A professor drove a 500-mile trip across the state of Tennessee on Nov. 1 in a car powered by hydrogen made only from water and the sun, according to the Knoxville News Sentinel.

Middle Tennessee State University professor Cliff Ricketts said that hydrogen vehicles have been around for awhile, but where the hydrogen came from is what made this trip so unusual. Most hydrogen comes from processing natural gas or coal, which creates some pollution during processing. But Ricketts' trip used hydrogen produced through electrolysis, which uses energy from the sun to create hydrogen and oxygen from water. The oxygen is vented and the hydrogen collected and stored for use, Ricketts said.

The vehicle, a Toyota Tercel, was modified to burn hydrogen. If the engine is tuned correctly, the only exhaust is water, said Ricketts, a professor of agricultural education at MTSU and an alternative fuels expert.

The car was able to carry 8.4 kilograms of hydrogen at a time, equal to 8.4 gallons, and averaged about 45 miles per gallon during the trip, he said. The car had to stop only once to refuel at MTSU in Murfreesboro during its cross-state trip.

Ricketts said he made the trip to demonstrate other alternatives that exist, which can be used to power the nation in case of a national emergency.