The challenges facing the adoption of green hydrogen

Dr Rod Crompton, visiting adjunct professor in the African Energy Leadership Centre at Wits Business School, and Dr Bruce Douglas Young, senior lecturer at the centre, explain green hydrogen’s potential benefits, and the challenges that need to be overcome before it can be used on a wide scale.

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Hydrogen is used mainly to make chemicals such as fertiliser, and in oil refineries. Most hydrogen in the world today is made from natural gas or coal, using methods associated with large carbon dioxide emissions. Developed countries are therefore looking to ‘green hydrogen’ instead, which is produced using renewable electricity such as solar and wind power.

GREEN HYDROGEN IS EXPENSIVE

Global hydrogen demand reached 94 million tons in 2021, and contained energy equal to about 2,5% of global final energy consumption. Only about 0,1% of current global hydrogen production is green, but big expansions are planned. New applications for green hydrogen are also envisaged.

Since the objective of using green hydrogen is really to reduce carbon dioxide, the applications to target first should be those that will yield the largest reductions in emissions. The manufacturing of fertiliser is a strong potential market for the efficient use of green hydrogen.

But green hydrogen currently costs much more to make than less clean types of hydrogen. Using it to produce the 180 million tons of ammonia required per annum globally for fertiliser production would have a severe knock-on effect on food prices. So it is difficult to see how this transition is going to occur.

HOW IS GREEN HYDROGEN MADE?

Green hydrogen is made from water. Using renewable (‘green’) electricity, equipment called electrolysers separate the hydrogen from oxygen in water. The process is called electrolysis.