Switzerland-based Synhelion and Mexican construction materials supplier Cemex have started building a high-concentration solar tower designed to produce synthetic fuels for a cement production facility near Madrid, Spain.

“This is an exciting milestone for everyone involved, achieved through the excellent collaboration between the teams of Cemex and Synhelion,” said Synhelion CEO, Gianluca Ambrosetti.

Ambrosetti said that the facility will provide enough heat to produce “clinker” concrete without using fossil fuels.

“Clinker is produced in a rotary kiln at temperatures nearing 1,500 C. Fossil fuels are typically used to heat the kiln and are responsible for approximately 40% of direct CO₂ emissions,” the company claims. “Additionally, the technology creates the conditions to separate, and therefore capture, the remaining CO₂ from calcination in concentrated form without additional efforts.”

Synhelion's solar tower technology captures energy from a field of solar mirrors, concentrating it onto a receiver atop the tower to convert solar radiation into high-temperature process heat. This heat is then directed to a thermal chemical reactor that generates syngas, a blend of carbon monoxide (CO) and hydrogen (H2).

The syngas undergoes processing through standard gas-to-liquids technology to create fuels like jet fuel, gasoline, or diesel. Excess heat is stored in a thermal energy storage (TES) unit for continuous 24/7 operation.

Synhelion and Cemex introduced the first solar clinker production in a small-scale pilot process in early 2022.

“From the pilot installation, we foresee completing our first small-scale industrial plant in Móstoles by 2026,” a company spokesperson told pv magazine. “We also expect to complete our first large-scale industrial plant, with a capacity of 150 MWth, by the end of the decade.”

Synhelion and Cemex have secured $3.2 million in funding from the US Department of Energy to study the conditions needed to maximize heat transfer to the raw cement mix. Sandia National Laboratories helped the Swiss company to develop the concept.