Liquid fuel from solar power


In recent years, scientists and engineers have turned to biofuels—fuels generated from living things, and hence renewable—as a means of weaning us off of fossil fuels in favor of something cleaner, less likely to run out, and less wrapped up in international geopolitics.

Fermenting the sugars found in corn or other grains into ethanol has been around for a long time, of course, and it’s pretty much a proven technology. On the other hand, do we really want to be turning food into fuel?

More promising have been recent advances in turning lignocellulose, the stuff that makes up the cell walls in plants, into ethanol and other fuels: that would allow us to use grasses, wood chips, straw and other non-food as biomass.

Now comes word of a fuel-producing technology that doesn’t require biomass of any sort: just carbon dioxide and sunlight. And no, I’m not talking about trees.

On Monday, a Massachussetts company called Joule Biotechnologies announced that it has the technology to convert carbon dioxide directly into transportation fuels and chemicals. Not only that, they say, “this eco-friendly, direct-to-fuel conversion requires no agricultural land or fresh water.”

The company was founded in 2007, and relies on something it calls “Helioculture” technology, mixing, as the New York Times’s article on the announcement puts it, “CO2, Slime and Sunshine.”

More specifically, the company grows genetically engineered microorganisms in specially designed bioreactors. The microorganisms are photosynthetic, able to use energy from the sun to convert carbon dioxide and water into ethanol or hydrocarbon fuels.

The process works well in the laboratory, so the real question is if it can be scaled up to an industrial-sized plant. To find out, Joule plans to break ground on a modular pilot plant early in 2010 that will produce ethanol (trademarked as SolarEthanol), and the following year hopes to begin construction on a commercial-scale operation that can also produce hydrocarbons and associated chemicals, “several of which have already been demonstrated at laboratory scale.

It’s looking for sites near CO2 producers such as coal-fired power plants and cement kilns, with locations in Texas, Arizona, Nevada and New Mexico, places with lots of sun and lots of space, under consideration

Open spaces are needed because a large plant would look a lot like a solar array: a huge field covered with panels, except these panels, rather than producing electricity, would produce liquid fuels

The company estimates that a single acre covered with its “SolarConverter” panels (flat, transparent, and about the size of a sheet of plywood) could produce 20,000 gallons of ethanol at a cost of $50 a barrel. (That makes it competitive with oil, although it’s worth noting that that price includes existing subsidies: what the unsubsidized cost would be, I don’t know.)

At that level of production, if you built enough plants to cover, in total, an area the size of the Texas panhandle, you could meet all of the United States’ transportation fuel needs.

In Technology Review, writer Kevin Bullis notes that the company’s technology sounds similar to that of biofuels produced by algae—but the company says it is not using algae, and its stated production estimates are an order of magnitude greater than algae-based biofuels, which are estimated to have potential yields of only 2,000 to 6,000 gallons per acre.

Its estimated cost of production is also only a fraction of that of algae-based biofuels, which currently would require crude oil to rise to $800 a barrel in order to be competitive.

Besides, algae produces oils that have to be refined, whereas Joule says its microorganisms will produce ethanol or hydrocarbons directly. The Joule microorganisms also excrete the fuels, whereas algae has to be harvested and processed to extract oil.

Too good to be true? Maybe. But there are other companies in the race to develop the same kinds of technology. And with the push to reduce carbon dioxide emissions and move away from fossil fuels, that race is only going to get hotter.

So remember the name: Joule Biotechnologies.

Someday, its genetically modified critters could be cheerfully churning out the fuel that powers your car.

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