Techno-economic analysis of co-fired biomass integrated gasification/combined cycle systems with inclusion of economies of scale

This work focuses on short-term application of biomass integrated gasification/combined cycle (BIG/CC) technology with co-firing of natural gas and biomass derived gas. Co-firing leads to higher efficiency and lower costs of BIG/CC technology. A full technical and economic analysis was carried out by integrating performance modeling from co-fired CC and scale effects over a wide range of capacities (20–300 MWe). The gasification technology is directly air-heated and the feedstock is sugar cane residue. Co-firing alleviates the need for de-rating gas turbines, which would reduce efficiency. It also allows combined cycles to be scaled up beyond the limits imposed by single vessel gasifiers. Mixing of LCV gas and natural gas can greatly improve the cost-effectiveness of power generated by BIG/CC. The cost of electricity (COE) for biomass reaches a minimum with 50% proportion of natural gas in the mixture. For proportions of natural gas higher than 60%, the biomass-based power in a co-firing scheme may become less cost-effective than a BIG/CC. A sensitivity analysis shows that if the energy input consists of 50% biomass, the most sensitive parameters—in decreasing order—are the efficiency, the capital costs of the combined cycle, the gas cleanup equipment and the biomass fuel costs.