Commercial demonstration of biomass gasification the Vermont project

Thermal gasification of biomass for use in gas turbine combined cycle plants will improve efficiencies and reduce capital intensity in the forest and paper industry. One such technology has over 20,000 successful hours of operation at Battelle Columbus Labs (BCL) process research unit (PRU), including the first U.S. demonstration of a gas turbine operating on fuel gas produced by the thermal gasification biomass. A commercial scale demo of the technology (rated at 200 dry tons per day) will be constructed and put into operation during the first quarter of 1997. The initial project phase will provide fuel gas to McNeil`s power boiler. A subsequent phase will utilize the fuel gas in a combustion gas turbine. The technology utilizes an extremely high throughput circulating fluid bed (CFB) gasifier in which biomass (which typically contains 85 percent to 90 percent volatiles) is fully devolatilized with hot sand from a CFB char combustor. The fuel gas is then cooled and conditioned by a conventional scrubbing system to remove particulate, condensable organics, ammonia and metal aerosols which could otherwise cause turbine emission and blade fouling problems. Alternate hot gas conditioning systems are also being developed for final gas clean-up. The fuel gas heating value more » is 450 to 500 Btus per standard cubic foot. A mid size gas turbine combined cycle plant utilizing the technology will have an approximate net cycle efficiency of 35-40 percent. This compares to a conventional biomass plant with an overall net cycle efficiency of 20-25 percent. Capital costs are expected to be low as the process operates at low pressures without the requirement of an oxygen plant. « less