Harvard Professor of Energy Daniel G. Nocera has genetically engineered bacteria (Ralstonia eutropha) to absorb hydrogen and carbon dioxide and convert them into alcohol fuel: isopropanol, isobutanol and isopentanol. The hydrogen could come from Nocera’s previous invention, the artificial leaf. It converts sunlight ten times more efficiently than plants.
If hydrogen from the leaf can combine with CO2 to make alcohol fuel, the fuel can be used the way diesel is now. Similar to the bionic leaf, the engineered bacteria produce energy and biomass far more efficiently than plants do on their own. A one-liter reactor full of Nocera’s bacteria can capture 500 liters of atmospheric CO2 per day, he said. For every kilowatt hour of energy they produce, they’ll remove 237 liters of CO2 from the air.
However, when the alcohol is burned, CO2 will return to the air. “This isn’t solving your CO2 problem,” Nocera said, “but you’re not going to use any more stuff out of the ground.”
The leaf can make hydrogen from any water – dirty water, even urine – and CO2 is present to excess in the atmosphere, so the technology has promise as a local renewable energy source in areas that lack an electric grid. In addition, in such areas new energy sources can develop without having to compete with established industry.