Instead of burning fossil fuels to smelt steel and cook cement, what if we trapped solar energy directly from the Sun?

That’s what researchers at ETH Zurich, Switzerland are exploring. Their proof-of-concept study, published May 15 in the journal Device, uses synthetic quartz to trap solar energy at temperatures higher than 1,000°C (1,832°F). The research could lead to using clean energy for carbon-intensive industries, which currently account for about 25% of global energy consumption.

“To tackle climate change, we need to decarbonize energy in general,” says corresponding author Emiliano Casati of ETH Zurich, Switzerland, in a press release.

Researchers have prevsiously explored a clean-energy alternative using solar receivers, which concentrate and build heat with thousands of sun-tracking mirrors. But that technology has difficulties transferring solar energy efficiently above 1,000°C.

Light from 136 suns

To boost the efficiency of solar receivers, Casati turned to semitransparent materials such as quartz, which can trap sunlight—a phenomenon called the “thermal-trap effect.”

The team crafted a thermal-trapping device by attaching a synthetic quartz rod to an opaque silicon disk as an energy absorber. When they exposed the device to an energy flux equivalent to the light coming from 136 suns, the absorber plate reached 1,050°C (1,922°F), while the other end of the quartz rod remained at 600°C (1,112°F). 

“Previous research has only managed to demonstrate the thermal-trap effect up to 170°C (338°F),” says Casati. “Our research showed that solar thermal trapping works not just at low temperatures, but well above 1,000°C.”

Casati and his colleagues are now optimizing the thermal-trapping effect and investigating new applications for the method. By exploring other materials, such as different fluids and gases, they were able to reach even higher temperatures, noting that these semitransparent materials’ ability to absorb light or radiation is not limited to solar radiation.

Citation: Casati et al. Solar thermal trapping at 1,000ºC and above. Light from 136 suns. Device https://cell.com/device/fulltext/S2666-9986(24)00235-7 (open access)

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