Biomass and Alternative Methane Fuels Are Widely Adaptable Energy Sources

November 1, 2002

Photo of a wastewater treatment digester

Wastewater treatment digester gas can yield more methane fuel.

If there is a reliable source of biomass near your facility, chances are good that you can use it to lower your energy bills and improve your energy security. Biomass, including waste products, can be processed and delivered to energy applications in the form of either a solid fuel or a gas. The biomass fuel is then converted into energy utilities in the form of electricity, heat, hot water, and steam.

Biomass can be processed and used directly to fire boilers, or can be converted, using biomass gasification technologies, into a synthesis gas consisting of hydrogen, carbon monoxide, and methane. Additionally, the microbial conversion of organic materials in wastewater treatment plants and landfills produces a biogas with high concentrations of methane. Wastewater treatment plants using anaerobic digesters produce a gas consisting of 50 to 75 percent methane and 20 to 50 percent carbon dioxide, along with trace levels of other gases. Landfills produce a gas consisting of 45 to 60 percent methane and 40 to 60 percent carbon dioxide, along with small amounts of other gases.

Only minor modifications are required to use these alternative methane fuels in equipment that normally uses natural gas. Treatments to remove moisture and impurities, including activated charcoal to absorb hydrogen sulfide and halogens (fluorine, chlorine, and bromine), make these fuels suitable as a substitute for natural gas in boilers, engines, gas turbines, micro-turbines, and fuel cells. Since the methane content of landfill gas or digester gas is approximately one half of that contained in natural gas, twice the flow is required to supply the equivalent energy content. To accommodate this difference in flow, the valve orifices for fuel control must be enlarged. It is also sometimes necessary to have natural gas as a back-up fuel to ensure fuel consistency and flame stability.

Many energy technologies are being developed or adapted for biomass and alternative methane fuels. For example, DOE is currently sponsoring demonstration projects for fluid bed gasification and Biomass Gasification Combined Cycle (BGCC) electricity generation using wood waste. Combined-cycle systems combust the synthesis gas in a gas turbine and recover part of the exhaust heat for a steam cycle.

The tremendous variety of biomass fuels and the wide range of potential energy applications mean that these renewable resources represent a green energy opportunity for many Federal facilities.

For more information on how your facility can use biomass and alternative methane fuels to meet its energy requirements, please contact your FEMP Regional Office Representative (see list of contacts). For additional information, please contact Christopher Abbuehl, National Program Representative for the BAMF Super ESPC, at 215-656-6995 or; Steve Cooke, BAMF Technical Lead, at 304-285-5437 or; or Danette Delmastro, FEMP BAMF Team Lead, at 202-586-7632 or