Technoeconomic Analysis of Microalgae Cofiring Process for Fossil Fuel-Fired Power Plants

Abstract

The concept of cofiring (algal biomass burned together with coal or natural gas in existing utility power boilers) includes the utilization of CO2 from power plant for algal biomass culture and oxycombustion of using oxygen generated by biomass to enhance the combustion efficiency. As it reduces CO2 emission by recycling it and uses less fossil fuel, there are concomitant benefits of reduced greenhouse gas (GHG) emissions. The by-products (oxygen) of microalgal biomass can be mixed with air or recycled flue gas prior to combustion, which will have the benefits of lower nitrogen oxide concentration in flue gas, higher efficiency of combustion, and not too high temperature (avoided by available construction materials) resulting from coal combustion in pure oxygen. A technoeconomic analysis of microalgae cofiring process for fossil fuel-fired power plants is studied. A process with closed photobioreactor and artificial illumination is evaluated for microalgae cultivation, due to its simplicity with less influence from climate variations. The results from this process would contribute to further estimation of process performance and investment. Two case studies show that there are average savings about $0.264 million/MW/yr and $0.203 million/MW/yr for coal-fired and natural gas-fired power plants, respectively. These cost savings are economically attractive and demonstrate the promise of microalgae technology for reducing GHG emission from fossil fuel-fired power plants.