Gas-to-Energy System

In September 2008, Waste Management and the City and County of Denver cut the ribbon on a new facility that captures waste gas from Lowry Landfill and the nearby Denver Arapahoe Disposal Site and recycles it into renewable energy for the surrounding community. According to Waste Management—which funded, built and operates the plant—similar systems are in place at landfills across the country, but Lowry Landfill’s is the only such system in Colorado to date.

The Process

Landfill gas—which consists of approximately 50 percent methane, 45 percent carbon dioxide, and a balance of nitrogen and other gases—is created naturally by the biological decomposition of organic matter in landfills under low-oxygen conditions. Under the originally approved Lowry Landfill cleanup plan, landfill gas from the site was collected at extraction wells and delivered through pipelines to a large burner that destroyed the gas through combustion.

Rather than destroy the waste gas, the Landfill Gas-to-Energy Plant converts it into 2.7 megawatts of electrical power for distribution by Xcel Energy, reducing greenhouse gas emissions in the process and helping the utility meet statutory requirements for using renewable energy sources. An added benefit to taxpayers: The City and County of Denver receives royalty payments from the sale of the energy.

The System

The Lowry Landfill gas collection system consists of 64 extraction wells that are drilled into and screened across buried landfill solids. The wells are connected by a series of buried pipes that convey extracted gas to the gas-to-energy plant. In addition, 21 gas-monitoring probes surrounding the site confirm that gases are not leaving it. These monitoring probes will remain in place throughout operations of the gas-to-energy plant.

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Benefits

  • Reduces greenhouse gases and air pollution
  • A sustainable, long-term energy source
  • Beneficial use of a waste byproduct
  • Produces enough electricity to satisfy the annual electrical demands of approximately 3,000 households
  • Protects human health from inhalation of landfill gas
  • Protects humans and the environment from gas-related explosion hazards