HYDROGEN

Hydrogen is the simplest element. An atom of hydrogen consists of only one proton and one electron. It's also the most plentiful element in the universe. Despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas on the Earth - it's always combined with other elements. Water, for example, is a combination of hydrogen and oxygen (H2O). Hydrogen is also found in many organic compounds, notably the hydrocarbons that make up many of our fuels, such as gasoline, natural gas, methanol, and propane. Hydrogen can be separated from hydrocarbons through the application of heat - a process known as reforming. Currently, most hydrogen is made this way from natural gas. An electrical current can also be used to separate water into its components of oxygen and hydrogen. This process is known as electrolysis. Some algae and bacteria, using sunlight as their energy source, even give off hydrogen under certain conditions. According to the majority of energy experts and researchers, hydrogen is currently impractical as an alternative to fossil-based liquid fuels. While hydrogen has a very high energy content by weight, it has a very low energy content by volume, making it very challenging to store in average-sized vehicles. Hydrogen can be stored as compressed hydrogen, as cryogenic liquid hydrogen, or in compounds containing hydrogen which must undergo a chemical change to release the gas such as metal hydrides.[10] However, because of the lower volumetric energy, hydrogen gas tanks would need to be two to three times as large for compressed hydrogen storage as conventional gasoline tanks.Today, there are an estimated 400 to 500 hydrogen-fueled vehicles in the U.S., mostly in California. Most of these vehicles are buses and automobiles powered by electric motors. They store hydrogen gas or liquid on board and convert the hydrogen into electricity for the motor using a fuel cell. Only a few of these vehicles burn the hydrogen directly (producing almost no pollution). The present cost of fuel cell vehicles greatly exceeds that of conventional vehicles in large part due to the expense of producing fuel cells. About 9 million metric tonnes of hydrogen are produced in the United States today, enough to power 20-30 million cars or 5-8 million homes. Nearly all of this hydrogen is used by industry in refining, treating metals, and processing foods. Most of this hydrogen is produced in just three states: California, Louisiana, and Texas.
The National Aeronautics and Space Administration (NASA) is the primary user of hydrogen as an energy fuel; it has used hydrogen for years in the space program. Liquid hydrogen fuel lifts the space shuttle into orbit. Hydrogen batteries—called fuel cells—power the shuttle’s electrical systems. The only by-product is pure water, which the crew uses as drinking water. Hydrogen fuel cells (batteries) make electricity. They are very efficient, but expensive to build. Small fuel cells can power electric cars. Large fuel cells can provide electricity in out of the way places with no power lines.
Because of the high cost to build fuel cells, large hydrogen power plants won't be built for a while. However, fuel cells are being used in some places as a source of emergency power to hospitals and to wilderness locations. Portable fuel cells are being sold to provide longer power for laptop computers, cell phones, and military applications.