Design and development of fiber sorbent based direct air capture systems

Abstract

As atmospheric CO2 levels continue to escalate, driving severe climatic and environmental disruptions, Direct Air Capture (DAC) technologies have emerged as a critical solution to mitigate carbon concentrations. DAC technologies are essential for achieving negative carbon emissions, a cornerstone in the suite of strategies required to meet global climate goals outlined in international frameworks such as the Paris Agreement. Unlike traditional carbon capture methods that target point sources, DAC captures CO2 directly from ambient air, offering the unique advantage of being decoupled from specific industrial emissions. Captured CO2 can either be permanently sequestered underground or repurposed in industrial applications, making DAC an integral component in advancing a circular carbon economy. The significance of DAC lies in its versatility and scalability, allowing deployment across diverse geographic regions irrespective of industrial activities. DAC systems leverage chemical sorbents or physical adsorbents to selectively capture CO2 from the air. Recent technological advancements have enhanced the energy efficiency and economic feasibility of DAC, facilitating the transition toward large-scale deployment. Moreover, the integration of DAC systems with renewable energy sources enhances sustainability by reducing carbon footprints. This approach enables the conversion of captured CO2 into value-added products, such as synthetic fuels, chemicals, and building materials, thereby creating a closed-loop carbon economy. Despite these advancements, scaling DAC technologies to meet global demand presents substantial challenges. These include the high energy intensity of the process, significant capital investments, and the need for robust infrastructure to transport and store captured CO2. Additionally, the current pace of deployment must increase significantly to achieve meaningful reductions in atmospheric CO2 concentrations. Addressing these obstacles necessitates technological innovation coupled with supportive policy frameworks that incentivize DAC integration into climate action plans. Future research should prioritize optimizing DAC materials and processes, reducing operational costs, and minimizing energy consumption. Collaborative efforts among governments, industries, and academic institutions are essential to transition DAC technologies from pilot projects to global-scale implementations. This work explores unique pathways to scale laboratory-scale DAC technologies for broader applications, supported by a detailed examination of chemical and engineering principles. Chapter 2 provides foundational theoretical and background knowledge on DAC systems, including their chemical and engineering aspects. Chapter 3 introduces a novel, electrically driven DAC system, emphasizing its innovation and practicality. Chapter 4 discusses the scale-up production and demonstration of a bench-scale DAC system, complemented by a techno-economic assessment and a life cycle analysis. Chapter 5 proposes a rapid temperature-vacuum cycle system as a potential energy-efficient advancement in DAC technologies. Collectively, this work showcases the successful implementation of innovative DAC cycles, from the selection and application of adsorbents to the development of scale-up production methodologies. By addressing industrially applicable sorbent packing and providing guidelines for DAC modulation, this study serves as a valuable resource for future research and industrial adoption.