Carbon capture and storage technologies enable industrial processes to reduce their carbon emissions by sequestering them underground.
Carbon capture involves collecting, treating and transporting carbon dioxide for long-term geologic storage locations.
Storage typically occurs in deep, porous rock formations such as saline aquifers, depleted oil and gas reservoirs or unmineable coal areas. Monitoring is conducted in both the injection formation as well as its surroundings to ensure no CO2 leaks back into the environment.
Capture
Carbon Capture and Storage (CCS) technology aims to mitigate climate change emissions by extracting them from fossil-fuel exhaust prior to it entering the atmosphere, making a key contribution toward meeting net-zero emission goals outlined by Paris Agreement.
The technology consists of three steps – capture, transport and storage – which can be applied across various sectors critical to our economy, such as oil refining, cement production, steelmaking and power generation. Furthermore, direct air capture and storage (DACCS) technology may also be utilized as a method of mitigating historic atmospheric emissions.
CO2 captured during CCS can also be utilized in industrial processes or injected into active oil reservoirs for enhanced oil recovery (EOR), making CCUS also known as carbon capture, utilization and storage (the “U” stands for Utilization). CCS currently holds 26 million tons per year capacity across power plants and industrial facilities worldwide.
Compression
Carbon Capture and Storage (CCS) involves collecting CO2 at emission sources such as power plants or industrial facilities, transporting it for long term storage in an underground geological formation and then preventing its release into the atmosphere. CCS technology is one of many that can help nations meet their climate goals while reaching the global target of net zero anthropogenic greenhouse gas emissions by 2050.
No matter which CCS technology is utilized, all capture systems must compress the CO2 stream prior to liquefaction and transportation. Compressed CO2 typically is transported as either sub-cooled liquid for ship transport, or dense phase through pipeline transportation systems.
If the source and storage site aren’t colocated, CO2 must be transported via trucks, trains, ships or pipelines to its storage site before being injected into an appropriate geological formation – common examples being depleted oil/natural gas reservoirs; saline formations; unmineable coal beds or basalt formations.
Transport
Transportation of CO2 from its source to storage locations requires significant infrastructure. The UK has proven its capacity in transporting gas across its territory for heating and power generation; an effective CO2 network could therefore be established using existing technology.
Captured carbon dioxide is compressed to reduce its volume before being transported by pipeline or ship to an appropriate geological storage site for injection into deep underground geological formations rather than being released back into the atmosphere. Possible storage locations may include depleted oil and gas fields, saline aquifers or unminable coal seams.
Some of the captured carbon dioxide may be utilized for enhanced oil recovery (EOR) or manufactured into chemicals; however, less than 10% is currently utilized; incentives must be provided to encourage CCS deployment at scale or else only large fossil fuel power plants and industrial facilities in close proximity of suitable storage locations will utilize it.
Storage
CO2 collected from power plants or industrial facilities can be stored long term in underground geological formations for future use as fuel or other materials – an approach known as utilization or carbon capture, use, and storage (CCUS).
Point-source CCS involves installing technology at specific emission sources such as coal power plants or fossil fuel processing facilities, while large-scale, grid-connected CCS is more of an energy infrastructure concept that must encompass various technologies for it to work effectively.
Carbon can be stored safely underground using geological formations like saline aquifers and depleted oil and gas fields, with careful monitoring of injection formation and surrounding structures necessary to ensure that CO2 does not escape into shallower geological formations or the atmosphere. CO2 could also be put to good use through enhanced oil recovery (EOR), cement manufacturing, steel making or chemical manufacturing but this would require more carbon-free electricity, potentially increasing CCS costs significantly.