Duke Energy

Flue gas from Duke Energy’s East Bend plant in Kentucky provides carbon dioxide to feed algae in fuel tanks in a pilot to test carbon reduction technology. Photo: Duke Energy

Duke Energy has been hosting a project at their East Bend Power Plant in Kentucky to demonstrate an algae-based system for CO2 mitigation from coal-fired power plants. Project participants include the University of Kentucky Center for Applied Energy Research and the University of Kentucky Department of Biosystems and Agriculture Engineering.

WKRC-TV’s Josh Knight reports on Duke’s progress, not just to use algae to reduce CO2 emissions produced by coal-fired power plants, but also to study the production of biofuels and other bioproducts from the algae and demonstrate the economic feasibility of using algae to capture the CO2.

About half of the electricity produced in the United States is done at coal fired plants like the Duke Energy East Bend Station in Boone County. The gas released into the air by that process is now being trapped and used to grow algae to make other valuable products. “We’ve made jet fuel, and we’ve made renewable diesel fuel,” said Biofuels Research Engineer Michael Wilson with the University of Kentucky.

Applied Energy Research

Duke Energy’s algae photobioreactor array for carbon capture was originally developed at the University of Kentucky, and has an ultimate capacity of 40,000 gallons when fully operating at the powerplant. Photo: University of Kentucky Center for Applied Energy Research

Making new materials out of coal burning byproducts is not a recent development. Doug Durst, Technology Development Manager with Duke Energy, explained the majority of what can be seen at a power plant isn’t actually generating electricity. The coal burning and the spinning turbine are housed in one area and the rest is all environmental equipment. Over the years, as environmental laws are passed, new equipment is added that traps different chemicals.

At this plant, sulfur, ash, and mercury are no longer released into the air, but it goes one step farther. The byproducts created by capturing these chemicals can be sold and used in concrete and even drywall manufacturing. “The flue gas coming from a coal fire plant, ten percent of it is CO2,” Durst said. Nitrogen is the most abundant gas coming from the stack, and the part you can see is predominantly water vapor.

Duke’s algae are growing in clear tubes several feet tall. The gas coming out the stack is actually the same gas running through the tubes. Inside the tubes with the flue gas, the algae have all the carbon dioxide they want. “It’s a Kentucky alga, readily found in many of the waterways around here. We’re harnessing its ability to do photosynthesis very, very fast. So it’s consuming CO2 as it grows. We’ve got it in an applied nature at a pilot level and now we’re just going to be improving efficiencies,” said Wilson.

At this point, the amount of gas being diverted is miniscule, “It’s the equivalent to a leak in the duct work,” said Durst. However, they’re proving it’s possible. “They call it research for a reason, there’s a ‘re’ in research, so you’re going to (search) over and over again until you find a way that works,” Wilson said.

In order to scale all of this up, to take on all of the flue gas, it would be a much bigger operation. “We’re talking hundreds of acres, potentially square miles. That’s just a factor of how quickly the organism grows and how much CO2 is being generated,” Wilson said.

“If you look at that from a positive side, you could say that’s an awful lot of biomass we’re producing, an awful lot of final product. They can double every day. So you could potentially take a harvest out of this reactor, if the growth conditions are right, every day,” he said.

This project is still experimental, but Wilson believes that algae are the answer to reducing carbon emissions. “It can be done – but when it is done, it will be done in a big way.”