According to Swedish researchers, storing energy as compressed air rather than in batteries would reduce the price of hybrid cars. Some hybrid and electric vehicles are already using brake energy to activate a generator that charges the batteries.
However, pneumatic hybrids (or air hybrids) would be much cheaper to manufacture, says Per Tunestal, a researcher at the Department of combustion engines, Lundt University, Sweden. “The technology is fully realistic. I was recently contacted by a vehicle manufacturer in India which wanted to start making air hybrids,” he claims.
The technology is especially attractive for low speed running vehicles, such as buses or city cars. “My simulations show that buses in cities could reduce their fuel consumption by 60%,” says Sasa Trajkovic, a doctoral student in Combustion Engines at the same University.
After some calculations made by Traykov, 48% of the energy produced by brakes, which is compressed and stored in a small tank that is also connected to the engine, could be reused later. The engine is cheap to manufacture because it does not require any expensive materials. Unlike an electric hybrid engine, the compressed air one takes up much less space. The method works with diesel, petrol and natural gas.
The idea of pneumatic hybrids was first launched by Ford in the ’90s, but the company has dropped plans due to lack of necessary technology. Today, one of the companies who wants to invest in this technology is American Scuderi. “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,” said Trajkovic.