India's largest automaker, Tata Motors, announced this week it will partner up with MDI of France, a technology invention company, to develop engines powered by compressed air. Tata says the agreement "envisages Tata's supporting further development and refinement of the technology, and its application and licensing for India." MDI is the company behind The Air Car.

The way the Air Car's CAT (compressed air technology) works is that an "innovative system" - MDI isn't releasing true technical details because of corporate secrecy - controls the movement of four two-stage pistons (giving eight compression/expansion chambers) and a single crankshaft. A 5kW electric moto-alternator compresses air, recharges the battery, serves as an electric moderator/brake and as a temporary power supply (e.g. for parking).

That sounds positive, but reader Fabio Alemagna says the key problem for MDI's technology is the fundamental problem that the "fuel" conducts freeze thanks to the subzero temperature of the compressed air.

Tata is also working on engines powered by Hithane, a mix of hydrogen and compressed natural gas. For its part, MDI is not limiting itself to India or Tata. MDI president Guy Negre said his company was happy to work with Tata but, "We are continuing the development with our own business concept of licensing car manufacturers in other parts of the world where the production is located close to the markets."

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[Source: Tata Motors, h/t to Fabio Alemagna]