If hydrogen is the answer to energy security, let’s talk carbon, not colour
We are on the brink of a clean-hydrogen revolution, but we need a change of language and the development of a global clean hydrogen market.
Maurits van Tol
CTO, Johnson Matthey
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The simplest and most abundant element in the universe is key to tackling Earth’s most challenging problem – climate change. It is an oft-repeated joke that ‘hydrogen is the fuel of the future, and always will be’, but its time really has come at last. Soon we will see hydrogen working alongside other green technologies – cutting carbon emissions and helping to achieve net zero.
Hydrogen can help decarbonise activities that electrification cannot. Think shipping, HGV trucks and buses, and industrial processes that need very high temperatures, such as steelmaking. We cannot reach net zero without it.
Technological advances in this field are everywhere. Johnson Matthey’s HyCOgen process, for example, uses clean hydrogen and atmospheric or waste CO₂ to produce syngas, which can be upgraded into sustainable aviation fuel, for example, and dropped into existing supplies (Johnson Matthey, 2022a).
As a fuel, hydrogen leaves behind only water, and none of the CO₂ or pollutants associated with fossil fuels. But before we can really declare this to be a clean-energy vector, we need to consider the carbon footprint associated with its production, and it is here that things start to get complicated.
Right now, most hydrogen is made by reforming natural gas – a process that creates so-called ‘grey hydrogen’. But this process also yields CO₂, making it ripe for replacement.
We will rely on two technologies in the future: the first is ‘blue hydrogen’ – created in the same way as grey, but with the troublesome CO₂ captured and stored. Second, there is green hydrogen, produced by the electrolysis of water using electricity from renewable sources, such as wind or solar.
There is a rainbow of colours, too, including pink (nuclear), turquoise (methane pyrolysis), and even white (naturally occurring and mined from rock).
However, I believe the hydrogen colour naming convention does not tell the full story. Though an engaging and memorable way to classify what is, ironically, a colourless gas, what is needed now is a more nuanced approach to hydrogen nomenclature.
Let’s talk carbon
It is more appropriate to talk about the carbon intensity of hydrogen. The ease of the colour-naming convention tends to invite simplistic comparisons of hydrogen production routes. For instance, it is common to see arguments favouring green hydrogen (electrolysis from renewable electricity) over blue hydrogen (natural gas + CCS) because the blue variant still produces CO₂ and uses a fossil fuel (natural gas) as a feedstock, and dealing with this is both expensive and has a carbon footprint all of its own.
However, this argument fails to acknowledge the ease with which existing grey hydrogen plants can be retrofitted with CCS to make them blue – a process that has a much smaller carbon footprint than building a green hydrogen plant from scratch. For instance, JM’s suite of CLEANPACE technologies enables the revamp of steam methane reformers with existing, proven technology to achieve CO₂ emission reductions of up to 95% (Johnson Matthey, 2022b).
Such retrofitted blue hydrogen plants have an important role to play in expanding the hydrogen market in which new blue hydrogen plants, and green hydrogen electrolysis facilities, can then thrive.
The colour naming convention also fails to take into account the technology variations within these categories. As analysis by the Hydrogen Council shows, the greenhouse gas emissions associated with green hydrogen production depend on how the electricity was generated (Hydrogen Council, 2021).
Similarly, a blue hydrogen analysis by UK government department BEIS highlights the impact of the reforming method on lifecycle emissions, with autothermal reformers (ATR) being more efficient and more compatible with CCS than steam methane reforming (SMR). Though, it is also worth noting that half of the hydrogen produced through SMR actually comes from the water used, not the methane (UK Gov BEIS, 2021).
At JM, our own LCH technology captures more than 95% of associated CO₂ emissions, and has excellent environmental credentials for ATR blue hydrogen production (Johnson Matthey, 2022c).
Blue hydrogen is often looked on as an intermediate technology – something to tide us over until green hydrogen electrolysis plants are ready to take over. We don’t see things this way.
Rather than two opponents – one in the blue corner, the other in the green corner, slugging it out for supremacy – we see blue hydrogen and green hydrogen as being pieces of the same jigsaw. In the future, we will need both methods, working together to diversify supply and boost energy security.
Diversity is important to insulate the market from price fluctuations. Both of these hydrogen generation methods have dependencies: CCS network capacity and natural gas prices in the case of blue hydrogen; and the availability and price of low-carbon electricity for green.
Other factors to consider are speed and scale: blue hydrogen is ready to go now; green hydrogen will need until about 2030. At JM, we believe every molecule of CO₂ entering the atmosphere is a problem – and something that blue hydrogen can help prevent in the short and medium term.
Blue hydrogen’s potential to ‘move the needle’ quickly can be seen in the HyNet clean hydrogen project in the North West of the UK, which has adopted JM’s LCH technology. When this comes on-stream in 2025, production capacity will be 3 TWh, with the potential to scale to 30 TWh by 2030. In contrast, Shell Rotterdam – reported to be Europe’s biggest renewable electrolytic hydrogen production facility – will produce about 1 TWh when it comes on stream in 2025 (HyNet North West, 2022).
The suitability of hydrogen production methods will also change according to location. Newly built blue hydrogen plants will often be more attractive to countries that have reserves of natural gas and the geological formations to deal with the captured CO₂. The HyNet project in the UK is a great example.
On the other hand, green hydrogen will suit territories that have an abundance of renewable electricity. For example, in NEOM – Saudi Arabia’s futuristic city under construction – the country’s bountiful solar and wind resources will help produce 1.2 million tonnes of green hydrogen every year by 2026 (NEOM, 2022).
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