CHARACTERISTICS

A variety of waste products can be converted into liquid and gaseous fuels for use in generating electricity. These include municipal solid waste—which can also be processed into refuse-derived fuel (RDF) that yields a higher Btu, lower ash energy source—or biogas created from organic waste or biomass through fermentation. Also, methane gas can be recovered from landfills and used in place of natural gas. Methane is a flammable gas produced from landfill wastes through anaerobic digestion, gasification or natural decay.

Using these waste-derived fuels not only consumes what would otherwise be waste, it also produces fuels with lower emissions than those associated with fossil fuels. Where methane is recovered, it avoids the release of methane, a greenhouse gas.

SIZE:
1-5 MW_e (modular combustion); 30-100 MW_e (field-erected).

FEATURES:
MSW is 25% efficient when used for power generation. Biogas can be used in internal combustion engines for shaft power or electricity; it can also be used as cooking and heating fuel. Methane recovery can achieve 70-80% efficiency.

COST:
$91,000/Mt of daily capacity for MSW; $4,750/kW_e for biogas. Methane recovery can be relatively inexpensive to operate, but if pipelines or other infrastructure needs to be built, the project cost increases dramatically.

CURRENT USAGE:
Many European countries currently combust their waste streams; additional efficiency may be achieved through recovering heat or electricity. Currently, more than 100 power plants in 31 of the United States burn landfill-generated methane.

POTENTIAL USAGE:
Applicable everywhere that waste is generated. Especially applicable in highly populated regions that produce significant quantities of waste.

ISSUES ASSOCIATED WITH IMPLEMENTING ACTION

• Creates ash as a by-product that must be disposed of, requiring a landfill. These disposal costs add to O&M costs.
• Operators must have access to a significant quantity of garbage (100 TPD). Also, a storage area is required for the waste.
• For biogas, retention time is limited—for cattle manure 20-25 days; for other animal waste 12-15 days.
• Siting of facilities can be difficult because of state regulations as well as public sentiment—"not in my backyard" (NIMBY).

CLIMATE CHANGE IMPACT

EMISSION EFFECT:
    

CONDITIONS FOR EMISSIONS MITIGATION:

EMISSION ESTIMATE:
No carbon emissions are produced

COST-EFFECTIVENESS:
N/A

SECONDARY EFFECTS:
Some NO_x SO_x emissions are produced (depending on fuel stock), but emissions are significantly less those generated by any fossil fuel.

RESOURCES

• Bushnell, C. et al., 1992, Municipal Solid Waste Combustion: Testing and Evaluating the Combustion Characteristics of Waste Fuels, Northwest RBEP, Bonneville Power Administration, Portland, OR.

CONTACTS

National BioEnergy Industries Association
Washington, DC
Tel: (202) 383-2540
Fax: (202) 383-2670
http://www.bioenergy.org

National Renewable Energy Laboratory Dave Lazarz
Golden, CO
Tel: (303) 275-3835
Fax: (303) 275-2905
http://www.nrel.gov

Renewable Fuels Association
Washington, DC
Tel: (202) 289-3835
Fax: (202) 289-7519

United BioEnergy Commercialization Association (UBECA)
Joe Badin
Director
Columbia, MD
Tel: (301) 621-8432
Fax: (301) 621-8997
http://www.ubeca.org