I wonder how exactly one could use solar to make cement. The Portland cement process requires heating up ingredients to 1500 C. The concentrated solar systems as they actually exist do not get anywhere close to that. You could get this high temperature from concentrated solar, but I don’t know how you could effectively transfer the heat to the ingredients: I don’t think that there exists a practical pumping technology that can work with this hot working fluid, as this is literally hot enough to melt steel.