New technology processes to produce green ammonia from hydrogen could result in a 21pc fall in the cost of the derivative fuel compared with traditional processes, according to a government-sponsored study by the technology’s developer, Supercritical Solutions.

The ‘GreeNH3’ study, carried out with UK energy firm Scottish Power and ammonia technology company Proton Ventures, explored the potential for integrating these new technology processes into a traditional Haber-Bosch ammonia production process.

85pc – Efficiency of fuel cell

Supercritical has filed multiple patents for a new electrolyser cell design that removes the need for a membrane and precious group metals and enables higher electrical efficiencies of up to 85pc, reducing costs.

“We have developed a new class of electrolyser that operates on high pressure and intermediate temperatures. That combination gives us advantages in bringing down costs both in the electrolyser and afterwards in delivery to end users,” Supercritical CEO Matt Bird tells Hydrogen Economist.

The electrolyser uses nickel alloys, which can result in a higher capital cost per unit mass of material needed but offer excellent durability and high densities—minimising the size of the unit—as well as very high levels of end-of-life material recovery, resulting in a levelised cost of pressurised hydrogen that is 35pc lower than that delivered by traditional proton-exchange membrane (PEM) electrolysers.

“We are also an all-metal design, which means we use no forever chemicals and therefore there is no supply chain risk if these chemicals are banned,” Bird continues.

Many PEM electrolysers use a fluorocarbon called Nafion in their membranes. In February 2023, the European Chemicals Agency published a proposal, on which it is currently consulting to ban per- and polyfluoroalkyl substances, which could include Nafion.

Under pressure

As well as the advantages in the fuel cell, the study found that its technology processes can also reduce cost by delivering both hydrogen and oxygen from its electrolysers at high pressures of around 220 bar.

“Many of the early adopters of hydrogen—including the ammonia production, and the refinery and transport sectors—need compressed hydrogen,” says Bird. “And storing hydrogen also requires compression. If it’s already compressed, then that can cut costs.”

Feed compressor capital costs can be a significant factor in the overall levelised cost of ammonia (LCOA). Supercritical says it makes the only electrolyser able to deliver hydrogen at 220 bar pressure.

“Transportation uses 350 bar pressure. To go from 220 bar to 350 bar you only need one stage of gas compression, whereas hydrogen delivered by a PEM electrolyser needs three stages of gas compression,” Bird notes.

Overall, the new technology process could result in a 21pc fall in the LCOA when compared with traditional PEM electrolysers, the study found.

Further study

The UK government provided the ‘GreeNH3 project’ with c.£146,000 (c.$181,000) of funding under its Low Carbon Hydrogen Supply 2 Competition, which aims to support innovation on the hydrogen supply side.

Supercritical is in talks with Scottish Power about the next stage of the trial. The Scottish energy firm is exploring the potential to export green hydrogen or ammonia from the UK to countries such as Germany through the Scot2Ger initiative.

Supercritical will hold a funding round later this year to add to its initial investments from mining firm Anglo American and clean energy investment funds Jericho Energy Ventures and Lowercarbon Capital. The firm has an ambition to take its technology to gigawatt-scale by 2030.

High conversion and reconversion costs are often cited as barriers to the uptake of ammonia as a carrier molecule for hydrogen. Technologies that address these costs could accelerate that uptake and make ammonia the preferred carrier amongst a number of other potential options, including methanol, liquefaction and liquid organic hydrogen carriers.

Ammonia will be responsible for transporting 55mn t/yr of green hydrogen by 2050, according to global CEO-led initiative the Hydrogen Council’s Global Hydrogen Flows report—representing over 25pc of a total of 400mn t/yr traded.

---

Author: Tom Young