Start-up GreenFuel uses 3-meter-high tubes to mix algae with sunlight, water and carbon-carrying emissions from power plants to create biodiesel fuel.

Credit: GreenFuel

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The algae system is being put to the test with the help of MIT and an energy utility in the southwestern United States.

Credit: GreenFuel

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GreenFuel isn't alone in its work on biodiesel. Others include the Virginia Biodiesel Refinery, which President Bush visited on May 16.

Credit: White House photo by Eric Draper

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While GreenFuel's biodiesel is intended for use in power plants, other companies are producing plant-based fuel for cars, as at this filling station in Toronto.

Credit: Zuma Press

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Bloomington, Ind., uses the biodiesel fuel B20 in some vehicles in its public transportation fleet.

Credit: National Biodiesel Board

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