The Department of Defense (DoD) owns and operates more than 100 landfills on its installations. These landfills produce waste gas streams containing methane at a wide range of concentrations that are typically vented to the atmosphere or destroyed via flaring. Flaring landfill gas wastes energy, while venting releases significant amounts of greenhouse gases. Many industrial processes including wastewater plants and coating operations also produce waste gas streams that contain methane, organics, and other potential energy sources that typically require energy intensive treatment processes to control emissions. Traditional combustion-based energy generation technologies cannot utilize most of these potential sources of energy.

Under the ESTCP project Joint Demonstration and Verification of the Performance of Microturbine Power Generation Systems Utilizing Renewable Fuels with the U.S. EPA’s Environmental Technology Verification Program (EW-200823), Southern Research Institute (SRI) is demonstrating the FlexEnergy Powerstation™ FP250 (Flex) system, which utilizes landfill gas or other low quality waste fuels to provide efficient on-site power production. The demonstration at the 1st Division Road landfill at Fort Benning, Georgia, is providing an independent third party evaluation of the system’s energy production. This demonstration will characterize emissions from the Flex system, quantify emissions reductions relative to other systems, and document the economics of the Flex system and its performance as a landfill gas energy recovery system.

The Flex system is a unique power plant that uses a thermal oxidizer system in place of the turbine’s combustor to destroy hydrocarbons in the waste fuel stream. The oxidizer allows the Flex system to operate using fuel gas or vapor that is below the typical requirements for combustion by diluting methane gas to 15 Btu/scf or 1.5% methane. The Flex system uses conventional, off-the-shelf gas turbine/generator technology with a long history of reliable operation.

The chief advantage of the Flex technology is the ability to utilize very low Btu fuel sources to provide electrical energy and heat while reducing emissions. The low value fuel sources are often waste streams, which are expensive to treat. Because of the ability to utilize low Btu gas, the energy generating potential of a landfill can extend well beyond the period when methane concentrations are high enough to support traditional combustion-based technologies. Moreover, the thermal oxidization process enables effective destruction of non-methane organic compounds, yielding emissions that are as good as or lower than alternate landfill gas destruction and utilization technologies.

Earlier this summer, the Flex system completed factory acceptance testing and was transported to Fort Benning and installed at the landfill. The system has completed initial test runs and is currently undergoing final commissioning. It will generate about 220 kW of renewable electric power that will feed directly into Fort Benning’s electrical distribution system. This project is one of the first ESTCP Installation Energy Test Bed projects to generate electricity. The researchers at SRI will collect data for several months to validate the cost and performance of the Flex system.

The potential utilization of landfill gas and other low quality waste fuels at DoD facilities can provide significant economic, environmental, and energy security benefits while contributing to the achievement of DoD’s stated goals and objectives for implementing renewable domestic energy production.
 

Related Links

• SERDP and ESTCP Installation Energy Featured Initiative
• Joint Demonstration and Verification of the Performance of Microturbine Power Generation Systems Utilizing Renewable Fuels with the U.S. EPA’s Environmental Technology Verification Program