Comparative techno-economic analysis of biomass fuelled combined heat and power for commercial buildings

Abstract

The technical, environmental and economic analysis of two small scale biomass fuelled CHP applications is the subject of this study. For this analysis, the process simulation software ECLIPSE is used. Modelling and simulation have been conducted over two configurations: Organic Rankine Cycle (ORC) based and biomass gasification based systems for generating heat and electricity. The nominal power outputs of both systems are given at around 150kWe. Based on the results achieved, the key technical and environmental issues have been examined. The study also investigates the impact of different biomass feedstock on the performance of CHP systems. Finally, an economic evaluation of the system is performed. According to the ECLIPSE simulation, the overall efficiencies of the ORC based CHP system are around 76% when willow chip was used and around 81% with miscanthus. The difference was found to be due to the moisture content. For the biomass gasification based CHP system, the overall efficiencies of CHP were found to be around 58% with willow chip and 64% with miscanthus. These values are better than for any other biomass-fired electricity generation technologies of similar scale. On the other hand, the results of the economic analysis demonstrated that the breakeven electricity selling price (BESP) for the ORC-CHP systems varies from 40 to 50£/MWh and for the biomass gasification based CHP systems was between 87 and 97£/MWh. These values could be further improved if agricultural or forestry wastes could be used at lower costs.