Newswise — Hybrid automobiles could be made even more environmentally friendly by the addition of solar cells embedded in the cars' body panels.

So says Steven Letendre, associate professor of business, economics and the environment at Green Mountain College in Poultney, Vermont.

"If the 200 million cars in the United States had 500 watts of solar cells integrated into their body panels, it would represent roughly one-seventh of the total installed generating capacity in the United States," he says.

Letendre, Richard Perez of SUNY-Albany and Christy Herig, formerly of the National Renewable Energy Laboratory in Golden, CO, and now an independent consultant, have written a paper about "vehicle integrated photovoltaic technology" (VIPV).

With an estimated additional $1,500 cost onto the price of a car, they say, solar cells could be embedded into panels exposed to sunlight such as the hood, roof and possibly the trunk depending on a car's design.

"This would allow a hybrid vehicle to be partially powered using solar energy," says Letendre. Hybrid cars use both an internal combustion engine and electric motor to power the vehicle.

Obviously, the sunnier the clime, the greater the contribution that solar cells could make toward fuel efficiency. Letendre estimates that in the nation's sunniest regions, a hybrid car equipped with 500 watts of solar cells embedded in the body panels could generate up to 1,051 kilowatts of energy per year, and account for about 5,100 miles traveled -- one-third of annual miles traveled-assuming an average yearly mileage of 15,000. In a very cloudy area, it might only account for 850 of the miles driven in a year.

He admits that the annual fuel cost savings from the VIPV system "would be rather marginal." Even with gas now well over $2.00 per gallon it would take more than five years, on average, for a VIPV car to payback from avoided fuels costs, he estimates.

"But having a solar fuel option reduces the risks associated with possible fuel shortages and price spikes," he notes. "Even if gasoline supplies were eliminated, a VIPV car owner could still maintain some degree of mobility." For that reason, he thinks the military might find the concept appealing.

"In addition, environmentally conscious consumers interested in hybrids may find having a solar option an attractive feature."

Alternatives to oil and gasoline only become news, Letendre knows, when gas prices spike and fuel supplies become uncertain.

"Cars and trucks account for one-third of all energy consumed in the United States," he points out, "and over two-thirds of all petroleum. The U.S. now imports a record 55 percent of its oil and many of the oil-rich nations are subject to political and social unrest, creating the potential for price and supply risks."

Dependence on oil also creates environmental problems because "vehicle engines produce pollutants that cause serious health and eco-system problems."

Since hybrid electric technology is now commercially available to consumers, Letendre says that VIPV vehicles "could offer a near-term opportunity for solar cells to potentially provide 25 percent of the energy requirements for personal transportation."

If you would like to see the paper by Letendre, Perez and Herig titled "Vehicle Integrated PV: A Clean and Secure Fuel for Hybrid Electric Vehicles," which was first presented in June 2003 at the annual meeting of the American Solar Energy Society in Austin, TX, please let me know and I'll send it to you.