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HomeMy WebLinkAbout1.2 Pre-Feasibility Assessment Appendix Part 2_July-24-12 APPENDIX D Air Quality Report   55 Railroad Row      White River Junction, Vermont 05001  TEL 802.295.4999      FAX 802.295.1006      www.rsginc.com  INTRODUCTION At your request, RSG has conducted an air quality feasibility study for three biomass energy installations in Manley, Minto and Nenana. These sites are located in the interior of Alaska near Fairbanks. The following equipment is proposed:  Minto ‐ one 300,000 Btu/hr (heat output) cord wood boiler at the Minto Health Clinic.  Manley ‐ one 150,000 Btu/hr (heat output) cord wood boiler at the Village Express Maintenance Shop.  Nenana – one 4,200,000 Btu/hr (heat output) wood chip boiler at the Nenana School. MINTO STUDY AREA A USGS map of the Minto study area is provided in Figure 1 below. As shown, the area is flat with much low‐lying areas to the east and hilly to the west. The site is adjacent to a hillside. The area is relatively sparsely populated. Our review of the area did not reveal any significant emission sources or ambient air quality issues. To: Nick Salmon From: John Hinckley Subject: Fairbanks Cluster Feasibility Study Date: 24 July 2012 Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 2   Figure 1: USGS Map Illustrating the Minto Study Area Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 3   Figure 2 shows CTA Architects’ plan of the location of the proposed biomass facility and the surrounding buildings in Minto. The site is relatively flat and sparsely populated with buildings. The facility will be located in a remote building on the southeast side of two buildings. The precise dimensions of that building, the stack location and dimensions, and the biomass equipment specifications have not been determined. The degree of separation of the biomass building from the other buildings will create a buffer for emissions dispersion. Figure 2: Location of Proposed Facility in Minto Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 4   A USGS map of the Manley study area is provided Figure 3. As shown, the area is hilly to mountainous to the north and flat to the south. The site is near the higher terrain to the north. The area is relatively sparsely populated. Our review of the area did not reveal any significant emission sources or ambient air quality issues. Figure 3: USGS Map Illustrating the Manley Hot Springs Study Area Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 5   Figure 4 shows CTA Architects’ plan of the location of the proposed biomass facility and the surrounding buildings. The site is surrounded by forest, relatively flat and has only a few buildings. The facility will be located in a new building on the west side of the site. A generator building is also indicated on the plan. The precise dimensions of that building, the stack location and dimensions, and the biomass equipment specifications have not been determined. Figure 4: Location of Proposed Facility in Manley Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 6   A USGS map of the Nenana study area is provided Figure 3. As shown, the area is hilly to mountainous to the north and flat to the south and northeast. The site is across the river from higher terrain to the north. The area is moderately populated relative to the other sites discussed. Our review of the area did not reveal any significant emission sources or ambient air quality issues. Figure 5: USGS Map Illustrating the Nenana Study Area Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 7   Figure 6 shows CTA Architects’ plan of the location of the proposed biomass facility at the Nenana School and the surrounding buildings. The site is relatively flat and relatively densely populated with one to two story tall buildings. The proposed biomass equipment will be installed in a remote building located to the east of the school. This will provide a buffer for dispersion of air emissions between the stack and surrounding buildings. The precise stack location and dimensions, and the biomass equipment specifications have not been determined. Figure 6: Overview of Nenana School Cluster Site Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 8   METEOROLOGY Meteorological data from Fairbanks, AK was reviewed to develop an understanding of weather conditions. While Fairbanks is approximately 90 miles, 50 miles, and 45 miles away from Manley, Minto, and Nenana respectively, it is located in a similar climactic zone (Alaska Interior) and is therefore a good proxy of weather in those locations. As shown, there is a relatively high percentage of “calms” or times when the wind is not blowing during the colder months.1 These conditions create thermal inversions which are unfavorable for the dispersion of emissions. Figure 7: Wind Speed Data from Fairbanks, AK DESIGN & OPERATION RECOMMENDATIONS The following are suggested for designing the stack: 1 See: http://climate.gi.alaska.edu/Climate/Wind/Speed/Fairbanks/FAI.html Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 9    Burn natural wood, whose characteristics (moisture content, bark content, species, geometry) results in optimal combustion in the equipment selected for the project.  Do not install a rain cap above the stack. Rain caps obstruct vertical airflow and reduce dispersion of emissions.  Construct the stack to at least 1.5 times the height of the tallest roofline of the adjacent building. Hence, a 20 foot roofline would result in a minimum 30 foot stack.  Operate and maintain the boiler according to manufacturer’s recommendations.  Perform a tune‐up at least every other year as per manufacturer’s recommendations and EPA guidance (see below for more discussion of EPA requirements)  Conduct regular observations of stack emissions. If emissions are not characteristic of good boiler operation, make corrective actions.  For the Nenana School: while there are no state or federal requirements mandating advanced emission control from and ESP or baghouse, we feel advanced emission control should be strongly considered. Alternatively, the school should consider using pellets in lieu of wood chips. STATE AND FEDERAL PERMIT REQUIREMENTS This project will not require an air pollution control permit from the Alaska Department of Environmental Quality given the boilers’ relatively small size and corresponding quantity of emissions. However, this project will be subject to new proposed requirements in the federal “Area Source Rule” (40 CFR 63 JJJJJJ). A federal permit is not needed. However, there are various record keeping, reporting and operation and maintenance requirements which must be performed to demonstrate compliance with the requirements in the Area Source Rule. The proposed changes have not been finalized. Until that time, the following requirements are applicable:  Submit initial notification form to EPA within 120 days of startup.  Complete biennial tune ups per EPA method.  Submit tune‐up forms to EPA. Please note the following:  Oil and coal fired boilers are also subject to this rule.  Gas fired boilers are not subject to this rule.  More requirements are applicable to boilers equal to or greater than 10 MMBtu/hr heat input. These requirements typically warrant advanced emission controls, such as a baghouse or an electrostatic precipitator (ESP). The compliance guidance documents and compliance forms can be obtained on the following EPA web page: http://www.epa.gov/boilercompliance/ Fairbanks Air Quality Feasibility Study Resource Systems Group, Inc. 24 July 2012 page 10   SUMMARY RSG has completed an air quality feasibility study for Minto, Manley, and Nenana, Alaska. The boilers are not subject to state permitting requirements, but are subject to federal requirements. Design criteria have been suggested to minimize emissions and maximize dispersion. The following conditions suggest advanced emission control devices (ESP, baghouse) are not mandatory: 1. The wood boilers, with the exception of the boiler at Nenana, will be relatively small emission sources. 2. The wood boilers will be located in a separate building which will create a dispersion buffer between the boiler stack and the building. 3. There are no applicable federal or state emission limits. Sustained poor meteorology suggests emissions should be minimized as much as possible. Given these findings, we would recommend at minimum the following be done to minimize emissions: 1. Nenana: consider burning pellets in lieu of wood chips or consider advanced emission control. If wood chips are preferable, consider conducting air dispersion modeling to determine the stack height and degree of emission control. 2. While not mandatory, we recommend exploring the possibility of a cyclone or multi‐ cyclone technology for control of fly ash and larger particulate emissions for all the aforementioned boilers. 3. Obtain a not‐to‐exceed emission guarantees from boiler equipment vendors. We also recommend developing a compliance plan for the aforementioned federal requirements. Please contact me if you have any comments or questions. APPENDIX E Wood Fired Heating Technologies WOOD FIRED HEATING TECHNOLOGIES CTA has developed wood-fired heating system projects using cord wood, wood pellet and wood chips as the primary feedstock. A summary of each system type with the benefits and disadvantages is noted below. Cord Wood Cord wood systems are hand-stoked wood boilers with a limited heat output of 150,000- 200,000 British Thermal Units per hour (Btu/hour). Cord wood systems are typically linked to a thermal storage tank in order to optimize the efficiency of the system and reduce the frequency of stoking. Cord wood boiler systems are also typically linked to existing heat distribution systems via a heat exchanger. Product data from Garn, HS Tarm and KOB identify outputs of 150,000-196,000 Btu/hr based upon burning eastern hardwoods and stoking the boiler on an hourly basis. The cost and practicality of stoking a wood boiler on an hourly basis has led most operators of cord wood systems to integrate an adjacent thermal storage tank, acting similar to a battery, storing heat for later use. The thermal storage tank allows the wood boiler to be stoked to a high fire mode 3 times per day while storing heat for distribution between stoking. Cord wood boilers require each piece of wood to be hand fed into the firebox, hand raking of the grates and hand removal of ash. Ash is typically cooled in a barrel before being stock piled and later broadcast as fertilizer. Cordwood boilers are manufactured by a number of European manufacturers and an American manufacturer with low emissions. These manufacturers currently do not fabricate equipment with ASME (American Society of Mechanical Engineers) certifications. When these non ASME boilers are installed in the United States, atmospheric boilers rather than pressurized boilers are utilized. Atmospheric boilers require more frequent maintenance of the boiler chemicals. Emissions from cord wood systems are typically as follows: PM2.5 >0.08 lb/MMbtu NOx 0.23 lb/MMbtu SO2 0.025 lb/MMbtu CO2 195 lb/MMbtu Benefits: Small size Lower cost Local wood resource Simple to operate Disadvantages: Hand fed - a large labor commitment Typically atmospheric boilers (not ASME rated) Thermal Storage is required Page 1 Wood Pellet Wood pellet systems can be hand fed from 40 pound bags, hand shoveled from 2,500 pound sacks of wood pellets, or automatically fed from an adjacent agricultural silo with a capacity of 30-40 tons. Pellet boilers systems are typically linked to existing heat distribution systems via a heat exchanger. Product data from KOB, Forest Energy and Solagen identify outputs of 200,000-5,000,000 Btu/hr based upon burning pellets made from waste products from the western timber industry. A number of pellet fuel manufacturers produce all tree pellets utilizing bark and needles. All tree pellets have significantly higher ash content, resulting in more frequent ash removal. Wood pellet boilers typically require hand raking of the grates and hand removal of ash 2-3 times a week. Automatic ash removal can be integrated into pellet boiler systems. Ash is typically cooled in a barrel before being stock piled and later broadcast as fertilizer. Pellet storage is very economical. Agricultural bin storage exterior to the building is inexpensive and quick to install. Material conveyance is also borrowed from agricultural technology. Flexible conveyors allow the storage to be located 20 feet or more from the boiler with a single auger. Emissions from wood pellet systems are typically as follows: PM2.5 >0.09 lb/MMbtu NOx 0.22 lb/MMbtu SO2 0.025 lb/MMbtu CO2 220 lb/MMbtu Benefits: Smaller size (relative to a chip system) Consistent fuel and easy economical storage of fuel Automated Disadvantages: Higher system cost Higher cost wood fuel ($/MMBtu) Page 2 Page 3 Wood Chip Chip systems utilize wood fuel that is either chipped or ground into a consistent size of 2-4 inches long and 1-2 inches wide. Chipped and ground material includes fine sawdust and other debris. The quality of the fuel varies based upon how the wood is processed between the forest and the facility. Trees which are harvested in a manner that minimizes contact with the ground and run through a chipper or grinder directly into a clean chip van are less likely to be contaminated with rocks, dirt and other debris. The quality of the wood fuel will also be impacted by the types of screens placed on the chipper or grinder. Fuel can be screened to reduce the quantity of fines which typically become airborne during combustion and represent lost heat and increased particulate emissions. Chipped fuel is fed from the chip van into a metering bin, or loaded into a bunker with a capacity of 60 tons or more. Wood chip boilers systems are typically linked to existing heat distribution systems via a heat exchanger. Product data from Hurst, Messersmith and Biomass Combustion Systems identify outputs of 1,000,000 - 50,000,000 Btu/hr based upon burning western wood fuels. Wood chip boilers typically require hand raking of the grates and hand removal of ash daily. Automatic ash removal can be integrated into wood chip boiler systems. Ash is typically cooled in a barrel before being stock piled and later broadcast as fertilizer. Emissions from wood chip systems are typically as follows: PM2.5 0.21 lb/MMbtu NOx 0.22 lb/MMbtu SO2 0.025 lb/MMbtu CO2 195 lb/MMbtu Benefits: Lowest fuel cost of three options ($/MMBtu) Automated Can use local wood resources Disadvantages: Highest initial cost of three types Larger fuel storage required Less consistent fuel can cause operational and performance issues