Solar Thermal Production of Lime and Cement

Funding source: external page BfE - Swiss Federal Office of Energy, external page Paul Scherrer Institute, external page QualiCal AG

Background – The decomposition of limestone (mainly CaCO₃) is the main endothermic step in the production of lime (CaO) and cement: The project aims at substituting concentrated solar energy in place of carbonaceous fuels as the heat source for the production of lime. Decreasing the use of fossil fuels as the prime energy resource for calcination is a means to reducing the process's dependence on conventional energy resources, and it is a means to reducing carbon dioxide emissions. The principal motivation behind the project is the conviction that solar technology can contribute as an energy source for producing versatile chemicals like lime. The challenge is to develop a cost effective technology that is adapted to a specific location (e.g. in a developing world setting) and for a specific purpose (e.g. using lime as building material) that leads to local development and prosperity. The question of technically feasibility will be addressed by first designing, constructing, and then experimentally evaluating the performance of a 5 to 10 kW thermal input solar reactor for effecting the calcination reaction. Such a solar reactor will operate at temperatures up to 1600 K. Experimental results obtained at the small scale will be extrapolated to 0.5 MW using, in part, a numerical model. Finally, the combination of experimental and numerical results along with current economic information on solar and lime production technology will be used to estimate the cost of the large-scale plant.