Research team fuels hopes for new generation of cleaner cars

 

Peanut oil, sunflower and canola oil, even refined tallow and fuel derived from algae could be used to power the next generation of road vehicles. Not only will the fuel sources be renewable and cheap to buy, the emissions from these vehicles will be much cleaner and less damaging to the environment.

Researchers from the Massachusetts Institute of Technology (MIT) in the US have completed a series of laboratory tests on a new device that would broaden the range of fuels that could be burned in today's car engines.

The team from the Institute's Plasma Technology Division at the Plasma Science and Fusion Centre (PSFC) has developed a device called a "plasmatron" which acts like a miniature oil refinery, breaking down hydrocarbons to produce a hydrogen rich gas fuel.

The hydrogen rich gas is mixed into the vehicle's normal petrol or diesel fuel system. It was found to reduce nitrogen oxides a hundred-fold when petrol was used and was also shown to increase engine efficiency during the tests. The MIT group mounted its plasmatron on a commercial car engine and ran a series of lab experiments over a fortnight.

"This is a major milestone in showing the feasibility of a plasma-boosted fuel reformer for reducing vehicle pollution," stated Dr Daniel R. Cohn who heads the Plasma Technology Division. The next step would be to install a plasmatron on a road vehicle, he said. "We're ready to take the show on the road."

Dr Cohn's colleagues on the project are Dr Leslie Bromberg, principle research engineer; PSFC research engineer, Dr Alexander Rabinovich; and visiting scientist, Dr Nikolai Alexeev.

Essentially the new style plasmatron is a fuel reformer, changing hydrocarbon sources such as oils into other fuel forms, in particular hydrogen rich gases. It is about the size of a wine bottle and will reform liquid hydrocarbon sources such as vegetable oils, petrol, diesel and even by-products from algal growth.

The fuel source is injected into the plasmatron and is exposed to an electric discharge that turns the fuel and surrounding air into an electrically charged gas or plasma. This encourages the production of hydrogen-rich gases which are then injected into the existing vehicle fuel cycle.

The plasmatron concept is not new. Large car engine-sized units have been used to produce hydrogen-rich gases for industrial applications such as metallurgical processing. These large devices would be no use in a road vehicle however and they have high energy demands.

The MIT group came up with a much smaller, lighter unit that has a low-energy demand. "To our knowledge we were the first to develop a plasma-boosted fuel reformer that is this small and that operates at low power [less than one kilowatt]," Dr Cohn said.

"The real achievement of the recent tests was our ability to run our new plasmatron connected to an engine for long periods of time," said Dr Rabinovich. "We ran it reliably for four to six hours a day over two weeks with no traces of deterioration."

The team showed that engine exhaust output of nitrogen oxides could be reduced from 2,700 parts per million to about 20 parts per million. On the road the reductions would be smaller, Dr Cohn said, but could still easily be reduced to just a tenth of normal nitrogen oxide output. The group also found that virtually no particulates were produced - the small particles of soot-like material.

It estimated that a production plasmatron for road vehicles could be built for about $300 (€291) and require very low service costs. Its use also meant that a far wider range of fuels could be used to power conventional engines including cheap biofuels such as rape seed, peanut or sunflower oils.

The researchers also pointed out that because several animal and vegetable oils were being displaced in the US food market because of health issues, these oils could readily be used as biofuels in road transport.

Even when used with conventional petrol the plasmatron "could significantly reduce emissions" and increase engine efficiency, the researchers stated. The addition of hydrogen to the fuel cycle meant that the engine could be run much "leaner" with lower total fuel demand. The experiments showed that the plasmatron could be used to reform up to 25 per cent of the total fuel used by the engine without loss of engine efficiency, but with greatly reduced pollution output.

The research team has already taken out five patents on its new plasmatron and hopes to have a plasmatron unit installed in a bus for road tests later this year.