Breakthrough solar energy technology could replace fossil fuels in heavy industry

A potentially groundbreaking solar-powered device has reached temperatures of more than 1,000°C, raising hopes of using green energy to power some of the most fossil-fuel-intensive manufacturing processes on Earth.

New verification technology uses synthetic quartz crystals to capture solar energy at temperatures exceeding 1,000°C, demonstrating its potential to provide clean energy for carbon-intensive industries such as metals, cement and chemicals production.

The production of materials such as glass, steel and ceramics requires temperatures in excess of 1,000°C, which is currently typically only achieved by burning fossil fuels.

These manufacturing industries account for almost a quarter of global energy consumption.

Scientists have previously tried to harness solar energy to power these industries by capturing and concentrating sunlight using an array of thousands of sun-tracking mirrors. But such methods have failed to effectively achieve the required temperatures.

The new device, built by attaching synthetic quartz crystals to an opaque silicon disk, uses a phenomenon called the thermal trapping effect to capture sunlight with unprecedented efficiency.

The technological breakthrough was described in a study published in the journal Device on Wednesday.

The operating principle is that opaque materials exposed to solar radiation absorb it on the surface and transfer it to the interior by conduction, while semi-transparent materials allow sunlight to penetrate and be absorbed throughout the internal volume.

By appropriately matching semi-transparent materials to the appropriate source of energy radiation, it is possible to achieve higher temperatures in a larger part of the material than on the surface exposed to solar radiation – in other words, to create a thermal trap.

When the researchers exposed their device to an energy flux equivalent to light from 136 suns, the temperature at one end of the device reached 1,050°C and at the other end to 600°C.

“Previous studies have only shown the thermal trapping effect up to 170°C. Our study shows that thermal capture of solar energy works not only at low temperatures, but well above 1000°C,” said Emiliano Casati from ETH Zurich, co-author of the study.

“This is crucial to show its potential in real industrial applications.”

Scientists are currently optimizing the heat trap effect and investigating new applications of this method.

Preliminary analysis of other materials has shown that even higher temperatures can be achieved.

“This research contributes to the development of more efficient solar receivers that will allow the decarbonization of key heat-intensive industrial processes, such as cement and metal production and the thermochemical production of solar fuels,” said Dr. Casati.

“To truly motivate industry adoption of this technology, we need to demonstrate the economic viability and benefits of this technology at scale.”