A new coolant system that uses hydrogen instead of Freon could replace conventional car air-conditioning that releases substances destroying the earth's protective ozone layer, a scientist said Sunday.

The system is propelled by the car's own exhaust heat and uses a pair of special hydrogen-containing metal alloys called hydrides to create cool temperatures, its inventor, Carnegie Mellon University researcher Edward Wallace, said.The device, which is still in its prototype stage, could eliminate the need for Freon-based air-conditioners in cars, which Wallace said are largely responsible for the rapid depletion of ozone in upper parts of the earth's atmosphere.

Ozone is found in the stratosphere, about 30 miles above the earth's surface, and blocks out many of the sun's ultraviolet rays. Without ozone, too much ultraviolet radiation would reach the earth.