Long profile of Dean Kamen, discusses his Stirling engine

Ben Hazell says: "Dean Kamen invented the Segway. He's also made a fortune in medical technology and now thinks he's built a working Stirling Engine - efficient electrical energy from heat. If it's true it's amazing and world changing - the breakthrough we need to face climate change. Even if it's not, he's a fascinating guy."

Now he and his engineers have built and tested a range of Stirling engines suitable for mass production that can be run on anything from jet fuel to cow dung. The one in the boot of the small blue car is designed to extend its range and constantly recharge its batteries to make a new kind of hybrid vehicle: one fit for the roads of the 21st century. A Stirling-electric hybrid, Kamen tells me, can travel farther and more efficiently than conventional electric cars; it generates enough power to run energy-hungry devices such as heaters and defrosters that are essential for drivers who, unlike those he calls the 'tofu heads' of California, must cope with a cold climate; and even using petrol, the engine runs far cleaner than petrol-electric hybrids such as Toyota's Prius.

However, Kamen confesses, his new creation isn't quite finished yet: 'The Stirling engine's not hooked up. Which really pisses me off.'

But it could work?

'It will work,' he says. 'Trust me.'

Dean Kamen: part man, part machine