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The levelised cost of hydrogen (LCOH) is a term commonly used to compare different hydrogen generation technologies. It is often unclear as to whether things like water purification costs or compression costs have been included and to what pressure the system delivers the hydrogen. In this study, the levelised cost of hydrogen delivered at 200bar of pressure, LCOH200, and the levelised cost of ammonia (LCOA) have been used. The study includes costs from water purification all the way through to high pressure hydrogen and ammonia delivery respectively. A number of scenarios were considered, with the ‘Other Electrolyser’ being of a PEM technology basis. The GreeNH3 study, with full results presented in the published GreeNH3 Hydrogen Supply 2 Competition report, concludes that commercial deployment of Supercritical’s electrolysis technology for high pressure, ultra-efficient hydrogen production is feasible for green ammonia production with continued development.


Supercritical’s LCOH200 is predicted to be 35% lower than current incumbent technologies at commercial scales, resulting in a 21% drop in LCOA for the modelled integrated ammonia production. Based on emissions and contained carbon, it is estimated that a reduction of 24.2 - 35.2 MtCO2e/year compared to a polymer electrolyte membrane (PEM) electrolyser and 170.1 MtCO2e/year compared to SMR for a given commercial plant of 43,000 kgH2/day (0.47 TWh/annum) output could be achieved.

Considering commercial ammonia production; pressurised hydrogen delivery enables the H2/N2 feed compressor to be bypassed, reducing the feed compressor capital cost by a factor of 10 and its duty by a factor of 4. Heat integration between the hydrogen and ammonia plant is not considered likely to be economical at scale and is not considered for early demonstrations.

The Problem 

Today, ammonia (NH3) is responsible for 43% of the world’s grey hydrogen production and is essential for feeding the world’s population through its role in synthetic fertiliser production. This market alone is responsible for ~500 million tCO2e/annum, approximately 1.8% of global emissions and it needs to be decarbonised to achieve net zero in the sector, helping the UK reach its 2050 carbon net zero goal.
In the near future, green ammonia has the potential to play a crucial role in facilitating the transport of renewable energy or as a zero emission fuel itself. With an energy density ~3x greater than compressed hydrogen and an existing distribution network, ammonia is considered as a medium for global transportation of green energy and plays a leading role in enabling the hydrogen economy.

The Opportunity 

The green hydrogen and ammonia market is dynamic and is in its infancy relative to the century old, established grey ammonia market. There is huge potential to decarbonise the existing ammonia use markets as well as disrupt and  decarbonise markets that have not traditionally used ammonia. IRENA predicts that ammonia production will more than triple by 2050, with more than 80% coming from renewable energy sources.

The Project

The GreeNH3 (Green Ammonia) project explored the feasibility of Supercritical’s green hydrogen producing system integrated into a traditional Haber-Bosch ammonia synthesis loop, designed by Proton Ventures, to produce green ammonia at both a demonstrator and commercial scale. The commercial GreeNH3 system will be fed by air and water and powered by energy from renewable sources to produce green ammonia.
The consortium aims to produce high-purity (99.999mol%) hydrogen >200bar for direct use in ammonia synthesis (99.9wt%). Demonstrating hydrogen delivery at this purity and pressure also facilitates translational benefits to multiple sectors for green hydrogen, surpassing Grade D under ISO 14687, making it suitable for fuel cells and the majority of other applications. The study leans upon Supercritical’s proprietary electrolyser which can minimise cost and waste through its ultra-high system efficiencies. This patented novel approach removes the need for a membrane, enabling higher electrical efficiencies, with extended lifetime expected. Its membraneless design is uniquely positioned to exploit high pressure, intermediate temperature conditions, offering benefits including complete bubble removal, accelerated kinetics and rapid mass transfer. Producing hydrogen at the pressure that the ammonia industry needs; greater than 200 bar. In addition, at the end of life of an asset, Supercritical will be the only electrolyser that is almost entirely recyclable and have no “forever chemical” usage, maximising return on valuable commodity materials and being truly environment first.

Download the executive summary here >

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