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Top 10 Alternative Fuels on the Road Right Now


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Liquid Nitrogen
Dr. Carlos Ordonez takes the "CooLN2Car" for a spin across the campus of the University of North Texas in Denton, Texas, on Aug. 18, 1997. The car, a 1973 Volkswagen, runs on liquid nitrogen and has a top speed of 25 miles per hour.
Dr. Carlos Ordonez takes the "CooLN2Car" for a spin across the campus of the University of North Texas in Denton, Texas, on Aug. 18, 1997. The car, a 1973 Volkswagen, runs on liquid nitrogen and has a top speed of 25 miles per hour.
AP Photo/Eric Gay

Liquid nitrogen is another alternative fuel. Like hydrogen, nitrogen is abundant in our atmosphere. Also like hydrogen, nitrogen-powered cars make fewer harmful emissions than gasoline or diesel. But while hydrogen is used in fuel cell cars as well as hydrogen-combustion engines, liquid nitrogen cars use a different type of engine altogether.

In fact, a liquid nitrogen car uses an engine similar to the engine used in a compressed-air car. In a liquid nitrogen car, the nitrogen is kept cold, keeping it in a liquid form. To power the car, the nitrogen is released into the engine where it is heated and it expands to create energy. While a typical gasoline- or diesel-powered engine uses combustion to move pistons, a liquid nitrogen engine uses the expanding nitrogen to power turbines.

While it's a clean an efficient way to power a vehicle, liquid nitrogen faces the same hurdles as many other alternative fuels: At this time, there's no nationwide network of fueling stations to deliver it to consumers.