Algae CO2 Capture at the University of Kentucky: Part 1

Algae CO2 Capture at the University of Kentucky: Part 1

December 4, 2019 41 By Kody Olson


VO: More than 90 percent of Kentucky’s power
comes from coal. With federally mandated CO2 limits on the horizon, work under way at the
University of Kentucky Center for Applied Energy Research is more critical than ever.
CAER is developing green technology to capture CO2 emissions from coal-fired power plants. Jack Groppo: The industry will adapt technology,
which right now doesn’t exist, so that’s our challenge, is realistically what type of technologies
can we be working on in order to help the industry have something to adapt in the future? VO: One of CAER’s technologies uses chemical
solvents to capture the CO2 from emissions. Another technology isolates CO2 by combusting
the fuel with only oxygen. Jack Groppo: Once we have captured the CO2,
we have to do something with it. Right now the only feasible option is to pump it underground
into geologic formations, of which we in Kentucky do have some but if you look at other major
coal areas, they don’t have the geologic formations, it’s not an option for them. VO: Four years ago, CAER and UK’s Biosystems
& Ag Engineering Department set out to prove that an algae-based system could recycle the
CO2 in flue gas. With $1.8 million in funding from the Kentucky
Energy and Environment Cabinet, CAER is now partnering with Duke Energy to test a pilot-scale
algae system at East Bend Station. Jack Groppo: The nice thing about the algae
is that it actually does capture and sequester the CO2. Michael Wilson: The heart of our process is
the photobioreactor. And it’s a fancy word for a place to grow algae. And if you look
at the word and break it down you’ve got “bioreactor” which means you are using a living organism
to do a job for you and you’ve got “photo” meaning light. We are harnessing algae’s ability to grow
very fast and perform photosynthesis in order to take the carbon dioxide in flue gas and
turn it into biomass. VO: Instead of acres of ponds, CAER’s strategy
is based on a closed system of photobioreactors to grow algae. Jack Groppo: We have the ability to eliminate
evaporation because we have an enclosed system. We have a way to minimize contamination because
we don’t have ducks landing in our tubes. Having a closed system, it actually offers
a lot of advantages, particularly from a weather point of view. Even in the cold of winter,
even in the limited sunshine that we had, the algae did grow. The algae that we’re using is a native species,
it’s here for a reason, it likes this environment. The challenge for us has been to develop a
photobioreactor that would be expandable, and that would scale up in a cost-effective
manner. So the target price was $1 per liter of photosynthetic volume and that’s where
we are. VO: CAER’s system, made of plastic mailing
tubes and off-the-shelf PVC pipes, is built by UK students and glued together on-site.
Expanding the system simply means adding more tubes. Michael Wilson: I think they might be to close
together at this point. Where these are getting shaded by the rest. So looking at tube spacing
and making most efficient use of capital will be another major effort as we move forward. Jack Groppo: We’re located on the east side
of the power plant with southern exposure to maximize the allowable. We have installed
a 5,000-gallon feed tank with 2 centrifugal pumps. Mike Wilson: that main tank services as the
hub, that’s where we add our CO2, that’s where we add our nutrients, that’s where we return
our water. VO: Algae comes out of the photobioreactors
and it goes into the harvest tank. In a few hours, thanks to flocculation that helps the
algae stick together, it settles to the bottom of the tank. Jack Groppo: It’s a very dark green and the
consistency of pesto. That material is what we would feed to an anaerobic digester. VO: The anaerobic digester can turn the algae
into methane that the power plant could burn for fuel. Or, using gravity filtration, wet lipid extraction,
and upgrading you can make renewable diesel and jet fuel. Or, by removing more moisture with a solar
drier and dry lipid extraction, you can make jet fuel or produce fish food and animal feed. Jack Groppo: We have to work in the realm
of feasible economics, from a biofuels processing point of view, it makes sense. It is not extremely
profitable, but when you look at what’s happened you have actually captured CO2 from a dilute
stream and turned it into a value-added product. We certainly have the ability to develop the
technology to do this and I think we’re well on our way right now. We will bring back very large volumes of dewatered
algae so we can keep the chemists supplied for years. They can’t do what they want to
do unless they have a large quantity of algae and that’s something we have the ability to
produce at East Bend. Mike Wilson: we’re actually doing this, we’ve
seeded a reactor, we’ve grown algae off flue gas, we’re looking at expanding the facility
and really proving the kinetics and the economics of it and it’s all in mind with, “what happens
next?”, “where do we take this next?”