By Carbon capture and storage is a process that traps carbon dioxide emissions from point sources like power plants or factories, compresses them, and transports them to an underground location where they are permanently stored. It is one of many technologies being considered as part of a suite of tools needed to reduce greenhouse gas (GHG) emissions and help limit global warming to 1.5 degrees Celsius above pre-industrial levels. For more detailed information on how carbon capture and storage works and its role in mitigating climate change,click here.
CO2 is a naturally occurring substance that is released into the atmosphere when fossil fuels are burned. Carbon capture and storage, which is also known as CCS or CCUS, is a key part of a comprehensive plan to address climate change that includes a rapid shift away from fossil fuels and toward renewable energy sources.
CCUS works by separating CO2 from the flue gases produced by coal- and natural gas-powered power plants or other industrial sources. The CO2 is then pumped deep underground into geological formations like used-up oil and gas reservoirs or into saline formations that contain unusable salty water. Canada has several large-scale CCS projects, including the Weyburn-Midale field and the Sleipner field in the North Sea. In the United States, the Petra Nova project is currently the largest post-combustion CCS facility.
The captured CO2 can then either be buried underground for as long as it takes to form carbonate or, more commonly, it can be used in products such as concrete, chemicals and synthetic fuels. If the CO2 is used to make synthetic fuels, it will be re-emitted when they are combusted, but if the CO2 is used to make cement or other durable products, it will be sequestered for decades or more.
In some countries, a portion of the captured CO2 is stored in depleted oil fields for enhanced oil recovery. Other uses for injected CO2 are being researched, including the use of the CO2 to grow algae or other types of biomass that could be combusted to produce electricity.
While some scientists, governments and businesses are promoting CCUS as an important tool to combat climate change, others are skeptical or opposed to the technology. Some nongovernmental organizations and environmental justice advocates see CCUS as a moral hazard that gives companies a green light to continue using fossil fuels, especially in the power sector where other decarbonization options are available. They argue that CCUS can be used only as part of an overall strategy that includes a steep decline in the use of fossil fuels, along with other clean energy alternatives. Other concerns about CCUS include its high cost and risk of leakage. If the CO2 is leaking from a storage site, it can be re-emitted into the atmosphere and undermine the benefits of other climate change mitigation measures. For these reasons, it’s crucial that any potential uses for CCUS be assessed on a lifecycle basis, taking into account the source of the captured CO2 as well as its end use. This helps ensure that the climate impact of CCUS is understood on a full range of mitigation pathways that would help limit warming to 1.5°C or less.
