Carbon Capture and Storage (CCS): An Overview of Technologies and Current Development

Capturing carbon dioxide (CO₂) emitted from anthropogenic activity is critical for mitigating global climate change and achieving net-zero targets. Several innovative technologies have been developed to address this pressing issue. Once CO₂ is captured, it is transported and stored safely for the long-term in deep underground or subsea geological formations. This comprehensive approach is collectively called carbon capture and storage (CCS).

In CCS, CO₂ can be captured directly from the atmosphere or from point sources such as coal or gas-fired power plants, refineries, manufacturing facilities (cement, steel, aluminum, and chemicals production), and waste-to-energy facilities. 

Carbon Capture Technologies

The most widely used technology for capturing CO₂ directly from the atmosphere is Direct Air Capture (DAC), where CO₂ is directly separated from the ambient air through chemical or physical process. Major companies leading in DAC technologies include Carbon Engineering, Climeworks, Holocene and Deep Sky. Other innovative technologies to capture CO₂ directly from the atmosphere include Direct Ocean Capture (DOC), and Bioenergy with Carbon Capture and Storage (BECCS). DOC is similar to DAC, in which CO₂ is extracted directly from seawater through an electrochemical process. BECCS involves capturing and permanently storing CO₂ produced during electricity generation from sustainable biomass. Future Biogas and Drax are utilizing the BECCS in their CCS process. While DAC and BECCS have shown potential for scalability, DOC is still in the development phase.

Several technologies are also used or are in the development phase to capture CO₂ from the point sources and hard-to-abate sectors such as natural gas processing, cement, steel, and chemical production plants. Notable examples include amine-based systems, membrane-based systems, metal-organic frameworks, indirect heating calcination process, and the Allam-Fetved cycle. Broadly, these technologies are classified into absorption, adsorption and, physical separation methods.

In absorption technology, CO₂ can be absorbed from flue gases using amine-solvent based method and later released at high temperature for its safe storage. For instance, Heidelberg Materials uses amine-based technology at its Brevik plant to absorb CO₂ from flue gases. Companies like Aqualung and Cool Planet have developed membrane that separate CO₂ molecules passively, functioning much like filters. 

Novomof has developed adsorption-based technology such as metal-organic frameworks for capturing CO₂from point source. Calix uses Leilac’s technology – indirect heating calcination process – for capturing CO₂from cement and lime production plant.

8 RIVERS has developed Allam-Fetvedt Cycle (oxy-combustion process) that capture CO₂ from natural gas processing power plant transforming natural gas to clean energy. 8 RIVERS has entered into partnership with NET Power to use its proprietary Allam-Fetvedt Cycle to combat the climate change through clean energy production.  

By applying these technologies across diverse industries, CCS helps reduce overall CO₂ emissions, advancing climate goals and promoting sustainability.

Carbon Transportation

Once CO₂ is captured from industrial sources, it must be transported from the capture site (e.g., a power plant or industrial facility) to a storage site by pipelines, ships, or rail.  

Pipelines are the most widely used transportation method for captured CO₂. Made of steel, they are designed to withstand the pressure required to keep CO₂ in a dense, supercritical state. They often include pumps or compressors to maintain the required pressure and can span hundreds of kilometers, delivering CO₂to storage sites, typically depleted oil/gas fields or deep saline aquifers. Fluxys is working with Equinor to develop a 1000-kilometer subsea pipeline between Zeebrugge and Norway for CO₂ transport.

Ships are often used when storage sites are offshore or located far from capture facilities. CO₂ is liquefied at the capture site and transported in specialized vessels equipped with cooling and pressurization systems. Air Liquide, Fluxys Belgium and Port of Antwerp-Bruges  received EU Commission grant to build shared CO₂ transport and export facilities at the Antwerp Port Platform. The facility will provide open-access infrastructure to transport, liquefy and load CO₂ onto ships for onward permanent offshore storage.

K-Line has an agreement with Northern Lights to provide vessels for scalable transportation of CO₂ across Europe. KNCC, a joint venture between Knutsen Group and the NYK Group provides marine transportationof CO₂ at ambient temperatures, reducing the need for compression and heating required for cryogenic and low-temperature solutions during offshore discharge.

OSG has been awarded a $3 million grant from the U.S. Department of Energy to design a new vessel intended to transport liquefied CO₂ from emitters in Florida to sequestration sites in the Gulf of Mexico.

For shorter distances or when pipelines are not feasible, CO₂ can be transported by truck or rail in pressurized containers or as a liquid in tank cars. However, these methods are generally limited in volume and distance compared to pipelines and ships.

Carbon Storage

After reaching a storage site, captured CO₂ is injected into deep underground geological formations for secure and long-term storage, thereby preventing its release into the atmosphere.

Common storage locations include:

Depleted Oil and Gas Reservoirs: These are sites where oil and gas have been extracted, leaving behind porous rock formations. These formations are ideal for CO₂ storage because they have already demonstrated the ability to trap hydrocarbons, and they often have cap rocks that act as seals, preventing the CO₂ from migrating to the surface. Aquaterra Energy is involved in repurposing depleted offshore oil and gas fields for CO₂ storage.

Deep Saline Aquifers: These aquifers are layers of porous rock saturated with saltwater (brine), typically located several kilometers below the surface. They are abundant and provide vast storage capacity. CarbonCapture Inc. uses deep saline aquifers via Class VI injection wells for permanent CO₂ storage.

Unmineable Coal Seams: CO₂ can be stored in deep coal seams that are too difficult to mine, where it is absorbed onto the coal. Over time, the CO₂ becomes trapped in the coal matrix, providing another storage option.

Conclusion

Carbon Capture and Storage (CCS) is a crucial technology in the fight against climate change, offering a viable way to reduce industrial CO₂ emissions and support global net-zero targets. By capturing carbon from power plants, cement and steel production, refineries, and biogas facilities and securely storing it underground, CCS helps mitigate global warming while facilitating low-carbon industrial processes.

The most common technologies for the capturing CO₂ directly from the atmosphere are DAC and BECCS. Several other technologies have been developed to capture CO₂ from hard-to-abate sectors including – amine-based, membrane-based, metal-organic frameworks, indirect heating calcination, and the Allam-Fetved cycle. After capturing, CO₂ is transported to the storage site via pipelines, ships, rail or trucks. Once delivered, CO₂ is injected deep underground or under the seabed for safe, long-term storage.

Innovative CCS technologies continue to evolve worldwide. Integrating CCS with renewable energy and strengthening regulatory frameworks will be essential for maximizing its climate impact. As industries and governments worldwide recognize the urgency of climate action, CCS will play a key role in reducing emissions and ensuring a sustainable, low-carbon future.