Carbon Capture, Utilization and Storage, or CCUS, is a process that will allow Louisiana’s industries that emit carbon dioxide (CO2) to both maintain their business plans and reduce CO2 emissions. First, it uses special equipment to remove the CO2 from their facilities’ exhaust before it reaches the air. Once captured, the CO2 can either be provided to companies for other uses or transported by pipeline to an underground storage area for safe and permanent storage. The same type of impermeable rock layers that have kept oil, natural gas and naturally occurring CO2 locked underground for millions of years can safely store CO2.
Proper storage areas have special characteristics. First, part of the rock formation must be porous because the pores provide the space in which the CO2 is stored. The second characteristic is permeability, meaning the porous rock is arranged in layers that allow the CO2 to move through the rock formation. The third is the existence of a cap rock, an impermeable rock layer that acts as a seal trapping the CO2 underground. Finally, the rock formation must be deep enough to have multiple layers of rock above it and to be subject to enough pressure to keep the CO2 stored within the pores of the rock.
CO2 is compressed from a gas into an almost liquid state before being put underground through a well into the rock formation. Once underground, some of the CO2 will remain lower in the pore space, while other parts will float up and stay trapped under the cap rock. A large portion of the CO2 will dissolve into the brine that is also trapped in the pore space. Over time, some of this dissolved CO2 will react with the minerals in the rock and solidify.
ExxonMobil Pipeline Company will leverage its decades of experience operating underground storage facilities for various energy products to safely operate and monitor the subsurface CO2 storage sites once they start operations. A combination of technologies is planned to monitor for and detect any potential leaks at the atmospheric, near-surface and deep sub-surface levels.
For more information, visit the Global CCS Institute or the National Energy Technology Laboratory.