Jul 07 2010

Don't Bury CO2, Recycle It

Posted by: Jonathan Marshall

Unlike frogs in a pot of boiling water, humankind has no place to jump as the earth warms. We have no choice but to find a way to turn down the greenhouse thermostat until we can phase out fossil fuels in favor of clean, renewable energy sources.

One widely discussed option is to capture the CO2 from utility and industrial flues, pipe it to a remote location, and pump it deep underground for permanent storage. Pilot projects suggest the approach can work, at least in limited scale. But critics complain about the potentially high cost, danger of leakage and the possibility of insufficient underground storage capacity.

But what if CO2 could instead be converted chemically and stored in the form of cement, liquid fuels, or other valuable materials? That could be a win for the environment and a win for the economy—if the energy required for the recycling process doesn’t defeat the purpose.

The U.S. Department of Energy yesterday announced grants to support six promising projects for converting CO2 into marketable chemicals, including substitutes for Portland cement and even methane gas, using a variety of novel catalysts and chemical reactants.

But similar research is already underway in a wide variety of laboratories:

• Singapore’s Institute of Bioengineering and Nanotechnology announced a “breakthrough” method to convert CO2 into methanol—a valuable chemical feedstock and liquid fuel that can power relatively clean vehicles—at room temperature.
• A chemist at Newcastle University announced the discovery of an aluminum-based catalyst that slashes the energy needed to turn CO2 into organic compounds called cyclic carbonates, with many industrial applications, including gasoline additives. These applications could use up to 30 million tons of CO2 annually in the UK market alone, he estimated.
• At the University of Illinois, an engineering project team is developing a novel membrane to separate CO2 from power plant flue gases, then take waste heat from the plant to convert CO2 cost-effectively into methane, methanol or carbon monoxide. “The energy produced from the fuel cell using any one of these three fuels could then be used to supply additional electricity to the power plant, thereby creating a near zero-loss power cycle,” the team notes.
• Many researchers are also exploring the use of bioenegineered algae to absorb carbon dioxide and produce molecules that can in turn be synthesized into biofuels. So far their success has been limited. Another promising biological process, pioneered by a UCLA engineer, is the use of genetically modified bacteria to produce liquid isobutanol fuel from CO2.

Exciting as these announcements appear to be, it’s worth heeding the words of John Sheehan, former head of the National Renewable Energy Laboratory’s (now defunct) algae research program.

“There aren’t any silver bullets,” he said. “The energy problem is the most fundamental, most difficult challenge we have faced for a long time. After 150 years of punching a hole in the ground and getting fuel to come out as a liquid, it is not going to be easy.”

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