Scientists use sunlight to make liquid fuel

Researchers have extracted isopropanol fuel from genetically engineered bacteria and solar-powered catalysts.

Someday soon, we could be filling the gas tank with some help from the sun and some bacteria. Harvard researchers have developed a method to turn solar power into liquid fuel.

The first step involves using a solar panel to drive a chemical reaction. The panel powers a special catalyst that reacts in water to separate it into hydrogen and oxygen.

Harvard researcher Daniel Nocera created just such a catalyst — which he calls the artificial leaf — a few years ago.

One problem, he told National Geographic, “it makes hydrogen. You guys,” meaning us average fuel-using consumers, “don’t have an infrastructure to use hydrogen.”

Now Nocera and a team of researchers at Harvard University have engineered bacteria to convert the hydrogen into isopropanol.

That’s rubbing alcohol, basically. It’s a household solvent, and it’s added to gasoline to keep it from getting diluted by water in the gas tank.

And the researchers say it’s also a step closer to something consumers could use someday. “This is a proof of concept that you can have a way of harvesting solar energy and storing it in the form of a liquid fuel.”

But for now, it still doesn’t have the infrastructure it needs to be a viable alternative fuel. And some critics don’t think it’s addressing the real issue. CBS quotes Stephen Mayfield, director of the California Center for Algae Biotechnology:

“Our problem is not that we have too much H2 and O2 sitting around generated by PV cells that we need to convert it to liquid fuels. Our problem is that fossil fuels were cheap so we burned a boat load of them and now we have problems with our climate.”

Nocera, for his part, is undaunted. He told CBS, “If we used his argument, we would stop working on renewables.”

In less than two years Nocera and his team have equalled the efficiency of photosynthesis in plants, which converts about 1 percent of available sunlight to usable energy. Their goal is 5 percent efficiency.

They have published their latest findings in the Proceedings of the National Academy of Sciences.

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