LEXINGTON — Researchers from the University of Kentucky Center for Applied Energy Research (CAER) last week demonstrated a system that uses algae to absorb carbon dioxide emissions at Duke Energy’s East Bend power station in Northern Kentucky.
Duke invited the scientists to present their work to a small group of special guests, including representatives from the Cincinnati Enquirer and radio station WUKY. The pilot-scale system, built with $1.8 million in funding from the Kentucky Energy and Environment Cabinet and UK with in-kind contributions from Duke Energy, is the only one of its kind currently operating in a “real-world” setting at a coal-fired power plant.
“UK has been a great partner to work with on this project,” said Duke Energy’s Emerging Technology Senior Project Manager Doug Durst. “This pilot-scale system provides Duke Energy with actual results from the algae cultivation, using flue gas from our coal-fired unit as the carbon dioxide source, while UK works on lowering the costs for a possible future larger-scale demonstration.”
Representing UK at the event were project coinvestigator Mark Crocker, CAER associate director in biofuels and environmental catalysis, CAER Research Program Manager Jack Groppo, research engineer Mike Wilson and researcher Stephanie Graham.
The system works by pumping carbon-dioxide-rich flue gas into a tank full of liquid medium containing tiny, single-celled, plantlike organisms called microalgae. While taking up the carbon dioxide, the algae circulates through a “photobioreactor” — a long course of clear plastic tubes — to absorb sunlight, after which it is returned to the tank and the entire process repeats.
The algae uses carbon dioxide and sunlight for photosynthesis to create the energy it needs to grow, which — in the enriched environment of the photobioreactor — it does very rapidly. Algae biomass is harvested from the system at regular intervals, after which it is dried and formed into sheets. Algae grown in this manner could potentially be used to make a variety of products, such as renewable diesel fuel.
“We talk about carbon dioxide as ‘pollution,’ but it’s also plant food,” Groppo said. “Algae not only does a great job of capturing and sequestering carbon dioxide, but it also gives us a useful raw material.”
That’s key, researchers say, because the value created by converting flue gas to biomass can help to offset the costs of the carbon capture technology. At a certain scale, it could even prove profitable. The pilot-scale photobioreactor occupies less than 1,000 square feet and contains 23,000 liters (roughly 6,000 gallons) of medium in an array of 8-foot-tall tubes. A full-scale system might occupy as much as 100 acres.