How Green is your Hydrogen?

Hydrogen is emerging as an exciting future energy source to help drastically cut emissions from those ‘hard to decarbonise’ sectors (heat, transport and industry) that have haunted the dreams of our Energy and Environment Ministers over the last decade.

However, not all hydrogen is created equal. At the point at which we use hydrogen it may have no emissions, but hydrogen doesn’t just appear as a CO2 free miracle gas, it has to be produced, and this can happen in a myriad of ways with varying levels of CO2 emissions.

Hydrogen from electrolysis is often termed ‘green’ hydrogen, whilst hydrogen from natural gas using a Steam Methane Reformer (SMR) is sometimes called ‘brown’ hydrogen, or ‘clean’ hydrogen when it is partnered with carbon capture and storage (CCS).

I’d argue that these adjectival descriptions have reached the end of their useful life, since, for example, it is possible to use grid electricity for electrolysis, which may have been generated by fossil fuels, including, in some countries, coal.

So as the hydrogen economy develops, it’s important that we have a clear and simple method of communicating what emissions are associated with different types of hydrogen production.

As a starting point, I’m proposing an emissions performance chart like the one shown. Simple, colourful and in keeping with other energy sources and products.

Carbon intensity hydrogen

A numerical analysis and simple presentation chart would help progress our understanding of hydrogen production emissions. To allow for accurate emissions analysis, we need transparency on the chain of energy required to produce the hydrogen, including consideration of any transport or storage for either the hydrogen or its original energy source.

The chart shown is proposed as a starting point for describing emissions. Further detailed work is required to calculate emissions for different hydrogen production methods at specific sites, so that performance levels can be fairly compared.


This article was co-written by Kirsty Lynch and Sam Gomersall.

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