Carbon capture and storage has been a political buzzword for years, even though it remains expensive and largely elusive on a commercial scale.
The first part of the equation, capturing carbon dioxide from power plants and other large emitters of carbon pollution, is the relatively easy part. The problem has been what to do with it. Injecting it underground is expensive, and turning it into fuel takes a lot of energy and often involves rare or toxic chemicals.
Researchers at the University of Delaware have taken a different approach, using an inexpensive catalyst that relies on electricity from solar energy to convert carbon dioxide (CO2) into carbon monoxide (CO) that can be used for a range of industrial applications, including liquid fuel.
Gold and silver have traditionally been used as the catalyst to convert CO2 into CO, but Joel Rosenthal, a chemist at the University of Delaware, found that the metal bismuth works just as well, if not better. “Despite its low cost, bismuth has been virtually ignored as a cathode material for CO2 electrolysis,” Rosenthal wrote in a study that appeared in the June 19 issue of the Journal of the American Chemical Society.
An ounce of bismuth is 2000 times cheaper than an ounce of gold and found in many places as a byproduct of refining lead, tin and copper, according to Rosenthal. “Most catalysts do not selectively make one compound when combined with carbon dioxide — they make a whole slew,” Rosenthal said in a press release. “Our goal was to develop a catalyst that was extremely selective in producing carbon monoxide and to power the reaction using solar energy.”
Carbon monoxide is a valuable commodity chemical, said Rosenthal. It is used to make hydrogen gas, but also in the production of synthetic petroleum, which researchers are developing across the globe.
Cheaply converting CO2 to useful products that don’t require a lot of energy is an area of active research, especially as countries look to curb carbon emissions. Although the U.S. may never have a carbon tax, President Obama’s recently unveiled climate plan included provisions for the U.S. EPA to regulate greenhouse gas emissions from existing power plants, which will only increase the interest in CO2 conversion research. Obama’s plan included $8 billion in loan guarantees for advanced fossil energy technologies, including carbon capture.
There are also many other researchers and burgeoning companies trying to find low-cost, low-energy solutions to CO2 pollution. Skyonic, a company with a technology to turn CO2 into baking soda, recently raised $128 million in venture capital. Researchers at the University of Texas at Arlington are converting CO2 to liquid methanol using copper oxide nanowires and sunlight. Researchers at the University of Georgia have created a microorganism that feeds on CO2 and can then be manipulated to make chemicals for fuels or plastics.
But for every breakthrough, there is far more work that needs to be done. University of Delaware’s Rosenthal said there are at least a dozen issues his lab needs to follow up on, which they will pursue this summer.
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