In the future, solar energy could be used to produce cement or steel. Currently, fossil fuels are usually burned to achieve the required heat for the kilns, which releases large amounts of greenhouse gases. Heating with renewable electricity is not an alternative, as this would be inefficient at these high temperatures. One possible solution is a thermal trap that researchers at ETH Zurich have now developed.
A team led by Emiliano Casati, a scientist in the Energy and Process Systems Engineering Group, and Aldo Steinfeld, Professor of Renewable Energy Sources, developed the thermal trap. It uses solar radiation to generate the high temperatures required for the production processes and also emits this heat. The key component is a quartz rod which, thanks to its optical properties, can efficiently absorb sunlight and convert it into heat. In the laboratory experiments, this quartz rod had a diameter of 7.5 centimetres and was 30 centimetres long. The researchers illuminated it with artificial light with an intensity 135 times that of concentrated sunlight, reaching temperatures of up to 1050 degrees Celsius. "Our approach significantly improves the efficiency of sunlight absorption," says Casati. "We are therefore confident that this technology will enable the development of high-temperature solar systems," he says.
Source: Casati E, Allgoewer L, Steinfeld A: Solar thermal trapping at 1,000°C and above. Device, May 15, 2024, doi: external page10.1016/j.device.2024.100399
