The Hybrid Car That Runs on Air
A car that runs on air is being developed by engineers at a top British university.Posted May 15, 2009
A car that runs on air is being developed by engineers at a top British university.
The team have achieved what could be a major breakthrough in the battle to create greener and cheaper motoring.
They have found a way to adapt a normal petrol (gas) combustion engine to run on compressed air – generated within the vehicle – to give an extra boost to power the motor and considerably reduce the cost of running a car.
The result is a new low-cost ‘air hybrid’ engine which significantly cuts emissions of carbon dioxide – the so-called greenhouse gas blamed for global warming – cuts fuel consumption by around 30 per cent and offers the driver of a family car fuel economy of around 65mpg.
Existing ‘green’ hybrid cars – such as the Toyota Prius and the Honda Insight – use a petrol engine and braking energy to generate on-board electricity to give supplementary power to the vehicle.
The new Brunel engine uses the same principle. But in this case, the engine and the braking generates its own compressed air to provide the added boost to the car.
The work by Brunel University’s School of Engineering and Design in west London could lead to an engine which would be considerably cheaper and cleaner to run.
A spokeswoman for the Brunel team said:
‘The idea is that using the engine’s compression to brake the vehicle not only could slow the vehicle down, but also the pistons could compress air and drive it into a compressed air tank.’
‘It could then be used later to briefly power the piston and to provide compressed air for turbo charging during a period of turbo lag – normally at low revolutions.’
She added: ‘Hybrid vehicles use engine management to save fuel. This includes switching off the engine when not in use, restarting the engine when needed and recovering the braking energy for other use.
‘The means of achieving this type of energy management could be electric – such as with the Toyota Prius. But it is equally feasible to use mechanical means such as pneumatic – an air hybrid.
‘The new air hybrid engine will be considerably cheaper to run and deliver significantly less carbon emissions.’
It also has advantages over petrol-electric hybrids like the Prius, say the engineers: ‘Transforming an existing combustion engine in an electric hybrid is very expensive. It requires a complete redesign of the transmission system.
‘It is heavier because it uses extra batteries, more space is required to house these batteries and they have a limited life-cycle.’
By contrast, they say of their air-hybrid: ‘It requires only small alterations to adapt a normal combustion engine. The simple and cost-effective solution needs no transmission alteration or engine redesign.’
She added: ‘The fuel consumption benefits [miles per gallon] you’d get from an air hybrid engine are the same as you’d get from an electric hybrid engine. The top speed you could achieve would be exactly the same as the standard engine you modify to make the air hybrid engine.
‘So, if the car’s top speed is 110 mph, it will still be 110mph even if it uses air. The big advantage is that the air hybrid engine is much cheaper to make than an electric hybrid engine, so cars with air hybrid engines will be much more affordable.
‘As with electric hybrids, the benefits of air hybrid engines are highest with city driving – as it takes advantage of the continuous stopping and starting.’
The Brunel team is now looking to test the scheme with vehicle manufacturers.
The inventors believe they may have got round the problems which have beset engineers who have been attempting for some years to transform an existing combustion engine into an air hybrid.
Professor Hua Zhao, director for advanced power train and fuels research at Brunel University’s School of Engineering and Design, said: ‘Significantly reducing the cost of driving through reducing fuel consumption and lowering carbon emissions for commercial vehicles is an ongoing battle.
‘Our simulations prove that we have achieved a major breakthrough. Now, we need to test it with vehicle manufacturers.’
The Toyota Prius uses electric engine management, but engineers at a British university believe compressed air generated by the car could serve the same function.
By Ray Massey, dailymail.co.uk