ENERGY CONSERVATION AND EMISSION REDUCTION POTENTIAL THROUGH SOLAR ENERGY APPLICATIONS IN CEMENT INDUSTRY

Abstract

Cement is one of the most versatile construction materials used in the world. World cement consumption increased from 4.8 billion tons to 6 billion tons from 2016 to 2022. Cement production utilizes a considerable amount of fossil fuels to fulfill its thermal energy requirements. Coal, Petro coke, natural gas, and biomass are the most commonly used fossil fuels. Moreover, the combustion of fossil fuels releases many toxic gasses into the atmosphere. As a result, reducing fossil fuel usage is critical while maintaining the cement sector's thermal energy requirements. One best approach to minimize greenhouse gas emissions is to use fewer fossil fuels. This may be done by either increasing system efficiency to use less fossil fuel or by switching to renewable energy sources like solar energy in place of fossil fuel. Enhancing system efficiency is undoubtedly a good strategy, but only for a short period. However, the long-term benefits of solar energy implementation in the cement sector are significant. This study describes the potential of solar thermal calciner technology and consequent carbon mitigation for Indian cement industries. Approach used to provide solar energy involves the installation of a solar tower system with a solar reactor atop the solar tower or preheater tower in a conventional cement plant. For potential estimation, locations of the clusters of cement plants with their actual annual cement production have been identified. Based on the annual actual cement production, the yearly process heating demand for the calcination process for each cement plant is estimated. The annual thermal energy savings by the use of solar calciner reactors was found to be 771.35 PJ. When all of the calciner's required thermal energy is replaced by solar energy, a maximum of 21% of the total CO2 emission may be prevented. The usage of concentrated solar energy can prevent an estimated 45.193 MT of CO2 emissions. vi Furthermore, A case study was done on a conventional cement plant that is situated at a location with a DNI value of 438 (W/m2 ). 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 a minimum thermal loss in the solar reactor. Payback time (PBT) and internal rate of return (IRR) for the design model were 10.4 years and 5.4% when there were 45% thermal losses in the 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. The overall research work has undergone extensive analysis to produce responsible, system-effective results that are nourished by a detailed discussion of the results and conclusions, as well as future recommendations that may enlighten the researchers and inspire them to pursue additional potential developments in this field for the benefit of society, the environment, and the ecologically sustainable growth of peoples.