Biogas Fueled Microturbine Applications at Small Wastewater Treatment Facilities

A nationwide trend toward sustainable development and a focus on the use of renewable energy resources has created great interest in the use of biomass as a fuel source.This trend is reflected in the increased applications of biogas-to-energy systems installed in wastewater treatment facilities.The use of biogas produced by anaerobic digestion processes at municipal wastewater treatment facilities dates back to in 1930's. The practice of operating biogas fueled reciprocating engines to power generators or process equipment wained in the 1950's and 1960's as a result of relatively inexpensive utilities and the high O&M cost of reciprocating engines.Escalating energy costs, state, and utility incentive programs and advancements in technology through the 1990's have resulted in economics that can favor biogas-to-energy systems applications at mid-size and small wastewater treatment facilities.As a result of this market trend, small (- current operation of the plant's anaerobic digestion system- quantification of the quantity and quality of biogas produced- preliminary sizing and selection of a microturbine system- estimates of digester heating and building heating needs- capital, operations and maintenance cost estimates- economic analyses- funding and incentives sourcesMajor design considerations include:- biogas conditioning (i.e. removal of moisture, hydrogen sulfide and siloxanes)- selection of the microturbine system and heat recovery system- integration of the microturbine's electrical and heat recovery and control systems into the plant's systemsOperating results for installed systems include:- actual power produced and energy cost savings- actual capital, operation and maintenance costsThis paper summarizes the information obtained from the plants is summarized. These summaries present capital costs, O&M costs, power savings and paybacks that are expected when biogas-to-energy systems are installed in small municipal wastewater treatment facilities.