Performance and emissions of liquefied wood as fuel for a small scale gas turbine

This study investigates for the first time the combustion in a micro gas turbine (MGT) of a new bioliquid, a viscous biocrude, which is a liquefied wood (LW) produced via solvolysis of lignocellulosic biomass in acidified glycols. The test rig includes a modified fuel injection line, a re-designed combustion chamber and revised fuel injection positions. The main novelties of this work are: (1) producing of liquefied wood with pure ethylene glycol as a solvent, and methanesulfonic acid as a catalyst, to obtain a bio-crude with lower viscosity and higher lignocellulosics content than previous tested formulations; (2) upgrading raw liquefied wood by blending it with ethanol to further reduce the viscosity of the mixture; (3) utilizing a commercially available MGT Auxiliary Power Unit (APU) of 25 kW electrical power output, with notably reduced extent of adaptations to use the newly obtained fuel mixture. Fuel properties, and their impact on combustion performance using liquefied wood, are investigated by analyzing MGT performance and emissions response at different load and blend ratios. Emissions revealed that the presence of LW in the blends significantly affects CO and NOX concentrations compared to conventional fuels. CO roughly increased from 600 ppm (pure ethanol as fuel) to 1500 ppm (at 20 kW electrical power). The experimental study reveals that it is possible to achieve efficient MGT operation while utilizing high biocrude to ethanol ratios, but a number of adaptations are necessary. The achieved maximum share of liquefied wood in the fuel blend is 47.2% at 25 kW power output. Main barriers to the use of higher share of liquefied wood in these type of systems are also summarized.