Despite oil prices that hover around $100 a barrel, it may take at least 10 years of intensive research and development to reduce the cost of solar energy to levels competitive with petroleum, according to Harry Gray, Ph.D., who spoke at the 235th national meeting of the American Chemical Society (ACS).

“Solar can potentially provide all the electricity and fuel we need to power the planet,” Gray said. “The Holy Grail of solar research is to use sunlight efficiently and directly to split water into its elemental constituents—hydrogen and oxygen—and then use the hydrogen as a clean fuel.”

This research has the goal of transforming the industrialized world from one powered by fossil fuels to one powered by sunlight. Work in the Caltech Center for Sustainable Energy Research focuses on generating electricity from sunlight and developing fuel cells.

In his talk at the ACS Presidential Symposium, Gray cited the vast potential of solar energy, noting that more energy from sunlight strikes the Earth in one hour than all energy consumed on the planet in one year.

The biggest challenge, Gray said, is reducing costs so that a large-scale shift away from coal, natural gas and other nonrenewable sources of electricity makes economic sense. Gray estimated the average cost of photovoltaic energy at 35 to 50 cents per kilowatt-hour. By comparison, other sources are considerably less expensive, with coal and natural gas hovering around 5–6 cents per kilowatt-hour.

Because of its other advantages—being clean and renewable, for instance—solar energy needs not match the cost of conventional energy sources, Gray said. According to him, the breakthrough for solar energy probably will come when scientists reduce the costs of photovoltaic energy to about 10 cents per kilowatt-hour.

“Once it reaches that level, large numbers of consumers will start to buy in, driving the per-kilowatt price down even further. I believe we are at least 10 years away from photovoltaics being competitive with more traditional forms of energy.”