Calderys takes part in TWINGHY: A green hydrogen project in the steel industry

Calderys is a partner in TWINGHY, an EU project testing hydrogen as a fuel to replace natural gas in the reheating furnaces of the steel sector. The project kicked-off in the summer of 2023 and is scheduled to conclude in 2027.

Based at the CELSA Group plant in Barcelona, Spain, the project will evaluate and demonstrate an advanced heat transfer process in the reheating furnaces of the steel-making sector, utilizing hybrid burners in order to increase the introduction of hydrogen for direct combustion with oxygen. The process will be controlled by a digital twin of the furnace, hence the name:  (digital) TWIN for Green HYdrogen.


Calderys is the only refractory maker chosen to participate in this project, and our team of experts will study how modifications to the furnace affect the refractory lining. Based on these findings, Calderys will adapt refractories, or develop new refractories, suitable for the working conditions of furnaces burning mixes of natural gas, hydrogen, and oxygen.

Diego de la Fuente Diez, Industrial Operations Managing Director at Calderys, explains: “Since the official project launch in summer 2023, our team of refractory specialists has sent samples of Calderys’ castables to RWTH Aachen University, for testing. We’ve also installed multiple test bars into the existing reheating furnace, to allow us to analyze the effect of one year working under natural gas conditions. Later, we’ll install new test bars when the furnaces begin to use different fuel mixes, so we can compare the effects of the different fuels and environments.”


Calderys has several decades of experience in creating customized refractory solutions for Reheat furnaces. Our refractory products are designed to optimize the overall cost and performance of equipment, from installation, and including manpower, energy consumption, and CO2 emissions. Calderys also offers local, dedicated service thanks to an extensive network of experts.

The future of steelmaking: Green hydrogen 

Green hydrogen is produced using industrial electrolysis, powered by electricity from renewable sources. The electrolysis process splits water molecules into hydrogen and oxygen, capturing and storing the hydrogen to be used as fuel.

However, introducing hydrogen as a fuel source in reheating furnaces isn’t completely straightforward, and some challenges need to be addressed, including:

  • The cost and reliability of production: The process is energy intensive and the supply of renewable electricity must be cost-effective, consistent and reliable.
  • Higher gas compression: Hydrogen requires more energy to compress than natural gas. 
  • Pipeline leakage and reactivity: hydrogen is the lightest and smallest molecule of all the elements and reacts differently to different metals, increasing the likelihood of leaks and corrosion.

Given these challenges, steelmakers may have to adapt their industrial processes. Calderys’ aim is to accompany customers as they reduce their carbon emissions. With our expertise and support, we play an important and strategic role in helping customers achieve their emissions goals with our high quality, efficient, and sustainable solutions.

Bruno Touzo, Global Vice President, Innovation & Technology Calderys, says “We’ll be involved in many more hydrogen projects, working towards the future of steelmaking in coming years, as the industry moves towards the EU’s targets for zero emissions. What we’re learning from our participation in the TWINGHY project will eventually bring operational and cost benefits - and sustainability, of course, to all of our customers, not just in Europe, but worldwide.”

Calderys is also participating in HYDREAMS, a project coordinated by French firm UGITECH, part of the Swiss Steel Group. HYDREAMS aims to remove carbon emissions from steel treatment thermal processes by using green hydrogen made from renewable energy sources. Its stated objective is full decarbonization of thermal processes for steel reheating and heat treatment by means of clean hydrogen oxyfuel combustion. The process will also improve the energy-efficiency of the thermal treatments, and simultaneously cut nitrogen oxide (NOx) emissions.

Learn more about the HYDREAMS project:…