Sustainable Energy

A Cheaper Way to Catch CO2

Genetically engineered enzymes are the key to a new carbon-capture method.

Jul 23, 2010

Adding carbon-capture technology to a conventional coal plant can nearly double the price of the electricity it produces. This fact represents one of the big obstacles to passing legislation to regulate carbon-dioxide emissions. Now researchers at Codexis, based in Redwood City, CA, are using genetically engineered enzymes to make carbon-dioxide capture less expensive–their method could increase electricity costs by less than a third.

Gene machine: A Codexis researcher operates a high-volume liquid-handling system used to make gene variants–part of a process for engineering new enzymes.


The standard way to capture CO2 is to use a solvent called monoethanolamine (MEA). Carbon dioxide is absorbed by the solvent, which separates it from the other flue gases. To store the carbon dioxide it has to be freed by applying heat–this produces a pure stream of carbon dioxide that can be compressed and permanently sequestered. The energy required to do this decreases the power output of a coal plant by about 30 percent. Combined with the extra equipment and materials needed to capture the CO2, this increases the cost of the electricity produced by roughly 80 percent. Codexis’s approach could limit this cost increase to 35 percent or less, says James Lalonde, the company’s vice president of biochemistry and engineering R&D.



The company has successfully engineered enzymes for drug development in the past. It has won two “green technology” awards from the U.S. Environmental Protection Agency for developing enzymes for making two drugs–atorvastatin, the active ingredient in the cholesterol-lowering drug Lipitor, and sitagliptin, the active ingredient in the diabetes drug Januvia. The enzymes simplified drug synthesis and reduced waste.

Codexis uses a proprietary version of directed evolution. In its simplest form, directed evolution involves making random changes to existing genes. These mutations alter one amino acid in the enzyme at a time. The genes that work best are then selected and changed to further increase performance. Codexis’s researchers have developed a faster version of the process that involves swapping relatively large segments of the gene sequence–making multiple changes to amino acids each time. They’ve also developed computational techniques that allow them to determine what parts of the gene are most likely to lead to improvements in performance if they are modified. The changes make the process more efficient, and lead to big changes in performance in a relatively short amount of time.

“Codexis’s technology has certainly proven itself quite powerful,” says Stefan Lutz, associate professor of biomolecular chemistry at Emory University. He cautions that it may be more difficult to work with carbon dioxide than with pharmaceuticals. “If they do succeed, it would be a huge deal,” he says.