The performance and economics of power from biomass

The paper presents the results of performance and economic evaluations of advanced biomass power production technologies. The work was carried out as part of the International Energy Agency (IEA) Bioenergy. Models were used to determine performance and to evaluate the cost of new concepts. The modelling tools employed were AspenPlus and GateCycle. The economic models were developed by the IEA working group. Several plant configurations based on gasification and pyrolysis processes with diesel engines, gas turbines and steam turbines were analysed at capacities from 5 to 60 MWe. The study included both technical sensitivities (gasification pressure, dryer type, feed moisture, co-generation of heat, etc.) and economic sensitivities.Compared to conventional steam cycle power plants, the new systems generally have higher efficiencies (especially combined-cycle based on pressurised gasification, IGCC). The IGCC concepts have potential of becoming an attractive alternative at capacities higher than 30–50 MWe. In smaller scale, gas engines using gasification fuel gas have a relatively high efficiency, but still a high specific investment. The steam injected gas turbine (STIG) cycles analysed did not appear competitive. Pyrolysis systems generally have a lower overall efficiency than gasification systems. However, there is potential for reducing the cost of pyrolysis oil production further. Diesel power plants using pyrolysis oil in peak load and especially in intermittent operation for electricity production appear interesting.Biomass is often more expensive than fossil fuels. Consequently present commercial applications are generally limited to special cases where biomass residues are available, or when combined-heat and power production is viable. It is difficult to commercialise biomass technologies in larger scale (for example IGCC) in spite of favourable economics, due to the large scale needed for demonstration. It results in a large investment, and a high risk for developers. Development of power production based on pyrolysis systems may be feasible, as it appears viable in small niche projects