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Gasoline and diesel have already become the fuel of the past; they even contaminate the air that’s becoming unhealthy to breath with every passing day, and even the price of the petroleum is increasing at an unbelievable pace.

Most automotive manufacturers are concentrating towards greener energy resources like batteries, which can be charged with energy; they have spent lots of time in developing the fuel of the future and they feel even air could become a better energy source, but the great news is that this isn’t a dream anymore – we’re talking about real air cars!

What are Air Cars?


The idea of operating a vehicle on air seems almost too great as its non-polluting, since air is all around us and free, it’s none less than a fantasy.

Unfortunately, air alone can’t be used as a fuel at the first place as the energy has to be accumulated in it by compressing the air tightly with the help of a mechanical air compressor device. Once the compressed air expands, it can be used to drive pistons to deliver energy to an engine, just like expansion of steam in a steam engine.

The idea of using compressed air isn’t new; there have been prototype air cars since 1920s, even before the invention of internal combustion engine, but none of those prototypes could be converted into a real-time implementation.

How Do They Work?

An air car is equipped with a motor driven by compressed air, which stores air in a tank at high pressure of 30MPa (300 bar or 4500 psi)… Compressed air cars make use of mechanism of release-and-expansion of air to drive engine pistons, rather than ignited air-fuel mixture that we see on the usual internal-combustion engines.

The carbon fiber tanks can safely store compressed air at a higher pressure, making them comparable to steel tanks. The squeezed air has relatively low energy density; air at 4500psi contains energy of about 50Wh/l and when you compare it with a lithium ion battery, it contains 250-620Wh/l… A lead acid battery has about 60-75Wh/l and typical gasoline engine with 20 percent of efficiency can only recover the equivalent of 1700Wh/l.

The energy density of compressed air can be doubled if the air is heated prior to expansion. Some systems may use gases that can be solidified or liquefied upon further expansion of energy density.

Principle of Operation

Since their source of energy is electricity, the compressed air cars are emission-free and their efficiency also depends upon how clean the source of the electricity is… They may range from low-emission power source (wind) to high-emission energy source (coal).

The principle behind the compressing the gas and air is same; the compressors in the air cars will use the surrounding air to refill the air tank and complete refilling is a slow process, which may probably take around 2-2.5 hours.

Current Air Car Manufacturers

Various companies are researching and developing cars on compressed air engine and the first air car was manufactured by a French company, MDI. In order to double the energy output, they implemented ‘active chamber’ for heating the air via usage of fuel.

Another French company, K’Airmobiles has built prototypes of air-fueled light road cars and Tata Motors of India has promised to introduce the Mini CAT air car in upcoming years.




The Spanish company, Air Car Factories, has an air car engine currently lined-up, and it achieves about 100mpg and runs on small conventional engine and compressed air.



Pros and Cons

One of the major advantages of this type of a car is that it produces no pollution but of course that’s not the end of the story… Here are some more benefits of air cars -

• Minimal cost of vehicle construction as there is no need to build spark plugs, cooling system, starter motors etc.

• Refueling the air can be done at home using an air compressor.

• Development of compressed air reduces its temperature.

The main downside is the indirect use of energy; for compressing air, it requires lots of energy and as we all know conversion of energy between different forms results in loss, and in this case, there’s a severe loss of energy involved in the process, making the practical implementation of this concept tougher than it sounds!