ETH prototype targets solar heat for industry up to 150°C

On an ETH Zurich rooftop, a collector built from reflective elements, insulation and a small amount of metal has reached the temperatures its designer was targeting. Engineer and Pioneer Fellow Luca Thommen is developing the solar thermal prototype to supply industrial heat without burning natural gas, with applications requiring temperatures of up to 150°C.

The mechanism is direct. Mirrors and other reflective elements concentrate sunlight onto an absorber panel, which transfers the energy to air or water. Insulation limits heat loss, allowing the heat to flow directly into processes such as pasteurizing, sterilizing, cooking, cleaning, dyeing, drying and distillation rather than first being converted into electricity.

Cost is the obstacle Thommen is tackling. Solar thermal collectors already exist in principle, he says, but have not yet been cost-effective enough for broad industrial adoption. His design uses lightweight, readily available insulation material across much of the collector and reserves metal for places where it is necessary. The goal is the same performance at a significantly lower cost than earlier collectors.

The first prototype has already demonstrated that the concept works on a roof. Discussions with companies including Climeworks have also pointed to potential demand: its absorption and desorption processes for extracting carbon dioxide from the atmosphere use heat at around 100°C, within the collector’s stated range. Those conversations are signals of interest, not proof that the technology is ready for deployment.

So what, concretely? If the costs hold up, factories could gain another way to reduce fossil-fuel use and exposure to volatile energy prices in the low-temperature heat range. Thommen plans to develop a market-ready product within a year and to test it at a pilot facility. Until those trials establish performance and economics outside the initial prototype, the industrial case remains promising but unproven.