Fuel-flexible micro-gas turbines for biomass utilization: an externally-fired case

This paper focuses on investigating the fuel flexibility of an externally-fired micro-gas turbine that exploits the syngas produced by a biomass gasifier. Biomass-renewable fuels can play a vital role in the transition to net-zero greenhouse gas emissions by 2050. In contrast to fossil fuels, however, biomass fuels are characterized by varying syngas compositions, dependent on the utilized raw material. This study evaluates the syngas composition effect using a validated micro-gas turbine off-design thermodynamic model coupled with a gasification equilibrium model. An off-design control logic was also developed to avoid any operational hazards related to exceeding temperatures that may occur when utilizing various syngas fuels. The investigation focuses on the effect of variable feedstock moisture contents, various feedstocks, and syngashydrogen blends. The key fuel property affecting system performance is the syngas Lower Heating Value. The results show that the complete externally-fired micro-gas turbine performance analysis can be generalized as a function of the thermal input rate. The electrical power maximizes at 100% of the nominal thermal input rate, while the efficiency maximizes around 55%, independently of the syngas composition. The proposed system can maintain high relative efficiency while utilizing a wide range of biomass fuels under various operating conditions.