A car that runs on compressed air may be making its way to
the market soon. Indian carmaker Tata is hoping to build a production model of
the AirPod. The AirPod is based on technology that Tata licensed from MDI, a Luxembourg
company. MDI has been working on the technology for several years but signed a
licensing deal with Tata in 2007. A concept
car was revealed in 2011 but a production model has yet to hit dealer floors.
The AirPod is an extremely light, one seater car that should
be able to reach between 28 to 43 miles per hour. The AirPod is powered by a
tank of compressed air instead of gas or electricity. Compressed air can be
pumped into the car via a charging station or taken in while the car is moving
using a small electric engine. Like many hybrids the AirPod will also recapture
energy during the braking process.
In May, Tata successfully tested the engine in two concept
cars. Since then Tata and MDI have been working to move the AirPod to the next
stage, actually creating a production car that can be sold to consumers. If
they succeed they could change the face of transportation by creating an
emissions free car that runs on something as plentiful as air.
MDI is not the first company to work with compressed air
engines. They were actually created over a century ago and were commonly used
in mining operations until electric motors became widespread. Compressed air
still powers pneumatic tools that are often used in auto shops.
A compressed air engine is very similar to an internal
combustion engine. Fuel forces the pistons to turn a crankshaft, which powers
the car. The main difference is that in the compressed air engine, air moves
the pistons instead of gasoline. Swedish researchers have also worked with
single-cylinder compressed air engines.
The main problem with compressed air engines is the power,
or lack of power that is created. Compressed air alone will only get a car up
to about 35 miles per hour. In order to supplement the power, the vehicle needs
to take in additional air as it gets moving. This is done using an onboard air
compressor. The compressor is usually electric or gasoline powered. While this
will add to the complete emission picture of a compressed air vehicle, the total
emissions are much lower than an internal combustion engine as the gas engine
is not running at low speeds.
Range can be another limiting factor. The tanks that store
the compressed air must be stronger than steel due to the pressure required to
store the air. These tanks can only be so big due to weight which limits the
total range of the vehicle. Completely filling a tank with an air compressor
could take up to two hours making refueling a lengthy process. While range can
be an issue, compressed air is much safer than compressed hydrogen or natural
At this point in time, Tata is alone in the compressed air
car field. Honda unveiled a concept car in 2010 but has gone no further in
pursuing a production vehicle. If Tata is successful these cars could drastically
reduce emission levels in India and around the world.