Hydrogen is colorless, odorless, tasteless and non-toxic. It is a gas at temperatures above -423° F and is highly diffuse, having a density approximately 14 times less than that of air. Because it is buoyant and diffusive, hydrogen dissipates quickly in open areas and can move through small spaces, which makes it difficult to store. Hydrogen is flammable over a broad range of gas concentration (from 4 to 74 percent), although its lower flammability limit – that is, the lowest temperature and pressure at which it will combust – is higher than those for some common fuels such as gasoline, propane or diesel.1
Hydrogen has been described as “the fuel of the future.”
On Earth, hydrogen is found in combination with other elements such as carbon (hydrocarbons), oxygen (water) and nitrogen (ammonia). Although hydrogen may sometimes be used as a fuel, it is most often used as an energy carrier, such as electricity, and not an energy source. To make hydrogen a usable, stand-alone fuel, it must be separated from these other elements by chemical, thermal or electrochemical processes.
boothreb99 on 11 Mar 13"Such a system, experts say, would effectively eliminate most of the benefits offered by hydrogen. Although the fuel-cell cars themselves may emit nothing but water vapor, the process of producing the fuel cells from hydrocarbons will continue America's dependence on fossil fuels and leave behind carbon dioxide, the primary cause of global warming."
