Scottish Greens are urging the Scottish Executive to take hydrogen seriously as the clean transport fuel of the future.

The party's energy spokeswoman, Shiona Baird, believes ministerial support is needed to ensure Scotland is a world leader in the development of hydrogen technology.

The north-east MSP's challenge to ministers to show where they stand on the issue comes as a new attempt will be made to set the fuel-efficiency record by a Scottish-designed and built hydrogen-powered car at the Grampian Transport Museum in Alford tomorrow.

The only emission from the dolphin-shaped BOC Gh2ost is water. The car is expected to need the equivalent of two gallons of petrol to circumnavigate the world using 25watts of power.

Aberdeen company siGEN is supplying the fuel-cell technology that enables the car to run on hydrogen.

The designers hope to beat the world record of 10,705 miles per gallon, set at Rockingham Motor Speedway in Corby last year.

Ms Baird said hydrogen has the potential to provide a clean replacement to petrol when oil supplies run low.

"Hydrogen has immense potential as a transport fuel for the future, and when it is generated from renewable energy sources it is almost pollution-free," she said. "Global oil supplies are now in decline, and we must create new opportunities and solutions for Scotland post-oil.

"Thanks to the pioneering work of some small Scottish companies, like siGEN, we are well-placed to be among the leaders in developing new hydrogen technology and I believe the Scottish Executive needs to think strategically about how to maintain that lead.".