A Novel Use for Captured CO2 from Flue Gas at Coal-Fired Power Plants

Fossil fuels are valuable for electricity generation, transportation energy, and plastics production. However, they are a finite resource. The use of algae to produce biofuels for energy production has been proposed to alleviate some of the dependence on this limited resource. But, current algal growth methods are too costly to compete with the fossil fuels industry.

Researchers at ISTC are working on improving algal growth rates by growing it in municipal wastewater combined with captured carbon dioxide (CO2) from coal-fired power plant flue gas. Algae require nutrients and carbon dioxide to grow. Municipal wastewater can be used to feed algae because it contains high nutrient concentrations that must be removed before the water is sanitized and released. Traditional nutrient removal processes involve a series of biological and chemical methods. If the nutrients are used to grow algae, then the costs of removing those nutrients go down. In addition, algae growers do not need to purchase nutrient products to enhance the growth of the algae.

Similar to other plants, algae utilize CO2 to convert sunlight into energy that the plant can use along with the nutrients to grow, a process called photosynthesis. Algae grow and can uptake CO2 faster than any other photosynthetic crop, which gives it a lower environmental footprint than the other crops. Therefore, feeding captured CO2 from coal-fired power plants into the algal growth tanks can give an additional boost to their growth rates. In addition, the captured CO2 will be used to create algae that can then be converted into a new energy product. Coal-fired power plants could potentially reduce their carbon emissions with this method of utilizing CO2. Furthermore, using these waste products (nutrients in wastewater and captured CO2) to grow algae could make the algal biofuels cost competitive or even lower than fossil fuels.

This project is in collaboration with Helios-NRG, LLC and is funded by the Department of Energy. Results from this study are expected in Fall 2020.