My brother sent me a neat article about a car that runs on compressed air and has many promising qualities.
Many respected engineers have been trying for years to bring a compressed air car to market, believing strongly that compressed air can power a viable "zero pollution" car. Now the first commercial compressed air car is on the verge of production and beginning to attract a lot of attention, and with a recently signed partnership with Tata, India’s largest automotive manufacturer, the prospects of very cost-effective mass production are now a distinct possibility. The MiniC.A.T is a simple, light urban car, with a tubular chassis that is glued not welded and a body of fibreglass. The heart of the electronic and communication system on the car is a computer offering an array of information reports that extends well beyond the speed of the vehicle, and is built to integrate with external systems and almost anything you could dream of, starting with voice recognition, internet connectivity, GSM telephone connectivity, a GPS guidance system, fleet management systems, emergency systems, and of course every form of digital entertainment. The engine is fascinating, as is and the revolutionary electrical system that uses just one cable and so is the vehicle’s wireless control system. Microcontrollers are used in every device in the car, so one tiny radio transmitter sends instructions to the lights, indicators etc. ...90m3 of compressed air is stored in fibre tanks. The expansion of this air pushes the pistons and creates movement. The atmospheric temperature is used to re-heat the engine and increase the road coverage. The air conditioning system makes use of the expelled cold air. Due to the absence of combustion and the fact there is no pollution, the oil change is only necessary every 31.000 miles.
My only hesitation is that carrying highly compressed gases can be extremely dangerous. Despite what you may see in action movies, gasoline-powered cars rarely explode; however, a compressed air car could easily explode if involved in an accident that impacts or punctures its air tank.
As far as I remember from the news and so on, it seems like a lot of people want a hydrogen car, or did recently. This implies that most people probably do not worry about having an extremely explosive fuel tank.
In any case, the compressed-air car sounds like a good idea. The energy is cheaper than the energy in gasoline, although not as cheap as just electricity... But this compressed-air energy allows for a car with good range without expensive bulky batteries that become toxic waste. Sounds good to me.
PS: While on the subject of small, affordable, low-power, super-efficient cars...
http://blog.wired.com/cars/2007/03/200mpg_for_real.html
Finally it looks like a car company hired an aerodynamicist! I never thought I'd see the day.
A joule of energy from the power socket on the wall costs less to a consumer than a useful joule of energy from the gas pump. So no, fossil-fuel energy is already not any cheaper than nuclear, coal, hydro, wind, or solar energy. If it were, we'd all have small generators.
But a car that can run on electricity will, in general, have a much poorer performance-to-cost ratio than a car that runs on gasoline. So people are happy to buy a car that uses more expensive energy but that is more capable.
The reason why electric cars are expensive and not very capable is because batteries carry energy MUCH more poorly than gasoline. So you pay less for the energy, but you need bulky hardware to carry it. Compressed air might allow you to pay almost as little for the energy as if you were buying electricity (i.e. you just factor in some inefficiencies of the compressor, and some profit for the owner of the compressor unless you get your own), but carry almost as much energy as you do in your gas tank, in a container that is not as expensive or bulky as a battery. At least, that's the idea.
As for moving the pollution somewhere else... Power plants use large-scale very efficient generators. Even the ones that do burn fossil fuels can capture their energy (and combust them into CO2 and water) more completely than our cars can, primarily because their size-to-power ratio is much greater. So you get more energy and less pollution (where "pollution" is not CO2 but the other emissions of a car engine like CO, oxides of Nitrogen, hydrocarbon emissions, and other things your car could NOT make if it only had more time to burn its fuel). Besides, in the future the grid might move to energy sources that are more sustainable and less polluting
Bernardo: You didn't mention it, but hydrogen fuel cells fit right in to your explanation as well. Hydrogen, like compressed air, is a way to store energy in a car. The reason it isn't used is because fuel cells are expensive and there aren't many electricity-to-hydrogen stations around. Plus, think their performance is about the same as a battery car (am I wrong?).