Possible Alternative to Established CCS Technologies: Technical and Economical Evaluation
Authors: Wolicki R. D. , Barbacane N. , Ciulla M. , Arca S. , D'Alessandro E. , Parisi P. , Morodei F. , Di Profio P. 
Published: October 2024

The current landscape of Carbon Capture and Storage (CCS) technologies is rapidly evolving, moving towards more cost-effective solutions to address the economic challenges associated with energy transition. Greenhouse gas emissions pose a significant threat to millions of people, as the global temperature continues to rise. Despite the close link between emissions and industrialization, many companies are actively engaged in developing high-performance, affordable CCS systems to reduce their carbon footprint without compromising their financial stability. As of early 2021, there were 24 operational commercial CCS and carbon capture and utilization (CCU) facilities worldwide, with the capacity to capture approximately 0.04 billion metric tons per annum (Gtpa) of CO2 emissions from energy and industrial processes. These facilities include natural gas processing plants, a coal power plant, chemical plants, hydrogen production facilities, and iron and steel plants. While some plants have ceased operations, 30 more are in various stages of development. Additionally, there are 16 small-scale pilot and demonstration plants currently in operation, with 19 in development and 24 already completed and closed. If all 30 commercial plants under development are completed, the capture capacity would increase to about 0.1 Gtpa. Notably, there are three operational commercial plants utilizing bioenergy with CCS (BECCS), with seven more in development. The current capture capacity of operational BECCS plants is relatively low, at 1.13 million metric tons per annum (Mtpa), but it could rise to 9.7 Mtpa if all the plants in development become operational. Furthermore, there are nine smaller-scale BECCS pilot and demonstration plants active, with six completed and four in various stages of development.2

There are several ways to capture CO2 and stabilize it under atmospheric conditions but the most studied systems commercially available are based on the formation of carbamate between CO2 and an amine in post combustion capture systems. First, the CCS systems can be divided in two main technological approaches, depending on the target application of such technology. There are direct air capture and industrially derived capture. Direct air capture, being the most ambitious and technological challenging approach, still requires plenty of work to deliver commercially scalable and economically viable solutions, as it accounts only for the 1% of total CCS technologies available. Currently, there are two plants using Direct air carbon capture and storage (DACCS), with one under development, in addition to 15 pilot and demonstration plants either in operation or in development; however, collectively, their capture capacities are quite limited. Capture technologies are at different levels of technological readiness (TRL), with some at TRL 1. Industrially derived capture is the most used one and can be further divided in three different technologies: Pre-Combustion Capture, Post-Combustion Capture and Oxy-fuel combustion capture.

Post-combustion carbon dioxide (CO2) capture is mainly relevant to traditional natural gas and pulverized coal-fired (PC) power generation. In a typical PC power plant, fuel undergoes combustion with air in a boiler to produce steam, which then drives a turbine to generate electricity. The resulting boiler exhaust, or flue gas, primarily consists of nitrogen (N2) and CO2. The separation of CO2 from this flue gas stream poses significant challenges for several reasons: CO2 is present at a dilute concentration (typically 13 to 15 volume percent for PC power plants and 3 to 4 percent for natural gas-fired plants) and at low pressure (slightly above atmospheric), necessitating the treatment of a large volume of gas; trace impurities such as particulate matter, sulfur dioxide (SO2), and nitrogen oxides (NOx) in the flue gas can impair sorbents and reduce the efficiency of certain CO2 capture processes; CO2 is captured at low pressure, and compressing it from atmospheric to pipeline pressure (about 2,000 pounds per square inch absolute [psia]) will result in a substantial auxiliary power load on the overall power plant system.3