TUSCALOOSA, Ala. (AP) — A Colorado company has licensed a method of capturing carbon dioxide pioneered by a University of Alabama assistant professor, with the hope of developing the method as a more energy-efficient way of reducing emissions at fossil-fuel power plants.
ION Engineering in Boulder, Colo., has licensed a carbon-capture process using imidazole solutions, or solvents, developed by Jason Bara, an assistant professor of chemical and biological engineering at UA. The clean energy company funded Bara's early work on a more energy-efficient solution through a sponsored research agreement, according to CEO Buz Brown.
Bara started working with solvents and carbon capture as a doctoral student at the University of Colorado at Boulder, but said he did not begin working with imidazole, a commercially available organic compound, until after arriving at Alabama in 2010.
"The imidazole stuff just kind of clicked when I was at UA," he said. "It's been under my nose the whole time. And it never clicked."
Alabama was granted a patent by the U.S. Patent and Trademark Office on Aug. 13, based on Bara's work on imidazolium-based solutions for capturing carbon dioxide.
What makes the imidazole solution attractive is its potential to be a more efficient method of carbon capture that uses less energy than alternatives, according to Brown.
"As a company, it is our intent to find the most efficient, the most economical carbon-capture process available so that we can facilitate the bridge between fossil fuels and less carbon-intensive fuels," Brown said.
Bara and Brown said carbon capture is a technology in its trial phases as developers work to make it viable on a commercial scale.
"The challenge is power plants are very big, and to scale this up, there are several scales sizes that are typically gone through to validate the technology to make sure it's effective and safe," Brown said, adding that ION Engineering's system still had about two scales of operation to go before the company would know if it's commercially viable.
At a commercial scale, the cost of carbon capture remains the biggest challenge, according to Bara.
"Essentially, what you do when you capture carbon dioxide is steal energy from the power plant," Bara said.
Instead of the energy being sold as electricity on the grid, it is used in the process to capture carbon dioxide. It is an expense Brown and Bara speculate could be passed on to customers as power plant operators try to cover the cost.
Brown said alternatives to imidazole solvents such as aqueous amine solutions, a well-established process for removing carbon dioxide from natural gas, work but are costly to operate at the scale of a power plant.
Amines are organic compounds derived from ammonia.
The aqueous amine solutions, which are a mixture of water and amine, are energy intensive because they requires boiling to separate the captured carbon dioxide from the solution.
Bara's research involves combining imidazoles, which have a lower boiling point than water, with amines to create a solvent.
"Essentially, you are just not expending energy boiling water," Bara said. "If you can find a solvent that has a higher boiling point, you don't spend that energy."
In his process, Bara said the imidazole solution is added at the top of an absorption column, a tall cylinder, while the emissions from a plant are added at the bottom. As the gas rises and the liquid descends, the carbon dioxide is extracted from the gas, Bara said.
By the time the liquid reaches the bottom of the column, it is loaded with carbon dioxide. The solvent is sent to a regeneration column, where the carbon dioxide is cooked off and captured and the recycled solvent is sent back to the absorption column.
The captured carbon dioxide is usually compressed and can be stored underground or shipped off for use in other industrial applications, Bara said.
Bara said the imidazole may be more expensive on the front end than solutions using water, but it could potentially mean significant long-term savings.
"It's a significant decrease in energy," Bara said.
Brown said scale tests so far show about a 50 percent savings compared to aqueous amine systems.
"That is a very good result at this stage," Brown said.