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Hydrogen (H2) is the simplest and most abundant element in the universe. It exists in water, hydrocarbons (such as methane), and organic matter. Hydrogen fuel is a colorless, odorless gas at ambient temperature and atmospheric pressure. In nature hydrogen bonds with other elements, therefore pure hydrogen gas must be produced by separating it from other compounds.

Hydrogen Production and Distribution

Although abundant on earth as an element, hydrogen is almost always found as part of another compound, such as water (H₂O) or methane (CH₄), and it must be separated into pure hydrogen (H₂) for use in fuel cell electric vehicles. Hydrogen fuel combines with oxygen from the air through a fuel cell, creating electricity and water through an electrochemical process.

Production

Hydrogen can be produced from diverse, domestic resources, including fossil fuels, biomass, and water electrolysis with electricity. The environmental impact and energy efficiency of hydrogen depends on how it is produced. Several projects are underway to decrease costs associated with hydrogen production.

There are several ways to produce hydrogen:

• Natural Gas Reforming/Gasification: Synthesis gas—a mixture of hydrogen, carbon monoxide, and a small amount of carbon dioxide—is created by reacting natural gas with high-temperature steam. The carbon monoxide is reacted with water to produce additional hydrogen. This method is the cheapest, most efficient, and most common. Natural gas reforming using steam accounts for the majority of hydrogen produced in the United States annually.

  A synthesis gas can also be created by reacting coal or biomass with high-temperature steam and oxygen in a pressurized gasifier. This converts the coal or biomass into gaseous components—a process called gasification. The resulting synthesis gas contains hydrogen and carbon monoxide, which is reacted with steam to separate the hydrogen.

• Electrolysis: An electric current splits water into hydrogen and oxygen. If the electricity is produced by renewable sources, such as solar or wind, the resulting hydrogen will be considered renewable as well, and has numerous emissions benefits. Power-to-hydrogen projects are taking off, using excess renewable electricity, when available, to make hydrogen through electrolysis.
• Renewable Liquid Reforming: Renewable liquid fuels, such as ethanol, are reacted with high-temperature steam to produce hydrogen near the point of end use.
• Fermentation: Biomass is converted into sugar-rich feedstocks that can be fermented to produce hydrogen.

Several hydrogen production methods are in development:

• High-Temperature Water Splitting: High temperatures generated by solar concentrators or nuclear reactors drive chemical reactions that split water to produce hydrogen.
• Photobiological Water Splitting: Microbes, such as green algae, consume water in the presence of sunlight and produce hydrogen as a byproduct.
• Photoelectrochemical Water Splitting: Photoelectrochemical systems produce hydrogen from water using special semiconductors and energy from sunlight.

The major hydrogen-producing states are California, Louisiana, and Texas. Today, almost all the hydrogen produced in the United States is used for refining petroleum, treating metals, producing fertilizer, and processing foods.

The primary challenge for hydrogen production is reducing the cost of production technologies to make the resulting hydrogen cost competitive with conventional transportation fuels. Government and industry research and development projects are reducing the cost as well as the environmental impacts of hydrogen production technologies. Learn more about hydrogen production from the Hydrogen and Fuel Cell Technologies Office.