Hydrogen Cars

Hydrogen Cars could be around the corner as experiments onboard the International Space Station could accelerate the drive toward a hydrogen-based economy.

Imagine pulling up to a filling station, inserting the nozzle into the tank and the gas flowing into your tank is ... hydrogen. It's colourless, odourless and the byproduct of burning hydrogen is water vapour, quickly and safely absorbed by the environment. One pound of hydrogen supplies three times as much energy as a pound of gasoline. And it's the most plentiful element in the universe! No wonder scientists are trying to figure out how to make hydrogen work as a practical fuel.

"Dozens of companies, including all the major automobile manufacturers, have designed engines that burn hydrogen - they're a lot like the internal combustion engines we have in cars today," says Al Sacco, director of the NASA-supported Centre for Advanced Microgravity Materials Processing (CAMMP) at Northeastern University in Boston. "Fuel cells - another possible source of power for cars - use hydrogen, too. To make these technologies work in the real world, scientists must find a way to store and transport hydrogen safely at a cost comparable to that of gasoline which powers the cars we use today."

It's not easy: Hydrogen gas is light and elusive. Tiny H₂ molecules like to sneak through cracks and seals - and once free they quickly disperse. Hydrogen diffuses four times faster than methane and ten times faster than gasoline vapours. This is great for safety because a leak is quickly diluted and rendered harmless. It's a headache for anyone who wants to store the gas.

Credit and copyright: Fuel Cell Today A prototype hydrogen fueling station in Las Vegas, NV.

Liquid hydrogen is more compact and easier to contain, but it can be troublesome, too. Hydrogen liquefies at a temperature of about 20^oK (-253^oC). Maintaining a tank full of liquefied hydrogen requires a heavy cryogenic support system, which may not be practical for passenger cars. Liquid hydrogen is actually cold enough to freeze air. This could cause plugged valves and unwanted pressure build-ups. Insulation to prevent such problems adds to the weight of the storage system.