Carbon–Egg Cycle: An Engineering Framework toward Carbon Neutrality through Eggshell Valorization and Waste Heat Utilization from Local Industries for Resource, Economic, and Community Sustainability

Abstract

This article presents the Carbon–Egg Cycle framework, aiming to establish a circular carbon system by integrating local waste management with the utilization of surplus energy from industries, thereby advancing environmental engineering and circular economy approaches. The process converts eggshells, primarily composed of calcium carbonate (CaCO₃), through calcination using surplus industrial heat, producing calcium oxide (CaO) for further applications while capturing and storing the released carbon dioxide (CO₂) for subsequent use. The resulting CaO is formed into CO2 capture materials for community-scale activities, and through carbonation, it reverts to CaCO3, which can re-enter the calcination process, forming a continuous carbon cycle that reduces both waste and greenhouse gas emissions. Simultaneously, captured CO₂ can be utilized in various sectors, and CaCO₃ obtained from carbonation can serve as a soil amendment to reduce acidity and enhance productivity. The value of the Carbon–Egg Cycle lies in its integration of biowaste with energy reuse, minimizing resource loss and providing community- and small-industry-scale CO₂ management solutions. This framework demonstrates a pathway toward carbon neutrality and offers scalability for broader applications.