I'll Admit The Idea Of A Compressed Air Car Is Cool, But Is It Practical?
If you're interested in efficient and economical transportation, you have likely heard rumors about the compressed air car. Just like it sounds, it's a car that runs on nothing but, you guessed it, compressed air. Clean, simple and efficient, this new technology could be the solution to smog clouded cities and foreign oil right?
Not so fast.
This technology has been "under development" for quite some time. The French company M.D.I (Motor Development International) partnered with India's Tata Motors in 2008 and assured the world that we would see the first compressed air powered car in under two years. We're still waiting.
Why the air car isn't going to save the world
There are several reasons why the compressed air car will never be a reality, at least on North American streets. First off, the car needs 4350psi to operate. By way of comparison, the tires on a semi truck usually run between 80-100psi and are capable of a spectacular explosion. 4350psi makes the car a rolling bomb. Under any circumstances, even if the tank is placed in an armoured box within the frame of the car, there's still a real danger to the occupants of the vehicle and anybody within the vicinity of it if the tank we ruptured. A collision could easy rupture a tank and with 4350psi of compressed air inside, the results would be devastating. It won't pass safety testing here in North America.
Another reason that the compressed air car is not a viable transportation option is that special equipment is required to even fill a tank to such a pressure. A gas station air compressor might do 100psi, but it wouldn't get that car even ten feet. Millions would have to be spent on infrastructure just to get them rolling. Given the current level of investment in electric cars, I'd say they don't even stand a chance.
The other problem with the compressed air car is that it's just plain inefficient. With even the most basic understanding of how energy works you can see why this car is a waste. In an electric car, you are taking potential energy that already exists on the power grid, transferring it into your car, and converting it to kinetic energy to move your car. Each time you convert energy to a different type, there are losses, so you want to minimize this.
It looks like this.
Potential energy (power from your wall outlet) turns into
Mechanical energy (motor driving your car)
The energy flow in the compressed air car looks like this.
Potential energy (power from your well outlet) turns into
Kinetic energy (compressor motor spinning to compress the air) turns into
Potential energy (compressed air in your tank) turns into
Kinetic energy (driving the motor to move the car)
Sorry M.D.I., but the compressed air car is a pipe dream, and I severely doubt that we will be seeing them on our streets anytime soon. The idea may have taken off 50 years ago when gasoline and electric cars were far less efficient than they are today. The compressed air car doesn't have what it takes to beat out the modern electrics like the Nissan Leaf or the Mitsubishi MiEV.