Landfill Gas Use by GM Highlighted
02 April 2006
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| The pipeline from landfill to GM plant in Shreveport. One of seven GM LFG projects. |
General Motors is the largest direct, corporate user of landfill gas (LFG) as a replacement for natural gas in the United States. General Motors has reduced its natural gas consumption by 21% since 2000 and is expected to achieve its goal of a 25% energy reduction by the end of 2006.
At GM facilities, the LFG is piped to the plant and combusted in boilers, providing a cost-effective, renewable energy source. The sum of landfill gas capacity at the seven GM operations using the fuel is equivalent to the energy needed to heat over 25,000 households, which represents about 1.6 trillion BTUs per year.
Landfill gas is a natural product of the biological decomposition of organic waste. The resulting gas has a variety of chemical components, but at most sites the two principal components are methane (CH4) and CO2, with much smaller amounts of hydrogen sulfides (H2S), inerts and volatile organic compounds (VOCs).
A problem with LFG projects is the presence of trace components. Typical LFG contains heavy hydrocarbons (both aliphatic and aromatics such as benzene) as well as numerous chlorinated hydrocarbons. These trace compounds are in some cases toxic or hazardous and also cause rapid failure or engine and turbine components. There are now federal statutes which cover landfill emissions.
GM’s LFG use is being featured this spring on two television programs airing on public and cable television stations throughout the United States and on Voice of America programming internationally. Both programs look at how the rotting garbage in landfills generates a gas that is used as an energy source at seven GM facilities.
The “Learning About” educational series is hosted by actor Michael Douglas and will air during March. Later in the spring, GM will be featured on “The Global Learning Series” education program.
GM’s Orion Township, Michigan, assembly plant is highlighted in the “Learning About” and “The Global Learning Series” television programs.
Other GM facilities using landfill gas are: assembly plants located in Oklahoma City, Okla. ; Fort Wayne, Ind. ; Shreveport, La. ; and a powertrain plant located in Toledo, Ohio. Two additional warehouse sites in Grand Blanc and Flint, Mich., utilize landfill gas by purchasing 13 million kilowatt-hours of electricity annually, which is generated from a landfill gas-to-electricity program.
The US Environmental Protection Agency (EPA) awarded GM one of its Landfill Methane Outreach Program (LMOP) awards for the Ft. Wayne Truck Assembly Plant LFG project.
An 8-mile pipeline delivers LFG from the Macbeth Road Landfill to the plant, providing about 450,000 million BTU per year. This represents about 16% of the plant’s energy needs, saving GM $500,000 annually. The LFG use delivers annual greenhouse gas reductions equivalent to planting 6,000 acres of forest, removing the emissions of 4,200 vehicles, or preventing the use of 51,200 barrels of oil.
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Surprisingly wise decision for GM to position their facilities close-by to major landfills.
Posted by: Andrey | 02 April 2006 at 04:24 AM
I sincerely doubt that proximity to a large landfill was a major site selection criterion. It's just that wherever you have a major car plant, you also have a supply chain and that adds up to a lot of people living nearby. I.e. the landfill will be established within reasonable distance of the factory, not the other way around.
Burning landfill gas is a good idea from a cost and a GHG perspective, but great care has to be taken with the halogen contaminants, and not just because of possible damage to the power generating equipment. These contaminants are converted to dioxins, furans and thiophenes in a flame combustion process (not all of these are toxic, but some are highly so).
It is not clear if GM goes to the trouble of pre-treating the gas to filter out halogenated compounds but at least LFG combustion in boilers is better than combustion in ICEs. An even better solution would be to convert the LFG methane into methanol and siphon off the remaining gases as toxic waste prior to burning the liquid.
http://www.energyjustice.net/lfg/
Posted by: Rafael Seidl | 02 April 2006 at 06:46 AM
Rafael: The problem you described is relevant to combustion of waste, when Cl and F bearing plastics, such as PVC and Teflon, are burned. Since these plastics are not biodegradable, biogas does not contain more then trace amount of halogenated. components
Corrosion and plugging problems of biogas are caused by hydrogen sulfide and siloxane content.
EPA is required to flare of or burn other way biogas from landfills irrelevantly to GHG emissions. The reason is to eliminate emission of substantial amount of VOC, smell nuisance, and prevent vegetation destruction on landfill cover.
Posted by: Andrey | 02 April 2006 at 09:14 PM