Let the Sunshine In

At UM, Caltech Chemist Speaks to the Potential of Solar Power

By Emily Darrell, 10-16-07

“The greatest problem in 21st century chemistry,” said Harry B. Gray during a lecture at the University of Montana Monday night “is how to make clean energy from sunlight and water.”

Gray, a professor of chemistry at the California Institute of Technology, has won many prestigious awards from the scientific community including the National Medal of Science in 1986, the Benjamin Franklin Medal in Chemistry in 2004, and six national awards from the American Chemical Society. Gray has been working for decades on developing cheap, clean, and dependable solar energy technology.

Gray said that of the five sustainable, carbon-neutral energy options—wind power, hydroelectricity, geothermal energy, biofuels, and solar power—“solar is the one we have the most hope for in the long run on this planet.”

“I say that,” Gray said, “because there’s a lot of sun.”

Chemists know that it is possible to combine sunlight and water to make clean energy, Gray said, because “cyanobacteria [a.k.a. blue-green algae] have been doing it for years.”

Gray said that to meet America’s current energy needs with solar power it would require 1.7 percent of the United States’ total land area to be taken up with solar panels. Gray said that lining America’s interstate highways with solar panels is an option that is “being discussed seriously by many people.”

“So why don’t we do it?” Gray said. “It’s the costs. It just costs too much to do solar right now.”

Currently solar power can be produced for about 25 to 50 cents for a kilowatt hour. For a kilowatt hour of gasoline the costs are between 2.3 and five cents; for coal it’s one to four cents.

Gray said the current goal of his Caltech research team, and their MIT partner team, is to bring the cost of solar energy down to 10 cents per kilowatt hour within the next year.

Cost, however, isn’t the only thing prohibiting solar power from becoming a immediately viable and widespread energy source, Gray said. Many of the chemicals currently used to convert light into usable hydrogen fuel are toxic and harmful to humans and their environment.

“We cannot solve this problem of solar conversion with toxic materials. We have to have materials that are biocompatible,” Gray said.

Gray said that The National Renewable Energy Laboratory in Golden, Colo. has developed a water-splitting solar cell that operates at 12.5 percent efficiency. (The highest possible efficiency level for a solar cell would be 18 percent, Gray said; green leaves turn water into hydrogen fuel with about one percent efficiency.)

The problem with this cell? “It costs a fortune,” Gray said, “and it’s full of toxic materials.”

Gray and his Caltech team have created a type of solar paint, that if applied to a house could supply it with all its energy needs. The main problem with the paint, however, is that it contains organic compounds that degrade rather quickly, ruining its effectiveness. “You would have to paint your house every four or five weeks,” Gray joked. “I’d be like an old dope peddler. I’d be selling it to you every month.”

Another problem? The solar paint currently only works in a limited color selection. “There are aesthetics in this field,” Gray said. 

Although Gray said he doesn’t believe that the problems with solar energy will be solved in his lifetime, he is hopeful that when today’s children are grown they will live in a world run by the power of the sun.

A fact that may be surprising to some is that much of the research of Gray and his colleagues is funded by the oil company BP. “Industry is behind us,” Gray said. “The big oil companies are not our enemies . . they see us as our future.”

Though there are some who see biofuels or nuclear power as possible solutions to our oil dependency, Gray believes that perfecting solar technology is the only real option.

“The best place to house a nuclear reactor,” Gray said, “is 93 million miles away.”

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