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Understanding Carbon Capture and Storage: Process, Potential, and Challenges

Explore how carbon capture and storage works, its role in climate solutions, and the debate over its promise and pitfalls.

By Medha deb

Created on Sep 27, 2025

Explore how carbon capture and storage works, its role in climate solutions, and the debate over its promise and pitfalls.

What Is Carbon Capture and Storage?

Carbon Capture and Storage (CCS) is a set of advanced technologies designed to prevent carbon dioxide (CO₂) emissions from large industrial sources—such as fossil fuel power plants and heavy industry—from entering the atmosphere. The main goal of CCS is to significantly reduce greenhouse gas emissions, thereby helping to mitigate climate change by permanently storing CO₂ deep underground.

CCS is seen as a transitional tool for industries difficult to decarbonize, such as cement, steel, and chemical manufacturing.
CCS is sometimes bundled with “utilization,” in processes known as CCUS, where captured CO₂ is put to commercial use.

How Does Carbon Capture and Storage Work?

Typical CCS operation involves three key stages: capture, transport, and storage.

1. Capture

Post-combustion capture: Most common. CO₂ is separated from gases after fuel is burned, usually from power plant flue gas using chemical solvents.
Pre-combustion capture: Fuel is converted into a mixture of hydrogen and CO₂ before burning; CO₂ is separated out for storage, and hydrogen can be used as clean energy.
Oxy-fuel combustion: Burning fuel in nearly pure oxygen yields a CO₂-rich exhaust from which CO₂ is easier to separate.
Direct air capture: Extracting CO₂ directly from ambient air—a more expensive process, as CO₂ is diluted.

2. Transport

Once captured, CO₂ is compressed into a liquid and moved—usually via pipelines, or, less commonly, by ships, trucks, or trains—to a dedicated storage site. The integrity and safety of this stage is critical to prevent leaks.

3. Storage

The last stage is pumping CO₂ deep underground—commonly one mile (1.6 km) or more below the surface—into stable geological formations like:

Depleted oil and gas reservoirs
Deep saline aquifers
Unmineable coal seams

Here, CO₂ is expected to remain for thousands of years, effectively removed from the atmosphere.

Where Is CCS Used, and What Are the Main Applications?

CCS is mainly applied at large-scale stationary sources because it is most efficient when emissions are highly concentrated. Typical sites include:

Coal- and natural gas-fired power plants
Cement, steel, and petrochemical plants
Hydrogen production facilities

Some projects combine CCS with enhanced oil recovery (EOR), injecting CO₂ to extract more oil from depleted wells, with the CO₂ theoretically staying underground.

CCS facilities can theoretically capture up to 90% or more of CO₂ emissions from a given source under optimal conditions, but real-world rates often fall below this.

CCS and Direct Air Capture

A newer CCS variant is direct air capture (DAC), where specialized machinery filters CO₂ directly from ambient air. While promising for eventual large-scale atmospheric cleaning, DAC is currently energy-intensive and expensive due to the low concentration of CO₂ in air.

How Secure Is CO₂ Storage?

CCS relies on finding underground geologies that can trap CO₂ safely for millennia. The security of storage sites depends on:

Cap rocks: Impermeable layers above the storage reservoir prevent upward CO₂ migration.
Depth: Sites are typically chosen at least 1 kilometer underground, where temperature and pressure keep CO₂ in a supercritical state.
Monitoring: Ongoing surveillance detects leaks, with injection stopped and corrective action taken if CO₂ moves as expected.

To date, studies and experience (notably in Norway’s Sleipner and U.S. projects) indicate that well-chosen sites can retain stored CO₂ securely, but long-term data is limited as most projects are relatively new.

Carbon Capture Utilization: What Is CCUS?

Sometimes, captured CO₂ is utilized rather than stored—the basis for the term CCUS (Carbon Capture, Utilization, and Storage). Example uses include:

Enhanced oil recovery, where CO₂ is used to extract more oil from wells
Use in the beverage industry (carbonating drinks)
As a feedstock for chemicals and new fuels
Concrete curing and certain plastics

However, unless CO₂ is permanently sequestered, most short-term uses only delay eventual emissions, so the true climate impact depends on the longevity of the use.

Current Status: How Widespread Is CCS?

As of recent global estimates, there are approximately 30 major commercial CCS facilities operating or under construction worldwide, with the capacity to capture roughly 40 million metric tons of CO₂ annually. For perspective, global emissions are over 30 billion tons per year, meaning CCS accounts for a tiny fraction of the total needed to impact climate change.

The United States hosts multiple large-scale CCS projects, especially in the Midwest and Gulf Coast states.
Europe (Norway, UK, Netherlands) is pursuing major offshore storage initiatives.

Benefits and Potential of Carbon Capture and Storage

Large-scale emissions reductions: CCS can help decarbonize hard-to-abate industries such as cement and steel, which are not easily electrified.
Negative emissions: When paired with bioenergy (BECCS), CCS can yield “negative emissions”—removing CO₂ from the atmosphere.
Energy transition: Provides a path for fossil-fuel facilities to reduce emissions while renewable energy capacity scales up.
Job creation and economic stimulus: Retrofitting existing facilities and building new infrastructure can foster local employment.

Controversies and Limitations

CCS has generated considerable debate about its cost, scalability, and climate relevance. The major points of controversy include:

High costs: Building and operating CCS systems is expensive—capital intensive and reliant on continued policy incentives in many cases.
Energy use: The capture, compression, and transport processes consume significant energy, potentially offsetting some emissions reductions.
Scale: Current global CCS deployment is nowhere near what’s needed to make a meaningful dent in atmospheric CO₂ concentrations.
Lock-in effect: Critics argue CCS enables continued fossil fuel use, potentially delaying investment in true clean energy solutions like wind, solar, and battery storage.
Uncertain permanence: The long-term integrity of underground CO₂ storage remains a concern, although evidence so far is positive for well-chosen sites.

Challenges Facing Carbon Capture and Storage

Infrastructure investment: CCS requires extensive pipelines, storage sites, and retrofits—major up-front investments are needed.
Public acceptance: Communities may resist projects over fears of leaks or earthquakes. Transparent communication and robust monitoring are necessary.
Policy and incentives: Most current CCS projects depend on subsidies, tax credits, or carbon pricing. Stable and ambitious policies are crucial to encourage investment.
Technological limitations: Not all emission sources are suitable for CCS, and retrofitting old plants can be technically challenging.

Future Prospects: Is CCS Part of the Climate Solution?

The Intergovernmental Panel on Climate Change (IPCC) and other leading bodies suggest that meeting the world’s climate goals will likely require some CCS—particularly in industries that are otherwise hard to decarbonize. However, most experts agree that CCS cannot substitute for rapid deployment of renewable energy, improvement of energy efficiency, and reduction of fossil fuel use.

CCS is best seen as one tool in a broader array of climate solutions, with its role—and investment—determined by careful analysis of costs, risks, and climate impact.

Frequently Asked Questions (FAQs)

Q: How much CO₂ can CCS remove?

A: Currently, global CCS projects collectively capture about 40 million metric tons of CO₂ each year, a small fraction compared to global emissions (over 30 billion tons annually). Dramatic scaling would be needed for significant global climate impact.

Q: Is stored CO₂ truly permanent?

A: Geologically, CO₂ can remain trapped for thousands of years or longer if injected into suitable formations with proper safeguards. Most projects have so far shown positive long-term integrity, but large-scale, centuries-long records are not yet available.

Q: Does CCS allow the continued use of fossil fuels?

A: While CCS can reduce emissions from fossil fuel use, critics argue it may delay the phaseout of fossil energy. Most climate analysts recommend CCS for sectors that cannot easily switch to renewables, not as a pathway for continued broad fossil fuel expansion.

Q: What are the environmental risks of CCS?

A: Risks include potential for CO₂ leakage, induced seismicity (earthquakes), and local water contamination, though these can be minimized with careful site choice and monitoring. The most prominent risks come from poorly regulated or monitored projects.

Q: How much does CCS cost?

A: Costs vary substantially depending on the facility, technology, and location, but are consistently high relative to other emissions reduction strategies. CCS usually depends on policy incentives or a high carbon price to be viable at present.

Summary Table: Key Aspects of Carbon Capture and Storage

Aspect	Details
Main Goal	Prevent CO₂ from entering the atmosphere
Core Steps	Capture, transport, storage (or utilization)
Common Sources	Power plants, cement, steel, chemicals
Current Scale	40 million tons/year globally
Barriers	High cost, infrastructure, public concern
Potential Benefits	Decarbonize industry, negative emissions, transition aid
Main Critiques	Enables fossil fuel use, scale, permanence, cost

Conclusion

Carbon capture and storage is a complicated but potentially vital tool in the global push to mitigate climate change. Its success will depend on technological advances, policy frameworks, market conditions, and sustained public trust. CCS is not a silver bullet, but in concert with other sustainable strategies, it may help build a lower-carbon future.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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