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Hydrogen Basics

Source: U.S. Department of Energy

The U.S. Department of Energy is working to build a new energy economy based on hydrogen. In the hydrogen future, we will use energy produced from a variety of sources, including fossil fuels and renewable sources, like the sun, the wind and even water. Read on to learn

What Makes Hydrogen so Useful for Energy Production?

Hydrogen is the simplest element and most plentiful gas in the universe. Yet hydrogen never occurs by itself in nature—it always combines with other elements such as oxygen and carbon. Once it has been separated, hydrogen is the ultimate clean energy carrier. How clean? Clean enough that the U.S. Space Shuttle program relies on hydrogen-powered fuel cells to operate shuttle electrical systems, and the crews drink one of the byproducts: pure water! Hydrogen is an obvious alternative to hydrocarbon fuels, such as gasoline. It has many potential uses, is safe to manufacture, and is environmentally friendly. Today many technologies exist that can use hydrogen to power cars, trucks, electrical plants, and buildings—yet the absence of an infrastructure for producing, transporting, and storing large quantities of hydrogen prevents its practical use.

How is Hydrogen Produced?

Most methods of producing hydrogen involve splitting water (H2O) into its component parts of hydrogen (H2) and oxygen (O). The most common method involves steam reforming of methane (from natural gas), although there are several other methods.

Steam reforming converts methane (and other hydrocarbons in natural gas) into hydrogen and carbon monoxide by reaction with steam over a nickel catalyst

Electrolysis uses electrical current to split water into hydrogen at the cathode (+) and oxygen at the anode (-)

Steam electrolysis (a variation on conventional electrolysis) uses heat, instead of electricity, to provide some of the energy needed to split water, making the process more energy efficient

Thermochemical water splitting uses chemicals and heat in multiple steps to split water into its component parts

Photoelectrochemical systems use semi-conducting materials (like photovoltaics) to split water using only sunlight

Photobiological systems use microorganisms to split water using sunlight

Biological systems use microbes to break down a variety of biomass feedstocks into hydrogen

Thermal water splitting uses a very high temperature (approximately 1000°C) to split water

Gasification uses heat to break down biomass or coal into a gas from which pure hydrogen can be generated

What's Preventing Wide-Scale Hydrogen Production Today?
Cost is the biggest impediment to using hydrogen more widely as a fuel. Many expensive changes must be made in our nation's energy infrastructure to accommodate hydrogen. For example, electricity is required by many hydrogen production methods, which makes hydrogen more expensive than the fuels it would replace.