Techno-economic analysis of a solar calciner for CO2 emissions reduction in the Chilean cement industry

Clinker, a crucial component in cement production constitutes about 72% of cement's composition, is formed by heating limestone and other materials in a calciner and in a rotary kiln. This process is highly energy- intensive and, therefore, a major source of CO2 emissions in cement production. In this context, this paper analyzes the potential integration of a solar calciner into the Chilean cement industry. Specifically, it examines and compares two Concentrated Solar Thermal (CST) scenarios: (I) the Top of Tower (TT) system and (II) the Beam-down (BD) system. These scenarios are evaluated for their economic and technical feasibility in reducing CO2 emissions in the calcination process. The analysis focuses on the region of Antofagasta, Chile, which has an annual DNI of 3,250 kWh/m2. Notably, Antofagasta consumes 30% of the energy used in the cement sector in Chile. Key parameters influencing CO2 emission reduction are examined, with an emphasis on the potential for greater reductions through increasing solar field size and thermal energy storage capacity. However, economic feasibility still faces significant challenges, primarily due to the low cost of coal in Chile. Moreover, the efficiency of the solar calciner is identified to be crucial for maximizing CO2 emission reductions in the calcination process, highlighting its importance for scaling up this technology and its widespread adoption in the Chilean cement industry. Despite the LCOH for the proposed plants being higher than the conventional coal-fired calciners, potential reductions in heliostat costs and higher carbon taxes from the current levels of 5 USD/tCO2 could enhance the economic viability of CST plants in Chile. Furthermore, potential CO2 emission reduction projections in the Chilean cement industry until 2050 are evaluated based on the implementation of CST systems in the calcination process and the alternatives proposed by the Instituto del Cemento y Hormig & oacute;n, such as reducing the clinker/cement ratio, co-processing, and reducing the cement content in concrete. The study forecasts potential reductions in specific CO2 emissions, which may down to 630 kgCO2/tclinker in an optimistic scenario, and to approximately 661 kgCO2/tclinker in a pessimistic scenario. This represents a reduction of 25% and 21%, respectively, from current specific emission levels of 839 kgCO2/tclinker in Chile. Further reductions are expected by incorporating carbon capture technologies, which focus on the main source of CO2 emissions: the calcination chemical reaction, which produces about 556 kg-