This Car Runs on Thin Air!

Can noncombustion technology create a no-pollution way to drive? Imagine pulling into a service station to fuel up your car. But not at the gas pump or electric battery charger—at the air pump! That's not hot air, either! The next generation of cars may run on thin air. Wouldn't that be an incredible way to cut both pollution and dependence on foreign oil?

If you've ever inflated a balloon and then let it go, you've got the basics to test-drive the amazing MiniCAT, currently being developed by Moteur Développement International (MDI), headquartered in Luxembourg. Invented by Formula One racing car designer Guy Negre, this experimental vehicle is unlike any car you've ever seen. While your family's traditional sedan or SUV draws its horsepower using combustion (flammable gasoline explodes inside the engine's cylinders), the only fuel that MiniCAT needs (CAT stands for Compressed Air Technology) is the air we breathe.

Start with about 25,000 gallons of air (enough air to fill a small house). Now, squash it all into a space smaller than your school locker—because that's the size of two super-strong, high-pressure air tanks, custom-fabricated from exotic, spun-carbon fiber and mounted beneath the air car.

Talk about a tight squeeze! Confining that much air inside those little tanks (it's done using special compressors) generates an internal pressure of over 4,000 pounds per square inch. That's over 300 times normal air pressure.

When this cold, high-pressure air enters MiniCAT's unique, multichambered engine, it interacts with warmer air to create pressure waves that pump the engine's ingeniously engineered pistons to propel the car. MiniCAT's projected top speed is 60 miles per hour, with a range of 120 miles on a full air supply.

And pollution? Traditional internal combustion engines spew out carbon monoxide and other poisonous hydrocarbons, producing smog that is dangerous to human health and greenhouse gases that contribute to global warming. MiniCAT's only exhaust is air—filtered so that it's cleaner than the air we breathe. This negative contamination (called “minus pollution”) marks a revolutionary advance. While driving an ordinary car increases pollution, driving a MiniCAT actually cleans the atmosphere. That's not just zero pollution—it's even better!

Because there's no fuel burned, this car's air-exhaust comes out cold—so cold, at minus 22 degrees F, that you can blow it inside the car to produce no-cost air conditioning! In fact, this car's advanced, four-cylinder engine runs so clean that it's lubricated using just three and a half cups of vegetable oil! (Like you'd put in a salad—just change it every 30,000 miles!) The air car engineers are also experimenting with Earth-friendly body panels made from natural hemp fiber and mounted on an aircraft-inspired aluminum chassis.

Are you ready to take a test drive?

With no combustion (explosions) in the engine's cylinders, MiniCAT's ride is extremely quiet. Need to slow down for a curve? MiniCAT's brakes reduce the car's speed—but they also refuel the car! Called “regenerative braking,” this works by absorbing the energy of the car's forward motion to operate a pump that raises the pressure in the air tanks. That extra pressure later helps run the car. Stop at a red light, and the engine literally stops, too—another feature to conserve power. The really cool part is the engine's automatic and instantaneous restart when you step on the gas pedal.

When it's time to refuel, just pull into an air station—where in three minutes, via a high-pressure hose, your air tanks are refilled. At home, simply plug MiniCAT's onboard electric air compressor into an ordinary wall socket (like running a tire pump from your car's cigarette lighter). Projected cost to fill your tank? About two dollars—or 1.6 cents per mile.

When you leave the city, flipping a switch will turn MiniCAT into a standard gasoline car. That's because the MDI engine is an “ultra hybrid”; the same engine that “breathes” compressed air to run pollution-free in populated areas burns combustion fuels (gas, diesel, or liquefied natural gas) in rural places, where emissions are less of a problem.

So will your family's next car be air-powered? MDI debuted its vehicles at Johannesburg, South Africa, in 2000, offering an opportunity for the developing world to enter the Auto Age without the pollution of gasoline. A fleet of 40,000 compressed air taxicabs is already planned to replace gasoline-powered taxis in heavily polluted Mexico City. Instead of building huge auto factories (which create lots of pollution, too), MDI plans small regional plants to conserve land and labor use. Sites in cities from Paris to Tel Aviv are already in development.

Of course, this new technology has its critics. Some argue that air power really only moves pollution from one place to another, especially since the air stations used to refuel the cars run their compressors on energy derived from fossil fuels. Like many new technologies, air cars are still experimental, so they don't run perfectly yet—prompting other opponents to say about the air car, “Don't hold your breath!”


A solid cylinder or disk that fits snugly into a larger cylinder and moves under fluid pressure.

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  1. What is one simple machine that you learned about in Lesson 3 that you could find inside of the MiniCAT?
  2. Since the MiniCAT's top speed is 60 miles per hour, would this car be most useful in an urban, suburban, or rural area? Why?
  3. What is one drawback that some people see in the MiniCAT?
  4. Think about another device that can benefit the environment and also uses a wheel and an axle: the wind turbine. The wind blows and turns the blades of the wind turbine. The blades then turn an axle. Wind turbines turn the kinetic energy of wind into power for other things, such as batteries and appliances. Although wind turbines have environmental benefits, they also have drawbacks. Some people think entire hillsides covers with wind turbines is an ugly sight.
    Waves are a form of naturally occurring kinetic energy in the ocean. Scientists have invented a machine that floats on the surface of the water and captures wave energy. Write a short paragraph about the potential benefits and drawbacks of a machine that captures wave energy. How might the energy be used? What are some of the potential drawbacks? Think about where the machines would be located. How would the machines be fixed if they broke? Where might the energy they capture be stored? What effect might they have on the plants and animals around them?