Carbon Capture vs. Carbon Removal

In the global fight against climate change, two terms are frequently discussed: carbon capture and carbon removal. Both are critical in mitigating the effects of human-caused carbon dioxide (CO₂) emissions, but they serve distinct roles in our journey toward achieving net-zero emissions. While the two concepts are sometimes used interchangeably, there are important differences in their mechanisms, objectives and long-term implications. Understanding these differences is essential for developing effective climate solutions.

The Urgent Need for Action on Climate Change

Before diving into the nuances of carbon capture and carbon removal, it’s crucial to understand why these technologies are important.

Since the Industrial Revolution, human activities – especially the burning of fossil fuels such as coal, oil and natural gas – have released vast amounts of CO₂ into the atmosphere. CO₂ is one of the most significant greenhouse gases (GHGs) contributing to global warming. As the concentration of these gases rises, so does the Earth’s temperature, leading to a host of environmental problems, including melting ice caps, rising sea levels, extreme weather events and the degradation of ecosystems.

The 2015 Paris Agreement set a goal of limiting global temperature rise to well below 2°C above pre-industrial levels, with efforts to limit it to 1.5°C. To achieve this, we must focus on drastically reducing emissions while also finding ways to address the CO₂ already in the atmosphere. For instance, the United Kingdom recently retired its last coal power plant to become the first major economy to wean itself off fossil fuels as renewables increasingly power the country. But to reach its net zero by 2050 target, the country will need to innovate and scale promising solutions that both trap carbon at the source and bring it back down from the atmosphere. 

This is where carbon capture and carbon removal come in.

What is Carbon Capture?

Carbon capture refers to the process of trapping CO₂ emissions at the source – typically from industrial processes like power generation, steel production or cement manufacturing – before they enter the atmosphere. The captured CO₂ is then stored, usually deep underground, in geological formations. Carbon capture is often part of a broader process known as carbon capture, utilisation and storage (CCUS), which includes not only capturing and storing CO₂ but also using it in industrial applications.

How Does Carbon Capture Work?

The process typically involves three steps:

 1. Capture: CO₂ is separated from other gases produced by industrial processes using various technologies, such as chemical solvents, membranes or adsorption techniques. The most common method is post-combustion capture, where CO₂ is removed after fossil fuels are burned.

2. Transport: Once captured, the CO₂ is compressed and transported, typically via pipelines, to a storage location. Some projects use shipping or rail transport when pipelines aren’t feasible.

3. Storage: The captured CO₂ is injected into underground reservoirs, such as depleted oil and gas fields or deep saline aquifers, where it can be securely stored for thousands of years.

Benefits of Carbon Capture

Carbon capture offers several advantages:

– Emission Reduction: It can significantly reduce emissions from hard to decarbonise industries, such as steel, cement and chemical production.

– Compatibility with Existing Infrastructure: Many carbon capture technologies can be retrofitted to existing fossil fuel-based power plants, allowing for continued energy production with fewer emissions.

– Potential for Utilisation: Captured CO₂ can be repurposed for various industrial applications, such as enhanced oil recovery (EOR), where CO₂ is injected into oil fields to extract more oil. Alternatively, it can be injected into concrete during the production process to not only lock up CO₂ but also enhance concrete strength or it can be repurposed in the beverage industry, providing an alternative to industrially produced CO₂ to carbonate drinks.

Limitations of Carbon Capture

Despite its benefits, carbon capture faces several limitations:

– Energy Intensive: The process of capturing, compressing and transporting CO₂ requires a significant amount of energy, which can reduce its overall effectiveness in terms of emissions reduction.

– Cost: Carbon capture technologies are still relatively expensive, though costs are expected to decline as the technology matures and scales.

– Focus on Emissions at the Source: Carbon capture only addresses emissions from current industrial processes; it can encourage business-as-usual operations by being used to extract more fossil fuels via EOR and does not remove the CO₂ already present in the atmosphere. This is why carbon removal is essential.

What is Carbon Removal?

Carbon removal, also known as carbon dioxide removal (CDR) or negative emissions, refers to technologies and natural processes that remove existing CO₂ from the atmosphere. Unlike carbon capture, which prevents future emissions, carbon removal targets the legacy CO₂ that has already been emitted. This helps to reverse the accumulation of greenhouse gases in the atmosphere and mitigate their long-term effects on the climate.

Natural Carbon Removal Methods

There are several natural approaches to carbon removal, which rely on enhancing existing carbon sinks and stores like forests, soils and oceans:

– Afforestation and Reforestation: Planting new forests or restoring degraded ones can capture large amounts of CO₂ as trees absorb carbon during photosynthesis.

– Soil Carbon Sequestration: Improving agricultural practices, such as no-till farming and cover cropping, enhances the soil’s capacity to store carbon. This not only removes CO₂ from the atmosphere but also improves soil health.

– Wetland and Peatland Restoration: Wetlands and peatlands are natural carbon sinks and stores. Restoring these ecosystems can significantly increase their capacity to sequester CO₂ while providing benefits like flood control and biodiversity preservation. In fact, ​​peatlands cover just 3% of the Earth’s land surface but store roughly twice as much carbon as all the world’s forests combined, making them one of the largest terrestrial carbon reservoirs.

– Ocean-Based Solutions: Some approaches aim to enhance the oceans’ natural ability to absorb CO₂. For example, adding minerals to seawater can increase its carbon storage capacity, though this approach is still in the experimental stages.

Technological Carbon Removal Methods

Technological solutions are being developed to remove CO₂ from the atmosphere at a much larger scale and faster rate:

– Enhanced Rock Weathering (ERW): This method accelerates the natural process of weathering, where minerals like silicates react with CO₂ to form stable carbonates that can be stored for long periods. This approach is gaining attention as it offers a highly scalable permanent solution of locking CO₂ away in solid form.

– Direct Air Capture (DAC): DAC involves using machines to extract CO₂ directly from the air. Once captured, the CO₂ can be stored underground or used in industrial processes. DAC holds great potential for large-scale carbon removal but is currently energy-intensive and costly.

– Bioenergy with Carbon Capture and Storage (BECCS): BECCS involves growing biomass (such as crops or trees) to absorb CO₂, which is then used to produce bioenergy. The CO₂ released during the energy production process is captured and stored. BECCS is seen as a promising approach, but it requires significant land and water resources, which could compete with food production, as well as the transportation of the biomass to facilities, which are often in different regions of the world

Benefits of Carbon Removal

Carbon removal technologies and methods provide essential benefits:

– Addresses Legacy Emissions: Carbon removal is the only way to deal with the CO₂ that has already been emitted into the atmosphere. This makes it crucial for achieving net-zero or even net-negative emissions.

– Long-Term Storage: Once CO₂ is removed from the atmosphere, it can be stored securely in long-term forms, such as underground reservoirs or solid carbonates.

– Restores Natural Ecosystems: Many natural carbon removal methods, like reforestation, enhanced rock weathering and wetland restoration, offer additional benefits such as improving biodiversity, water retention and ecosystem health.

Limitations of Carbon Removal

Like carbon capture, carbon removal also faces significant challenges:

– Scale: To have a significant impact, carbon removal methods must be deployed at an enormous scale. The 2022 Intergovernmental Panel on Climate Change’s (IPCC) Mitigation Report says that billions of tons of CO₂ need to be removed annually to keep global warming within safe limits.

– Cost: Many carbon removal technologies, particularly DAC, are still in the early stages of development and remain expensive to deploy. Scaling these technologies will require significant investment in infrastructure and innovation.

– Land and Resource Use: Some natural carbon removal methods, such as afforestation, require large amounts of land, which may compete with other essential land uses like agriculture.

– Standardised Monitoring Protocols: In order to be able to select high-quality CDR solutions, having a standardised approach to monitoring protocols will simplify the process for buyers while providing greater certainty to project developers in terms of the associated costs.   

Carbon Capture vs. Carbon Removal: Key Differences

While both carbon capture and carbon removal are important tools in the fight against climate change, their differences lie in their scope, application, and purpose.

Objective

– Carbon Capture: Aims to prevent CO₂ emissions from entering the atmosphere by capturing them at the source (e.g., power plants, factories).

– Carbon Removal: Focuses on removing CO₂ that is already in the atmosphere, addressing legacy emissions.

Timing

– Carbon Capture: Mitigates ongoing or future emissions.

– Carbon Removal: Deals with emissions that have already occurred.

Application

– Carbon Capture: Primarily used in industrial settings, such as power generation and manufacturing i.e. hard to abate industries

– Carbon Removal: Can be applied both naturally (e.g., through afforestation) and technologically (e.g., direct air capture, enhanced rock weathering).

Scale of Impact

– Carbon Capture: Typically more localised, targeting specific emission sources.

– Carbon Removal: A global solution aimed at reducing atmospheric CO₂ levels on a large scale.

Co-Benefits

– Carbon Capture: Generally limited to emissions reduction and potential utilisation of captured CO₂.

– Carbon Removal: Can offer additional environmental benefits, such as improved biodiversity, ecosystem restoration and soil health.

Why We Need Both

The key takeaway is that carbon capture and carbon removal are not mutually exclusive; we need both to tackle climate change effectively. Carbon capture is crucial for reducing emissions from industries that are difficult to decarbonise, while carbon removal is essential for addressing the excess CO₂ already in the atmosphere.

Neither solution alone can achieve the deep emissions cuts necessary to meet the Paris Agreement targets. A comprehensive climate strategy must include aggressive emissions reductions, carbon capture and carbon removal to ensure a sustainable and stable climate future.

The Importance of Combining Carbon Capture and Removal

Carbon capture and carbon removal play complementary roles in mitigating climate change. Carbon capture is about preventing new emissions from entering the atmosphere, while carbon removal focuses on taking CO₂ out of the atmosphere to reverse the damage already done. As we continue to develop and scale these technologies, they will become vital components of a multi-faceted approach to addressing the climate crisis. The future of our planet depends on deploying these solutions at the scale and speed necessary to keep global warming in check.

Navigate Carbon Capture and Removal with Confidence

Understanding the roles of carbon capture and removal is vital for effective climate action. At UNDO, we provide tailored solutions to help you achieve net-zero goals and make informed carbon decisions that drive real impact.

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