What is Carbon Capture and Storage (CCS)? How Does it Work?

Carbon Capture and Storage (CCS) is a critical technology in the fight against climate change, offering a pathway to significantly reduce carbon dioxide (CO₂) emissions from industrial processes and fossil fuel combustion.

Published: February 21, 2024.

Understanding Carbon Capture and Storage

CCS encompasses a set of technologies designed to capture, transport, and securely store CO₂ emissions from power plants and industrial facilities.

The primary goal of CCS is to prevent CO2 from entering the atmosphere and contributing to global warming. It targets the CO₂ produced in electricity generation and industrial processes, such as steel and cement production, which are challenging to decarbonize.

Components of Carbon Capture and Storage

Capture: The first step involves capturing CO2 emissions at their source, typically power plants or industrial facilities. This can be achieved through three main methods:

• Post-combustion capture: CO₂ is removed from flue gases after combustion using solvents or solid sorbents.
• Pre-combustion capture: Involves converting fossil fuels into a gas mixture of hydrogen and CO₂ before combustion. The CO₂ is then separated from the mixture.
• Oxy-fuel combustion: This process burns fossil fuels in pure oxygen instead of air, resulting in a flue gas composed primarily of CO2 and water vapor, which is easier to separate.
• Transport: Once captured, the CO₂ needs to be transported to a storage site. This is typically done via pipelines, although ships, trains, and trucks can also be used for transport to remote locations.
• Storage: The final step involves storing the captured CO₂ underground in geological formations, such as depleted oil and gas fields or deep saline aquifers. The CO₂ is injected into these formations, where it is physically trapped by cap rocks or dissolved in underground brine.

How Does CCS Work?

The CCS process begins with the capture of CO₂ from power plants or industrial processes. The captured CO₂ is then compressed to a liquid-like state, making it easier to transport.

Once transported to a suitable storage site, the CO₂ is injected into rock formations thousands of meters below the Earth's surface, where it is securely stored away from the atmosphere. Monitoring technologies are employed to ensure the CO₂ remains contained and does not leak back into the atmosphere.

The Role of CCS in Mitigating Climate Change

CCS is considered a crucial technology for achieving global climate targets, including those outlined in the Paris Agreement. Its potential to significantly reduce emissions from the industrial sector and power generation makes it an essential component of a broader strategy to limit global warming to well below 2 degrees Celsius above pre-industrial levels.

Moreover, CCS is vital for enabling the transition to a low-carbon economy, offering industries a means to decarbonize while continuing to use fossil fuels during the transition to renewable energy sources.

Challenges and Opportunities

Despite its potential, CCS faces several challenges that must be addressed to realize its full potential. These include high costs, technological readiness, regulatory hurdles, and the need for significant infrastructure development.

However, ongoing research and development, coupled with supportive policies and incentives, could help overcome these challenges, making CCS a more viable and cost-effective solution for reducing greenhouse gas emissions.

Furthermore, CCS opens up opportunities for negative emissions technologies, such as Bioenergy with Carbon Capture and Storage (BECCS), where CO₂ is captured from biomass combustion or processing, potentially removing CO₂ from the atmosphere.

CCUS vs. CCS: What is Carbon Capture, Utilisation, and Storage (CCUS)?

Carbon Capture, Utilisation, and Storage (CCUS) is an extension of the Carbon Capture and Storage (CCS) concept, encompassing technologies and processes that capture carbon dioxide (CO₂) emissions from sources like power plants and industrial facilities, preventing CO₂ from entering the atmosphere.

The distinctive aspect of CCUS is the utilization phase, where the captured CO₂ is not just stored underground but is also repurposed for various applications, adding a beneficial use to the captured carbon.

How Does CCUS Work?

CCUS involves three main steps: capture, utilization, and storage, each with its specific processes and technologies.

Capture: Similar to CCS, the CO₂ is captured at the source using one of several methods, such as pre-combustion capture, post-combustion capture, or oxy-fuel combustion. This step prevents CO₂ from being released into the atmosphere.

Utilization: The captured CO₂ is then used in various applications. Some of the key uses include:

• Enhanced Oil Recovery (EOR): Injecting CO₂ into oil fields to increase the pressure and extract more oil.
• Chemical Manufacturing: Using CO₂ as a raw material to produce chemicals such as urea (for fertilizers), methanol, and other industrial chemicals.
• Building Materials: Converting CO₂ into carbonates that can be used as aggregates or other materials in the construction industry.
• Algae Production: Utilizing CO₂ in algae cultivation, where algae can be used for biofuels, animal feed, or as a component in products like plastics and cosmetics.

Storage: Any CO₂ not utilized is then transported and securely stored underground in geological formations, such as depleted oil and gas reservoirs or deep saline aquifers, similar to the CCS process.

The Role of CCUS in Climate Change Mitigation

CCUS plays a crucial role in global efforts to mitigate climate change for several reasons:

• Reduction of Industrial Emissions: It offers a solution for reducing emissions from industrial sectors that are hard to decarbonize, such as cement, steel, and chemical production.
• Versatility: By providing options for utilizing the captured CO₂, CCUS expands the potential economic benefits and applications of carbon capture technologies.
• Negative Emissions: When combined with bioenergy sources (BECCS), or direct air capture (DAC) technologies, CCUS can result in negative emissions, effectively removing CO₂ from the atmosphere.

CCUS Challenges and Opportunities

Despite its potential, CCUS faces challenges, including high costs, energy requirements for capture and conversion processes, and the need for market development for CO2-based products.

However, the increasing focus on reducing greenhouse gas emissions, coupled with technological advancements and supportive policies, could enhance the viability and adoption of CCUS technologies.

BECCS vs. DAC vs. CCS: Different Approaches to Carbon Management

• Bioenergy with Carbon Capture and Storage (BECCS) combines biomass-based energy production with carbon capture and storage technologies. By using bioenergy crops or waste biomass as fuel, BECCS not only generates energy but also captures CO₂ released during biomass combustion or processing. Since biomass absorbs CO₂ as it grows, BECCS can result in net negative emissions, effectively removing CO2 from the atmosphere when the captured carbon is stored underground.
• Direct Air Capture (DAC) is a technology that captures CO₂ directly from the atmosphere, independent of a specific emission source. DAC systems use chemical processes to absorb CO₂ from ambient air, concentrating it for storage or utilization. This approach has the advantage of addressing both past and present emissions and can be implemented in locations not tied to industrial sites. However, DAC is energy-intensive and currently more expensive than other carbon capture methods.
• Carbon Capture and Storage (CCS) refers to the capture of CO₂ emissions from industrial and energy-related sources, such as power plants and factories, before it is released into the atmosphere, followed by its transport and storage in geological formations. CCS is a crucial strategy for reducing greenhouse gas emissions from existing sources of energy and industrial processes that are challenging to decarbonize.

Each of these technologies plays a vital role in the portfolio of solutions needed to tackle climate change, offering different pathways to reduce atmospheric CO₂ levels and mitigate global warming.

BECCS targets the energy sector and can achieve negative emissions, DAC offers flexibility in capturing atmospheric CO₂, and CCS is essential for decarbonizing heavy industries and fossil fuel-based power generation.

Carbon Storage vs. Carbon Sequestration: Understanding the Differences

When discussing strategies to mitigate climate change by managing carbon dioxide (CO₂) emissions, two terms often come up: carbon storage and carbon sequestration. While they are closely related and sometimes used interchangeably, there are nuances in their meanings and applications worth understanding.

Carbon Storage refers to the process of capturing CO₂ emissions and storing them in a way that prevents their release into the atmosphere. This storage can occur in various forms, such as injecting CO₂ into underground geological formations, including depleted oil and gas fields or deep saline aquifers.

Carbon storage is a critical component of both CCS (Carbon Capture and Storage) and CCUS (Carbon Capture, Utilisation, and Storage) technologies, aimed at reducing the amount of CO₂ entering the atmosphere from industrial processes and power generation.

Carbon Sequestration, on the other hand, encompasses a broader range of processes that remove CO₂ from the atmosphere and store it in different carbon sinks.

These can be either biological, as in the growth of trees and plants that absorb CO₂ during photosynthesis, or geological, similar to the underground storage methods mentioned above. Carbon sequestration thus includes both natural processes and human-engineered solutions like CCS, focusing on the long-term removal and storage of CO₂ to mitigate climate change.

The main difference lies in the source and method of CO₂ management: carbon storage directly addresses the anthropogenic emissions by capturing and storing CO₂ before it reaches the atmosphere, while carbon sequestration includes both the capture of existing atmospheric CO₂ through natural or artificial means and its subsequent storage in various sinks.

Both approaches are vital in the global strategy to reduce atmospheric CO₂ levels and combat global warming.

Few Final Words

Carbon Capture and Storage represents a promising technology in the arsenal against climate change, offering a pathway to substantially reduce CO₂ emissions from the most challenging sectors to decarbonize.

While challenges remain, the continued advancement and deployment of CCS technologies are essential for achieving global climate goals and ensuring a sustainable future for all.