The role of hydrogen

Hydrogen gas’ role in the energy transition has been ascribed enormous potential – offering a solution to several of the challenges faced in making the transition a reality. It could essentially replace fossil fuels with a clean energy source across the economy, with only water as a by-product.

It is important to note though that hydrogen is not a source of energy but is an energy carrier that is derived from another source of energy.
Although hydrogen has many advantages, there are sizable barriers and disadvantages that need to be overcome.

Advantages of hydrogen
  • Burns cleanly, releasing only water and energy.
  • Stores more energy per unit of weight than most other fuels.
  • Can be made from low-carbon sources.
  • Can be used as a fuel, to transport energy from one place to another, as a form of energy storage or as a chemical feedstock.
  • Can be used to decarbonise “hard to abate” sectors with few alternatives.
  • Offers wider benefits for energy security, industrial strategy and air quality.
Disadvantages of hydrogen
  • Almost all production of hydrogen today is from high-carbon sources.
  • Currently expensive to produce and cost reductions are uncertain.
  • Bulky and expensive to transport and store.
  • Inefficient to produce, raising costs and requiring a larger energy supply overall, with even faster scaling up of clean energy production.
  • Supply and value chains for its use are complex and need coordination.
  • Needs new safety standards and societal acceptance.
Types of hydrogen

Hydrogen is the lightest and most abundant element on the planet, but is not easily available as a gas, and so needs to be produced using different resources and processes. These combinations are often described in different colours – with brown, grey, blue, green and pink the main types. As almost all production of hydrogen today from high-carbon sources (grey or brown), the aim is to scale the other ‘colours’ to be able to produce ‘clean hydrogen’.

Brown hydrogen
Hydrogen extracted from coal, using the process of gasification

Grey hydrogen
Hydrogen extracted from natural gas, using steam-methane reforming

Blue hydrogen
Fossil-based (brown or grey) hydrogen production with carbon capture technology. Up to 90% of emissions can be captured and stored / reused this way.

Green hydrogen
Hydrogen produced by electrolysis (of water) using renewable energy sources. This process produces zero carbon (renewable) hydrogen.

Pink hydrogen
Hydrogen produced by electrolysis using nuclear power. Low carbon, but not renewable energy source. Also known as purple or red hydrogen.

Clean hydrogen
Typically refers to blue and green hydrogen.

Note: there are a number of other variants, including producing hydrogen through methane pyrolysis or electricity directly from the grid. However, the main focus current is moving from existing fossil based production to either low carbon (blue) or zero carbon (green) hydrogen.

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