There may be life in the old dog yet - engines have never been the cleanest of machines, requiring fossil fuels for their power and releasing all manner of gases, elements and chemicals through the combustion process.

Carmakers have come on in leaps and bounds over the last few decades to make the internal combustion engine cleaner than ever whilst improving economy and performance, but ever-tightening emissions regulations worldwide are certainly making things difficult for the industry.

Help could be at hand though, in the form of the Wave Disk Generator (WDG). Conceived by researchers at Michigan State University, the new gasoline engine works on the age-old KISS (Keep It Simple, Stupid) philosophy and requires no transmission, crankshafts, pistons or valves. It doesn't even need a cooling system, nor the associated fluids that a regular engine needs to operate.

There are two figures that astound with the WDG. The first is the aforementioned 90 percent reduction in emissions. The second is the reduction in weight - as much as 1,000 pounds, compared with a regular engine. It's also around 3.5 times more efficient - operating at around 60 percent efficiency compared to a gasoline engine's 15-20 percent.

The Wave Disk Generator looks at first glance like a take on the rotary engine, but rather than having just a few combustion chambers, the WDG has small channels to trap and mix oxygen with fuel as the rotor spins. Spark plugs are not required as pressure within each chamber ignites the air and fuel mixture instead, a little like a diesel engine.

The WDG is apparently only suitable for hybrid vehicles at this stage, and the prototype is only small, but Michigan State's team hope to have a full size and car-suitable 25-kilowatt version up and running by the end of the year. In the meantime, you can watch a video explaining the unit here:

The video was actually recorded in 2009, but just last week the prototype was presented to the energy division of the Advanced Research Projects Agency, and the project has been granted $2.5 million in funding.

Will we ever see the WDG in a production vehicle? It's too early to tell, but we'll be keeping our eye on the University's findings. It looks like the hybrid vehicles of the future could be getting even cleaner...