievable Control Technology (MACT Part 63) DENR reviewed the Maximum Achievable Control Technology Standards and determined that the following may be applicable to Midwest Dairy Institute. Draft 5

8 4.5-1 ARSD 74:36:08:03 40 CFR, Part 63, Subpart DDDDD, National Emission Standards for Hazardous Air Pollutants for Commercial, and Institutional Boilers and Process Heaters EPA has recently finalized the MACT standard for Industrial/Commercial/Institutional boilers and process heaters. However, Part 63 is applicable to sources considered a major source of hazardous air pollutants. Based on the potential emissions calculations, this facility is not applicable to this or other MACT standards because it is not a major source for hazardous air pollutants. 4.6 State Requirements Particulate and Sulfur Dioxide Emission Limits The State of South Dakota regulates particulate and sulfur dioxide emissions. The emission limits are derived from ARSD 74:36:06. Particulate matter emission limit for fuel burning units less than 10 million Btus per hour are established at 0.6 pounds per million Btus (ARSD 74:36:06:02(1)(a)). In accordance with ARSD 74:36:06:02(2) the sulfur dioxide emission limit is three pounds per million Btus of heat input to a fuel-burning unit. The uncontrolled emission factors for the boiler and the two generators are shown in Table 3 for comparison to the state emission limits. Table 3 Potential Emission Rate versus State Emission Limit Potential Emission Rate State Emission Limit Unit ID Pollutant [pounds per million Btus] [pounds per million Btus] Unit 1 Unit 2 Unit 3 Unit 4 TSP SO TSP SO TSP SO TSP SO Based on the comparison the facility is capable of operating in compliance with the state air emission limits. 4.7 Summary of Applicable Requirements Based on its potential emissions, Midwest Dairy Institute will be classified as a minor source under the air quality permit program. A minor source is one that has the potential to emit less than 100 tons per year of a criteria pollutant before accounting for control equipment. Midwest Dairy Institute will be required to operate within the requirements stipulated in the following regulations: ARSD 74:36:06 - Regulated Air Pollutant Emissions; ARSD 74:36:11 - Stack Performance Testing; and Draft 6

9 ARSD 74:36:12 - Control of Visible Emissions; 5.0 RECOMMENDATION Based on the information submitted in the permit application, the department recommends conditional approval of a Minor air quality operating permit. Direct any questions regarding this permit recommendation to Jim A. Anderson, Natural Resources Project Engineer. Draft 7