Hydrogen Production Methods

Hydrogen is an abundant element of earth but is almost always found as a compound such as water (H2O). Before the hydrogen can be used as a usable fuel source it needs to be separated from is compound.

Hydrogen can be produced from a number of resources which may include fossil fuels, biomass, and water. The environmental impact and energy efficiency are dependent on the process used and the compound from which the hydrogen is produced.

Processes like reforming use fossil fuels to produce hydrogen and therefore can’t be labeled as a clean energy source. On the other hand, electrolysis provided that the energy being used for the separation process is coming from a renewable source can be a 100% clean energy source (not taking into account the manufacturing process of the renewable energy equipment).

Ultimately the aim will be to move to a clean hydrogen production process, but this will take time. For hydrogen to become the main source of energy it will have to go through a process that may include hydrogen production using technologies such as reforming.

Schematic of near-term, mid-term, and long-term hydrogen production pathways.

There are a number of ways to produce hydrogen:

  • Natural Gas Reforming/Gasification
  • Electrolysis
  • Renewable Liquid Reforming
  • Fermentation

Other hydrogen production technologies in development:

  • High-Temperature Water Splitting
  • Photobiological Water Splitting
  • Photoelectrochemical Water Splitting

Natural Gas Reforming/Gasification

Gas reforming or gasification produces a product called Synthesis Gas. Synthesis gas a mixture of hydrogen, carbon monoxide and a small amount of carbon dioxide. The production process involves the reacting of natural gas with high-temperature stream. In the production process, the oxygen in water is combined with the carbon monoxide leaving behind liberated hydrogen. Gasification currently is the cheapest and most efficient way to produce hydrogen and makes up the bulk of all hydrogen produced.

Electrolysis

Electrolysis is the most enviro-friendly method to produce hydrogen if the electricity used in the production process comes from a renewable energy source. Electrolysis uses an electric current applied to water to separate the hydrogen from the oxygen in a process called electrolysis.

Renewable Liquid Reforming

Renewable liquid reforming is similar to that of gasification but makes use of a renewable source such as ethanol.

Fermentation

Biomass is converted into sugar-rich feedstocks that can be fermented to produce hydrogen.

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, producing hydrogen as a by-product.

Photoelectrochemical Water Splitting

Photoelectrochemical systems produce hydrogen from water using special semiconductors and energy from sunlight.

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