Steam cleaner

A UK company has developed a hybrid steam and petrol system that re-uses fuel energy from internal combustion engines that would normally be wasted. The technology is expected to cut emissions and achieve 30 to 40 per cent fuel savings.

The developer,

, estimates that 36 per cent of fuel energy in a typical internal combustion engine is lost via the exhaust pipe in the form of heat. A similar amount is dissipated by the cooling system. Clean Power's system captures the lost energy from the exhaust and uses it to heat steam that is later injected into the engine.

The company did this by converting two Mazda RX8 rotary engines, which do not have piston strokes. Mike Burns, the developer of Clean Power's heat-recovery unit, said this kind of engine is perfect for a hybrid steam and petrol system.

'The rotary engine is an ideal steam expander engine,' he said. 'It also produces a lot of energy for the amount of fuel it burns.'

The Clean Power engines maintain the normal combustion chamber of an internal combustion engine, but steam accumulators that heat steam to an extremely high temperature are added to the system.

Steam is injected through valves into the engine in a closed loop, and then returned to the accumulators so the system does not lose steam or need to be refilled.

The petrol is combusted through a normal process and waste products come out of the exhaust pipe in the usual way, but the designers said that when the engine runs on steam, emissions will be eliminated.

Many people might associate steam with mechanical 19th-century technology, but Clean Power's hybrid system relies heavily on electronics as well. An engine-management system controls the entire heat-recovery and steam injection process. Another engine-management system controls the use of petrol and vapour in the engine.

Clean Power is not ready to reveal exactly how the heat recovery unit works, but Burns said it recovers heat energy from the exhaust through the same technology used in a modern coal-burning heat-generation system.

The company aims to license its technology to any interested party. Since every car engine is configured differently, companies will have to decide how they want to place the steam accumulator and steam valves within their vehicles' engine compartments. 'If you were going to mass-produce a vehicle with our technology you would end up with completely different vehicle architecture,' said Burns.

Some might wonder how steam accumulators could be fitted into tightly-packed engine compartments. But the designers of the technology claim there will be plenty of extra space, as vehicles using this system would not require a radiator. The steam accumulator is able to perform all the functions of the radiator.

Steam has been a recognised source of energy for centuries, but although it potentially contains large amounts of usable energy, engineers have had to find smart ways to develop practical uses for it. Clean Power claims to be the first to find a way to use heat from engine exhausts to heat steam that can then be used to power a vehicle.

Burns said most people would be excited at the idea of using energy that would otherwise be wasted. Particularly since only 27 per cent of the calorific value of fuel in the tank is is used to power a vehicle.

'For each pound you spend on fuel for your car you're only really getting 27p of return,' he said. 'All we're doing at the moment is using fuel in a more efficient manner.'