Carbon capture and sequestration: Meaning, Criticisms & Real-World Uses

What Is Carbon Capture and Sequestration?

Carbon capture and sequestration (CCS) is a set of technologies designed to prevent large quantities of carbon dioxide (CO₂) emissions from entering the atmosphere by capturing them at their source and storing them permanently underground. This process is a key component of broader environmental finance efforts aimed at reducing the concentration of greenhouse gases in the atmosphere and mitigating climate change. CCS specifically targets emissions from major stationary sources, such as power plants that burn fossil fuels and large industrial processes like cement and steel production. The captured CO₂ is typically compressed and then transported, often via pipelines, to suitable deep underground geological formations for long-term storage, preventing its release into the atmosphere.

##³⁴ History and Origin

The concept of carbon capture and sequestration has roots dating back to the late 1970s, with early discussions around CO₂ injection for enhanced oil recovery (EOR) paving the way for storage considerations. However, dedicated research and development into CCS as a climate change mitigation strategy significantly ramped up in the late 20th and early 21st centuries. The U.S. Department of Energy (DOE) began funding carbon capture research and development activities as early as 1997, initially focusing on coal-fired power plants and underground geologic storage. This ³², ³³foundational work helped build the knowledge base for the technologies currently employed in carbon capture and sequestration projects. The International Energy Agency (IEA) has also tracked the development of carbon capture, utilization, and storage (CCUS) projects, noting substantial growth in recent years, with over 700 projects in various stages globally as of 2023.

K³¹ey Takeaways

Carbon capture and sequestration (CCS) aims to reduce atmospheric CO₂ by capturing emissions at large point sources and storing them underground.
The process involves three main steps: capturing CO₂, transporting it, and injecting it into deep geological formations for long-term storage.
CCS i³⁰s a component of broader climate change mitigation strategies, particularly for hard-to-decarbonize industrial sectors.
Government support and financial incentives, such as tax credits, play a significant role in the development and deployment of carbon capture and sequestration projects.
Despi²⁸, ²⁹te its potential, carbon capture and sequestration faces criticisms regarding its cost, energy requirements, and long-term storage integrity.

Interpreting Carbon Capture and Sequestration

Interpreting the role and effectiveness of carbon capture and sequestration involves understanding its intended application within global investment strategies for decarbonization. The technology is primarily designed to address emissions from stationary sources that are difficult to abate, such as heavy industries and power generation. The success of carbon capture and sequestration is often measured by the volume of CO₂ captured and securely stored, usually in millions of metric tons per year (MtCO₂/year). For example, the IEA reported that global operational CO₂ capture capacity reached over 50 million tonnes as of early 2025, with announced projects aiming for significantly higher capacities by 2030. Assessing carbo²⁶, ²⁷n capture and sequestration also involves evaluating the safety and permanence of the storage sites, which often include depleted oil and gas fields or saline formations. Effective imple²⁵mentation requires robust monitoring and regulatory frameworks to ensure long-term containment and prevent leakage.

Hypothetical Example

Consider a hypothetical cement manufacturing plant that currently emits 1 million metric tons of CO₂ annually. To reduce its environmental impact and align with net zero emissions targets, the plant decides to implement a carbon capture and sequestration system.

Capture: The plant installs equipment to capture CO₂ from its flue gas emissions. Using post-combustion capture technology, a chemical solvent absorbs CO₂ from the exhaust stream.
Compression and Transport: The captured CO₂ is then compressed into a dense fluid. Pipelines are constructed to transport this compressed CO₂ to a suitable underground storage site, perhaps a nearby depleted natural gas reservoir several miles below the surface.
Sequestration: At the storage site, the CO₂ is injected deep underground into porous rock formations, where it is intended to remain permanently trapped by impermeable caprock layers above.

If the system has a 90% capture rate, the plant would reduce its direct CO₂ emissions to the atmosphere by 900,000 metric tons annually. The success of this carbon capture and sequestration project would depend on the continued efficiency of the capture technology and the long-term integrity of the geological storage.

Practical Applications

Carbon capture and sequestration is primarily applied to large point sources of CO₂ emissions. Its most common applications include:

Power Generation: Capturing CO₂ from coal- and natural-gas-fired power plants to reduce their carbon footprint.
Industrial Facilities: De²⁴carbonizing heavy industries such as cement production, iron and steel manufacturing, and chemical plants, where CO₂ is an inherent byproduct of the manufacturing process.
Hydrogen Production: Facili²³tating the production of "blue hydrogen" by capturing CO₂ emissions generated during the steam methane reforming process.
Enhanced Oil Recovery (EOR): In some cases, captured CO₂ is injected into aging oil fields to increase oil extraction, a process where CO₂ storage can be a secondary benefit.
Direct Air Capture (DAC): While d²²istinct from point-source capture, DAC facilities directly remove CO₂ from the ambient air, and this captured CO₂ also requires sequestration, often linking it to carbon capture and sequestration infrastructure.

The U.S. Environmental Protection Agency (EPA) regulates the underground injection of CO₂ through its Underground Injection Control (UIC) program, specifically Class VI wells for permanent geological storage. This regulatory oversight is critical for the s²¹afe deployment of carbon capture and sequestration technologies. Furthermore, government initiatives, such as those within the U.S. Department of Energy, continue to fund research and demonstration projects to expand the deployment and improve the energy efficiency of carbon capture and sequestration.

Limitations and Criticisms

Despite its pot²⁰ential, carbon capture and sequestration faces significant limitations and has drawn considerable criticism. A primary concern is the high cost and economic feasibility of implementing and operating CCS technology. The process itself is energy-intensive, requiri¹⁸, ¹⁹ng additional energy to capture, compress, and transport the CO₂, which can lead to an "energy penalty" and potentially increase overall emissions if that energy is not sourced cleanly.

Another major critique revolves around the long-¹⁷term integrity of geological storage. While intended for permanent storage, there are concerns about the potential for CO₂ leakage from underground reservoirs, which could negate environmental benefits and pose risks to groundwater or ecosystems. Additionally, critics argue that carbon capture and¹⁶ sequestration may prolong reliance on fossil fuels by allowing polluting industries to continue operations rather than investing in cleaner renewable energy alternatives. Some projects have also faced technical challenges ¹³, ¹⁴, ¹⁵and have failed to meet their promised capture rates, highlighting the technological immaturity and regulatory hurdles that still exist. For instance, the Petra Nova project in Texas, a ma¹¹, ¹²jor U.S. fossil-fueled power plant with CCS, suspended operations in 2020 due to economic factors.

Carbon Capture and Sequestration vs. Carbon Off¹⁰setting

Carbon capture and sequestration (CCS) and carbon offsetting are both strategies aimed at addressing greenhouse gas emissions, but they differ fundamentally in their approach.

Feature	Carbon Capture and Sequestration (CCS)	Carbon Offsetting
Primary Action	Captures CO₂ emissions at their source (e.g., power plants, factories) before they enter the atmosphere, then stores them underground.	Compensates for emissions made elsewhere by investi⁹ng in projects that reduce or remove an equivalent amount of greenhouse gases from the atmosphere.
Directness	Directly reduces emissions from a specific polluting source.	Indirectly reduces global emissions by funding projects that avoid or remove emissions.
Mechanism	Technological process invol⁸ving capture, transport, and geological storage.	Market-based mechanism typically involving the purchase of carbon credits from projects like reforestation or renewable energy development.
Goal	To prevent new emissions fr⁷om reaching the atmosphere.	To balance out unavoidable emissions, often to achieve a carbon neutral status.

While CCS focuses on preventing emissions at the p⁶oint of generation, carbon offsetting involves activities that occur away from the emitter's direct operations. A company might use CCS to reduce its own plant's emissions, while simultaneously purchasing offsets to account for other emissions, such as those from its supply chain or employee travel. Both tools are considered part of a comprehensive strategy for managing carbon, but they serve different roles in the broader climate mitigation landscape.

FAQs

What is the primary purpose of carbon capture and sequestration?

The primary purpose of carbon capture and sequestration is to significantly reduce the amount of carbon dioxide released into the atmosphere from large industrial and power generation sources, thereby helping to combat global warming.

Is carbon capture and sequestration a new techno⁵logy?

No, the underlying concepts and technologies for carbon capture and sequestration have been researched and developed since at least the late 1990s, with some applications, like CO₂ injection for enhanced oil recovery, existing even earlier.

Where is captured CO₂ stored?

Captured CO₂ is typi⁴cally compressed and then injected into deep underground geological formations for long-term storage. These formations can include depleted oil and gas fields, unmineable coal seams, or deep saline aquifers.

What are the main challenges facing carbon capture and³ sequestration?

Key challenges include the high cost of implementation, the significant energy required for the process, concerns about the permanence and safety of underground storage, and the need for extensive infrastructure development.

How does carbon capture and sequestration contribute t¹, ²o climate goals?

Carbon capture and sequestration is seen as a critical technology for decarbonizing hard-to-abate sectors like heavy industry and power generation, which are difficult to transition entirely to renewable energy sources in the short to medium term. It allows these sectors to continue operating with significantly reduced emissions, contributing to overall net zero emissions targets.

Carbon capture and sequestration