A novel concept is presented to capture CO2 from a large-scale (>100 MWe) dedicated biomass-fired power plant by using CaO as the CO2 sorbent. Biomass is burnt in a circulating fluidized bed at sufficiently low temperature to allow in situ CO2 capture at atmospheric pressure. The product, CaCO3, is then calcined in an interconnected oxy-fuel combustor, or calciner, that delivers CO2 ready for subsequent purification, compression, and permanent geological storage. A detailed process analysis using Honeywell's UniSim R400 is carried out to reveal process performance and economics of the proposed power plant which is compared against biomass-air-fired and biomass-oxy-fired power plants. A heat exchanger network is designed using a pinch analysis aimed at the recovery of the maximum amount of excess heat from high temperature gas and solid streams in the plant, while the recovered heat is transferred into a subcritical steam cycle for power generation. The entire process simulation also includes a CO2 purification and compression unit that allows reaching more than 95 mol % CO2 purity. The close similarity of the system with commercial coal based CFB power plants enables us to evaluate costs of electricity and CO2 avoided in detail. This process is capable of achieving 84% overall CO2 capture efficiency with additional cost of 43 (sic)/ton CO2 avoided excluding green certificate and European Trading Scheme (ETS) CO2 incentives. If current typical values for these subsidies are included, the avoided cost can even take negative values. The biomass-air-fired plant becomes the most attractive option when only green certificates are introduced. The biomass-oxy-fired and in situ calcium looping plants largely improve their economics when ETS price for CO2 credits increases. The in situ calcium looping option becomes slightly more economical and more flexible to adapt to different market conditions affecting the economic incentives to use biomass for power generation when the biomass plant is colocated with an oxy-fired coal power plant.
- FLUIDIZED-BED CARBONATOR
- HEAT-EXCHANGER NETWORKS
- CARBONATION/CALCINATION CYCLES