Opportunities for Fast Pyrolysis in Small-Scale Electricity Generation

Abstract

Various systems have been suggested for the generation of electricity from biomass that aim to improve on the low efficiency, capital intensive steam turbine cycles that are currently used. While the integrated gasification combined cycle (IGCC) system using gas turbines has been favoured at large scale (above 30 MWe), diesel engine systems are more suitable at smaller scales because their investment costs and efficiencies are less sensitive to scale. Diesel engines could be driven by liquids produced in fast pyrolysis, a technology that is rapidly gaining acceptance as a means of producing high yields of a liquid fuel. Models have been developed that calculate the costs of producing electricity from biomass via fast pyrolysis and diesel engines. It is expected that such systems would compete with atmospheric gasification and diesel engine systems and these systems have also been evaluated for comparison. Initial analyses have shown that electricity production costs are very similar for the two systems where the conversion (fast pyrolysis or gasification) stage is directly connected to the generating stage. However, fast pyrolysis may be de-coupled from the generator and this could give pyrolysis an advantage over gasification. Three de-coupling options are assessed in this paper to evaluate how de-coupling could be used to improve the economics of fast pyrolysis and hence increase the opportunities for its application in small-scale electricity generation.