The karts ran individual timed laps rather than racing directly against each other on the 550-metre (600-yard) circuit, because of the risks to car and driver from collision damage to the fuel cells.

In a fuel cell, stored hydrogen reacts with oxygen from the air to produce electricity. There are no emissions of greenhouse gases such as carbon dioxide, and the only waste product is water.

"Just getting this piece of work done is an accomplishment because it is so complicated, so difficult to build. We are so happy already. If we do win the race that's a bonus," said Sam Tippetts, project manager of Imperial College London's team. (Reporting by Tineke van der Struik; Editing by Kevin Liffey)