Sustainable cement production – can solar energy replace fossil fuels?

Solar researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have investigated how solar energy can replace fossil fuels for the cement production process. The initial manufacturing stage, the calcination of raw cement powder, has been successfully tested using a rotary kiln in the solar simulator at the DLR Institute of Solar Research in Cologne. Cement is one of the world’s most used commodities. Its production requires high temperatures that are predominantly produced by burning fossil fuels. The ‘solarisation’ of this process would therefore make a significant contribution to the reduction of global emissions.

The tests were conducted between December 2018 and January 2019 in the Cologne solar simulator. The rotary reactor can be operated with both natural and artificial light, but the researchers opted for the simulator because of the limited hours of sunshine in winter: “The main purpose of the simulator is to provide unchanging conditions. After characterising and optimising the reactor under these conditions, it is then possible to adapt this to real-life conditions, with very few changes to the parameter settings, such as adjusting the material flow rate, for example,” says Gkiokchan Moumin, who is writing his doctoral thesis on this project at the Institute of Solar Research.

The aim of the test campaign was to demonstrate the reliable, multi-hour operation of the reactor, spread over several days. The raw material was heated at various flow rates in the rotary kiln, to a temperature of 1000 degrees Celsius – the temperature at which the critical chemical reaction begins. The researchers succeeded in producing calcinated raw cement powder with the same product quality as is possible with conventional reactors.

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published on February 1st, on www.dlr.de

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