Techno-economic evaluation of membrane and enzymatic-absorption processes for CO2 capture from flue-gas

A large part of the global energy is supplied through fossil-fuel power plants which release a high amount of CO2 into the atmosphere. As long as this energy pattern prevails in the world, concerns about climate change due to sudden rise in the content of green-house gasses (GHGs) might be alleviated only through retrofitting the power plants to CO2 capture units. Gas separation methods such as amine-based absorption could be suggested to hit this target but they could result in a costly and highly intensive process. This study analyzes the integration of a 600 MWe power plant with two promising methods, including membrane technology and enzymatic-absorption process. A techno-economic analysis is then carried out to demonstrate the technical viability and economic efficiency of these two methods compared to traditional separation processes. It is found that the electricity losses are estimated at 95 and 89 MW respectively, to capture 90% of the CO2 which is as low as 15% of the output power. This study also presents cost optimization results including capital and operation expenditures for each method. In comparison, enzyme-based absorption is more economically attractive and results in a lower CO2 capture cost. Overall, this study allows to recognize bottlenecks in each process and then proposes initiatives to improve the capture efficiency.