There been quite a bit of buzz for several years now about the Tata Motors MiniCAT Air Car, a car that could purportedly run entirely on compressed air. Tata made an agreement back in 2008 with Zero Pollution Motors to market the car in the US by the end of 2009. The US version of the car would run exclusively on compressed air at low speeds. Above 35 mph, a small gasoline engine would kick in to provide the car with enough additional power to stand a chance of holding its own on US highways.
Then, early in 2009, Tata Motors’ vice-president S. Ravishankar told DNA Money the project was facing difficulties in terms of vehicle range and cooling. Ravishankar said, “Air is not a fuel, it is just an energy carrier. So a tank full of air does not have the same energy as a tank full of CNG. Any vehicle using only compressed air to run would face problems of range.” The car was also reported to have problems at low temperatures. (For more information on how air cars work, click here.)
In a Triple Pundit article last fall, Steve Puma reported that from a carbon emissions perspective, Zero Pollution’s AirPod, “an extremely strange-looking precursor to the Mini Cat” outperformed the Tesla Roadster (by 27%), the 2010 Toyota Prius (by 39%), the 2009 Honda Civic non-hybrid (by 63%) and the VW Jetta TDI Diesel (by 62%).
The lightweight car will be mostly made of fiberglass with a bonded tubular chassis. This compressed air-only version will cost roughly $2 to fill up with enough compressed air to take you 300 km (186 miles). That’s ten times better cost per mile than what you would get with gas today at 37 mpg. The fill-up will take only take a few minutes in a properly equipped service station, though a home compressor can fill up the car in three to four hours. And since this car has no combustion engine, it will only need its oil changed every 50,000 km (30,000 miles).
The estimated cost of the car is $8000, roughly four times the cost of Tata’s Nano, “the world’s most affordable car.” The MiniCAT was jointly developed with Motor Development International who has been working on compressed air engines since 1996.
According to an earlier release, the Air Car runs a specially developed piston engine that uses a new thermodynamic cycle offering exceptional energy efficiency. The compressed air is stored in carbon fiber tanks, at 4,351 psi.
The operation of the engine is as follows: Fresh air is drawn into the compression chamber and compressed to 290 psi. At the highest point of pressure (‘top dead center’), the air reaches 688°F, at which point, compressed air from the storage tank is injected into the combustion chamber. This compressed air heats and expands rapidly in the chamber, pushing the piston down.
This earlier release describes an 80 gallon a tank that will last for 120 miles. This differs from the recent announcement which claims 180 miles, so some additional changes must have been made.
The MiniCAT uses an electronically controlled continuously variable transmission (CVT)
There is no news yet on when a US version of this car might be available, though it will clearly be substantially different from the Indian version. There is no mention of either model on the company’s website as of this writing. Perhaps because of previous delays, the company is keeping a low profile this time until it is sure that the car will be ready. Though I don’t ever see this becoming a touring car or a family sedan, it certainly could be a worthy competitor to something like the Smart car.
[Image credit: Triple Pundit]
RP Siegel, PE, is the President of Rain Mountain LLC. He is also the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water. Now available on Kindle.
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