Bio-Energy Cogeneration Systems with CO2 Separation and Storage

This paper compares three different bio-energy co-generation power station concepts where CO₂ is sequestered and available for permanent storage instead of discharging into the atmosphere. The different bio-energy cogeneration systems are: The pre-combustion capture of CO₂, the post-combustion capture of CO₂ from the flue gas and the combustion in an atmosphere of pure oxygen (Graz-Cycle). The three schemes, all based on a thermal input of about 150 MW_th, are compared on the basis of their technological features, their performance, projected costs of electricity and CO₂ mitigation costs. Compared to a conventional bio-energy cogeneration system, CO₂ removal reduces net plant efficiency by 11 to 16 percentage points and increases the cost of electricity by approximately 54 to 89%. The scheme applying reforming and shift reaction and physical absorption of the syngas fuel appears the most appealing option for the short-term implementation of CO₂ sequestration bio-energy cogeneration systems. The Graz-Cycle where the syngas is burnt in pure oxygen appears the most appealing option for the long-term option for CO₂ sequestration.