Hydrogen is the lightest element on the periodic table and has been used for a variety of purposes. Petroleum and chemical companies use it to access and refine crude oil and in the creation of commercial products such as margarine. At one time, companies used it to elevate blimps and airships, but its combustible nature has led to disfavor in this application. Different forms of hydrogen have been utilized for a wide range of scientific applications, and it may be a source for clean or low-emission power in the future.
Commercial and Consumer Uses
Companies in the petroleum and chemical industries often use hydrogen in significant quantities. In a petrochemical plant, it can be used for hydrodesulfurization, which removes sulfur from other natural gas, and hydrocracking, a process by which complex chemicals are broken down into simpler components. Food companies often use it to hydrogenate oils or fats, which permits the production of margarine from liquid vegetable oil. Chemists also use it to produce methanol and hydrochloric acid, both of which can be used commercially or as part of consumer products.
Past Use in Aviation
In the early 20th century, hydrogen was used as a lifting gas for airships. This ended in 1937, however, when the Hindenburg disaster effectively brought an end to airships for commercial travel. While the exact cause of the disaster remains unknown, some individuals blamed it on the fuel. Modern zeppelins and blimps use helium or heated air.
Applications in Science and Manufacturing
Hydrogen also has applications in physics and engineering. It is used as a shielding gas for welding, isolating the site of the weld from atmospheric gases such as oxygen and nitrogen. Some companies use it for cooling rotors in electrical power generators because of its high thermal conductivity. In its liquid form, it is colder than 14° Kelvin (K), so scientists have used it for research in cryogenics and superconductivity.
Hydrogen's isotopes, especially deuterium, are used in nuclear reactors. Deuterium can be used as a neutron moderator for fission reactions, in which an atom is split, or a fuel for fusion reactions, in which atoms are combined. Tritium, another isotope, acts as a radiation source in luminous paints and is a component in some bombs.
Clean Fuel and Power
In the early 21st Century, using hydrogen as a clean fuel became an increasingly attractive prospect. It is so light, however, that all atmospheric hydrogen has evaporated into space, which means it needs to be created artificially. The environmentally friendly nature of using it to create fuel cells was somewhat questionable, since large quantities of fossil fuels may be consumed to generate it. As technology has improved, new methods for creating these fuel cells have been developed that make them more practical and "cleaner" than directly using fossil fuels.