Techno-economic analysis of power plant via circulating fluidized-bed gasification from woodchips

Biomass has emerged in the renewable energy area with high potential to contribute to the energy needs in both the industrialized and developing countries. The objective of this study is to evaluate and compare the economic feasibility of three different configurations of a woodchips power plant based on the circulating fluidized-bed (CFB) gasification: (1) a gas engine, (2) a gas turbine, and (3) gas & steam turbines. A comprehensive model of the power plant was developed employing the process simulator, Aspen Plus. The economic feasibility was analyzed in terms of the payback period (PBP), return on investment (ROI), and discount cash flow rate of return (DCFROR). It was proposed that the power plant has an economic benefit for plant sizes of over 150 t/d of dry woodchips in all the three cases. The gas engine was a better choice for the power plant sizes smaller than 200 t/d or 22 MWe, while the gas & steam turbines had the highest benefit at big plant sizes over 200 t/d. A sensitivity analysis was performed for the 150 t/d plant to identify key variables that have a strong impact on DCFROR. The total capital investment (TCI) and plant size had a major influence on DCFROR.