US-backed project to use solar for cement production

The US Department of Energy has awarded $3.2m to a new project that will use solar power to decarbonise parts of the cement production process.

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Solar MEAD is a collaboration between CEMEX, Sandia National Laboratories and Synhelion, the Swiss company whose concentrated solar thermal (CST) technology can deliver process heat in excess of 1,500°C. CEMEX and Synhelion have been investigating CST in the cement production process, using it to produce clinker, a key component in the building material. In 2022, they achieved a successful laboratory-scale pilot, producing the first-ever solar clinker. Sandia Laboratories will contribute its research facilities as part of the National Solar Thermal Test Facility, as well as providing domain expertise.

"Few renewable technologies are capable of generating heat at the temperatures needed to process raw cement feedstock," said Nathan Schroeder, Sandia researcher and principal investigator for the Solar MEAD project. "This project will advance our understanding of how to use concentrating solar technology to gather and deliver the heat to existing cement production facilities and will have crosscutting relevance to other ore processing industries such as refractory, ceramics, and battery production."

A rotary kiln firing in a cement plant - Adobe Stock

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.

Solar MEAD will investigate methods to reduce carbon dioxide emissions, lower process temperatures, and increase the efficiency of clinker formation using solar energy. The team will also assess the conditions required to maximise heat transfer to the raw cement mix.

"The project offers us the opportunity to use our sustainable technology to support the decarbonisation of energy-intensive cement clinker production,” said Gianluca Ambrosetti, Synhelion co-founder and CEO. “This solution can have a huge impact on the industry and will help to pave the way towards net-zero.”