Ventilation Air Methane (VAM)
Utilization Technologies
December 2010
Why is VAM Mitigation Important?
Methane, the principal component of natural gas, is often present in deep
coal seams and is a safety hazard to miners because it is explosive in con-
centrations ranging from 5 to 15 percent in air. Therefore, gassy underground
coal mines employ large-scale ventilation systems. These systems dilute
methane released into the mine workings as coal is extracted and remove
the gas from the mine, thereby maintaining safe working conditions. In-mine
methane concentrations must be maintained well below the lower explo-
sive limit, so ventilation air exhausts carry only very dilute concentrations
of methane (typically less than 1 percent and often less than 0.5 percent).
However, because flow rates are so high, ventilation air methane (VAM)
constitutes the largest source of methane emissions at most mines. VAM
exhausts not only waste a clean energy resource but also contribute signifi-
cantly to global greenhouse gas emissions. Methane has a global warming potential 23 times that of carbon dioxide, so
successfully deploying technologies to convert VAM into useful forms of energy (such as electricity and heat) can result
in very substantial greenhouse gas emission reductions.
Ventilation exhaust (evase) (Photo courtesy of H.
Lee Schuitz)
Utilization Technologies: VAM as Supplemental Fuel
Internal Combustion Engines/Turbines/Boilers: Some technologies for beneficial-
ly using the energy content of ventilation air exhausts are currently available, while
others are in the development and demonstration phase. One existing approach is
quite straightforward and entails using VAM as combustion air, thereby supplying
ancillary fuel to internal combustion (IC) engines, turbines, or industrial and utility
boilers. Such VAM use in IC engines running on drained coal mine methane has been
well demonstrated. The Appin Colliery in New South Wales, Australia implemented a
project employing 54 VAM/coal mine methane driven internal combustion engines
to power generators that produced 55.6 MW of electricity for the mine. Although
Available and Developing Options for VAM Utilization
•	VAM used as a supplemental fuel (i.e., combustion air)
Internal combustion engines
-	Turbines
-	Utility or industrial boilers
-	Hybrid rotary kiln/gas turbine
•	VAM used as the principal fuel
-	Flow-reversal oxidizers, with or without energy recovery
» Thermal
» Catalytic
-	Gas turbines—microturbines (e.g., 30 kW) and full sized turbines (>0.5 MW)
Appin power plant (Photo courtesy of EDL)
using ventilation exhaust as
combustion air in large utility
or industrial boilers has been
demonstrated on a pilot scale at
the Vales Point Power Station in
Australia, this option is limited
by the need to site the facility
near the mine. In contrast, IC
engines and turbines are readily
deployable at remote locations.
In addition, EESTech Inc. acquired
the rights to an innovative rotary
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Ventilation Air Methane (VAM)
Utilization Technologies
kiln system that burns waste coal with ventilation air methane or drained coal mine methane. In this application, VAM
again is a supplemental fuel. The mixed fuel is combusted in the kiln, and the exhaust gases pass through a specially
designed air-to-air heat exchanger. The heated clean air then powers a turbine to produce electricity. The waste coal
feed can be adjusted in response to variations in VAM flow or concentration, allowing for a constant energy feed to
the turbine for electricity generation. By combusting waste coal and VAM,
this technology offers the ability to mitigate methane emissions while also
reducing acid runoff from (and spontaneous combustion of) waste coal
piles. The technology was developed jointly by Australia's Commonwealth
Scientific and Industrial Research Organisation (CSIRO) and Liquatech
Turbine Company Pty., and a 1.2 MW pilot plant was constructed at CSIRO's
Queensland Centre for Advanced Technologies. EESTech is standardizing
designs for 10 MW and 30 MW systems and is actively commercializing the
technology in China and India. Because it avoids the water requirements of
steam-cycle power generation, the hybrid coal and gas turbine is appropri-
ate for remote locations where waste coal and methane are available but
water is scarce.
Utilization Technologies: VAM as Primary Fuel
Flow-reversal Oxidizers: Both thermal and catalytic systems are commercially available and capable of oxidizing VAM.
When VAM enters an oxidizer, the gas encounters a bed of heat exchange material that has been preheated to the oxi-
dation temperature of methane (1000° C). The VAM oxidizes and releases heat, which in turn maintains the temperature
of the heat transfer material at or above 1000° C, thereby sustaining the auto-oxidation process without requiring addi-
tional fuel input. Valves and dampers repeatedly reverse the flow of incoming VAM to keep the hot zone in the center of
the oxidizer. Catalytic and thermal systems both operate on this principal, although catalysts allow the reaction to occur
at lower temperatures. When VAM concentrations are high enough, thermal oxidizers can provide excess heat energy for
uses such as electricity generation.
This end-use is currently being employed at the West Cliff Colliery in New
South Wales, Australia. The West Cliff Ventilation Air Methane Project
(WestVAMP) is the world's first commercial-scale VAM-to-power project.
Building upon earlier demonstrations of VAM oxidation and steam genera-
tion in the UK and Australia, WestVAMP started operation in September
2007 and is producing 6 MW of power for use by the mine. It employs a
thermal flow-reversal oxidizer, the VOCSIDIZER™, manufactured by MEGTEC
Systems. Another project deploying the VOCSIDIZER™ is in the planning
stages at the Datong coal mine in China's Chongqing municipality. This
will be the largest VAM oxidation project in the world to mitigate methane
emissions and generate thermal energy.
Hybrid waste coalNAM rotary kiln (Photo
courtesy of Com Energy)
WestVAMP (Photo courtesy of MEGTEC)
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Ventilation Air Methane (VAM)
Utilization Technologies
Biothermica, a Canadian air pollution control equipment supplier, offers a VAM oxidizer called the VAMOX™. A VAMQX™
unit has been deployed in a successful demonstration program at the Jim Walters Resources mine in Brookwood,
Alabama since March 2009. The project is the first to operate at an active underground coal mine in the United States.
Lean-fuel Gas Turbines: CSIRO developed a lean-fuel gas turbine, the VAMCAT, that employs a catalytic combustor to
run on VAM concentrations in the 1 percent range. In most field applications, this technology will require the availability
of supplemental fuel (e.g., drained coal mine methane) that can be blended in to increase the methane concentration
entering the turbine to approximately 1 percent methane.
Three other oxidizer manufacturers have recently entered the VAM market. Gulf
Coast Environmental Systems, LLC provides a thermal flow-reversal oxidizer, the CH4
RTO (regenerative thermal oxidizer), that uses a shipping container as the oxidizer
shell, thereby reducing manufacturing costs. China's Shengdong Group is offering
a VAM oxidizer that has been field tested for energy recovery (i.e., steam produc-
tion) at two Chinese mines (Bingchang mine in Shanxi province and Pingmei mine
in Henan province). Diirr Environmental and Energy Systems manufactures both tra-
ditional oxidizers and the Ecopure® RL rotary RTO, which avoids the use of poppet
valves and dampers by employing a single rotary valve to control the flow-reversal
process. Finally, Canada's CANMET Energy and Technology Centre developed a
prototype catalytic VAM oxidizer called the CH4MIN.
VAMOX7" Project (Photo courtesy of
Biothermica)
Flex-Microturbine1M (Photo
courtesy of Flexenergy)
In cooperation with Capstone Turbines, FlexEnergy of-
fers a lean-fuel microturbine (Flex-Microturbine™) that
is capable of using methane concentrations as low as
1.5 percent for its principal fuel. The system accepts
fuel at atmospheric pressure and, by employing cata-
lytic combustion, is able to operate with very low NGX
emissions (below 0.1 ppm). The units can generate up
to 30 kW of electrical power each and, in proof-of-con-
cept testing, were shown to achieve nearly full power
running on fuels equivalent to <2 percent methane. A
FlexEnergy turbine has been installed at the DCOR oilfield near Santa Barbara, California, to
consume oilfield gas at concentrations ranging from 1.5 to 4.2 percent, and another is running
on coal process waste gas at the Western Research Institute in Laramie, Wyoming. Although
no VAM field testing has been performed to date, the system would be applicable to settings
where blending gas is available in quantities adequate to raise methane concentrations in the
mine exhaust up to the operating concentration of 1.5 percent.
VAMCAT schematic (Image courtesy
of CSIRO)
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Ventilation Air Methane (VAM)
Utilization Technologies
For More Information...
To obtain more information about emerging VAM mitigation technologies, contact;
Biothermica Technologies Inc.
426, rue Sherbrooke Est
Montreal, Quebec H2L1J6
Nicolas Duplessis, Director of
Development
Phone: (514) 488-3881
E-mail: nicolas.duplessis@biother~
mica.com
http://www.biothermica.com/technolo-
gies/en/air_vamox.html
CANMET
1615 Lionel-Boulet Boulevard
P.O. Box 4800
Varennes, Quebec, Canada J3X 1S6
Jacques Grau, Business Development
Officer
Phone: (450) 652-5177
E-mail: jacques.grou@nrcan.gc.ca
http://canmetenergy-canmetenergie.
nrcan-rncan.gc.ca
Commonwealth Scientific and
Industrial Research Organisation
PO Box 883
Kenmore, Queensland, Australia 4069
Dr. Su Shi, Project Leader
Phone: 61-7-3327 4679
E-mail: shi.su@csiro.au
http://www.csiro.au
Diirr
40600 Plymouth Road
Plymouth, Ml 48170-4297
Jim Stone, National Service Manager
Phone: (630) 443-0636
E-mail: james.stone@durrusa.com
http://www.durr.com/en
EESTech
Ground Floor, Engineering House
447 Upper Edward Street
Brisbane, Queensland, Australia 4000
Ian Hutcheson, CFO
Phone: 61-7-3832-9883
E-mail: ihutcheson@eestechinc.com
http://www.eestechinc.com/index.
php?page=16
FlexEnergy
22922 Tiagua
Mission Viejo, CA 92692
Edan Prabhu, President
Phone: (949) 380-4899
E-mail: EDANPRABHU@COX.NET
http ://w ww.f I exen e rgy. co m
Gulf Coast Environmental
Systems, LLC
18150 Interstate 45 North
Willis, TX 77318
Mark Owen, VAM Manager
Phone: (949) 783-0464
E-Mail: mowen@gcesystems.com
http://www.gcesystems.com
MEGTEC Systems
Theros Svenssons Gata 10
SE-417 55
Gothenburg, Sweden 41755
Richard Mattus, Business Manager
Phone: 46 (0)31 65 78 19
E-mail: rmattus@megtec.se
http://www.megtec.com
Contact EPA's Coalbed Methane Outreach Program for more information
about this and other profitable uses for coal mine methane:
Coalbed Methane Outreach Program Dr. Jayne Somers
U.S. Environmental Protection Agency Phone: (202) 343-9896
Washington, DC	E-mail: somers.jayne@epa.gov
Website http://www.epa.gov/coalbed
The mention of products or services in this case study does not constitute an endorsement by EPA.
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