Dirty exhaust gases could make cars cleaner

Dirty exhaust gases could actually help cars become cleaner - thanks to a world-beating British invention.

The British engineers have developed a simple but revolutionary way of recovering energy that would normally be lost down the exhaust pipe. The exciting ‘free power’ breakthrough has three key green benefits – it makes engines more efficient, reduces emissions and creates enough electricity to run all of a car’s power systems.

And, because the technology is fairly simple, it could be fitted on all car, van, bus and truck engines within a few of years.

It could reduce fuel consumption by up 10 per cent and help hit the Government’s commitment to reduce greenhouse gas emissions. But engineers working on the TIGERS project under the Society of Motor Manufactures and Traders Foresight Vehicle research initiative, say this is only the beginning.

So, how does it work? Just below the manifold, where the exhaust system joins the engine, the engineers have installed an extra waste pipe. A valve, linked to the engine’s management control system, allows some of the high energy gases to be drawn off to drive a special generator, using a device called a switched reluctance drive (SRD).

Because so much energy is tied up in the high temperature exhaust gas, that can reach 130mph, it can spin the generator at up to 80,000 rpm and creates an electrical power of up to 6kW – more than enough to drive a car’s electrical systems.

Dr Richard Quinn, one of the engineers leading the TIGERS – Turbo-generator Integrated Gas Energy Recovery System – project says the system could be developed to produce anything from 12v to 600v.

So the ‘free’ electricity could drive all of a car’s heating, lighting, air conditioning and in-car entertainment systems. Longer term, the cam belt, drive belts and alternator could be scrapped and TIGERS electric drive used instead. This would reduce friction losses.

In a hybrid electric car the TIGERS system could be even more efficient, feeding the ‘free’ power directly to boost the main drive motors, or back to the battery to give the car an even greater range.

On trucks the extra electricity could be used to power electrical systems to run refrigeration units for chilled food, turn the motors on cement mixers or power pumps on fuel tankers.

Researchers from Visteon UK in Coventry, Switched Reluctance Drives of Harrogate and The University of Sheffield Electrical Machines & Drives Research Group, form the TIGERS group.

Dr Quinn, of Visteon’s European Powertrain operations, said: "TIGERS is a really exciting development. Up to a third of the power that a conventional engine produces is wasted as exhaust gases. By harnessing some of that power we can make the engine more efficient."