Decarbonizing Ammonia Production and Refining with Green Hydrogen
Blog Post | 24.02.2025 | 6 min read | Jerome Henry
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The refining and chemical sectors together represent nearly 10% of global CO2 emissions1,2. A significant portion of these emissions are attributable to hydrogen production, a key feedstock for products like fuels and fertilizers.
Virtually all hydrogen produced today is via traditional methods, namely steam methane reforming of natural gas (i.e., "grey" hydrogen). A smaller amount is produced via coal gasification (i.e., "brown" hydrogen). Overall, hydrogen production represents an estimated 6% of annual natural gas consumption and roughly 2% of global coal consumption3.
Reducing the hydrogen industry's dependence on fossil fuels is seen as an essential step in decarbonizing the refining and chemical sectors. In this article, we look at applications that benefit the most from transitioning to green hydrogen (i.e., produced via water electrolysis powered by renewable energy) and discuss how Hitachi Energy supports these efforts with electrification and grid connection solutions for large-scale electrolyzer plants.
Ammonia production
The ammonia (NH3) industry is by far the world's largest user of hydrogen, representing more than half of global consumption.
Currently, around 70% of ammonia goes toward the production of fertilizers. The remainder is used to produce plastics, synthetic fibers, etc.
The Haber-Bosch process is the primary method for producing ammonia and involves combining hydrogen and nitrogen under high temperatures (400 – 500°C) and pressure in the presence of a metal catalyst. Today, virtually all the hydrogen used in the Haber-Bosch process is grey. In fact, steam methane reformers for ammonia production generate nearly 500 million tons of CO2 annually (or about 1.8% of worldwide CO2 emissions)4.
Every ton of ammonia produced using grey hydrogen emits around 2-3 tons of direct CO2e. For context, this is almost twice as carbon-intensive as crude steel and roughly four times that of cement5.
Ammonia plants that use coal gasification for hydrogen production have an even higher emission intensity of nearly 4 tons of CO2e per ton of ammonia produced. Overall, ammonia synthesis is the largest CO2 emitter of all chemical industry processes6.
By replacing grey hydrogen with green hydrogen, ammonia producers can significantly reduce their carbon footprint.
Today, green ammonia (i.e., eAmmonia) makes up a very small portion of the world's total ammonia production. However, this is expected to change as the industry comes under pressure to improve sustainability.
While most of the green ammonia produced in the near-term will go toward fertilizer production, other end-use applications are under consideration.
Ammonia contains 17.6% hydrogen by weight, making it an efficient carrier of green hydrogen, and in turn, renewable electricity. It is also very stable and can be liquefied under moderate pressure or at low temperatures, which makes it easier to store and transport compared to pure liquid hydrogen.
Additionally, green ammonia is being explored as an alternative to heavy fuel oil (HFO) in marine shipping applications, as it emits no carbon when combusted. Several OEMs are also looking at the potential of using it as a fuel for power generation equipment, including gas turbines.
Use cases for green hydrogen in refining
The second largest consumer of hydrogen after ammonia production is the refining sector.
Like ammonia, much of the on-purpose hydrogen produced for oil refineries is via dedicated steam methane reformers. Some plants also produce hydrogen as a by-product of other processes, such as olefin and chlorine production, as well as catalytic reforming of naphtha.
The main application of hydrogen in refineries is hydrodesulfurization, an important process used to remove sulfur compounds from crude oil derivatives like gasoline, diesel, and jet fuel.
Hydrogen is also used for hydrocracking, which involves breaking down heavy, long-chain hydrocarbons into shorter molecules. Hydrocracking increases the yield of high-value products like gasoline and jet fuel and improves the overall efficiency of the oil refining process.
Replacing on-purpose grey hydrogen with green hydrogen can drastically reduce the carbon footprint of traditional fuels. Some refineries are also exploring hydrogen to produce carbon-free heat and steam.
According to Wood Mackenzie, the global market for low-emissions hydrogen in the refining sector could reach up to 10 mtpa by 2050, translating roughly into a 10% reduction in scope 1 and 2 carbon emissions from refineries7.
How Hitachi Energy is Supporting Green Hydrogen Production
As a global technology leader, Hitachi Energy supports the execution of large-scale eAmmonia and eFuel projects with integrated solutions that enable safe and efficient green hydrogen production.
Grid-to-Stack is our holistic lifecycle solution for connecting green hydrogen plants to the high-voltage grid. It covers the complete power supply package of the plant and addresses key challenges that operators face, such as power conversion, reactive power compensation, harmonic filtering, safety, and grid code compliance.
From the grid connection to the electrolyzer stack terminals, we ensure that the 'plant's entire power supply infrastructure is interoperable and optimized.
To date, we have performed electrical pre-FEED8 and FEED studies for electrolyzer plants up to 2 GW in size, which are dedicated to the production of green ammonia and eFuels. We also supply electrification solutions, including e-Houses and static synchronous compensators (STATCOMs) for other major green ammonia projects.
In addition, Hitachi Energy has been a first mover in the development of asset health solutions to support operations and maintenance of electrolysis plants. Coupled with our long-term service agreements, we enable operators to maximize efficiency and employ predictive maintenance strategies, ultimately lowering their levelized cost of hydrogen production.
Conclusion
Although green hydrogen holds significant decarbonization potential for the chemical and refining sectors, fully replacing grey hydrogen production capacity comes with challenges.
Often, large hydrogen volumes are required, particularly in the case of ammonia production, which necessitates the construction of GW-scale electrolyzer plants. Ensuring grid compliance and electrical stability of these plants is a complex undertaking due to the large power draw and variable loads. Refiners and chemical producers also have limited experience operating and maintaining electrolyzers, presenting risks to uptime and reliability.
Hitachi Energy can help operators address these challenges by providing integrated solutions that cover the entire project lifecycle of the electrolyzer plant. From early-stage conceptual studies and electrical system design to operation and maintenance, we can serve as a strategic partner for projects of any size or complexity.
More information on Hitachi Energy's hydrogen solutions can be found here.
References:
1https://www.sciencedirect.com/science/article/pii/S2590332223002075#:~:text=Today%20the%20chemical%20industry%20emits,5%25%20of%20global%20GHG%20emissions
2https://www.frontiersin.org/articles/10.3389/fceng.2022.804163/full#:~:text=Owing%20to%20its%20role%20as,approximately%201.3%20Gt%20CO2
3https://www.sciencedirect.com/science/article/pii/S2666790822001574#:~:text=Currently%20nearly%20all%20hydrogen%20is,respectively%20(Liu%2C%202021)
4https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf
5https://www.iea.org/reports/ammonia-technology-roadmap/executive-summary
6https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf
7https://www.woodmac.com/press-releases/low-carbon-hydrogen-demand-in-refining-could-reach-50-mtpa-by-2050/#:~:text=Potential%20global%20market%20size%20for,to%20generate%20heat%20and%20steam
8FEED - Front-End Engineering and Design
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