The potential of sustainable algal biofuel production using CO2 from thermal power plant in India

Thermal power plants in India emit around 500 Mt of CO2 annually. All of it is released into the atmosphere untreated. Microalgae, a third generation feedstock for bio-fuel emerges as a viable option for partly sequestering the emissions. Moreover, its carbon capture capacity of 4.8 kg CO2/kg biomass, which is very much as compared to terrestrial substitutes like Jhatropa curcas, enables to produce bio fuel hence adding value to the entire process. This paper intends to build upon this idea and come up with strategies to integrate bio fuel production and CO2 sequestration with the existing thermal power plants. The raw materials needed for algal growth are available in the plant as elaborated in the paper. Thus the bio fuel produced can be routed back to power the plant consequently lowering the dependence on coal. This would help in putting a check on the carbon emissions thus making the existing systems more environmentally benign and suitable for long haul. This paper reviews currently employed carbon capture technologies and methods and comes up with a strategy to subsume carbon capture through microalgae with power plants of a certain capacity. 3 t/day is taken as the basis for calculations in the proposed flow sheet. An alternative of the above is also provided which substitutes the biofuel production with co-firing. This escalates the nitrogen content of flue gas but deescalates the investment. This brings down the capital investment in the plant but enhances N2 content of flue gas. Carbon leakage is accounted for in a table of atomic balance. It takes care of input and output of carbon. The paper is inclined towards the conclusion that the Microalgae possess incredible potential and if tapped efficaciously could prove to be extremely helpful in these days of power and environmental crisis.