What is CCUS?

Carbon Capture, Utilization, and Storage (CCUS) encompasses methods and technologies to remove CO2 from the flue gas and from the atmosphere, followed by recycling the CO2 for utilization and determining safe and permanent storage options.  Despite the adoption of alternative energy sources and energy efficient systems to reduce the rate of CO2 emissions, the cumulative amount of CO2 in the atmosphere needs to be reduced to limit the detrimental impacts of climate change [IPCC, 2013]. Therefore, regardless of the deployment of clean and efficient energy solutions, CCUS technologies need to be implemented.

In addition to addressing the technical aspects of CCUS, it is also critical to address the societal and economic costs of climate change.

Efforts to limit rising atmospheric CO2 concentrations while meeting increasing global energy demand, can only be achieved by deploying a comprehensive portfolio of technologies that include alternative energy sources, energy efficient systems, and carbon capture, utilization and storage (CCUS) measures [S. Pacala, R. Socolow, Science, 2004]. Despite the adoption of alternative energy sources and energy efficient systems to reduce the rate of CO2 emissions, the cumulative amount of CO2 in the atmosphere needs to be reduced to limit the detrimental impacts of climate change [IPCC, 2013]. Therefore, regardless of the deployment of clean and efficient energy solutions, CCUS technologies need to be implemented. CCUS involves multiple aspects that need to be in sync for the successful removal or capture of CO2 from the flue gas or the atmosphere, followed by utilization and storage.

Carbon capture involves the development of sorbents that can effectively bind to the CO2 present in flue gas or the atmosphere, which is expensive. In addition, there has been a considerable debate about the fate of the captured and compressed CO2. Ideally, converting CO2 into useful chemicals of commercial importance, or utilizing CO2 for oil extraction or remediation of alkaline industrial wastes, would add economic value to this greenhouse gas. However, the demand for CO2 is limited compared to the vast amount of CO2 that needs to be removed from the atmosphere, to reduce the detrimental environmental impacts of climate change. Therefore, various options for CO2 storage have been proposed. These options include injecting CO2 in geologic formations and oceans, and growing trees to enable biological fixation of CO2 via photosynthesis. Carbon utilization and storage schemes can be classified by their capacity and permanence of storage, environmental consequences, and cost of implementation. Any viable system for storing carbon must be (1) effective and cost competitive, (2) stable as long-term storage, and (3) environmentally benign.

Because the application of CO2 storage technologies or other carbon management strategies may raise the cost of energy, it is unlikely that they will be introduced without regulatory pressure, Therefore, sustainable integrated systems that involve the co-generation of energy while capturing CO2, such as chemical looping and sorption enhanced water gas shift, require further investigation. In addition to addressing the technical aspects of CCUS, it is also critical to address the societal and economic costs of climate change. The trade-off between ignoring the risk of climate change and paying for a carbon neutral energy infrastructure is more easily managed, if the cost of the carbon management can be held low.  Another challenge for the implementation of CCUS is determining and communicating the social cost of carbon across various communities that include scientists, engineers, policy makers and the general public. Therefore, various scientific, economic and societal aspects need to be addressed to ensure successful development and implementation of CCUS technologies.

Read more about research in CCUS.