Carbon Capture and Storage (CCS): How the Process Works in Practice
Carbon capture and storage (CCS) is often described as a climate solution for industries where CO₂ emissions are difficult to eliminate.
Unlike approaches that focus on reducing fuel use, CCS works differently. It captures carbon dioxide at the source, conditions it for transport, and stores it in suitable geological formations.
It is best understood not as a single technology, but as a complete value chain.
What Carbon Capture Means in Practice
Carbon capture begins at the emission source. CO₂ is separated from an industrial gas stream before it reaches the atmosphere.
That gas stream typically comes from:
- Flue gas, which is exhaust from combustion
- Process gas, produced during industrial reactions
The objective is simple in principle. Capture the CO₂. Purify it. Prepare it for transport. Then move it to storage.
One important factor is concentration. The more CO₂-rich the source gas is, the easier and more efficient it is to capture. By contrast, capturing CO₂ directly from ambient air requires much more energy because CO₂ is highly diluted in the atmosphere.
Why CCS Exists
Some industries generate CO₂ as part of their core chemical processes. In these cases, emissions cannot be eliminated simply by switching to renewable electricity.
For these industries, CCS offers a near-term and medium-term pathway to reduce emissions while longer-term transitions continue to develop.
How Carbon Capture and Storage Works
CCS is not one machine or one step. It is a sequence of stages that must operate together.
1) Capture and Compression
The first stage focuses on isolating the CO₂.
CO₂ contained in flue gas or process gas is captured and purified. It is then conditioned for transport. This usually means compressing it for pipeline transport or preparing it for liquefaction if shipping is required.
At this stage, the CO₂ becomes a manageable stream rather than a dispersed emission.
2) Transport and Distribution
Once conditioned, CO₂ must move from the capture site to a storage location.
This is typically done through pipelines, especially when connecting industrial facilities to shared infrastructure. In other cases, CO₂ is prepared for shipping, often via coastal terminals.
Some CO₂ can be reused in applications such as food processing, greenhouse cultivation or certain industrial uses. However, these applications generally do not absorb emissions at the scale heavy industry produces them.
3) Aggregation, Liquefaction and Temporary Storage
Many modern CCS systems are designed around shared infrastructure.
CO₂ from multiple emitters is aggregated at a central hub. It may be liquefied and temporarily stored before final transport. Export terminals can then send it to storage sites.
This hub model improves scalability. By sharing transport and storage infrastructure, industries can reduce cost and increase efficiency.
4) Sea Transport (When Applicable)
In some projects, CO₂ is transported by ship as a liquid.
This approach enables movement to offshore storage locations or to regions with suitable geological formations. It adds flexibility where pipeline connections are not feasible.
5) Sequestration: Long-term Geological Storage
The final step is long-term storage.
CO₂ is injected deep underground into suitable geological formations, commonly:
- Deep saline formations (saline aquifers)
- Depleted natural gas fields
- Stable geological reservoirs
This stage is the “storage” in CCS. The goal is long-term sequestration that prevents CO₂ from returning to the atmosphere.
Main Technologies Used for Carbon Capture
Carbon capture does not rely on a single technical approach. Different sources and gas compositions require different solutions.
Amine-Based Capture
Amine-based systems are widely used for capturing CO₂ from flue gas or syngas. These systems can deliver high-purity gaseous CO₂ at relatively low pressure.
They are often applied in large industrial settings where continuous capture is required.
Membranes and Adsorption
Capture systems may also incorporate membranes or adsorption technologies.
In many cases, these approaches are combined. Hybrid systems allow engineers to optimize purity, capture rate and energy use depending on the characteristics of the gas stream.
Cryogenic Separation
Cryogenic processes use extremely low temperatures to separate gases. In carbon capture, these systems can separate and purify CO₂ while also preparing it for transport.
This approach is particularly relevant where gas streams and operating conditions support low-temperature separation.
Clarifying the Difference Between CCS, CCU and DAC
| Acronym | Full Name | What It Does | Key Characteristic |
|---|---|---|---|
| CCS | Carbon Capture and Storage | Captures CO₂ from industrial sources and stores it in geological formations |
Designed for long-term geological storage |
| CCU | Carbon Capture and Use | Captures CO₂ and reuses it in industrial or commercial applications |
Creates value streams, but often does not provide permanent storage |
| DAC | Direct Air Capture | Extracts CO₂ directly from ambient air |
Requires significantly more energy due to low atmospheric CO₂ concentration |
What Makes CCS Work at Scale?
Large-scale CCS depends on more than capture technology.
It requires:
- Infrastructure such as pipelines, hubs and terminals
- Coordination between emitters, transport operators and storage providers
- Supportive regulatory and economic frameworks
For this reason, many CCS initiatives are developed as industrial clusters rather than standalone facilities.
Shared infrastructure and coordinated planning improve feasibility and long-term scalability.
Final Takeaway
Carbon capture and storage is best understood as an end-to-end chain:
capture → purification → compression or liquefaction → transport → aggregation and temporary storage → long-term sequestration
When applied to high-emitting, hard-to-abate industries, CCS provides a deployable pathway to reduce emissions at scale.
Its success depends not only on technology, but on infrastructure, coordination and long-term storage strategy.
Air Liquide’s Sustainability Commitment
Air Liquide develops advanced gas technologies that help industries enhance performance while reducing their environmental footprint. Guided by a strong commitment to climate action and the energy transition, our solutions deliver high operational efficiency while supporting lower-emission and more sustainable industrial processes.
Contact Air Liquide Egypt today to learn more about how our solutions can support you.
Frequently Asked Questions:
1. Is carbon capture good or bad?
Carbon capture is generally viewed as a mitigation tool. It is neither inherently “good” nor “bad” on its own. Its value depends on how and where it is applied.
For industries where CO₂ emissions are difficult to eliminate, CCS offers a practical pathway to reduce emissions while longer-term transitions scale.
However, capture, compression, and injection require energy. This additional energy demand, often referred to as the “energy penalty” of CCS, must be factored into system design and lifecycle emissions accounting.
2. What are the risks of carbon capture?
The risks associated with CCS are primarily linked to:
- Infrastructure (pipelines, compression systems, injection wells)
- Long-term storage integrity
- Operational safety
The technical risks are generally related to handling compressed CO₂ and ensuring that storage formations remain stable over time.
3. Can carbon capture leak?
Leakage is a key concern in CCS discussions.
During transport, CO₂ systems are designed similarly to other industrial gas infrastructure, with safety standards and monitoring in place to reduce risk.
For geological storage, CO₂ is injected deep underground into carefully selected formations. These sites are chosen based on geological stability and their ability to retain fluids over long periods.
Long-term monitoring is typically part of CCS project design to detect and manage any unexpected movement.