There’s been some speculation online recently about a new company called C12 Energy that’s received $4.5 million from Sequoia Capital. The president of the company is Kurt Zenz House, who, as a PhD candidate at Harvard, worked out the details of a plan to sequester carbon dioxide from the atmosphere by speeding up natural processes. These processes could counteract global warming on their own, although they’d take a long time–about 100,000 years–to do it. (The process has kept the temperature on Earth, over its long history, within a narrow band, even as the brightness of the sun has changed significantly, he says.) House’s idea is to hurry the process along using electrolysis. He published the idea in the fall of 2007, and he’s applied for a patent on the idea.

This has led to speculation that the company, which is known to be involved in carbon dioxide sequestration, was founded to commercialize this particular technology. This is something that House will not confirm, although he continues to be excited about his work at Harvard, which he’s continuing now as a research fellow (PDF) at MIT.

But this likely isn’t what C12 Energy is up to. The process faces some large obstacles to becoming a practical way to sequester significant amounts of carbon dioxide. For example, the amount of seawater that would need to be electrolytically treated would be huge–on the order of 6,000 cubic meters per second if it were to offset 15 percent of global emissions. This sort of volume is conceivable for some processes, but electrolysis is expensive. What’s more, the process would be very energy intensive and produce ozone-destroying compounds. But ultimately, the problem is that more cost-effective ways to sequester carbon dioxide already exist.

House says that these challenges could be overcome. He proposes selling by-products of the process for use in manufacturing PVC piping or cement. But David Keith, the director of the Energy and Environmental Systems Group at the University of Calgary, says that schemes relying on the sale of by-products will be hard to deploy at large scales because the markets for these products quickly become saturated.

This isn’t to say that the process doesn’t work–it does, Keith says. It’s just expensive and uses a lot of energy. “The energy cost is just deadly,” he says. There might be technical fixes to these issues, and it’s exciting that House is continuing to work on it. But for now, at least, it seems like an idea better suited to the lab than to a commercial enterprise.