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Air cars under testing but are they efficient?

It has been a long time coming, but Moteur Development International (MDI) has officially handed over the keys of two AirPods to KLM where they will undergo testing at the KLM E&M at Schipol Airport. The AirPod is one of five derivative vehicles designed by the company and based on its compressed air engine. At its core is a piston engine that is powered by the expansion of electronically injected compressed air. So far MDI has developed two versions – a single fuel engine that relies solely on compressed air for urban use; and a dual fuel version that uses both compressed air and a petroleum based fuel or biofuel. MDI engines feature an active chamber with two opposing cylinders. They use a proprietary connection rod that allows the retention of the piston at top dead centre during 70° of crankshaft rotation, which provides enough time to establish the required pressure in the cylinder. It is capable of a maximum speed of 28mph. However, the AirPod has come in from criticism following a recent study from UC Berkeley and colleagues from ICF International and Stanford University who compared the merits of compressed air to chemical storage of potential energy. The study concluded that even under highly optimistic assumptions the compressed air car is less efficient than a battery electric vehicle and produces more greenhouse gas emissions than a conventional gas powered car with a coal intensive power mix. It did state however, that a pneumatic combustion hybrid is feasible and inexpensive and could compete with hybrid electric vehicles. MDI has hit back at the paper, however, calling it an “act of bashing” and said an error was made by comparing the AirPod to a Smart because the weights are so different – the Smart petrol version weighs 837kg, the Smart electric weighs 924kg and the AirPod weighs 330kg (with driver). It stated that a more appropriate comparison to the Smart would be its larger variants, which will be equipped with dual fuel technology. It also stated that a compressed air tank has a life of 12,000 discharge cycles – approximately 30 years – compared to a battery lifespan which is only a twelfth as long.

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Paul Lucas

Filed under: Latest News, Green Cars



The AirPod specification of 330kg empty weight+driver is, like most other AirPod specifications, merely hot air.

The prototypes are well over 400kg.

MDI claims a range of about 20 to 30km for the existing prototypes, although they claim that, through various improvements, that they will increase this to 220km range in the final vehicles.

This is very much like the situation in 2002 when the actual observed range of the CityCat prototype was only 7.22 km, but they intended to make multiple improvements to increase the range to 200+km.

Obviously, this didn't happen and the announced 2002 introduction of the MDI e.Volutuion and CityCat cars did not happen.

Only time will tell if we are watching another failed introduction by MDI.


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