Harry Gray: Solar fuel cells will create fuel from sunlight

Harry Gray: This is what we call artificial photosynthesis, because natural photosynthesis uses natural materials, living materials. And artificial photosynthesis uses man-made materials. That’s the only difference.

Harry Gray, professor of chemistry at Caltech, is talking about solar fuel cells. Just as plants use sunlight to make their own energy, Gray says his solar fuel cells could one day create enough fuel from the sun to provide the energy humanity needs.

Harry Gray: Nature has already given us the example of what we must do.

In place of a leaf, Gray’s team is building a tiny solar device to capture sunlight. The energy of the sun is used to split water into hydrogen and oxygen to create hydrogen fuel. He said these solar devices could carpet rooftops or operate in middle of the ocean, connected to fuel cells that will convert the solar fuel to energy. But first, Gray said, scientists need to find a way to make it cheap.

Harry Gray: This is the challenge right now, to build a device as good as the ones we’ve already built that are extremely expensive. We need to build cheap devices, non-toxic devices, out of abundant materials.

He said these solar fuel cells are still about 20 years away. Gray believes that it will take what he calls a “solar army” of researchers to find cheap, abundant materials for the solar fuel cell device. The key element is the catalyst to split water.

Harry Gray: This is the big challenge now, is to find the world’s best catalyst to extract protons and electrons from water by controlled oxidation.

He said that hydrogen is an effective and flexible fuel.

Gray said this kind of fuel could be very similar to the type of fuel systems we have today, but renewable.

Harry Gray: It may well be that we will have solar power plants in the middle of the Pacific ocean, that will be making liquid fuel and we’ll be transporting that in with tankers, just the way we transport oil now.

Gray said that solar fuel cells could provide clean, carbon-free energy to the entire the world, including developing countries.

Harry Gray: The most important message I can give is, start thinking solar.

Our thanks today to the Camille and Henry Dreyfus Foundation