How liquid nitrogen could be used to power cars
Hydrogen fuel cell-powered cars have been touted as the next big thing when it comes to enviro-friendly transportation, but thanks to another abundant element, we could have one more alternative to gas-guzzling vehicles on our hands. So what is this next next big thing in renewable energy? Liquid nitrogen, says a group of British engineers.
According to a new report in the Economist, liquid nitrogen may just be a viable alternative to hydrogen fuel cells. As long as its storage container is well insulated, the liquid nitrogen can be kept at atmospheric pressure for long periods of time and since it’s dense and able to store significant amounts of energy per unit volume, cars can travel for a far distance on a tankful of it.
As SmartPlanet’s own Mark Halper pointed out earlier this month, the idea of liquid nitrogen as a power source has recently gained steam thanks to a new method of creating and storing liquid air. Developed by British engineer Peter Dearman, the method involves using nighttime electricity generated by wind turbines to cool air down to the point that it becomes liquid. This liquid is then stored in a vacuum, and heated back into gas at a later time.
Thanks to a novel engine design created by Dearman, liquid nitrogen could potentially be used to power cars.
The Economist describes the process:
A breakthrough in engine design has made liquid nitrogen an even more attractive alternative than the lithium-ion batteries used in electric cars. An invention made by an independent British engineer called Peter Dearman dispenses with the costly heat exchanger that is needed to vaporise the liquid nitrogen quickly. Instead, a small amount of water and anti-freeze (eg, methanol) is injected into the cylinder just as the liquid nitrogen is drawn in, causing it to boil and expand rapidly — thereby forcing the piston down inside the the cylinder.
The article also points to other benefits of liquid nitrogen including the fact that a liquid-nitrogen car is likely to be cheaper to build than an electric vehicle since it doesn’t need to withstand high temperatures and could therefore be made from cheap alloys or plastics. It would also be lighter and cheaper than an electric vehicle because it wouldn’t need bulky and expensive lithium-ion batteries.
Issues of safety and production as well as an industry inclination to stick with electric cars may mean that liquid nitrogen cars won’t ever see the light of day, but as Halper pointed out, you certainly have to admire Dearman’s “imaginative engineering.”
Image: Wikimedia Commons