Carbon Capture and Storage (CCUS) involves collecting carbon dioxide gas produced from large power and industrial facilities that utilize fossil fuels, then transporting and storing it deep underground in rock formations such as used oil reservoirs or saline formations.
CCUS technology can currently be found at several natural gas processing, coal-fired power plant and ethanol production facilities; additionally it may also be utilized for enhanced oil recovery (EOR) at existing petroleum facilities.
Capture
Carbon capture and storage technology works by collecting CO2 emissions from power plants and industrial facilities before they enter the atmosphere, then transporting and storing them underground geologic formations for storage. Also referred to as Carbon Capture Use Storage or CCUS technology, this innovative technique plays a significant role in mitigating greenhouse gas emissions that contribute towards meeting global climate targets.
Carbon dioxide can be captured from flue gases through various means, including pre-combustion, oxy-fuel combustion and integrated gasification combined cycle power plant technologies. Once captured, CO2 can then be stored underground using depleted oil and gas reservoirs, coal beds or deep saline formations as safe repositories.
CO2 can not only be stored in geologic formations, but it can also be put to other uses besides storage in geologic formations. This utilization, commonly referred to as CCUS+ or “utilization,” can lead to reduced emissions over its lifecycle depending on which fuel or other material it displaces.
Compression
Carbon dioxide capture technology works by extracting CO2 from power plant or industrial facility exhaust stacks and compressing it so that transport is easier, then stored underground – either depleted oil and gas reservoirs or saline aquifers, in which case this system is known as CCS or CCUS.
Compression is at the core of all CCUS systems. Compressors transform low pressure gas into dense liquid or supercritical states suitable for transport by ship or pipeline – an imperative task requiring precision and efficiency under difficult conditions.
CO2 can be utilized in numerous applications, from creating concrete to producing synthetic natural gas or ethanol; this process is known as utilization. Any revenue earned through utilization activities may offset the costs of capture technology while simultaneously contributing to emissions reductions. If no utilization activities exist, CO2 may also be permanently stored underground using geologic formations.
Transport
After carbon dioxide (CO2) has been captured through either post-combustion capture (separating CO2 from flue gas after fossil fuel combustion) or oxyfuel capture (combusting in pure oxygen), its transport must then occur to storage facilities for long-term storage. Transport modes including ports can provide efficient solutions, which is why both Clean Air Task Force and Bellona Europa have advocated for inclusion of port infrastructure within Trans-European Transport Network (TEN-T) policies.
The Northern Lights project provides an example of how to develop an agile carbon capture and transportation network. This is accomplished by installing multiple carbon capture units over time, selecting more cost-effective transport modes with lower environmental impact per unit CO2 managed, and eventually switching over to pipeline connections which are cheaper over longer distances. By year 15 Basel to Rotterdam barge transport connections were changed for pipeline connections which are less costly.
Storage
Carbon Capture and Storage (CCS) involves extracting carbon dioxide emissions from power plants or industrial facilities, transporting it underground geologic formations for permanent storage, and conducting research and development for technology advancement that could make carbon capture and storage an economically feasible industry that reduces human contributions to global climate change. DOE’s CCS Program conducts ongoing research to make CCS an industry that will reduce human contributions of CO2 into the atmosphere.
CCUS technologies may be combined with fossil fuels for low-carbon energy production or to produce products like concrete and chemicals. CO2 stored permanently underground may resurface when its product is burned off.
Natural forms of carbon capture and storage (CCS, or carbon sinks), known as carbon sinks, include forests, oceans and grasslands that absorb CO2 through photosynthesis to store it within plant tissues. There are two engineered forms of CCS as well – bioenergy with carbon capture and storage (BECCS) and direct air carbon capture and storage (DACCS) which remove CO2 directly from the atmosphere for storage in plant tissue or storage in bioenergy power stations.