Development of an Algae-based System for CO2 Mitigation from Coal-fired Power Plants - Year 3

Atmospheric carbon dioxide levels have risen since the industrial revolution due to the increase in fossil fuel combustion. These elevated levels of CO2 have been cited as a significant cause of climate change. Hence, there is a well motivated need to find ways of curbing CO2 emissions to the atmosphere, such that even when burning fossil fuels such as coal, the process is closer to being carbon neutral. One avenue for controlling the CO2 concentration in the atmosphere involves CO2 capture and long term storage underground. Another avenue involves using plant based organisms to utilize CO2 by conversion to biomass. In the latter approach, there is the potential to obtain valuable co-products at the end of the process. Hence, this CO2 mitigation strategy is an attractive option for Kentucky. This project seeks to investigate and demonstrate the potential of using waste CO2 and heat from a coalfired power plant to cultivate algae, which could then be processed into value added products. While the mitigation of CO2 emissions from coal-fired power plants forms the main focus of the project, in order to determine the most economically favorable strategy the production of biofuels or bioproducts from the algae will also be investigated. Microalgae, microscopic photosynthetic organisms that grow in salt or fresh water, are fast growing autotrophic plants that require CO2 as a nutrient. Microalgae can grow with just atmospheric CO2, 0.03- 0.06%, but are known to thrive at higher CO2 levels, up to 15-40%. Considering the CO2 level in flue gas is typically in the range 12-14% by volume, microalgae show potential as an avenue for CO2 mitigation (Wang et al, 2008). In addition, it has been estimated that microalgae could produce approximately 5,000-15,000 gallons of oil per acre per year (Table 1). This follows from the fact that microalgae have the ability to capture solar energy with efficiencies 10 to 50 times greater than other land based crops (Wang et al, 2008).