How is hydrogen produced?
To produce hydrogen, it must be separated from the other elements in the molecules where it occurs. Hydrogen atoms can be separated from water; from hydrocarbons in coal, petroleum, and natural gas; and from biomass.
The two most common methods for producing hydrogen are steam-methane reforming and electrolysis (water splitting).
Steam-methane reforming is a widely used method of hydrogen production
Steam-methane reforming is currently the least expensive way to produce hydrogen, and it accounts for nearly all commercially produced hydrogen in the United States. Commercial hydrogen producers and petroleum refineries use steam-methane reforming to separate hydrogen atoms from carbon atoms in methane (CH4). In steam-methane reforming, high-temperature steam (1,300°F to 1,800°F) under 3–25 bar pressure (1 bar = 14.5 pounds per square inch) reacts with methane in the presence of a catalyst to produce hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide.
Natural gas is the main methane source for hydrogen production by industrial facilities and petroleum refineries. Landfill gas/biogas is a source of hydrogen for several fuel cell power plants in the United States. Biofuels and petroleum fuels are also potential methane sources.
Electrolysis uses electricity
Electrolysis is a process that splits hydrogen from water using an electric current. The process can be used on a large or small scale. On a large scale, the process may be referred to as power-to-gas, where power is electricity and gas is hydrogen. Electrolysis does not produce any emissions other than hydrogen and oxygen. The electricity used in electrolysis can come from renewable sources such as hydro, wind, or solar energy. If the electricity used in electrolysis is produced from fossil fuels, then the pollution and carbon dioxide emissions produced from those fuels are indirectly associated with electrolysis.
Other methods of producing hydrogen
Research is underway to develop other ways to produce hydrogen, such as
- Using microbes that use light to make hydrogen
- Converting biomass into gas or liquids and separating the hydrogen
- Using solar energy technologies to split hydrogen from water molecules
Last updated: January 21, 2020