&EPA
www.epa.gov
.ology Verification Program
E
Environmental and Sustainable Technology Evaluations (ESTE):
Verification of Fuel Characteristics and Emissions from Biomass-fired Boilers
Impact Statement
The co-firing of biomass in coal-fired boilers may
reduce the emissions of criteria pollutants and
greenhouse gases while also reducing the use of finite
fossil fuel resources. This verification measured the
reductions of these emissions from biomass co-fired
boilers in the 100 to 1000 million Btu per hour
(MMBtu/h) size range. Impacts on ash quality were
also measured.
Background
With increasing concern about climate change and
fossil fuel energy supplies, there continues to be an
interest in biomass as a renewable and sustainable
energy source. Many studies have been conducted on
the efficacy and environmental impacts of biomass co-
firing on large, coal-fired utility boilers, but data have
not been available for biomass co-firing in industrial
size boilers. EPA's Office of Air Quality Planning and
Standards is interested in biomass co-firing in
industrial-commercial-institutional (ICI) boilers in the
100 to 1000 MMBtu/h range. The reason for this
emphasis is to provide support for development of a
new Area-Source MACT standard. There is also interest
in developing a guidance memo relating to PM2 5
emissions reductions.
ETV Program
The ETV Program operates as a public-private
partnership mainly through cooperative
agreements between EPA and private nonprofit
testing and evaluation organizations. These ETV
verification organizations work with EPA
technology experts to create efficient and
quality-assured testing procedures that verify the
performance of innovative technologies. ETV
operates six centers which cover a broad range
of environmental technology categories.
Vendors and others in the private sector, as well
as federal, state and local government agencies,
cost-share with EPA to complete priority ETV
protocols and verifications. In 2005, a new
element of ETV was initiated, Environmental
and Sustainable Technology Evaluations
(ESTE), in which the most important technology
categories for meeting EPA needs are verified
through contracts with verification
organizations. EPA has developed an ESTE
project to verify biomass co-firing in coal-fired
boilers. See http://www.epa.gov/etv/este.html
for more information.
In 2006, ETV initiated a study to verify biomass co-firing in coal-fired boilers. EPA contracted with
Southern Research Institute (SRI) to develop the protocol and perform the testing needed to verify these
technologies.
Objectives
This project evaluated performance and emission reductions for larger ICI boilers as a result of biomass
co-firing. The primary objectives were to:
• Evaluate changes in boiler emissions due to biomass co-firing
• Evaluate boiler efficiency with biomass co-firing
• Determine if the value of ash for beneficial uses is reduced due to added carbon and metals content
• Evaluate sustainability indicators including sourcing of biomass and disposal of ash.
Results
Two ESTE biomass co-firing verifications were completed in 2008: Minnesota Power's Rapids Energy
Center Boiler 5 (MP-5) which currently co-fires bark with coal, and the University of Iowa Main Power
Plant's Boiler 10 (UI-10) which co-fires wood derived pelletized fuel with coal. As noted above, impacts
on boiler efficiency and emissions were measured during both tests and varied depending on the
technology and application, as shown in the table on the following page.
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Table 1. Verified Biomass-fired Boilers
Performance Measure
Boiler
Efficiency
PM5
Emissions
Gaseous5
Pollutants
Heat Input
(MMBtu/hr)
Heat Output
(MMBtu/hr)
Efficiency, %
Total PM
Filterable PM
Condensable PM
SO2
CO2
NOx
CO
Minnesota Power's Rapids Energy Center Boiler
5 (MP-5)
Wood Waste Co-firing with Coal
Baseline1
Averages
299
223
74.5 ±0.3
0.03 17 ±0.005
0.0045 ± 0.0004
0.0249 ±0.0013
0.474 ± 0.02
160 ±7
0.527 ±0.01
0.230 ±0.02
Co-firez
Averages
363
223
61. 3 ±0.7
0.0060 ± 0.003
0.0037 ± 0.002
0.0034 ±0.0015
0.0013 ±0.0001
131±4
0.194 ±0.007
0.555 ±0.2
%
Difference3
21.8%
0.00%
-17.7%
-81.2%
-17.1%
-86.5%
-99.7%
-18.3
-63.2%
142%
Iowa Main Power Plant's
Boiler 10 (UI-10)
Renewafuel Pelletized Wood Fuel
Baseline1
Average
265
225.2
84.9 ±0.4
0.061 ±0.03
0.031 ±0.008
0.030 ±0.02
2.47 ±0.14
205 ±2
0.460 ± 0.02
0.088 ±0.010
Co-fire4
Average
273
230
84.1+0.7
0.044 ± 0.003
0.024 ±0.0018
0.020 ±0.0012
2.16 ±0.08
207 ± 0.3
0.506 ±0.018
0.083 ±0.05
%
Difference3
3.00%
2.10%
-0.90%
-28.1%
-22.8%
-33.9%
-12.4%
0.82%
10.2%
-5.02%
Baseline fuel = 100% coal; 2 Co-fire fuel = 8% Coal; 92% woody biomass; 3 Statistically significant changes are bolded:
Co-fire fuel = 85.1% coal; 14.9% wood; 5 Ib/MMBtu output
Carbon dioxide (CO2) emissions associated with sourcing and transportation of biomass and ash disposal
under baseline (no biomass co-firing) and test case (with biomass co-firing) conditions were also assessed
and the following annual CO2 emission reductions were estimated:
• Wood Waste Co-firing with Coal: 107,000 tons per year, based on a typical heat generating rate of
220 MMBtu/hr, an availability and utilization rate of 75% for Boiler 5, and an estimated CO2 emission
offset of 90% or 148 Ib/MMBtu output during co-firing.
• Renewafuels Pelletized Wood Fuel: 11,000 to 13,000 tons per year, based on a typical heat
generating rate of 160 to 190 MMBtu/hr, an availability and utilization rate of 80% for Boiler 10, and
an estimated CO2 offset of 10% or 20.7 Ib/MMBtu output during co-firing.
Metals content in the fly ash were measured and determined to be well below the TCLP metals criteria
(40 CFR 261.24) under baseline and co-fired runs during both verifications. Carbon content and ash loss
on ignition were also measured and the results indicated that none of the fly ash produced under baseline
or co-fired runs during the verifications met the Class F Requirements (C 618-05) for use in concrete.
Thus, biomass co-firing did not impact the quality of the fly ash with regard to fly ash TCLP metals and
Class F requirements were unchanged. For more information, including additional test results, visit
http://www.epa.gov/etv/este.html.
For further information contact:
Lee Beck
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
Mail Drop E343-02
Research Triangle Park, NC 27711
Phone: 919-541-0617
e-mail: beck.lee@epa.gov
www.epa.gov/etv
December 2008
EPA/600/S-08/026
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