Cryogenics is the science of dealing with the production of and effects of very low temperatures. However, there’s some debate over how low ‘low temperature’ must be to qualify as cryogenic. Some say lower than -1000C. Others, such as NIST, put it at below -1500C. At these temperatures most gases become liquid, which gives them some interesting uses. Cryogenic temperatures are mostly produced through the Joule-Thomson effect, which takes advantage of the relationship between pressure, temperature, and volume.
Gas producer, Air Products (AP), recently unveiled a solar-powered hydrogen fueling station. Their SmartFuel® technology uses electrolysis to make hydrogen from water, so providing fuel cell vehicles with power that’s truly ‘green.’
Fuel cells, which produce electricity by combining hydrogen and oxygen, offer a tantalizing glimpse of an oil-free future. An alternative to carrying heavy batteries, a fuel cell-powered car needs only a supply of hydrogen to generate all the energy it needs.