This is an excerpt from EERE Network News, a weekly electronic newsletter.
Fuel Cells Help Convert New York City Odors into Electricity
New York City Mayor Michael Bloomberg announced on February 26th that the city has completed installation of eight 200-kilowatt fuel cells at four of the city's wastewater treatment plants. The fuel cells are fueled with the biogas produced in anaerobic digesters at the treatment plants. That biogas—a combination of methane and carbon dioxide—is not only a greenhouse gas, but is also a source of noxious odors. DOE provided partial funding for the fuel cell installations. See the mayor's press release.
Researchers at Pennsylvania State University hope to simplify the process of generating power from wastewater, using a fuel cell based on microbes. In Penn State's microbial fuel cell, the wastewater is passed between the terminals of the fuel cell. As naturally occurring bacteria in the water oxidize the waste, they also pass electrons to the anode of the fuel cell, producing an electrical current. So far, the researchers have generated between 10 and 50 milliwatts of power per square meter of electrode while removing about 78 percent of the organic matter in the wastewater. See the Penn State press release.
While New York uses anaerobic digesters to process its wastewater, a growing number of dairy farms are using the same technology to convert manure into biogas, which can then be used to power a motor-generator set to produce electricity. Microgy Cogeneration Systems, Inc., a subsidiary of Environmental Power Corporation, has recently racked up five orders to install its digester systems at dairy farms in Wisconsin. The digesters are being installed as part of an agreement between Microgy and the Dairyland Power Cooperative. Microgy is also exploring the feasibility of installing up to 4 megawatts of generating capacity at two farms operated by the Gallo Cattle Company in California. See the Microgy press releases.