The hybrid, multi-megawatt DFC-ERGTM (Direct FuelCell Energy Recovery GenerationTM) system combines a Direct FuelCell® power plant with an unfired gas expansion turbine. The DFC-ERG generates Ultra-Clean electricity while recovering energy normally lost during natural gas pipeline distribution operations. The DFC-ERG is unique, with electrical efficiencies of 65%, low noise and virtually zero smog emissions.
Natural gas transmission networks utilize long-distance pipelines operating at very high pressures. These pressures are required to maintain a high volume of flow in the system. Gas distribution to homes and businesses, however, uses a much lower pressure for safety and to accommodate end use equipment. Pressure is reduced at local utility letdown stations to accommodate the distribution network. As pressure is reduced, the gas naturally cools because of the refrigerant effect of gas expansion. To prevent the gas systems and pipeline from freezing, the gas must be heated before it flows through the expansion process. Traditionally, the energy available in this letdown process is lost, and gas-fired boilers, which produce local emissions and CO2, provide the heat needed by the process.
The energy normally lost when natural gas expands is harnessed by the turboexpander to drive an electric generator. The DFC, operating on pipeline gas, produces additional electric power. Waste heat from the DFC provides the heat required by the expansion process, replacing fuel used in gas-fired boilers. The utility grade electric power produced by the turboexpander and DFC system can be used to service on-site power requirements or delivered onto the power grid.
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