(5a) Eliminating Supplemental Natural Gas in Biogas Fired Power Generation

Internal Combustion (IC) Engine Power Generation is used throughout California in municipal Sanitation Districts to produce power with renewably produced fuel from waste digesters in the form of biogas, typically with 65% methane with the balance of the dry composition primarily being Carbon Dioxide. The resultant biogas must be supplemented with at least a 10% natural gas feed to raise the heating value for a stable firing. Use of non-renewable natural gas is a significant operating cost, and takes away from sustainability. The goal is to maximize sustainability with use of 100% biogas fuel, and as well minimize operating costs. This is achieved by using the patent pending Black Swan Wig Membrane as manufactured by Generon to produce oxygen enrichment of air from ambient 20% to 25% in the lowest energy intensive/cost effective manner. This oxygen enriched stream is fed into the combustion air inlet zone of the power generation unit, without modification to the power generation unit. The oxygen enrichment raises the firing temperature of a 100% biogas feed to a level equivalent to a natural gas fired unit. A side benefit is that the flue gas is a higher concentration of CO2, and thus a more capturable/ usable exhaust from the stack. In this case, the pilot uses the stack gas to produce agricultural products (almonds)/ biomass via biosequestration. Proposed pilot and demonstration unit is funded by the California Department of Food and Agriculture and hopefully a pending grant application with the California Energy Commission.