Gasification of biomass and residues for electricity production

The technical feasibility and the economic and environmental performance of atmospheric gasification of biomass wastes and residues integrated with a combined cycle for electricity production are investigated for Dutch conditions. The system selected for study is an atmospheric circulating fluidized bed gasifier-combined cycle (ACFBCC) plant based on the General Electric LM 2500 gas turbine and atmospheric gasification technology, including flue gas drying and low-temperature gas cleaning (similar to the Termiska Processer AB process). The performance of the system is assessed for clean wood, verge grass, organic domestic waste, demolition wood and a wood-sludge mixture as fuel input. System calculations are performed with an ASPENplus model. The composition of the fuel gas was derived by laboratory-scale fuel reactivity tests and subsequent model calculations. The net calculated efficiencies for electricity production are 35.4–40.3% (LHV) for the fuels studied, with potential for further improvement. Estimated investment costs, based on vendor quotes, for a fully commercial plant are 1500–2300 ECU per kWe installed. Electricity production costs, including logistics and in some cases negative fuel price, vary between minus 6.7 and 8.5 ECUct/kWh. Negative fuel costs are obtained if current costs for waste treatment can serve as income to the facility. Environmental performance is expected to meet strict standards for waste incineration in the Netherlands. The system seems flexible enough to process a wide variety of fuels. The kWh costs are very sensitive to the system efficiency but only slightly sensitive to transport distance; this is an argument in favour of large power-scale plants. As a waste treatment option the concept seems very promising. There seem to be no fundamental technical and economic barriers that can hamper implementation of this technology.