What is Carbon Capture and Storage (CCS)?

As the world faces the urgent challenge of climate change, reducing carbon dioxide (CO₂) emissions is more important than ever. While renewable energy and energy efficiency improvements are vital, some industries—like cement, steel, and chemicals—produce emissions that are difficult to eliminate completely. This is where carbon capture and storage (CCS) comes in: a technology designed to capture CO₂ at its source and store it safely underground, preventing it from entering the atmosphere.

But how does CCS actually work, and why is it becoming such an important topic in climate discussions? In this article, we’ll explore the basics of CCS, how it works, and its potential role in building a more sustainable future.

What is carbon capture and storage (CCS)?

Carbon capture and storage (CCS) refers to a set of technologies that capture CO₂ from large sources—such as power plants and industrial facilities—before it is released into the air. The captured CO₂ is then transported and stored deep underground in geological formations, where it can be securely contained.

The concept of capturing and storing carbon dioxide has been around for decades. Early CCS projects were often linked to the oil and gas industry, where captured CO₂ was used to help extract more oil from aging fields. Over time, the focus has shifted toward using CCS as a climate solution, especially for industries with few alternatives for reducing emissions. ^1,5

Today, CCS technology is in use in several countries, with projects operating at power plants, cement factories, and chemical plants. While the number of large-scale CCS projects is still relatively small compared to global emissions, interest and investment are growing as governments and industries seek effective ways to meet climate targets. ^1,5

How does carbon capture and storage work?

CCS involves three main steps: capturing CO₂, transporting it, and storing it securely underground. 

Capture: Different ways to capture CO₂

Capturing carbon dioxide is the essential first step in CCS, and several methods are used depending on the type of facility and process:

• Post-combustion capture: This is the most common approach, especially for existing power plants and industrial sites. After fuel is burned, CO₂ is separated from the exhaust gases using chemical solvents. The CO₂ is then released from the solvent, purified, and prepared for transport. This method can often be added to existing facilities.^1,2
• Pre-combustion capture: Here, fuel is converted into a mixture of hydrogen and CO₂ before it is burned. The CO₂ is separated out, and the hydrogen can be used as a cleaner fuel. This method is often used in hydrogen and ammonia production and in some specially designed power plants.^1,2
• Oxy-fuel combustion: In this process, fuel is burned in pure oxygen instead of air, resulting in a flue gas that is mainly CO₂ and water vapor. After the water is removed, a concentrated stream of CO₂ remains. Oxy-fuel combustion is mainly used in new plants designed for this technology.^1,2
• Direct air capture (DAC): Unlike the other methods, DAC removes CO₂ directly from the air using chemical processes. While still developing and more energy-intensive, DAC can help remove CO₂ from the atmosphere regardless of where it was emitted.^1,2

Transport: Moving CO₂ to storage sites

Once CO₂ has been captured, it needs to be transported to a storage site. The most common way to move large volumes of CO₂ is through pipelines, which are similar to those used for natural gas. In some cases, especially for smaller quantities or when pipelines aren’t practical, CO₂ can also be transported by ship, truck, or rail.^1,2

For pipeline transport, CO₂ is typically compressed into a supercritical state, where it is dense like a liquid but flows like a gas. For shipping, trucking, or rail, CO₂ is usually cooled and pressurized into a liquid form for safe and efficient handling.^1,2

Storage: Securing CO₂ underground

The final step is to store the captured CO₂ deep underground, where it can be safely contained for thousands of years. There are several types of geological formations used for storage:

• Depleted oil and gas fields: These are former production sites that have already held oil or gas for millions of years, making them well understood and reliable for CO₂ storage.^1,3
• Deep saline aquifers: These are porous rock formations filled with salty water, found deep below the earth’s surface. They offer significant storage capacity and are widely available.^1,3
• Other options: In some cases, unmineable coal seams or basalt formations can also be used for CO₂ storage.^1,3

Who should care about carbon capture and storage?

CCS is relevant for a wide range of people and organizations:

• Industry leaders can use CCS to reduce their carbon footprint and meet regulatory requirements.

• Policymakers can include CCS in climate strategies to help achieve emissions targets.

• Researchers and engineers are working to improve the efficiency and affordability of CCS.

• Consumers can support companies that invest in sustainable practices, including CCS.

The future of carbon capture and storage

Recent developments suggest that CCS is at a pivotal moment. According to the World Economic Forum, investments in CCS are increasing, new infrastructure projects are underway, and policy-driven growth is expected to accelerate adoption of CCS, especially in hard-to-decarbonize sectors.⁴

Despite this momentum, CCS still faces challenges. The technology can be complex and costly to implement, and its success depends on supportive policies, long-term investment, and greater public understanding.³

Nevertheless, the value of CCS is clear. It offers a practical solution for reducing emissions in industries where alternatives are limited, and it supports national and global climate targets. When combined with bioenergy, CCS can even enable “negative emissions,” helping to remove CO₂ from the atmosphere. As part of a broader climate strategy, CCS has the potential to play a crucial role in the transition to a more sustainable, low-carbon future.⁵

Conclusion

Carbon capture and storage offers a valuable approach for managing industrial emissions that are otherwise difficult to eliminate. While it is not a standalone solution, CCS plays a key role alongside renewable energy and efficiency improvements in helping to achieve climate goals.

If you’d like to hear more from experts, listen to our podcast episode on CCS, where researchers from Chalmers University of Technology discuss the basics, challenges, and future of carbon capture and storage.⁵