Techno-Economic Assessment of Heat Supply Systems in Woodchip Drying Bases for Wood Gasification Combined Heat and Power

Among decentralized small-scale biomass energy sources with the potential to revitalize local communities, combined heat and power (CHP) from gasification is promising in terms of its high power generation efficiency. Still, it has yet to achieve operational stability, in part due to the variation in the moisture content of the woodchips used as fuel. In this study, a technical and economic evaluation was performed to establish a center for the efficient production of high-quality dry woodchips within a sawmill and to determine the technical characteristics and economic viability of a system using gasification CHP, wood waste-fired boilers or an organic Rankine cycle (ORC) as heat sources. The results showed that the net present values (NPVs) of gasified CHP, wood waste-fired boilers and ORC were -186 million, -402 million, and -103 million JPY, respectively. None of them were deemed profitable. Therefore, a sensitivity analysis was performed to determine the impact of low-quality wood prices, dry woodchips, heavy oil A, and the grid electricity charge on the NPV. The improvement of the low-quality wood price and dry woodchips sales price was effective for heat supply by gasification CHP and ORC turbines, and their combination was effective for woodchip-fired boilers.