Hydrogen fuel cells might not be as environmentally friendly as many believe, according to the results of new research in the United States.

Researchers at the California Institute of Technology say the new technology could lead to greater destruction of the ozone layer that protects Earth from cancer-causing ultraviolet rays.

If hydrogen replaced fossil fuels, 10-20 per cent could be expected to leak from pipelines, storage facilities, processing plants and fuel cells.

Because hydrogen readily travels skyward, researchers estimate its increased use could triple the number of hydrogen molecules (man-made and from natural sources) going into the stratosphere

It would then oxidize and form water, resulting in cooling of the lower stratosphere and the disturbance of ozone chemistry