10 Carbon Capture Technologies Explained: How They Work

Carbon dioxide is difficult to avoid completely. Even as renewable energy expands, industries such as cement, steel, chemicals, and power generation continue to produce large amounts of CO₂. That is one reason researchers and industries are exploring carbon capture technology as another way to reduce or remove CO₂.

But carbon capture isn’t a single technology. Some systems capture CO₂ directly from factory exhaust, while others pull it from the surrounding air. There are also approaches that store carbon in rocks, soils, plants, or other materials.

In this guide, we look at 10 carbon capture technologies, including Direct Air Capture (DAC), Bioenergy with Carbon Capture and Storage (BECCS), mineral carbonation, enhanced weathering, biochar, and ocean-based approaches. We’ll explain how each method works, where it could be useful, and the challenges that may limit its use.

Carbon capture is not a substitute for cutting emissions. Reducing fossil fuel use, improving energy efficiency, expanding clean energy, and protecting natural ecosystems remain essential. However, carbon capture and carbon removal could help address emissions from sectors where eliminating them completely is especially difficult.

Some technologies may also help remove carbon dioxide that is already in the atmosphere. That makes carbon removal particularly interesting as countries explore different ways to reach long-term climate goals.

Below, we’ll break down the major carbon capture methods one by one, starting with one of the most talked-about approaches: Direct Air Capture.

Contents show

What Is Carbon Capture Technology?

Carbon capture technology generally refers to methods that separate CO₂ from industrial or other concentrated gas streams before it reaches the atmosphere. Related carbon dioxide removal technologies, such as Direct Air Capture (DAC), instead remove CO₂ that is already present in the atmosphere. This guide covers both because they are often discussed together as ways to manage carbon emissions.

Many carbon capture systems focus on industries that are difficult to decarbonize, including cement, steel, chemicals, and power generation. These facilities can produce large amounts of CO₂, making them important targets for technologies designed to reduce emissions.

Other approaches work differently. Direct Air Capture (DAC), for example, removes CO₂ that is already present in the atmosphere rather than capturing it from a smokestack.

After CO₂ is captured, it can follow several paths:

Stored underground in suitable geological formations, including deep saline formations and depleted oil and gas reservoirs.
Used in products or industrial processes, such as certain fuels, chemicals, and building materials.
Converted into stable materials, including carbonate minerals that can hold carbon for very long periods.

Some carbon removal approaches covered later in this guide, including biochar and reforestation, store carbon through biological processes rather than conventional industrial capture equipment.

Carbon capture is not meant to replace renewable energy or efforts to reduce fossil fuel use. Its potential is especially important in sectors where eliminating emissions is technically difficult and for removing some of the CO₂ already present in the atmosphere.

Quick Answer: Carbon capture technology captures CO₂ from industrial sources or removes it directly from the air. The captured carbon can then be stored, used in products, or converted into stable materials to keep it out of the atmosphere.

How Carbon Capture Works

The exact process depends on the technology, but most engineered carbon capture methods involve three main stages: capturing the CO₂, transporting it when necessary, and either using it or storing it.

1. Capture the Carbon Dioxide

First, CO₂ has to be separated from other gases. At a cement plant, steel mill, or power station, this usually means capturing carbon dioxide from a concentrated stream produced by an industrial process.

Direct Air Capture (DAC) works differently. Instead of capturing emissions at their source, DAC systems pull ordinary air through materials that bind with the small amount of CO₂ it contains.

Depending on the system, carbon capture technologies may use chemical solvents, solid sorbents, membranes, or other separation methods.

2. Compress and Transport the CO₂

Captured CO₂ often needs to be compressed before it can be transported. Large quantities can be moved through pipelines or by ship, while smaller amounts may be transported by truck or rail.

Not every project requires long-distance transportation. Some facilities are located close to geological storage sites or places where the captured CO₂ can be used.

3. Use the Captured Carbon

Some captured CO₂ can be put to use instead of immediately being stored underground. Applications include certain chemicals, fuels, building materials, and industrial processes.

However, using CO₂ does not automatically mean the carbon has been permanently removed from the atmosphere. If captured CO₂ is turned into fuel, for example, much of it will eventually be released again when that fuel is used. Products that mineralize CO₂ can potentially store it for much longer.

4. Store the Carbon

For long-term storage, captured CO₂ can be injected deep underground into suitable geological formations. Deep saline formations and depleted oil and gas reservoirs are among the options being studied and used for geological carbon storage.

The storage site must be carefully characterized before injection begins. Monitoring is also important for verifying where the CO₂ goes and detecting potential leakage.

Is Carbon Capture Permanent?

It depends on what happens to the carbon after it is captured.

CO₂ that is successfully mineralized into stable rock or securely stored in suitable geological formations can potentially remain isolated for very long periods. Carbon stored in forests, soils, and other biological systems is less permanent because wildfire, deforestation, drought, land-use changes, or decomposition can return some of that carbon to the atmosphere.

This distinction is important when comparing carbon capture technologies. Capturing CO₂ is only the first part of the story—where the carbon ultimately goes and how long it stays there matter just as much.

Why Carbon Capture Matters

Cutting greenhouse gas emissions remains the most direct way to slow climate change. But some emissions are much harder to eliminate than others, particularly those produced by heavy industries. This is where carbon capture technology could have an important role.

Cement is a good example. Producing cement releases CO₂ not only from the fuels used to heat kilns but also from the chemical reactions involved in turning limestone into clinker. Similar challenges exist in parts of the steel and chemical industries. Capturing CO₂ at these facilities could reduce emissions that are difficult to address through renewable electricity alone.

Carbon removal addresses a different problem: CO₂ that is already in the atmosphere. Technologies such as Direct Air Capture (DAC) are specifically designed for this purpose. Nature-based approaches, including reforestation, can also remove atmospheric carbon as plants grow, while biochar can help store some biologically captured carbon for longer periods.

This distinction matters. Capturing CO₂ from a factory prevents some new emissions from reaching the atmosphere, while carbon dioxide removal takes CO₂ that is already there and stores it. Both approaches may be useful, but they solve different parts of the climate problem.

Carbon capture could also allow existing industrial facilities to reduce their emissions while lower-carbon production methods continue to develop. Its usefulness will depend on factors such as capture efficiency, energy requirements, cost, transportation infrastructure, and whether the captured CO₂ is permanently stored.

Carbon capture is therefore best viewed as one tool among many, not an alternative to reducing emissions. Renewable energy, energy efficiency, electrification, protecting ecosystems, and reducing fossil fuel use remain essential alongside technologies that capture or remove carbon.

Key Takeaway: Carbon capture can help reduce emissions from industries that are difficult to decarbonize, while carbon removal technologies can address some CO₂ already in the atmosphere. Neither replaces the need to cut greenhouse gas emissions at their source.

Examples of Carbon Capture Technology

Carbon capture and carbon removal can take many forms. Some technologies capture CO₂ from factories and power plants before it reaches the atmosphere, while others remove carbon dioxide that is already in the air or store carbon through natural and geological processes.

Below are 10 examples of carbon capture technologies and carbon removal methods, along with a closer look at how each one works, its potential benefits, and its limitations.

1. Direct Air Capture (DAC)

Direct Air Capture (DAC) removes carbon dioxide (CO₂) directly from the surrounding air. That makes it different from conventional carbon capture systems, which collect CO₂ from concentrated emission sources such as factories or power plants.

A typical DAC system moves large volumes of air across materials that selectively capture carbon dioxide. Some systems use liquid solvents, while others rely on solid sorbents. Once the material has absorbed enough CO₂, heat, pressure changes, or other processes are used to release a concentrated stream of carbon dioxide so the capture material can be used again.

The captured CO₂ can then be transported to a geological storage site and injected deep underground. It can also be used in products such as fuels, chemicals, and some building materials, although using CO₂ does not always result in permanent carbon removal.

Advantages of Direct Air Capture

Removes CO₂ that is already present in the atmosphere.
Does not have to be installed directly beside a major source of emissions.
Could help address residual emissions from sectors that are especially difficult to decarbonize.
Produces a concentrated CO₂ stream that can be stored or used.

Challenges

DAC also has some significant limitations. Because carbon dioxide makes up only a small fraction of the surrounding air, enormous volumes of air must be processed to capture meaningful amounts of CO₂.

The process also requires energy to move air through the system and regenerate the materials that capture the carbon. The overall climate benefit therefore depends partly on where that energy comes from.

Location matters too. A DAC facility may need access to low-carbon energy, suitable geological storage, CO₂ transportation infrastructure, and, depending on the technology, water. Cost remains another major obstacle to deploying DAC on a much larger scale.

Despite these challenges, DAC is attracting attention because it can do something conventional point-source capture cannot: remove carbon dioxide that has already entered the atmosphere.

If you want to explore the performance and limitations of these systems in more detail, read our guide to How Effective Is Carbon Capture Technology?

Quick Fact: Direct Air Capture uses chemical processes to separate CO₂ directly from ambient air. When that CO₂ is permanently stored, the process can result in net carbon dioxide removal—as long as emissions associated with operating the system are also accounted for.

2. Bioenergy with Carbon Capture and Storage (BECCS)

Bioenergy with Carbon Capture and Storage (BECCS) combines energy production from biomass with carbon capture and long-term CO₂ storage. Unlike systems that capture carbon from fossil fuel emissions, BECCS begins with plants that have already absorbed CO₂ from the atmosphere while growing.

The biomass—such as wood residues, agricultural waste, or other organic material—is then used to produce electricity, heat, fuels, or other forms of energy. CO₂ generated during processing or combustion is captured rather than released directly into the atmosphere. It is then compressed, transported, and stored in suitable geological formations.

If the biomass is produced sustainably and enough of the resulting CO₂ is permanently stored, the overall process has the potential to produce net-negative emissions. However, this is not automatic. The full carbon footprint of growing, harvesting, processing, and transporting the biomass must also be considered.

How BECCS Works

Plants absorb CO₂ from the atmosphere through photosynthesis.
Biomass is harvested and transported for processing.
The biomass is converted into energy or fuel.
CO₂ produced during the process is captured.
The captured carbon dioxide is transported to a suitable site and stored underground.

Advantages of BECCS

Combines bioenergy production with carbon capture and storage.
Has the potential to remove CO₂ from the atmosphere while producing useful energy.
Can make use of certain agricultural, forestry, and organic residues.
Could help address some residual emissions that are difficult to eliminate.

Challenges

BECCS requires a reliable supply of biomass, and where that biomass comes from matters enormously.

Growing dedicated energy crops on a very large scale could compete with food production, consume water, or place additional pressure on forests and natural habitats. Land-use changes can also release stored carbon and reduce or even eliminate the climate benefit of a project.

The process requires infrastructure for capturing, transporting, and permanently storing CO₂. Emissions associated with farming, harvesting, processing, and transportation must also be included when determining whether a BECCS project actually achieves net carbon removal.

For these reasons, BECCS is best evaluated on a full lifecycle basis rather than assuming that all biomass energy combined with carbon capture is automatically carbon-negative.

Quick Fact: BECCS can produce net-negative emissions when biomass absorbs atmospheric CO₂ and the carbon released during energy production is captured and permanently stored. The actual climate benefit depends on sustainable biomass sourcing, land use, capture efficiency, energy use, and the emissions produced across the entire supply chain.

For another look at how carbon capture is being developed in practice, see our guide to CO2 Capture Technology in India.

3. Post-Combustion Carbon Capture

Post-combustion carbon capture separates carbon dioxide from gases produced after fuel has been burned or after certain industrial processes have taken place. One of its main advantages is that the technology can potentially be added to some existing facilities rather than requiring an entirely new plant.

A common approach uses chemical solvents called amines. Exhaust or flue gas passes through a capture unit where the solvent binds with CO₂ while most of the other gases continue through the system.

The CO₂-rich solvent is then heated in a separate unit. This releases a concentrated stream of carbon dioxide and allows the solvent to be reused. The captured CO₂ can then be compressed, transported, and sent for geological storage or certain industrial uses.

How Post-Combustion Capture Works

A facility produces a CO₂-containing gas stream.
The gas enters a carbon capture system.
A solvent or other separation material captures the CO₂.
The capture material is regenerated, releasing concentrated carbon dioxide.
The CO₂ is compressed and prepared for transportation, storage, or use.

Advantages

Can potentially be retrofitted to some existing industrial facilities and power plants.
Uses capture processes that have been studied and demonstrated for decades.
Can reduce emissions from large stationary sources.
Can be applied to industries where process emissions are difficult to eliminate through electrification alone.

Challenges

Separating CO₂ and regenerating the capture material requires energy. This additional energy demand—often called an energy penalty—can reduce the efficiency of the facility and increase operating costs.

Retrofitting an existing plant can also require substantial equipment, space, and infrastructure. Solvents may degrade over time and need to be replaced or treated, while other capture materials come with their own technical and economic trade-offs.

Another important consideration is what happens after the CO₂ is captured. A facility needs access to transportation, utilization, or suitable long-term storage infrastructure for the system to deliver its intended climate benefit.

Quick Fact: Post-combustion carbon capture separates CO₂ from a facility’s exhaust or process gases after combustion or production has occurred. Because it can potentially be added to existing infrastructure, it is an important option for reducing emissions from some industrial facilities.

4. Pre-Combustion Carbon Capture

Pre-combustion carbon capture separates carbon dioxide before the resulting fuel gas is burned. Rather than trying to remove CO₂ from diluted exhaust gases afterward, the process creates a gas mixture in which carbon can be separated at an earlier stage.

In systems using coal or biomass, the feedstock can be converted into syngas, a mixture containing mainly hydrogen and carbon monoxide. Natural gas can undergo reforming to produce a similar hydrogen-rich gas mixture.

The carbon monoxide then reacts with steam in a process known as the water-gas shift reaction. This produces additional hydrogen while converting much of the carbon monoxide into carbon dioxide.

Because the resulting CO₂ is generally present at a higher concentration and pressure than it is in conventional flue gas, separating it can be easier in certain applications. The remaining hydrogen-rich gas can then be used as a fuel or as a feedstock for industrial processes.

How Pre-Combustion Capture Works

A fuel or feedstock is gasified or reformed to produce a hydrogen- and carbon-monoxide-rich gas.
Carbon monoxide reacts with steam to produce additional hydrogen and CO₂.
The concentrated carbon dioxide is separated from the gas mixture.
The captured CO₂ is compressed for transportation, storage, or use.
The remaining hydrogen-rich gas can be used for energy or industrial applications.

Advantages

Produces a relatively concentrated CO₂ stream that can make separation easier in certain systems.
Can be integrated with hydrogen production.
Is suitable for some gasification and industrial processes.
Allows carbon to be separated before the hydrogen-rich fuel is ultimately used.

Challenges

Pre-combustion capture requires more complex processing than simply burning a fuel and treating the exhaust afterward. Gasification, reforming, the water-gas shift reaction, CO₂ separation, and hydrogen handling all require specialized equipment.

That complexity makes the technology difficult to retrofit onto many conventional facilities. Building new plants designed around pre-combustion capture can also involve substantial upfront investment.

The climate benefit of the resulting hydrogen depends on more than simply capturing CO₂. The source of the feedstock, methane leakage when natural gas is involved, energy use, the percentage of carbon actually captured, and the permanence of CO₂ storage all affect its overall emissions.

Quick Fact: Pre-combustion carbon capture converts a fuel or feedstock into a hydrogen-rich gas and separates much of the carbon as CO₂ before the hydrogen is used. The concentrated CO₂ stream can make capture easier in some industrial applications.

5. Oxy-Fuel Combustion

Oxy-fuel combustion burns fuel using oxygen instead of ordinary air. Since air is roughly 78% nitrogen, conventional combustion produces exhaust containing large amounts of nitrogen alongside carbon dioxide, water vapor, and other gases.

Oxy-fuel systems remove most of that nitrogen before combustion takes place. Fuel is burned in an oxygen-rich environment, producing an exhaust stream composed largely of CO₂ and water vapor. This makes the carbon dioxide easier to separate than it is from conventional flue gas.

The oxygen is typically produced using an air separation unit. Because burning fuel in nearly pure oxygen would create extremely high temperatures, some of the exhaust gas can be recycled back into the combustion chamber to help control the temperature.

After combustion, the exhaust is cooled so much of the water vapor condenses. The remaining CO₂-rich stream still requires purification and processing before it can be compressed, transported, and sent for geological storage or other uses.

How Oxy-Fuel Combustion Works

Air is separated to produce an oxygen-rich stream.
Fuel is burned using oxygen rather than ordinary air.
Some exhaust gas may be recycled to control combustion temperatures.
The resulting exhaust consists largely of CO₂ and water vapor.
Water is condensed and other impurities are removed.
The CO₂-rich stream is compressed for transportation, storage, or use.

Advantages

Produces a much more concentrated CO₂ stream than conventional air-fired combustion.
Makes separating carbon dioxide from the exhaust easier.
Can reduce the volume of flue gas that must be processed.
May reduce the formation of some nitrogen-related pollutants compared with conventional combustion.

Challenges

Producing a high-purity oxygen stream requires substantial energy. This energy penalty can reduce the overall efficiency of the facility and increase operating costs.

Oxy-fuel systems also require specialized air separation equipment, exhaust-gas recycling, and CO₂ purification. Retrofitting an existing facility can therefore involve significant modifications.

The resulting CO₂ stream is not automatically ready for storage. Water, oxygen, nitrogen, and other impurities may still need to be removed before the carbon dioxide can be transported and injected underground.

Quick Fact: Oxy-fuel combustion burns fuel in an oxygen-rich environment instead of ordinary air. By keeping most atmospheric nitrogen out of the combustion process, it produces a concentrated CO₂-rich exhaust stream that is easier to prepare for capture and storage.

6. Mineral Carbonation

Mineral carbonation, also called carbon mineralization, stores carbon dioxide by converting it into stable solid minerals. Instead of keeping CO₂ in a compressed or fluid state, the process reacts carbon dioxide with calcium- or magnesium-rich materials to form carbonate minerals such as calcite and magnesite.

This reaction already occurs naturally when certain rocks are exposed to CO₂ and water, but natural weathering can be very slow. Carbon mineralization technologies attempt to speed up these reactions or create conditions where they happen more efficiently.

There are several ways to do this. Captured CO₂ can react with crushed rocks or alkaline industrial materials above ground. In other systems, CO₂ is injected underground into reactive rock formations, where it gradually reacts with minerals in the rock and becomes solid carbonate.

A well-known example comes from Iceland, where the Carbfix project has demonstrated underground carbon mineralization in basaltic rock. CO₂ is dissolved in water and injected underground, where it reacts with minerals in the basalt and forms stable carbonate minerals. Projects like this show how geological storage and mineralization can sometimes be combined, turning injected CO₂ into solid mineral forms rather than leaving it only as compressed carbon dioxide underground.

How Mineral Carbonation Works

CO₂ is captured from an industrial source or removed from the atmosphere.
The carbon dioxide comes into contact with calcium- or magnesium-rich material.
Chemical reactions convert the CO₂ into solid carbonate minerals.
Once mineralized, the carbon becomes part of a stable solid material.

Advantages

Can provide highly durable carbon storage.
Converts CO₂ into a solid form rather than keeping it as compressed carbon dioxide.
Uses chemical reactions that also occur naturally in rocks.
Some approaches can make use of suitable mine tailings, concrete waste, or other alkaline industrial materials.
Mineralized carbon has a very low risk of suddenly escaping back into the atmosphere.

Challenges

Natural mineralization can be slow, so some approaches require energy-intensive steps such as mining, crushing, grinding, heating, or pressurizing materials to accelerate the reaction.

The environmental footprint also depends on the source of the minerals. Mining large quantities of fresh rock specifically for carbon removal could create additional land disturbance, energy use, and transportation emissions.

Different approaches face different challenges. Above-ground mineralization requires handling large amounts of material, while underground mineralization depends on finding suitable geology and understanding how injected CO₂ will interact with the surrounding rock.

Despite these challenges, mineral carbonation is attractive because of the durability of the resulting carbon storage. Once CO₂ has been converted into stable carbonate minerals, reversing the process under normal environmental conditions is difficult.

Quick Fact: Mineral carbonation stores CO₂ through chemical reactions that transform carbon dioxide into stable carbonate minerals. Because the carbon becomes part of a solid mineral, this method can provide exceptionally durable carbon storage.

7. Enhanced Weathering

Enhanced weathering is a carbon dioxide removal method that attempts to speed up the natural chemical weathering of rocks. Over long periods, certain minerals react with carbon dioxide dissolved in rainwater, ultimately converting some of that CO₂ into dissolved bicarbonate and other forms of inorganic carbon.

Enhanced weathering accelerates this process by increasing the surface area of reactive minerals. One approach involves crushing silicate-rich rock, such as basalt, into smaller particles and spreading the material over agricultural fields or other suitable land.

When rainwater passes through the crushed rock, dissolved CO₂ reacts with minerals in the material. Some of the resulting dissolved carbon can move through soils, groundwater, streams, and rivers and eventually reach the ocean, where it may remain stored for long periods.

How Enhanced Weathering Works

Suitable mineral-rich rock, such as basalt, is obtained and crushed into smaller particles.
The material is spread over agricultural fields or other suitable land.
Rainwater containing dissolved CO₂ interacts with the minerals.
Chemical weathering converts some of the carbon into dissolved bicarbonate.
Some of that dissolved carbon may eventually travel through waterways to the ocean.

Advantages

Accelerates a naturally occurring carbon-removal process.
Could potentially be applied to existing agricultural land.
Some rock materials can add nutrients to soils as they weather.
The resulting inorganic carbon can potentially provide long-lasting storage.
Certain approaches may make use of suitable existing rock or mining materials.

Challenges

Enhanced weathering requires large quantities of material if it is to remove CO₂ at a meaningful scale. Mining, crushing, grinding, transporting, and spreading rock all consume energy and can create their own environmental impacts.

The actual rate of carbon removal also varies. Rock type, particle size, temperature, rainfall, soil conditions, and agricultural practices can all influence how quickly weathering occurs.

Another challenge is measurement. Researchers need reliable ways to determine how much additional CO₂ has actually been removed because of the added rock rather than through natural processes.

Potential effects on soils, waterways, and ecosystems also need to be understood before enhanced weathering is deployed across very large areas.

Quick Fact: Enhanced weathering speeds up natural chemical reactions between CO₂, water, and reactive minerals. The process can convert atmospheric carbon into dissolved bicarbonate and other inorganic forms that may store carbon for long periods.

8. Ocean Carbon Removal

Ocean carbon removal describes several proposed methods for increasing the amount of carbon dioxide the ocean removes from the atmosphere or for storing ocean carbon more durably. The ocean already plays a major role in the global carbon cycle, naturally exchanging enormous amounts of CO₂ with the atmosphere.

Researchers are studying whether some of these natural processes can be enhanced without causing unacceptable harm to marine ecosystems.

One approach is ocean alkalinity enhancement. This involves increasing seawater alkalinity so that the ocean can take up additional atmospheric CO₂ and convert more of it into dissolved bicarbonate and carbonate forms.

Other approaches involve biological processes. Seaweed and microscopic phytoplankton absorb carbon through photosynthesis, but growing more marine biomass does not automatically mean that CO₂ has been permanently removed from the atmosphere. Seaweed also has uses far beyond carbon removal research. See our guide to 10 Interesting Uses of Seaweed for examples in food, agriculture, materials, and other industries. Much of the carbon can return to the water or atmosphere as organisms are eaten or decompose.

For a method to count as durable carbon removal, researchers need to determine how much additional atmospheric CO₂ was actually removed and how long that carbon remains stored.

How Ocean Carbon Removal Works

There is no single ocean carbon removal process. Different approaches work in different ways:

Ocean alkalinity enhancement changes seawater chemistry to increase its capacity to take up atmospheric CO₂.
Seaweed cultivation uses photosynthesis to incorporate carbon into marine biomass.
Nutrient-based approaches attempt to stimulate phytoplankton growth and biological carbon uptake.
Other proposed methods aim to remove CO₂ from seawater directly, which may allow the ocean to absorb additional CO₂ from the atmosphere.

The amount and durability of carbon storage vary considerably between these approaches.

Advantages

Builds on the ocean’s existing role in the global carbon cycle.
Could potentially operate across very large areas.
Some approaches may provide long-duration carbon storage.
Marine biomass projects may offer additional benefits when developed for food, materials, or other uses.

Challenges

Ocean ecosystems are complex, and intentionally altering ocean chemistry or biology can have consequences that are difficult to predict.

Researchers need to understand potential effects on marine organisms, food webs, nutrient cycles, oxygen levels, and seawater chemistry. Some methods would also require moving and processing enormous quantities of material.

Measurement, reporting, and verification present another major challenge. Scientists must be able to distinguish additional carbon removal caused by an intervention from the ocean’s natural carbon cycle and determine how long the carbon remains stored.

Governance is also important because ocean currents cross national boundaries and activities in one location could potentially affect ecosystems elsewhere.

Quick Fact: Ocean carbon removal is not one technology but a collection of proposed approaches that attempt to increase atmospheric CO₂ uptake or make ocean carbon storage more durable. Many remain at the research or early demonstration stage, and their effectiveness and ecological impacts are still being studied.

9. Biochar Carbon Storage

Biochar is a carbon-rich material produced by heating biomass in an environment with little or no oxygen. When produced from sustainably sourced material and used appropriately, biochar can slow the return of biologically captured carbon to the atmosphere and potentially provide long-lasting carbon storage.

Plants absorb CO₂ from the atmosphere as they grow. Normally, much of that carbon eventually returns to the atmosphere when plant material decomposes or burns. Biochar production changes that pathway by converting a portion of the biomass carbon into more stable forms.

The process used to make biochar is called pyrolysis. Materials such as crop residues, forestry residues, wood waste, and other suitable biomass are heated under oxygen-limited conditions. The process can produce biochar along with gases and liquids that may also be used for energy.

Biochar is often applied to agricultural soils, but it can also be incorporated into other materials or used in environmental applications.

How Biochar Carbon Storage Works

Plants remove CO₂ from the atmosphere through photosynthesis.
Suitable biomass or organic residues are collected.
The material undergoes pyrolysis in a low-oxygen environment.
Part of the biomass carbon is converted into relatively stable biochar.
The biochar is placed in soil or another suitable long-term application.

Advantages

Can keep a portion of biomass carbon out of the atmosphere for long periods.
Can make productive use of some agricultural and forestry residues.
May improve water retention, nutrient availability, or other soil properties under certain conditions.
Pyrolysis can also produce useful heat, gases, or liquid products.
Can potentially combine carbon removal with agricultural or waste-management applications.

Challenges

The climate benefit of biochar depends heavily on how it is produced and where the biomass comes from. Harvesting trees specifically for biochar, transporting biomass over long distances, or using inefficient production methods can reduce its overall carbon benefit.

Not all biochar is equally stable. Feedstock type, pyrolysis temperature, production conditions, soil characteristics, and environmental conditions can influence how long its carbon remains stored.

Agricultural benefits also vary. Biochar can improve some soils, but it does not automatically increase fertility or crop yields in every location.

Accurately calculating carbon removal requires looking at the entire lifecycle, including biomass sourcing, processing, transportation, energy use, biochar stability, and what would have happened to the original biomass without the project.

Quick Fact: Biochar can provide long-term carbon storage by converting some of the carbon in plant material into forms that decompose much more slowly. Its actual climate benefit depends on sustainable biomass sourcing, production methods, biochar stability, and the emissions associated with the entire process.

10. Reforestation and Forest Carbon Removal

Reforestation is not an engineered carbon capture technology, but it is an important form of nature-based carbon dioxide removal. It involves restoring forests in areas where trees have previously been cleared or lost, allowing growing vegetation to remove CO₂ from the atmosphere through photosynthesis.

As trees grow, they convert atmospheric carbon dioxide into organic carbon that becomes part of their trunks, branches, leaves, and roots. Forest soils, dead wood, and other organic matter can store additional carbon, making an entire forest ecosystem part of the carbon cycle.

Unlike geological or mineral carbon storage, however, carbon stored in forests is reversible. Wildfire, drought, disease, logging, or future land clearing can release some of that stored carbon back into the atmosphere.

How Reforestation Removes Carbon

Trees absorb atmospheric CO₂ through photosynthesis.
Some of that carbon becomes part of new wood, roots, leaves, and other plant tissue.
Additional carbon can accumulate in forest soils and organic matter.
A growing forest can continue removing CO₂ as its biomass and soil carbon increase.
Protecting the restored ecosystem helps keep that carbon stored for longer.

Advantages

Removes CO₂ using a natural biological process.
Can restore habitat for wildlife and support biodiversity.
May reduce soil erosion and improve degraded land.
Can support watersheds and local water cycles.
Provides benefits beyond carbon removal, including shade, habitat, recreation, and ecosystem restoration.

Challenges

Reforestation takes time. Newly planted trees do not immediately store the amount of carbon found in mature forests, and carbon accumulation varies considerably by species, climate, soil, location, and forest management.

Permanence is another major challenge. A forest that removes carbon for several decades can lose part of that stored carbon during a severe wildfire or if the land is later cleared.

Reforestation projects also need to consider what ecosystem naturally belongs in a particular location. Planting trees in native grasslands, peatlands, or other naturally non-forested ecosystems can damage biodiversity rather than restore it.

Restoring degraded land also involves more than planting trees. Our guide to How Can We Prevent or Reverse Desertification? explores additional approaches to protecting and restoring vulnerable land.

For that reason, successful reforestation is about more than planting as many trees as possible. Restoring appropriate native forests, protecting existing forests, supporting biodiversity, and maintaining the ecosystem over the long term are all important.

If you want to explore biological carbon storage further, read our guide to Top 10 Carbon-Storing Trees.

Quick Fact: Reforestation removes CO₂ as growing forests convert atmospheric carbon into wood, roots, soils, and other organic matter. Unlike mineral or geological storage, forest carbon is not necessarily permanent and requires long-term ecosystem protection.

Advantages of Carbon Capture Technologies

Carbon capture is not a replacement for reducing fossil fuel use, improving energy efficiency, or expanding renewable energy. Its main advantage is that it can address some emissions that are particularly difficult to eliminate in other ways.

Different carbon capture technologies provide different benefits, and not every method is suitable for every industry or location.

1. Reducing Emissions From Heavy Industry

Some of the strongest potential applications are in industries such as cement, steel, chemicals, and refining.

Cement production is a particularly important example because CO₂ is released not only from burning fuel but also during the chemical conversion of limestone into clinker. Switching the plant to renewable electricity alone cannot eliminate these process emissions.

Capturing CO₂ at the facility offers another way to reduce them.

2. Removing CO₂ Already in the Atmosphere

Some of the methods covered in this guide go beyond preventing new emissions.

Direct Air Capture (DAC) removes CO₂ directly from ambient air, while approaches such as BECCS and biochar can potentially result in net carbon removal when their full lifecycle emissions are sufficiently low and the captured carbon is stored for long periods.

Reforestation and other ecosystem restoration methods can also remove atmospheric carbon through biological processes, although that storage is generally less permanent than geological or mineral storage.

3. Providing Durable Carbon Storage

Some carbon capture approaches can keep carbon away from the atmosphere for very long periods.

Geological storage places compressed CO₂ in carefully selected underground formations, while carbon mineralization converts CO₂ into stable carbonate minerals.

Durability matters because removing carbon temporarily is not equivalent to keeping it out of the atmosphere for centuries or longer.

4. Addressing Residual Emissions

Even with major improvements in renewable energy, electrification, efficiency, and manufacturing, some greenhouse gas emissions may remain difficult to eliminate.

Carbon dioxide removal could potentially counterbalance a portion of these residual emissions. However, the amount actually removed needs to be measured carefully and should account for emissions created while operating the carbon removal system itself.

5. Creating New Uses for Captured CO₂

Not all captured carbon dioxide has to be stored underground. CO₂ can also be used in certain building materials, chemicals, fuels, and industrial processes.

The climate benefit varies considerably depending on the product. If CO₂ is converted into a fuel and later burned, the carbon may quickly return to the atmosphere. If it becomes permanently mineralized in a building material, it can remain stored for much longer.

For that reason, carbon utilization and carbon storage should not be treated as interchangeable.

Key Takeaway: The main advantage of carbon capture is its ability to address CO₂ that can be difficult to eliminate through renewable energy and electrification alone. Some technologies prevent new emissions, while others remove CO₂ already in the atmosphere or provide durable ways to store captured carbon.

Challenges and Limitations of Carbon Capture

What Are the Biggest Limitations of Carbon Capture Technology

Carbon capture technologies can reduce or remove CO₂, but none of the methods covered in this guide comes without trade-offs. Cost, energy use, infrastructure, storage, environmental impacts, and the ability to verify actual carbon reductions all influence whether a project delivers a meaningful climate benefit.

1. Carbon Capture Can Be Expensive

Capturing CO₂ requires additional equipment, energy, maintenance, and infrastructure. The cost varies considerably depending on the technology and the concentration of carbon dioxide being captured.

Removing CO₂ from ambient air with Direct Air Capture (DAC) is particularly challenging because carbon dioxide is present at a very low concentration in the atmosphere. Capturing CO₂ from a more concentrated industrial gas stream can be easier, although costs still vary widely between facilities.

Transportation and permanent storage add further expenses.

2. Capturing Carbon Requires Energy

Carbon capture itself consumes energy. Solvents may need to be heated so they can release captured CO₂, compressors are needed to prepare carbon dioxide for transportation, and Direct Air Capture systems may require energy to move air and regenerate capture materials.

This creates what is often called an energy penalty.

The source of that energy matters. A carbon capture system powered by high-emission energy will generally deliver a smaller net climate benefit than one using low-carbon energy.

3. Infrastructure Is Not Available Everywhere

Capturing CO₂ is only one part of the process. Large projects may also need pipelines, ships, compression facilities, injection wells, geological storage sites, and monitoring systems.

Suitable storage geology is also unevenly distributed. In some locations, captured CO₂ may need to travel considerable distances before reaching an appropriate storage site.

Developing this infrastructure can take years and requires coordination between industries, governments, communities, and storage operators.

4. Capture Rate Is Not the Same as Total Emissions Reduction

A system might capture a high percentage of CO₂ from a particular exhaust stream, but that number does not necessarily represent the project’s total climate impact.

Emissions can also come from producing fuel, generating electricity, constructing equipment, transporting materials, moving CO₂, and operating the capture and storage system.

For technologies such as BECCS, biochar, and Direct Air Capture, lifecycle emissions are especially important when calculating how much CO₂ has actually been removed from the atmosphere.

5. Carbon Must Stay Stored

Capturing carbon has limited climate value if it quickly returns to the atmosphere.

Geological storage sites therefore need careful characterization, operation, and monitoring. Mineralized CO₂ can provide highly durable storage, while carbon stored in forests and other biological systems can be more vulnerable to wildfire, drought, disease, decomposition, or land-use change.

The durability of storage should be considered alongside the amount of CO₂ captured.

6. Some Methods Have Environmental Trade-Offs

Scaling carbon removal can require substantial amounts of land, water, energy, minerals, or biomass.

For example, large-scale BECCS could increase pressure on agricultural land or ecosystems if biomass is sourced poorly. Enhanced weathering may require extensive mining, grinding, and transportation of rock. Ocean carbon removal could alter marine chemistry or ecosystems if deployed without sufficient understanding of its effects.

Even a technology designed to address climate change can create other environmental problems if it is poorly planned.

7. Measuring Carbon Removal Can Be Difficult

Another challenge is determining exactly how much additional CO₂ a project has removed and how long that carbon will remain stored.

This is relatively straightforward in some engineered systems where captured CO₂ can be directly measured. It becomes more complicated with forests, soils, enhanced weathering, biochar, and ocean-based approaches.

Reliable measurement, reporting, and verification (MRV) are therefore essential for determining whether claimed carbon removal actually occurred.

Carbon Capture Is One Part of a Larger Strategy

Perhaps the most important limitation is that carbon capture does not eliminate the need to reduce emissions in the first place.

Renewable energy, electrification, energy efficiency, reducing fossil fuel use, protecting existing ecosystems, and improving industrial processes can prevent emissions before they occur. Carbon capture and carbon removal can complement those efforts, particularly where emissions remain difficult to eliminate.

Key Takeaway: The effectiveness of carbon capture cannot be judged only by how much CO₂ enters a capture system. Energy use, lifecycle emissions, storage durability, infrastructure, environmental impacts, and accurate measurement all determine the technology’s real climate benefit.

Future of Carbon Capture

Carbon capture research and deployment increasingly include larger projects designed to test whether these technologies can operate reliably and economically at scale. But the future of carbon capture technology will depend on more than simply building larger capture facilities.

The bigger questions are whether systems can capture CO₂ with less energy, whether sufficient transportation and storage infrastructure can be developed, and whether projects can demonstrate that the carbon they claim to capture or remove actually stays out of the atmosphere.

Lowering the Energy Required for Capture

One major area of research involves improving the materials used to separate CO₂.

New solvents, sorbents, membranes, and other capture materials are being investigated to reduce the amount of heat or electricity required. This is especially important for Direct Air Capture, where enormous volumes of air must be processed because atmospheric CO₂ is so dilute.

Reducing energy requirements could lower both operating costs and the emissions associated with running these systems.

Building CO₂ Transport and Storage Networks

Capturing carbon at a factory is only useful if there is somewhere for that CO₂ to go.

Larger deployment would require infrastructure to compress, transport, inject, and monitor carbon dioxide. In some regions, multiple industrial facilities could potentially share pipelines and geological storage sites rather than developing separate systems for every plant.

Finding and carefully evaluating suitable underground storage formations will therefore be just as important as improving the capture equipment itself.

Making Carbon Storage More Durable

Another area of development focuses on turning captured CO₂ into forms that are difficult to release again.

Carbon mineralization is one example. Instead of keeping CO₂ as a compressed fluid underground, mineralization converts it into stable carbonate minerals.

Researchers are also studying ways to incorporate CO₂ into concrete and other building materials. The amount of carbon stored and the durability of that storage vary by process, so these approaches still need careful lifecycle assessment.

Scaling Carbon Dioxide Removal

Technologies such as Direct Air Capture, BECCS, biochar, enhanced weathering, and ocean carbon removal are being studied as possible ways to remove CO₂ that is already in the atmosphere.

Scaling them presents different challenges. Some require large amounts of clean energy, while others depend on land, biomass, minerals, water, or suitable geological storage.

The central question is not simply how much CO₂ a system can capture, but how much net carbon removal remains after its full environmental footprint is considered.

Improving Measurement and Verification

As carbon capture and removal projects grow, accurately measuring their results will become increasingly important.

Engineered systems can often directly measure captured CO₂, but verifying removal from forests, soils, oceans, enhanced weathering, and other natural or semi-natural systems can be much more difficult.

Better measurement, reporting, and verification (MRV) will be needed to determine how much carbon was actually removed, where it went, and how long it is likely to remain stored.

Where Carbon Capture Goes From Here

Carbon capture is likely to develop differently across industries and regions. Point-source capture may prove particularly useful for certain industrial processes, while carbon dioxide removal could address some emissions that remain after other reduction measures have been exhausted.

Whether individual technologies succeed at large scale will depend on their cost, energy requirements, environmental effects, infrastructure needs, storage durability, and measurable climate benefit.

What is already clear is that carbon capture cannot be evaluated in isolation. Its role depends on how effectively it works alongside cleaner energy, efficiency, electrification, ecosystem protection, and direct reductions in fossil fuel emissions.

Key Takeaway: The future of carbon capture will depend less on any single breakthrough and more on solving several practical problems at once: lowering energy use and cost, building storage infrastructure, proving long-term carbon storage, limiting environmental trade-offs, and accurately measuring the CO₂ that is actually kept out of the atmosphere.

Frequently Asked Questions About Carbon Capture Technology

What is carbon capture technology?

Carbon capture technology refers to methods that separate carbon dioxide (CO₂) from industrial gas streams or other sources so it can be transported, used, or stored instead of being released into the atmosphere.

Some related technologies, such as Direct Air Capture (DAC), work differently by removing CO₂ that is already present in ambient air. This is generally considered carbon dioxide removal rather than conventional point-source carbon capture.

What is the most effective carbon capture technology?

There is no single carbon capture technology that is best for every application.

Post-combustion capture may be suitable for some existing industrial facilities, while pre-combustion capture can work well in processes designed around hydrogen-rich gas production. Oxy-fuel combustion offers another approach by producing a more concentrated CO₂ stream.

For removing carbon dioxide that is already in the atmosphere, Direct Air Capture serves a different purpose entirely.

The appropriate technology depends on factors such as the CO₂ concentration, industrial process, energy requirements, cost, available infrastructure, and access to suitable long-term storage.

Is carbon capture a solution to climate change?

Carbon capture can contribute to reducing greenhouse gas emissions, particularly in industries where some emissions are difficult to eliminate through electrification or renewable energy alone.

It does not replace the need to reduce fossil fuel use, improve energy efficiency, expand low-carbon energy, and protect ecosystems.

Carbon dioxide removal technologies may also be useful for addressing some CO₂ already in the atmosphere or counterbalancing residual emissions that remain difficult to eliminate.

Where is captured carbon dioxide stored?

Captured CO₂ can be injected into suitable deep geological formations, including deep saline formations and some depleted oil and gas reservoirs.

Carbon can also be stored through mineralization, where CO₂ reacts with calcium- or magnesium-rich materials and becomes part of stable carbonate minerals.

Not all captured CO₂ is permanently stored. Some is used to make fuels, chemicals, building materials, or other products. How long the carbon remains out of the atmosphere depends on the particular use.

Which industries could use carbon capture?

Carbon capture may be useful in industries with large, concentrated CO₂ emissions, particularly where eliminating those emissions through other methods is difficult.

Examples include cement, steel, chemicals, refining, hydrogen production, and some power-generation processes.

Cement is especially notable because part of its CO₂ emissions comes from the chemical conversion of limestone during production rather than simply from the fuel used to heat the kiln.

Is carbon capture expensive?

Carbon capture can be expensive, but there is no single price that applies to every technology or project.

Costs depend on factors such as the concentration of CO₂, capture method, energy requirements, facility design, transportation distance, and storage location.

Capturing CO₂ from a concentrated industrial stream can be very different from removing it from ambient air with Direct Air Capture, where CO₂ is much more dilute.

What is the difference between carbon capture and carbon sequestration?

Carbon capture is the process of separating and collecting CO₂. Carbon sequestration refers to keeping carbon stored away from the atmosphere over time.

Geological formations, carbonate minerals, forests, soils, and other reservoirs can all store carbon, but they differ greatly in how long that storage may last and how easily the carbon could return to the atmosphere.

What is the difference between carbon capture and carbon removal?

Carbon capture usually refers to collecting CO₂ from a concentrated source before it reaches the atmosphere. For example, a capture system installed at a cement plant can prevent some of the facility’s CO₂ emissions from being released.

Carbon dioxide removal (CDR) takes CO₂ that is already in the atmosphere and stores it. Direct Air Capture, reforestation, biochar, and enhanced weathering are examples of approaches that can potentially provide carbon removal.

The distinction is important: avoiding a new emission and removing an existing amount of atmospheric CO₂ are not the same thing.

Can trees replace carbon capture technology?

Trees can remove atmospheric CO₂ and provide valuable benefits for biodiversity, soils, water, and ecosystems, but reforestation and engineered carbon capture solve different problems.

Forests store carbon biologically, which means some of it can return to the atmosphere through wildfire, drought, disease, decomposition, logging, or land-use change. Geological storage and carbon mineralization can potentially provide more durable storage.

Rather than treating trees and engineered technologies as substitutes for one another, their benefits and limitations should be evaluated according to the specific climate and ecological goal.

Final Thoughts: Where Carbon Capture Fits

Carbon capture is not one technology and it does not solve one single problem.

Some systems capture CO₂ from cement plants, steel facilities, and other industrial sources before it reaches the atmosphere. Direct Air Capture (DAC) removes CO₂ that is already in the air. Other approaches, including biochar, enhanced weathering, and reforestation, use biological or chemical processes to remove and store atmospheric carbon.

The differences matter.

A technology that captures a high percentage of CO₂ from one industrial gas stream is not necessarily reducing the facility’s total emissions by the same percentage. A tree that absorbs carbon does not store it as permanently as CO₂ converted into stable minerals. And using captured carbon to make fuel is very different from storing it underground for centuries.

That is why carbon capture technologies need to be evaluated by more than the amount of CO₂ they capture. Energy use, lifecycle emissions, cost, environmental impacts, storage durability, and verification all help determine whether a project delivers a meaningful climate benefit.

Carbon capture also makes the most sense as part of a broader approach to climate change. Preventing emissions through cleaner energy, efficiency, electrification, and ecosystem protection remains essential. Carbon capture can complement those efforts, particularly where emissions are difficult to eliminate, while carbon dioxide removal can address some CO₂ that is already in the atmosphere.

The technologies covered in this guide are at very different stages of development, and each comes with its own trade-offs. Understanding those differences makes it easier to separate realistic climate applications from claims that sound more impressive than they are.