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The Technical University of Denmark, DTU, has designed, built and tested a gasifier [1, 8] that is fuelled with wood chips and achieves a 93% conversion efficiency from wood to producer gas. By combining the gasifier with an ICE and an electric generator a co-generative system can be realized that produces electricity and heat. The gasifier uses the waste heat from the engine for drying and pyrolysis of the wood chips while the gas produced is used to fuel the engine. To achieve high efficiency in converting biomass to electricity an engine is needed that is adapted to high efficiency operation using the specific producer gas from the DTU gasifier. So far the majority of gas engines have been designed and optimized for operation on natural gas. The presented work uses a modern and highly efficient truck sized natural gas engine to investigate efficiency, emissions and general performance while operating on producer gas compared to natural gas operation.

The Technical University of Denmark, DTU, has constructed, built and tested a gasifier [1, 11] that is fueled with wood chips and achieves a 93% conversion efficiency from wood to producer gas. By combining the gasifier with an internal combustion engine and a generator, a co-generative system can be realized that produces electricity and heat. The gasifier uses the waste heat from the engine for drying and pyrolysis of the wood chips while the produced gas is used to fuel the engine. To achieve high efficiency in converting biomass to electricity it necessitates an engine that is adapted to high efficiency operation using the specific producer gas from the DTU gasifier. So far the majority of gas engines of today are designed and optimized for SI-operation on natural gas.

About 2000 hours of gas engine operation with producer gas from biomass as fuel has been conducted on the gasification combined heat and power (CHP) demonstration and research plant, named “Viking” at the Technical University of Denmark. The plant and engine have been operated continuously and unmanned for five test periods of approximately 400 hours each. Two different control approaches have been applied and investigated: one where the flow rate of the producer gas is fixed and the engine operates with varying excess of air due to variation in gas composition and a second where the excess of air in the exhaust gas is fixed and the flow rate of produced gas from the gasifier is varying. It was seen that the optimal control approach regarding the gasifier operation resulted in engine operation with significant variation of the NOx emissions Producer gas properties and contaminations have been investigated.