The Hindu Business Line : Tata-MDI: A new engine is in the air

One of the companies that has done extensive research in the area of air engine technology is MDI of France. The French company has signed an agreement with Tata Motors. The partnership is expected to work towards developing the air engine for applications in India.

CityCAT.one of MDI's cars designed for the taxi segment

Can a car really run using just air? Even if such a technology can be developed, will it be economically viable? And what about safety and emissions? Would it be safe to carry compressed air tanks in the car?

The answer to all these questions is yes. Of course, there are a few buts too...

It has been a dream to develop a vehicle that runs on compressed air. It sounds like it will be unbelievably cheap to run, an answer to all of the world's oil-stained woes, and better still, be a zero-polluting vehicle with the exhaust being just regular air.

The Americans have tried to develop engines that run on air. So, have the Europeans and Asians. But only a few have managed to take the innovative technology past the development stage and apply it into vehicles that have gone into series production.

Even though a couple of manufacturers have rolled out vehicles with this type of engine, they have done so for the novelty value or to capture a niche segment of the market with very low volumes.

Despite the fact that these experimental vehicles have shown it to be possible, the big automobile manufacturers have not attempted to adapt the air engine to their vehicles.

One of the companies that has done extensive research in the area of air engine technology is MDI of France, also called Moteur Developpment International. The company, headed by Mr Guy Negre, developed the technology in the 1990s and has been fine-tuning it the last 14 years.

Earlier this week, the French company signed a technology licensing and co-development agreement with Tata Motors. The partnership is expected to work towards developing the air engine for applications in India, including for cars that could feature this technology or its variants.

How do air engines work?

Also called CATS (compressed air technology system), these engines feature a specially adapted engine to enable its pistons to be driven simply by the thermal expansion of the compressed air fed into it. There is no combustion of fuel, as in a traditional engine that uses fossil fuels. Instead, the redesigned parts of a two-stroke engine, including pistons, single crankshaft and connecting rods, are all tuned to handle the high pressure of the expanding air.

In the engine developed by MDI, for example, the changes to the con-rod system allows the engine's piston to be held at Top Dead centre for 70 degrees of the cycle. This way, enough time is given to create pressure in the cylinder. The torque is also better, so the force exerted on the crankshaft is less than in a classic system.

Will Tata Motors get this MiniCAT?

Compressed air is piped into the engine from tanks made of thermo plastic and/or fibreglass panels. To ensure smooth running and to opitimise energy efficiency, the MDI engines use a simple electromagnetic distribution system, which controls the flow of air into the engine.

Gear changes are automatic, powered by an electronic system developed by the French company. A computer, which controls the speed of the car, is effectively changes gears continuously. Naturally, no clutch is necessary, and the engine is idle when the car is stationary and the magnetic plate, which re-engages the compressed air, starts the vehicle. Parking manoeuvres are powered by an electric motor that is paired with the system for MDI cars.

Air and dual fuel

The French company has developed two technologies to meet the different needs, and these include single energy compressed air engines that use only air and the dual energy ones that uses compressed air plus fuel . Vehicles with the dual energy engine will work exclusively with compressed air while it is running under 50 km per hour in urban areas. But when the car is used outside urban areas at speeds over 50 km per hour, the engines will switch to the fuel mode.

The engine will be able to use petrol, gas oil, bio-diesel, liquified petroleum gas, alcohol, etc. Both engines will be available with 2, 4 and 6 cylinders, When the air tanks are empty, the driver will be able to switch to the fuel mode, thanks to the car's onboard computer.

MDI has also developed vehicles in-house that feature their air engine. These vehicles, including the CityCat and MiniCat, have fibreglass bodies which makes them lightweight and the car's body is tubular, and is said to be held together using aerospace technology.

The vehicles do not have normal speed gauges. Instead, they will have a small computer screen that shows the speed and engine revolutions. The system allows for infinite possibilities and additions such as GSM telephone systems, GPS satellite tracking systems, emergency systems, Internet connections, voice recognition, map presentation and traffic information. When there is no combustion, there is no pollution. So, the vehicle with an air engine will be a zero pollution unit and even if it is a dual fuel type, the average emission level will be very low.

Range and recharge

MDI claims that its vehicle's driving range is close to twice that of the most advanced electric cars (from 200-300 km or eight hours of circulation). This could be exactly what the urban markets need where a majority of the drivers commute less than 40 km a day.

The recharging of the car or refilling of air will be done at air stations, once the market is developed. To fill the car's tanks at the station, which will use a high-pressure delivery system, it will only take about to 2-3 minutes. After refilling, the car will be ready to run 200 km. The MDI car also has a small compressor that can be connected to a domestic electrical network (220V or 380V), which will pump air into and recharge the tanks completely in three-four minutes. Because the engine does not burn any fuel, the car does not need the kind of oils that traditional vehicles use. The MDI engine's oil is only a litre of vegetable oil that needs to be changed every 50,000 km.

Further, the temperature of the clean air discharged from the exhaust pipe is between 0 and 15 degrees below zero. This exhaust air can also be subsequently channelled and used for cooling the car's interior.

MDI has also developed hybrid-style dual fuel — air and fossil fuel — vehicles, wherein the air tank is replenished with compressed air generated by the car's on-board motor, every time that it is running on fossil fuel.

Overall, though the benefits seem obvious, the acceptance of this compressed air engine technology has been slow on the uptake. The critics of this experimental technology also point out that it is not all that environmentally friendly and that it is just taking away pollution from one place (the road), but releasing it elsewhere — at the thermal power plant, which generates the power needed to recharge the air tanks of the car.

Electric cars were not successful in European countries, where the inconvenience of a short driving range per charge and the need for frequent charging kept buyers away. They were also subject to the same criticism about polluting thermal power plants.

Tata Motors has been aggressively pushing to expand the horizons of its own research efforts. The tie-up with MDI of France could give this emerging global player access to what could potentially be a technology that will find increasing acceptance amongst vehicle manufacturers who plan hybrids of a different kind.

But in addition to the air engine, what Tata Motors may also want to look at are the cars that MDI has developed in-house. The CityCAT and the MiniCAT are cars that may be a perfect fit even for Tata Motors, which is looking to develop easy-to-produce, cheap cars (read one lakh car) that are also easy to maintain and run.

Particularly, the MiniCAT could be an ideal choice (check out the photos). Built with a tubular frame, the car's body panels are made of fibreglass and can be put together easily in a small workshop, all features that Tata Motors will want to consider for its people's car.

However, Tata Motors' official statement about the alliance with MDI does not talk about its licensing arrangement with the French company, extending to include the vehicles developed by the latter. If Tata Motors does get access to the cars and/or their designs, the alliance may well be that much more fruitful for both the partners.

(Response may be sent to: smuralidhar@thehindu.co.on.)

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