Scientists have been trying for years to find a nonfood source for ethanol. A company in Bonita Springs, Fla., Algenol Biofuels, thinks it has found one, with the added benefit of getting twice as much work out of each molecule of carbon dioxide added to the atmosphere.
The company and Dow Chemical are expected to announce on Monday that they are building a pilot plant on the site of a Dow plant in Freeport, Tex., that produces carbon dioxide as a by-product of several different processes.
The algae would be exposed to sunlight, in water mixed with carbon dioxide, and would give off ethanol and oxygen. Dow wants the ethanol as a feedstock for plastic, replacing natural gas. In that sense, the ethanol-producing algae would become another processing unit in a chemical factory.
But if the process works well, Algenol thinks it could be profitably married to a different kind of plant: a coal-burning power plant, with the oxygen going into the combustion chamber.
“Look at how much better coal-fired efficiency could be if you introduced pure oxygen into it,’’ said Paul Woods, the chief executive of Algenol. “It dramatically raises the burn temperature and the cleanliness of the coal.’’
It also simplifies the exhaust. Ordinary coal plant exhaust is mostly nitrogen, just as the air going in was mostly nitrogen. But coal burned in oxygen produces exhaust that is mostly carbon dioxide – which could go right back to the algae-growing tanks.
So a molecule of carbon dug from the ground as coal would help create electricity when burned in the coal plant, and then be incorporated into ethanol, eventually being released into the atmosphere when burned in a car — but only after having been put to work twice.
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