What is CO2 Storage?
Once CO2 is captured and compressed, the CO2 is transported by pipeline or tanker to a storage site, often to be injected into an underground storage site (or geological formation), where it will be safely stored for the long-term.
Although storage is one of the last steps in the Carbon Capture and Storage (CCS) process it is one of the first to be considered when developing a strategy to roll-out CCS infrastructure and systems. There is no benefit to capturing CO2 unless it can be stored and thus the total storage capacity and its location is an important constraint on how much CO2 can actually be managed.
Carbon dioxide capture and storage is a process for reducing GHG emissions into the atmosphere by first extracting CO2 from gas streams typically emitted during electricity production, fuel processing and other industrial process.
Where is CO2 Stored?
The most suitable sites for cost-effective long-term emissions storage in Canada include geological formations such as active or depleted oil, gas and coalbed methane reservoirs; deep saline aquifers; and salt caverns. Other potential storage options include mineral fixation or ocean storage. Although ocean storage is not currently underway in Canada, in 2006 The London Protocol legalized the storage of CO2 in the ocean as long as it is below the seabed. Nova Scotia is currently mapping their province for both on and off shore potential CO2 storage.
Ideal locations for large-scale CO2 capture include gas processing plants, fertilizer manufacturing facilities, thermal power plants and other sites that produce large amounts of CO2, often in excess of one million tonnes of CO2 equivalent annually (International Energy Agency, 2004). These industrial facilities are often located near others, thus increasing the amount of available CO2 for capture within the general vicinity.
Comprehensive research and testing on the site integrity must be done before a storage site can be selected.
Site selection criteria includes, but is not limited to the following:
- conducting detailed site characterization that encompasses an assessment of the geological characteristics of the storage reservoir and caprock, including the existence and characteristics of fractures and faults
- understanding the hydrogeology, geochemistry and geomechanics at the site
- assessing the volume and permeability of the storage formation
- understanding the site's geological trapping mechanisms
- an assessment of whether abandoned or active oil/gas wells will compromise the integrity of the seal
Once a site is selected and CO2 is being stored, a measurement, monitoring and verification program must be put into place.
CanmetENERGY researchers are involved in a number of groundbreaking projects in the CCS field. A low-emissions Canadian fossil fuel industry is the ultimate goal, with CCS playing a role.