Design of solar cement plant for supplying thermal energy in cement production

This work describes the implementation of concentrated solar energy for the calcination process in cement production. Approach used for providing solar energy includes the utilisation of a solar tower system with a solar reactor atop the solar tower or preheater tower in a conventional cement plant. Analysis considered thermal energy substitution ranging from 100% to 50%. Solar power output of the reactor was 793 MW after considering the 45% heat loss in the reactor. The number of heliostats required for generating 793 MW solar reactor power was 15066 with a total required land surface of 1130 ha. Depending on the thermal losses i.e., 15%, 30%, and 45%, the net conversion efficiency was 44, 56, and 69, respectively. Implementing concentrated solar thermal (CST) in the calcination process of the selected conventional cement plant could save 419 thousand tons of CO2 annually. Economic analysis suggests that approach is useful when there is minimum thermal loss in the solar reactor. Payback time (PBT) and internal rate of return (IRR) for design model were 10.4 years and 5.4% when there were 45% thermal losses in solar reactor. Major challenges are regarding the conversion of laboratory equipment to industrial size, working in high-temperature environments, raw material transportation systems, and thermal storage systems.