A study published today in the journal Science details how researchers at UCLA have succeeded in converting carbon dioxide into liquid fuel. Things gets a bit technical from here, so I'll give the summary upfront: A team at the Henry Samueli School of Engineering and Applied Science at UCLA created a microbe that, when used in a reaction involving CO2 as the only source of carbon and using electricity as the sole energy source, produces a liquid that might be able to power a motor.
"The current way to store electricity is with lithium ion batteries, in which the density is low, but when you store it in liquid fuel, the density could actually be very high," said James Liao, UCLA's Ralph M. Parsons Foundation Chair in Chemical Engineering and team leader for this research. "In addition, we have the potential to use electricity as transportation fuel without needing to change current infrastructure."
The team calls the lithoautotrophic microorganism that they genetically engineered 'Ralstonia eutropha H16'. A lithoautotrophic organism can generate energy using compounds found in minerals. Using carbon dioxide (of which the Earth has an ever-growing abundance) and electricity, the team's microbes convert the CO2 into isobutanol and 3-methyl-1-butanol. Isobutanol is a flammable solvent that has many industrial applications and 3-methyl-1-butanol is an amyl alcohol that, when heated, breaks down into the hydrocarbons acetylene, ethylene, and propylene. The process uses formic acid produced by the electricity as the intermediary in the reaction.
This entire process is based on photosynthesis (the process plants use to convert light to chemical energy), but with a twist. Normal photosynthesis takes place in two stages, a light stage and a dark stage. The light stage reaction, which must take place in light, converts light to chemical energy. The dark reaction doesn't need light and converts CO2 to sugar.
"We've been able to separate the light reaction from the dark reaction and instead of using biological photosynthesis, we are using solar panels to convert the sunlight to electrical energy, then to a chemical intermediate, and using that to power carbon dioxide fixation to produce the fuel," Liao said. "This method could be more efficient than the biological system."
Where plants need acres of agricultural land, Liao says his his method just needs solar panels, which could be placed in deserts or on rooftops.