The world's most important chemical process
Over 100 years ago, Fritz Haber and Carl Bosch developed a high-pressure, intermediate-temperature chemical process that changed the world. The Haber-Bosch synthesis of ammonia from nitrogen and hydrogen now underpins the fertiliser industry that feeds over 8 billion people. Without it, the global population could not have grown beyond roughly 2 billion.
Today, almost all ammonia is produced from natural gas via steam methane reforming. The process generates approximately 10 tonnes of carbon dioxide per tonne of hydrogen. With roughly 1.8 tonnes of hydrogen required per 10 tonnes of ammonia, that means approximately 18 tonnes of CO₂ for every 10 tonnes of ammonia produced. The fertiliser that feeds the world is one of its largest sources of industrial emissions.
The compressor problem
Zero-emission ammonia synthesis is technically achievable. In the early 20th century, water electrolysis plants powered ammonia production: Norway deployed 165 MW hydropower plants in 1928 and 1949, and Egypt brought a 203 MW facility online in 1959. Natural gas's cost advantage ended that era.
The obstacle today is not the electrolyser. It is the compressor. Haber-Bosch synthesis operates at high pressure, but almost every electrolyser on the market delivers hydrogen at low pressure. The gas must be compressed before it enters the synthesis loop, adding capital cost, operational complexity, and a major point of failure. A single compression stage from 10 bar to 350 bar requires significant energy. Multiple stages are needed, each with its own equipment, maintenance burden, and risk.
Supercritical's electrolyser delivers hydrogen at up to 220 bar directly. It integrates straight into the Haber-Bosch loop, eliminating the compressor entirely.
Supercritical delivers hydrogen at up to 220 bar at the battery limit. No downstream compression. A 10x reduction in compressor capital cost and a 75% reduction in compressor duty, in a single design decision.
The GreeNH3 programme
Supercritical and ScottishPower are exploring opportunities to pilot this optimised green ammonia production solution, with the aim of commercialising the technology this decade. ScottishPower has committed to deploying 1,000 MW of green hydrogen capacity within the next decade. Iberdrola, ScottishPower's parent company, has already deployed 20 MW of green hydrogen capacity in Spain, directly feeding ammonia production at Fertiberia.
Applications beyond fertiliser
The global population requires feeding while emissions must fall. Green hydrogen for ammonia production is the only credible decarbonisation pathway for this sector. Supercritical makes the economics work.
The International Maritime Organisation estimates shipping accounts for 2.33% of global CO₂ emissions. Ammonia is being actively evaluated for use in turbines, engines, and fuel cells for marine applications. High-pressure green ammonia produced at competitive cost is a prerequisite.
Studies indicate ammonia offers significant potential for long-distance hydrogen transport, enabling renewable energy to move from resource-rich areas to demand centres. Cracking ammonia back to hydrogen at point of use is an established process.
The scale of the opportunity
Global ammonia production is approximately 180 million tonnes per year. Decarbonising even a fraction of that represents an enormous emissions reduction opportunity. Supercritical's technology does not require a redesign of the Haber-Bosch process. It replaces one component: the hydrogen source. That is what makes the pathway commercially credible.