Process Engineering Perspectives on CO2 Capture Technology Development

This paper provides a broad overview of CO₂ capture technologies from the perspective of the process engineer who is challenged to develop, evaluate, and scale these technologies up from laboratory, bench and pilot-scale to full-scale, commercial applications.  The CO₂ capture problem will be stated in process engineering terms, and implications of the source characteristics including composition, temperature, pressure, flow, and the variability of these characteristics - and corresponding CO₂ purity/delivery specifications for various end uses will be analyzed.  The process engineer’s tasks will be described in terms of the wide range of process engineering activities that are involved, ranging from experimental data collection and process simulation, process and equipment design, and economic analyses, along with the challenges that each task presents.  The nature and importance of the universal thermodynamic constraints and resulting minimum energy requirements that govern all CO₂ capture process will be described, and the need to integrate the CO₂ capture process with the CO₂ source process and CO₂ use or storage locations will be explored.  CO₂ capture technologies will be categorized and compared in terms of the key process design parameters that affect each group of processes in a different way, revealing the various process advantages and disadvantages of the different approaches.  Capture approaches to be discussed will include chemical and physical absorption, chemical and physical adsorption along with temperature, pressure, and vacuum regeneration approaches, organic and inorganic membranes, cryogenic separation, as well as emerging approaches including chemical looping, electrochemical, and microbial capture technologies.  Equipment challenges such as the physical size of mass and heat transfer devices, mechanical limitations on compression technology, and materials of construction issues will be described.  Conventional methods of estimating and comparing capital and operating costs among CO₂ capture technologies will be reviewed.