HomeMy WebLinkAboutNenana Final Appendix 7-24 Part 2
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
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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 ($/MMBtu)
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Wood Chip
Chip systems utilize wood fuel that is either chipped or ground into a consistent size of
2-4 inches long and 1-2 inches wide. Chipped and ground material includes fine
sawdust and other debris. The quality of the fuel varies based upon how the wood is
processed between the forest and the facility. Trees which are harvested in a manner
that minimizes contact with the ground and run through a chipper or grinder directly into
a clean chip van are less likely to be contaminated with rocks, dirt and other debris. The
quality of the wood fuel will also be impacted by the types of screens placed on the
chipper or grinder. Fuel can be screened to reduce the quantity of fines which typically
become airborne during combustion and represent lost heat and increased particulate
emissions.
Chipped fuel is fed from the chip van into a metering bin, or loaded into a bunker with a
capacity of 60 tons or more. Wood chip boilers systems are typically linked to existing
heat distribution systems via a heat exchanger. Product data from Hurst, Messersmith
and Biomass Combustion Systems identify outputs of 1,000,000 - 50,000,000 Btu/hr
based upon burning western wood fuels. Wood chip boilers typically require hand raking
of the grates and hand removal of ash daily. Automatic ash removal can be integrated
into wood chip boiler systems. Ash is typically cooled in a barrel before being stock piled
and later broadcast as fertilizer.
Emissions from wood chip systems are typically as follows:
PM2.5 0.21 lb/MMbtu
NOx 0.22 lb/MMbtu
SO2 0.025 lb/MMbtu
CO2 195 lb/MMbtu
Benefits:
Lowest fuel cost of three options ($/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