Carbon Capture and Storage (CCS) technology aims to decrease greenhouse gas emissions by either preventing them from being released or sequestering existing ones. CCS works by extracting CO2 from large industrial facilities like steel mills or coal power stations as well as natural processes like deforestation and reforestation processes.
Capturing CO2
Carbon capture and storage (CCS) works by isolating CO2 from other gases before it escapes into the atmosphere at large industrial facilities such as coal, natural gas or oil power plants. Once captured, this CO2 is then transported via pipeline or ship for permanent storage at its final destination.
Most CCS projects use post-combustion capture; however, pre-combustion and oxy-fuel combustion processes are also being explored. Once separated CO2 has been compressed into supercritical state and injected deep underground in porous rock formations like depleted oil and gas reservoirs or coal seams to act as natural traps to keep its release back into the atmosphere over long periods of time.
Studies have demonstrated that there is ample underground storage capacity available to meet current and future emissions targets. Existing natural gas pipeline networks could potentially serve as storage facilities, with new, higher capacity pipes required as investments to store carbon dioxide effectively.
Transporting CO2
Once captured, CO2 must be transported to its storage location for long-term storage. This can be accomplished either via pipeline or sea. Pipelines offer the cheapest means to move large volumes of carbon dioxide; existing oil and natural gas pipelines may serve this purpose, although CCS projects often need specially designated pipelines built specifically for CO2 transportation due to higher temperatures and pressures involved.
These pipelines must be designed and constructed carefully, taking great care to meet strict purity and temperature specifications for CO2. In addition, any impurities present must not damage or leak from them into the pipelines.
Ship transport can cover greater distances. Once at its destination, CO2 must be injected into deep geological formations similar to those that have stored oil and natural gas for millions of years; this practice is known as structural trapping. Additionally, rock layers surrounding its injection site must act as seals that prevent CO2 from migrating out of storage formation.
Storing CO2
After carbon dioxide has been extracted from flue gas and stored safely underground geological formations at depths of one kilometer or deeper, it is stored there rather than being released back into the atmosphere.
CO2 can be stored in depleted oil and gas reservoirs, deep unmineable coal beds or deep saline formations (aquifers). Oil reservoirs are generally the best choice as their capped rock structures have successfully held oil and gas for millennia.
CO2 captured from power plants is typically transported via pipelines – similar to those used for natural gas transport – to its storage site for storage. Ships may also be used, although this method of delivery is less common.
CCS infrastructure requirements include a network of pipelines to transport captured CO2. Such networks may cost billions to construct and operate; companies capturing and storing CO2 qualify for a 45Q tax credit which provides additional incentives to invest in this technology.
Utilization
Carbon Capture, Utilization, and Storage (CCUS) technology can reduce emissions from coal-fired power plants and other industrial sources while simultaneously improving oil recovery in older oilfields.
EOR projects leverage captured CO2 to increase oil output from well sites, thus extracting more crude at reduced costs. CCUS technology can also be applied in various industrial settings.
Shell has long supported policies designed to incentivize CCS development, such as the 45Q tax credit. Furthermore, we assist commercially viable projects in this regard.