Landfill gas, that heady emanation from household trash, is about to assume an important role in the renewable energy strategy of the U.S. Department of Defense. As part of a net zero program to help military installations cut down on fossil fuels, the U.S. Marines are showcasing a new landfill gas recovery project at Marine Corps Air Station Miramar near San Diego.
The new project broke ground on July 14 at a 1.1 million-ton municipal landfill adjacent to the base, where trash from the City of San Diego is dumped. When it is completed, landfill gas will generate about 25 million kilowatt-hours per year, or about half of Miramar’s electricity needs.
Natural gas is released from landfills through decomposition, as microorganisms break down the organic materials in garbage. Landfill gas is mainly composed of methane, carbon dioxide and water vapor. Household products such as cleansers and paints can contribute small amounts of toxic pollutants to the mix.
Despite its sketchy origins, landfill gas is considered a desirable source of energy for military installations because a steady supply is available 24/7. Landfills are the third-largest source of methane emissions from human activity in the U.S. and methane is a potent greenhouse gas, so Miramar’s gas recovery project will also fulfill a global warming management function.
Miramar is also looking into the potential for getting up to 2.8 megawatts of local renewable energy in the form of sewage biogas from nearby sewage treatment plants.
Like landfill gas, sewage biogas is a methane-based byproduct of natural decomposition.
Dependence on humble fuels such as landfill gas and sewage gas may seem somewhat ironic for the U.S. Marines, given their history as an elite fighting force. However, the two fuels are part of a broad renewable energy and conservation effort at Miramar, which has earned the base national recognition as the first ever “Green Marine Corps” facility.
The green honor is an important one in terms of the Pentagon’s push for an energy strategy that enables military installations to transition out of fossil fuels, and function independently in case of widespread grid disruptions and fuel shortages. Miramar will be used as a model for similar net zero programs at military installations across the U.S.
Ideally, a net zero installation will use no more energy than it can produce on site, typically from alternative sources such as solar and geothermal. Local sources such as San Diego’s landfill, sewage treatment plants or nearby biofuel refineries can also form part of the strategy.
Miramar is also planning projects that take advantage of its solar resources, including solar hot water systems, photovoltaic panels for rooftops and carports, a concentrated solar power system, and the installation of solar powered street lights.
Together with energy conservation programs, these projects will enable Air Station Miramar to achieve a 43 percent reduction in its use of off-site energy sources by next year, excluding tactical aircraft fuel.
The National Renewable Energy Laboratory (NREL) recently analyzed Miramar and developed a new set of recommendations that includes an advanced micro-grid and the increased use of solar energy, along with biofuels from local crops and refineries. That will put Air Station Miramar on the road to a 90 percent reduction in just a few years, by 2017.
