Cemex to install world-first hydrogen process at UK cement plant

CEMEX is set to trial a process developed by Hiiroc that uses plasma to produce hydrogen for greener industrial heat at its cement plant in Rugby, UK.

Cemex is finalising contract details now with UK-based process developer Hiiroc and expects to start engineering studies early next year with hydrogen production set for a “hard deadline” of January 2026. The cement major thinks the process is a better bet for producing hydrogen than water electrolysis because it requires 80% less electricity and wins out over steam methane reforming because it doesn’t produce CO2.

How does the Hiiroc process work?

Hiiroc’s continuous thermal plasma electrolysis process sees hydrocarbons pass through 50 kW plasma torches where an electric field splits them into hydrogen and carbon. In a second chamber, the carbon is quenched into solid carbon black and passes to a third chamber for separation. Hiiroc says that by vaporising the carbon it eliminates sooting which hinders other methane pyrolysis processes.

The process is containerised and modular. It can be plugged directly into the gas grid and turned on and off to produce hydrogen when and where it’s required, eliminating the need for costly and hazardous hydrogen transport or storage.

---

---

The Rugby installation

“We're thinking of Hiiroc more like a plug and play solution,” said Alfredo Carrato, innovation advisor at Cemex Ventures. Cemex has a minority stake in Hiiroc, which has also received investment from Centrica, Hyundai, and Kia.

Carrato expects the changes required to integrate the process at the Rugby plant to be minimal. One or two of Hiiroc’s containerised process units will be plugged into the grid and pipes installed to carry hydrogen to the existing kiln where a new burner will be installed to combust the hydrogen producing heat to convert limestone to clinker.

Asked about the engineering challenges faced, Carrato said that he’s eager for the trial to discover the optimal hydrogen input. Rugby won’t become 100% hydrogen fuelled. Instead, the project’s engineers will work to find a “sweet spot” that allows operators to reduce fossil fuel input and dramatically increase the use of lower calorific alternative fuels. In 2022, the Rugby plant became the first in the Cemex fleet to house a facility producing so-called Climafuel from household residual and commercial waste.

Carrato declined to give specific figures on what proportion of Rugby’s fuel could be replaced by hydrogen.

“The absolute numbers are a bit sensitive but what I can say is that if we were to implement this at a large scale, we believe that our sweet spot would be having a reduction in our carbon footprint of over 50% in fuel-related emissions.”

He said the company chose to house the project in Rugby because the Hiiroc team is based just three hours away in Hull. “It is better to have the teams as close as possible in case we have issues along the way,” Carrato said, adding that “The size of the plant is average for what we do all over the world. So, it's a representative example in case we want to replicate.”

If successful, the Rugby plant could see eight or nine of Hiiroc’s modules installed at the site, Carrato said.

“We do have plans to expand this across our operations worldwide for a number of reasons. Hydrogen certainly is a relevant vector that we are considering to decarbonise our operations. And second, the modularity of the solution allows for a quick deployment.”

Inputs and outputs

Cemex has set itself a target of becoming net zero by 2050. The Hiiroc process can make use of biomethane so could allow Cemex to replace its use of fossil fuel natural gas. It could also use renewable electricity to power its plasma burners. In terms of output, the process produces carbon black which can be used as an additive in its cement-making operations or sold for use in tyres, rubbers, plastics, inks, and toners.

“Because of the stoichiometry, the volume of carbon black is pretty significant, meaning we are not able to take the entirety of what is produced. So, we need to figure out how to also monetise it.”

Hiiroc is searching for alternative markets too. It has partnered with researchers in Europe and the US to investigate how the carbon black from its process could be used in other applications including filters, soil enhancers, and animal feed.

Carrato said: “We’re looking at not only the carbon footprint, but also the stress on water. Water electrolysis has a lot of water demand, whereas technology such as Hiiroc has none. In regions where there’s a lot of water scarcity, we believe that Hiiroc can move the needle [for industrial decarbonisation] way better than water electrolysis.”

Earlier this month, Hiiroc signed a partnership with Siemens that will see the German major provide advanced control technology for its thermal plasma electrolysis process.