Adapted from Where Does Green Hydrogen Fit? by Paul Martin, Chemical Engineer and Process Development Expert.
Hydrogen is having a wake-up call. In the span of a few days, the European Union was warned its hydrogen targets are “unrealistic”, the architect of Australia’s clean hydrogen strategy conceded it is difficult to see hydrogen heating homes, and energy giant Fortescue announced 700 job cuts and scaled back its renewable hydrogen ambitions.
These reports highlight the emerging gap between hydrogen hype and scientific reality. The hydrogen conversation is maturing, and approaching moments like the EU’s Clean Industrial Deal offer opportunity for policymakers to implement a targeted, science-based vision of its role in the energy transition – rather than give up on renewable hydrogen completely.
So, what next for hydrogen? If the world is to achieve net-zero emissions by 2050, it’s time to get serious about deploying renewable hydrogen – also known as green hydrogen – for truly no-regret sectors.
IEA (2024), Global low-emissions hydrogen production and COP28 pathway, 2030
This graph from the International Energy Agency illustrates the stark reality that the world is not on track to decarbonise current hydrogen production and use, thanks to the scarce supply of low-emissions hydrogen. This doesn’t even take into account experimental new uses that science shows can be more effectively decarbonised via direct electrification.
Let’s not forget that 99% of the world’s hydrogen is still made from fossil fuels without carbon capture and storage, and each year produces more emissions than the global aviation industry.
Near-zero-emission renewable hydrogen, made from renewable electricity, thus remains a vital part of the most effective path to global decarbonisation, and we need to take a prioritised approach to where it is used.
We must deploy renewable hydrogen to replace current polluting fossil hydrogen first, followed only by a small number of targeted sectors that lack alternative decarbonisation options like direct electrification.
This is because renewable hydrogen requires vast amounts of renewable electricity to produce, making it highly energy inefficient. It is very expensive, and in scarce global supply.
Ultimately, renewable hydrogen is a niche solution that makes scientific and economic sense for applications where we need the special chemical properties of hydrogen – which is largely where the world uses emissions-intensive fossil hydrogen today.
Here are the five sectors where we need renewable hydrogen to decarbonise the 120 million tonnes of fossil hydrogen already produced each year:
Ammonia for fertiliser
About a third of fossil hydrogen is used each year to make the chemical ammonia, by reacting hydrogen with nitrogen.
Most of this ammonia is used to produce nitrogen-based fertilisers, which are responsible via improved crop yields for feeding about half of all the humans and food animals on earth.
To achieve net-zero, it will be essential to decarbonise this ammonia with renewable hydrogen. In the long-term, this must be coupled with improved agricultural practices and an overall reduction in nitrogen fertiliser use to alleviate further emissions and environmental impacts that result when nitrogen fertilisers are applied to soils.
Despite this high priority use case, there are just a handful of projects seeking to decarbonise fertiliser production with renewable hydrogen because there is currently little incentive for farmers to pay a premium for greener fertiliser.
Supporting the greening of the fertiliser industry must therefore become a priority for hydrogen policymakers. Without adequate policy to direct renewable ammonia into fertiliser production, it risks being deployed for inefficient, potentially hazardous and low-priority end uses that subsidies currently incentivise, such as a fuel in power plants.
Petroleum refining
About a third of the world’s fossil hydrogen is produced and used each year in petroleum refining.
Hydrogen is used in refineries to remove toxic sulphur and nitrogen species from petroleum cuts that will later be burned in a process known as “hydrotreating”. It is also used in “hydrocrackers”, which hydrotreat a petroleum feedstock and break large molecules into smaller ones, with hydrogen ensuring stability in the final product.
In a decarbonised future, hydrogen demand in petroleum refining will shrink greatly. We will still refine some petroleum once the world stops burning fossil fuels to make certain chemicals and materials, but just 15-25% of current levels.
Ultimately, because some important refining processes also produce hydrogen as a byproduct, petroleum refining is likely to become almost self-sustaining with its production and use of hydrogen. It is therefore not the highest priority use for renewable hydrogen today, and focus should remain on eliminating the burning of fossil fuels in this sector.
Methanol
Fossil hydrogen is used today to make the chemical methanol, which is almost exclusively made from synthesis gas (mixtures of carbon monoxide and hydrogen) produced from natural gas or from gasifying coal.
Methanol is currently used to make many other important chemicals and materials, such as formaldehyde, formic acid, acetic acid, and certain important polymers, used in everyday products from paint to car parts. It is also used as a solvent and antifreeze agent.
In a decarbonised future, renewable methanol can be made using either biomass or biogenic carbon dioxide. Renewable hydrogen is needed in both these production processes. This bio-methanol is likely to be much cheaper than e-methanol made from hydrogen and carbon dioxide, and is a high priority use case for renewable hydrogen.
Direct chemical uses
Fossil hydrogen is currently used in many other chemical reactions, and as a reagent to prevent others from happening.
Hydrogen is used to protect metals from oxidation inside furnaces, to hydrogenate vegetable and animal oils, as a coolant in turbines and certain electrical equipment, and in a host of reactions such as making halo-acids, hydroformylations and many others.
These individual uses each consume a small percentage of world hydrogen production, but together add up to many millions of tonnes of hydrogen per year. All require hydrogen for its chemical properties, making their decarbonisation with renewable hydrogen a high priority.
Iron for steelmaking
A future no-regret use for renewable hydrogen is for the production of iron as a raw material for steelmaking.
The direct reduction of iron (DRI) from an ore to metal removes the need for traditional blast furnaces powered by coal-derived coke. It currently accounts for a small percentage of worldwide iron production, but already makes up about 10% of global hydrogen consumption.
Renewable hydrogen can replace fossil natural gas-derived syngas currently used for DRI, slashing carbon emissions in the overall steelmaking process. It is important to note that hydrogen in DRI is used for its chemical properties as a reducing agent, and not as a fuel.
DRI with renewable hydrogen is the route to cutting iron production emissions with the highest technology readiness level. While direct electric iron reduction technologies are under development, they are at an early stage and will take at least a decade to commercialise.
This is thus a sector where the use of renewable hydrogen is a high priority for decarbonisation, and a potential growth area for hydrogen consumption – specifically in locations where surplus renewable electricity generation capacity and iron ore are located close together.
So what next?
Current hydrogen production remains a major decarbonisation problem. Greening this sector with renewable hydrogen will be no small task, requiring almost three times the amount of wind and solar electricity that the world produced in 2019.
Existing fossil hydrogen use is likely to shrink in a decarbonised future if we reduce our reliance on fossil fuel-derived fertilisers and refining. At the same time, there will be some targeted new uses of renewable hydrogen, such as in the production of green steel.
Any new uses of renewable hydrogen should generally require hydrogen for its chemical properties, rather than for use as a fuel or energy storage medium, justifying the large energy losses involved in its production.
Hydrogen’s current use as a fuel is limited to a very small number of specialty uses, such as in the upper stages of rockets. Its use as a fuel for vehicles and heating currently amounts to a trivial fraction of world hydrogen consumption, and this should not change in the future as it is always more effective to use renewable electricity directly wherever possible.
Ultimately, renewable hydrogen must be reserved to decarbonise and future-proof industries without other decarbonisation options, like fertiliser, chemicals, and steelmaking.
We can’t afford to give up on renewable hydrogen. The hype around hydrogen bursting should not mean we forgo the realistic and targeted role it must play in the energy transition – or forget that slashing at least 2% of global emissions depends upon it.
