Decarbonisation of industrial power generation gas turbines with bio-alcohols

Abstract

The intermittency of renewable power generation means that dispatchable power sources are required to meet global energy demands. Gas turbines firing low carbon fuels, such as bio- and e-alcohols, offer flexible dispatchable power generation. Despite previous work highlighting the suitability of ethanol in lean-premixed gas turbines, the present study shows that in practice evaporated ethanol is less attractive than previously suggested due to higher than anticipated NOx emissions and higher evaporation temperatures if the fuel has significant water content. This paper introduces a “dual phase” burner concept where methanol may be fired either as a liquid or evaporated as a gas. Liquid methanol could be fired in a normal dual fuel distillate-natural gas burner with little or no modification to the liquid fuel paths/nozzles. Evaporated methanol could be fired with relatively minor modifications to the fuel gas path and nozzle. The gas turbine could be started on liquid methanol until sufficient exhaust heat was available to evaporate the methanol. Switching to evaporated methanol firing would result in an estimated 5–6% reduction in fuel consumption compared to liquid firing because of the exhaust waste heat recovery. Whilst this study demonstrates the suitability of evaporated alcohols in a particular lean-premixed gas turbine combustion system, each different combustion system must be individually evaluated.