The world?s first commercial compressed air-powered vehicle is rolling towards the production line. The Air Car, developed by ex-Formula One engineer Guy N?gre, will be built by India?s largest automaker, Tata Motors.
The Air Car uses compressed air to push its engine?s pistons. It is anticipated that approximately 6000 Air Cars will be cruising the streets of India by 2008. If the manufacturers have no surprises up their exhaust pipes the car will be practical and reasonably priced. The CityCat model will clock out at 68 mph with a driving range of 125 miles.
Refueling is simple and will only take a few minutes. That is, if you live nearby a gas station with custom air compressor units. The cost of a fill up is approximately $2.00. If a driver doesn't have access to a compressor station, they will be able to plug into the electrical grid and use the car?s built-in compressor to refill the tank in about 4 hours.
The compressed air technology is basically just a way of storing electrical energy without the need for costly, heavy, and occasionally toxic batteries. So, in a sense, this is an electric car. It just doesn't have an electric motor.
But don't let anyone tell you this is an "emissions free" vehicle. Sure, the only thing coming out of the tailpipe is air. But, chances are, fossil fuels were burned to create the electricity. In India, that mostly means coal. But the carbon emissions per mile of these things still far outdoes any gasoline car on the market.
Unfortunately, the streets of North America may never see the Air Car, though; it's light-weight, glued-together fiberglass construction might not do so well in our crash tests. However, that does not mean the Air car is confined to the sub-continent. N?gre has signed deals to bring its design to 12 more countries, including Germany, Israel and South Africa.
And this isn't the last we'll hear of the technology. The folks making the Air Car are already working on a hybrid version that would use an on-board, gasoline-powered compressor to refill the air tanks when they run low. Negre says that technology could easily squeeze a cross country trip out of one tank of gasoline.
A variety of videos (of varying quality) on this technology can be found on YouTube, or after the jump.
But the carbon emissions per mile of these things still far outdoes any gasoline car on the market.
That I'm not so sure about. Internal combustion engine ~30% efficient, coal power station ~30-40% efficient, more CO2 per unit energy from coal than oil though. It'll be a bit better because it's small and light, needs less energy than a regular petrol car - but then why not just build a small and light petrol car?
Only that efficient between 20% and 80% of rated power. Driving studies indicate that most driving take place below 10% of rated power, and then efficiency is often less than 10%. A 100 hp engine use only 10-15 hp even when cruising at 100 km/h.
I can certainly see the uses of this technology, especialy if cheap off peak electricity is avaiable to compress the air, the remote control of such vehicle charging air compressors could be a useful way of better matching supply to demand on the grid.
However it must be remembered that compresed air is inherently inefficient as an energy storage medium.
When air is compressed, a significant proportion of the input power to the compressor appears as heat. Unless this heat can be used, perhaps for space or water heating, then it represents an unavoidable waste.
When the air expands in the engine, it produces "cold", which is again a waste, unless it can be put to use, perhaps by cooling the interior of the vehicle.
These losses are of less importance if surplus or off peak renewable energy if the ultimate source.
Despite the losses, the total costs may well compare favourably to petrol/diesel.
