"Electric cars and electric hybrid cars already make use of brake energy to power a generator that charges the batteries. However, according to Per Tunestål, a researcher in Combustion Engines at Lund University in Sweden, air hybrids, or pneumatic hybrids as they are also known, would be much cheaper to manufacture.
"The technology is fully realistic. I was recently contacted by a vehicle manufacturer in India which wanted to start making air hybrids," he says.
The technology is particularly attractive for jerky and slow driving, for example for buses in urban traffic.
"My simulations show that buses in cities could reduce their fuel consumption by 60%," says Sasa Trajkovic, a doctoral student in Combustion Engines at Lund University who recently defended a thesis on the subject.
Trajkovic also calculated that 48% of the brake energy, which is compressed and saved in a small air tank connected to the engine, could be reused later. This means that the degree of reuse for air hybrids could match that of today's electric hybrids. The engine does not require any expensive materials and is therefore cheap to manufacture. It also takes up much less space than an electric hybrid engine. The method works with petrol, natural gas and diesel.
The idea of air hybrids was initially hit upon by Ford in the 1990s, but the American car company quickly shelved the plans because it lacked the necessary technology to move forward with the project. Today, research on air hybrids is conducted at ETH in Switzerland, Orléans in France and Lund University in Sweden. One company that intends to invest in engines with air hybrid technology is the American Scuderi. However, their only results so far have been from simulations, not from experiments.
"This is the first time anyone has done experiments in an actual engine," says Trajkovic. "The research so far has only been theoretical. In addition, we have used data that means we get credible driving cycle results, for example data from the driving patterns of buses in New York."
The researchers in Lund hope that the next step will be to convert their research results from a single cylinder to a complete, multi-cylinder engine. They would thus be able to move the concept one step closer to a real vehicle."
"I know we can go 300 mph on compressed air," he says. "I'm sure of it."
"With gasoline prices projected to hit $5.00 a gallon in 2011, this car is great news.
The* Air Car, dubbed the “MiniCAT” could cost around $8 thousand in India and would have a range of close to 200 miles between refuels.The cost of a refill would be only two dollars.
The MiniCAT which is a simple, light urban car, with a tubular chassis that is glued, not welded, and a body of fiberglass powered by compressed air.* Micro-controllers are used in every device in the car, so one tiny radio transmitter sends instructions to the lights, indicators, etc.
There are no keys—just* an access card which can be read by the car from your* pocket.* According to the designers, it costs less than a tenth to operate compared to a car running on gasoline.* Its mileage is about double that of even the most advanced electric car, a factor which makes a perfect choice in cities where 80% of motorists drive less than 40 miles per day.* The MiniCAT has a top speed of 65 miles per hour.
Refilling the car will, once the market develops, take place at adapted petrol stations to administer compressed air.* In two or three minutes, and at a cost of approximately two dollars, the car will be ready to go another 200 miles.
Due to the absence of combustion and, consequently, of residues, changing the oil (1 quart of vegetable oil) is necessary only every 30 thousand miles.
Since the temperature of the clean air expelled by the exhaust pipe is between 0-15 degrees below zero, it can be used to air condition the MiniCAT with no loss of power or mileage."