Green hydrogen is hydrogen produced by electrolyzing water using electricity from renewable sources. It can help reduce emissions in some industries, but its benefit depends on the source of electricity and the efficiency of production, transportation, and end use.

From electricity to hydrogen

The electrolyzer separates water into hydrogen and oxygen. The system also needs to treat water, cool equipment, and compress or convert the gas into a form suitable for storage and transportation. Therefore, it is not enough to compare the analyst’s competence alone when evaluating the project; Energy consumption along the chain must be calculated.

Where can it be useful?

Using renewable hydrogen instead of hydrogen made from fossil fuels in industry is an obvious starting point. It may also serve some iron and steel applications, industrial fuels and long-term storage. When electricity can be used directly with greater efficiency, alternatives must be compared before choosing hydrogen.

Constraints to be calculated

  • Emissions: The absence of carbon dioxide at a certain point of use does not mean that the life cycle is emissions-free. The combustion of hydrogen in air may also produce nitrogen oxides.
  • Storage and transportation: Its low bulk density and pressure or cooling requirements make dealing with it an engineering challenge, rather than simply connecting it to any existing gas network.
  • Electricity and Water: The availability of renewable electricity, suitable water, and a suitable production location affects feasibility and cost.

Hydrogen is a means of carrying energy, not a primary source of it. The practical question is: Where does it achieve a benefit that exceeds the cost of producing and transforming it compared to alternatives?

Additional reading

IEA: Hydrogen.