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Energy from Urban Waste

As of 2008, Texas has 21 landfill gas energy projects and the potential to develop over 50 more sites. Landfill sites offer some of the best opportunities for power generation. About half of the gas emitted by landfills is methane, which is chemically the same as natural gas. Landfill gas is an energy source that can directly prevent atmospheric pollution.

Municipal solid waste landfills are the largest source of human-related methane in the United States, accounting for 34 percent of these emissions. Methane is a potent greenhouse gas that contributes to smog and to the global warming of the atmosphere, remaining in the atmosphere for 9-15 years. Current Environmental Protection Agency (EPA) regulations under the Clean Air Act require many landfill owners/operators to collect and combust landfill gas by either burning the gas off by flaring it, or by installing a landfill gas energy system.

Breaking Ground: Killeen Supports Emissions-Free Waste Management

In June 2008, the City of Killeen donated 40 acres of land to Zero-emissions Energy Recycling Oxidation Systems (ZEROS) to build a zero waste emissions-free power plant near the Williamson County landfill.

The plant, designed at Texas A&M University, will use an oxygenated system to convert as much as 300,000 tons of garbage annually into electricity with zero emissions. ZEROS has agreed to sell byproducts such as diesel fuel, gasoline and clean water back to the city at a reduced rate.

The estimated cost of $250 million to $300 million will be provided by private investors. The plant is expected to create 200 jobs in Killeen while reducing the city’s landfill waste treatment costs from $20 to $24 per ton to $10 per ton. The processing plant could go on-line in about three years.

When burned under controlled conditions rather letting it escape into the atmosphere, methane becomes a valuable renewable energy resource that can generate electricity, heat or fuel for vehicles. Turning hazardous landfill gas into marketable energy adds to landfill safety, improves the environment and decreases odors – all while generating revenue. Purified methane can be used on the premises for electricity or to fuel boilers or other thermal applications. Pipeline grade methane can be transported by pipeline for sale to the local power grid to run electric generators.

If the 70 largest landfills in Texas were fully developed for energy use, approximately 40 billion cubic feet of methane drifting into the atmosphere or being wasted in flares would be utilized. It is estimated that nearly 200 MW of electricity could be generated from this unutilized gas. This could provide electric power for over 100,000 Texas homes.

The natural anaerobic (without oxygen) decay and decomposition of landfill biomass waste materials causes emissions of landfill gas (biogas). To release the methane, landfill gas wells are drilled into a landfill. Then pipes from each well carry the gas to a central point where it is filtered and cleaned before burning. Biogas taps one of society’s least desirable items, garbage, and turns it into a useful, high-value energy producer.

Though environmentalists see landfill methane production as a common-sense way to use waste products, the technology has been slow to catch on because historically there have been few economic incentives. However, as landfills fill up, biomass power generation is becoming an economically attractive prospect.

Additional Resources

For an overview of the use of landfill and municipal waste, see the Landfill Gas overview and the Municipal Waste Combustion overview in the Texas Comptroller’s 2008 energy report.

Environmental Protection Agency (EPA) Publications and Sites

Additional Links

Creating Ethanol from Trash, Technology Review, Published January 2007.

Growing Energy is a Natural Resources Defense Council study that explores how biofuels can help end America’s dependence on foreign oil.

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