Solar capture devices capable of producing temperatures over 1000°C

Engineers have developed a device that can efficiently capture energy from the sun and generate temperatures in excess of 1000°C (1832°F). It could one day be used as an environmentally friendly alternative to burning fossil fuels in the production of materials such as steel, glass and cement.

The production of these materials requires burning fossil fuels to heat the raw materials to over 1000°C, which is extremely energy-intensive. “About half of the energy we use isn't actually converted into electricity,” he says. Emiliano Casati At ETH Zurich, Switzerland. “It is used in the production of many materials needed in our daily life and industry.”

Solar furnaces, which use a series of movable mirrors to focus sunlight onto a hot receiver, could be used in manufacturing as an alternative to burning fossil fuels. But converting solar energy to temperatures above 1,000 degrees Celsius is currently extremely inefficient, Casati said.

To improve the efficiency of such devices, Casati and his colleagues designed a heat-trapping solar receiver with a 300-millimeter layer of quartz around it.

Quartz is a translucent material that allows light energy to pass through but blocks thermal energy. This means that when sunlight is concentrated and heats up the silicon, the quartz prevents the back leakage of thermal energy and traps the heat, reducing energy loss in the system.

The team tested the improved solar receiver in a facility that uses LEDs to simulate sunlight. Their first experiments showed that the silicon absorber easily reached 1050°C.

According to heat transfer models, the silicon shield could potentially allow the receiver to reach temperatures of up to 1200°C while maintaining 70 percent of the energy input to the system. Without the silicon shield, energy efficiency drops to just 40% at the same temperature.

Although this is just a proof-of-concept device, Casati hopes it will one day be widely used as an environmentally friendly way to generate the high temperatures needed for manufacturing. “We really need to address the challenge of decarbonizing these industries, and this could be one of the solutions,” he says.