Synhelion claims clinker milestone for solar cement

The ETH Zurich spinout uses concentrated solar thermal (CST) energy to deliver industrial heat, reaching temperatures in excess of 1500°C. While its primary focus so far for CST has been solar fuels to help decarbonise sectors such as aviation, it has also been exploring other applications, including cement production.

Clinker is produced by fusing limestone, clay, and other materials in a rotary kiln at temperatures approaching 1,500°C. The fossil fuels generally used to heat the kiln are responsible for approximately 40 per cent of the direct CO2 emissions of the process. Replacing fossil fuels with solar energy will not fully decarbonise cement production, but it can significantly reduce its environmental impact.

Working with global cement and construction materials company Cemex, Synhelion delivered the first solar clinker in February 2022. Now it has announced that the technology has progressed to ‘industrially-viable levels’, including the continuous production of clinker with solar heat. Synhelion and Cemex say they will now take further steps towards building a solar-driven industrial-scale pilot cement plant.

“This is an exciting milestone for everyone involved, achieved through the excellent collaboration between the teams of Cemex and Synhelion,” said Gianluca Ambrosetti, co-founder and co-CEO at Synhelion. “Our technology can make an important contribution toward decarbonising cement production, and we look forward to more trailblazing achievements in this field.”

In February 2023, Cemex, Synhelion and Sandia National Laboratories were awarded $3.2m by the US Department of Energy to advance CST for low carbon cement. Solar MEAD saw the partners exploring the conditions to maximize heat transfer to the raw cement mix and improve the efficiency of clinker production using CST.

“I am convinced we are getting closer to the technologies that will enable net-zero CO₂ cement and concrete production,” said Fernando A González, Cemex CEO. “The solid progress I see here proves that solar cement is not just a dream; it is achievable through continued collaboration and backed up by rigorous research and testing.”