Swiss scientists are working on new ways to use energy from the Sun. 

Researchers have developed a new strategy to generate extreme temperatures using solar energy, potentially reducing the dependence on fossil fuels for industries like glass, steel, cement, and ceramics production. 

These industries account for about 25 per cent of global energy consumption, much of which is currently derived from fossil fuels. 

The new approach uses the thermal-trap effect in synthetic quartz to achieve temperatures over 1,000°C.

The research team, led by Emiliano Casati from ETH Zurich, has designed a solar receiver that uses semi-transparent materials, such as quartz, to trap sunlight and significantly boost thermal efficiency. 

Traditional solar converters have struggled to efficiently generate heat beyond 1,000°C, a necessary threshold for many industrial processes. 

The team’s device, however, reached 1,050°C when exposed to an energy flux equivalent to the light of 136 suns, marking a significant improvement over previous technologies.

“To tackle climate change, we need to decarbonise energy in general,” said Casati. 

“People tend to only think about electricity as energy, but in fact, about half of the energy is used in the form of heat.” 

The experimental device consists of a synthetic quartz rod attached to an opaque silicon disk, which serves as an energy absorber. 

When exposed to concentrated solar energy, the absorber plate reached 1,050°C, while the other end of the quartz rod maintained a temperature of 600°C. 

This demonstrates the potential of the thermal-trap effect to work at much higher temperatures than previously shown. Prior research only demonstrated this effect up to 170°C.

The team also used a heat transfer model to simulate the quartz's efficiency under various conditions. 

Their findings revealed that the device could achieve the target temperature at lower solar concentrations with the same performance, or at higher thermal efficiency for equal concentration. 

For instance, a state-of-the-art, unshielded receiver has an efficiency of 40 per cent at 1,200°C with a concentration of 500 suns. In contrast, the receiver shielded with 300 mm of quartz achieves 70 per cent efficiency under the same conditions.

“Our research showed that solar thermal trapping works not just at low temperatures, but well above 1,000°C. This is crucial to show its potential for real-world industrial applications," Casati said.

The researchers plan to continue optimising the device and exploring its applications in industrial settings. 

They are investigating other materials, such as different fluids and gases, which might achieve even higher temperatures. 

Additionally, they say that the semi-transparent materials' ability to absorb light is not limited to solar radiation alone.

“Energy … is a cornerstone to the survival of our society,” Casati says. 

“Solar energy is readily available, and the technology is already here. To really motivate industry adoption, we need to demonstrate the economic viability and advantages of this technology at scale.”

More details are accessible here.