A car that runs on air

Aug. 3, 2008

The energy crisis and the impending end of oil have people scrambling for alternate fuels. We read about fuel cells, hydrogen powered cars, cars running on used cooking oil, and biodiesel -- even cars that run on water that’s broken into its hydrogen and oxygen components.
But what about a car that runs on air?
There is one. Guy Negre has developed an engine that runs on compressed air. He’s developed two basic versions: one that runs on air alone, maximum speed only 30 mph, and a dual-energy source version that automatically switches to a carbon-based fuel when the driver wants to go faster. The claim is “the engine will be able to use gasoline, gas oil, bio diesel, gas, liquidized gas, ecological fuel, alcohol, etc.”
In that mode, with the engine running on an alternate fuel, the engine also runs the air compressor to regenerate it for city driving. It’s a little like the electric locomotive that generates electricity to put back in the grid when it’s coasting downhill or decelerating or the electric car that recharges its batteries while coasting.
If 30 mph sounds like moped or bicycle speeds to you, be aware that the average speed of vehicles driving in the city is no more than 26 miles an hour. Why should your vehicle spew out polluting carbon monoxide, CO2, and the makings of smog while you’re waiting for the light to change or to make that left turn? Sounds like a great idea.
You’d think that the range of a car running on compressed air would be pretty limited, but it’s claimed that the air car can travel almost 1,200 miles without refueling. The average city driver travels less than 100 miles a day.
Recharging the compressed air tank can take only three or four minutes at a filling station and the cost per mile is about six cents. The proposed top speed for the MDI air car on the highway is 120 mph. Only race car drivers have the reflexes for those speeds. I suspect the lightweight, boxy-looking MDI vehicle would be hard to keep on the road at those speeds.
While conventional internal combustion engines produce heat, the effect of the expanding air as it leaves the compressed tank is the opposite. Anyone who has ever punctured a gas cylinder like those used for recharging fire extinguishers or for air-powered model planes, knows that as the cylinder is discharged it gets cold enough to freeze your hands.
As the MDI car’s air expands to run the engine, the exhaust exits at a temperature below zero, so it can be channeled into the car’s air conditioning.
Astute Michigan drivers will immediately realize that with no engine heat to channel into the passenger compartment, the MDI needs a heater. Our old VW bus was a deep freeze in the UP winters. Some VW vans used to have a scary supplemental heater that burned gasoline with all the risks of carbon monoxide, fire, and reduced gas mileage that went with them. Before we threw in the towel on our old VW bus, we used a catalytic space heater to cut the chill in winter, not a particularly safe alternative. The air car will need something for Michigan winters or it will be limited to summer driving.
The rest is engineering and specifications you can fetch off the MDI, Moteur Development International, web site. Yes, it’s foreign. You might have guessed that an environmentally friendly vehicle of the future would not come out of Detroit.
If you’re wondering how much they cost and where you can buy one, the projected price for the city version of the MDI car in Europe is about $10,000. The company that developed the car wants to license its patents to other manufacturers.
Also in the news, a company in India has obtained a new patent for a compressed air car and is putting it into production.
Living up to U.S. safety specs can be daunting. VW enthusiasts know, for instance, that the old VW bug produced in South America could not be here because it didn’t meet U.S. standards. When we imported our 1956 VW Kombi, I had to replace the headlights, the turn signals, and eventually jury rig a windshield washer with a foot-powered pump!
As the problems of fuel shortages, global warming, city congestion, and simply the aggravation of hunting for a parking place become ever more acute, we’ll be seeing more and more tiny, lightweight vehicles like the MDI air car in our cities.
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