An anonymous reader brings us this article from Wired about a new method to produce fuel
with the help of concentrated sunlight and carbon dioxide. The process "reverses" combustion, breaking down the CO2 into carbon monoxide, which is then used as a building block for hydrocarbons. Quoting:
"The Sandia team envisions a day when CR5s are installed in large numbers at coal-fired power plants. Each of them could reclaim 45 pounds of carbon dioxide from the air daily and produce enough carbon monoxide to make 2.5 gallons of fuel. Coupling the CR5 with CO2 reclamation and sequestration technology, which several scientists already are pursuing, could make liquid hydrocarbons a renewable fuel."