Climate change poses a significant threat to our planet, with greenhouse gas emissions driving global warming. One promising solution is carbon capture technology, which captures and stores CO₂ emissions from power generation and industrial processes. By reducing CO₂ emissions, we can mitigate the impact of global warming.
Technologies such as capture and storage BECCS (Bioenergy with Carbon Capture and Storage) play a crucial role in removing carbon from the atmosphere. With advancements in permanent storage techniques, carbon capture has the potential to capture millions of tonnes of CO₂ per year, offering a long-term solution for a sustainable future.
What is Carbon Capture?
Carbon capture is an emerging sector of climate tech that prevents carbon from going into the atmosphere and damaging the environment.
The idea was born in the 1970s for enhanced oil recovery and has come a long way. While there are dozens of variations of carbon capture, it is usually either repurposed (i.e. in synthetic fuels, concrete, or plastics) or placed underground for long-term storage of carbon dioxide.
Some are highly successful, such as post-combustion capture, with capture rates of around 90%, whereas some are emerging technologies that are still in pilot phases or not yet cost-effective.
Carbon capture tech is primarily used in areas letting off high levels of emissions—such as power plants, steel mills, or cement factories, but can also extract CO₂ directly from the atmosphere (direct air capture, DAC).
With many methods still piloting, scalability poses a challenge, however, to combat this governments and private sectors are investing heavily in R&D, subsidies, and carbon credit incentives. While there is a high cost, over time, this should decrease as technology advances and economies of scale kick in.
This blog will cover 20 various types of carbon capture being used around the world and how they are helping in the fight against global warming.
1. Direct Air Capture (DAC)
DAC (Direct Air Capture) works by a process of air capture, taking in ambient air through fans with chemical sorbets or filters, separating the CO₂ with chemical reactions, releasing the CO₂ with pressure or heat through regeneration, and then utilising the carbon dioxide in products or storing it underground.
Developing from academic discussions in the late 20th century, often credited to Klaus Lackner with the idea of capturing CO₂ from air in the late 1990s. The first development of practical DAC systems began in the early 2000s, with major advancements from David Keith. Moreover, Jan Wurzbacher and Christopher Gebald founded Climeworks, which brought DAC into commercial function in 2009.
DAC systems can be modular units the size of a shipping container, such as Climeworks, or all the way up to large-scale plants, covering several acres from factories to industrial estates.
2. Carbon Capture at Power Plants
The only power plants left in the UK are gas-fired, nuclear, and renewable energy plants, and these plants will have carbon capture installed.
This can involve industrial-scale equipment attached to smokestacks, which look like large scrubbers or absorbers and are run through third-party companies such as Carbon Clean or Aker Carbon Capture.
Without these in place, power plants can emit up to 800,000 tons of CO₂ annually, but with these systems, emissions can be reduced by up to 90%. They need continuous maintenance, energy input, and monitoring, requiring jobs such as carbon capture technicians or plant operators.
Technologies to capture emissions include pre-combustion (separating it from other gases), post-combustion (capturing CO₂ from flue gases after combustion), or oxy-fuel combustion (where the fuel is burned in pure oxygen).
The CO₂, once captured, can be compressed into a transparent liquid, where it can be injected into geological formations such as depleted oil and gas fields or saline aquifers. This is because deep underground, large volumes of CO₂ can be stored safely.
On the other hand, the liquid CO₂ can be utilised for other purposes, like carbonating drinks, or enhancing the performance of some metals.
3. Enhanced Rock Weathering (ERW)
Enhanced rock weathering accelerates the natural process of rock weathering by crushing rocks to increase their surface area, exposing more minerals to react with CO₂. This reaction forms stable carbonate minerals, effectively removing CO₂ from the atmosphere and storing it in the rock. These carbonates can remain stable for thousands to millions of years, making it a long-term solution.
The broken down rocks can be spread through forests, on croplands, or on barren soils that can use the minerals. Soil health gets enriched by calcium, magnesium, and potassium, boosting biodiversity and crops.
In water, the rocks can be dissolved into seawater, making the ocean more capable of CO₂ absorption by increasing alkalinity and reducing acidification. This helps mitigate coral bleaching and improves marine life of shellfish and corals.
4. Aqueous Amine-Based CO₂ Capture
Aqueous (water-based) amine-based (organic compound-based) CO₂ capture means that liquid amines absorb CO₂ from emissions before they reach the atmosphere, allowing it to be stored or reused.
Similarly installed at power plants, industrial sites, or cement factories, the waste gas (“flue gas”) comes out of the smokestack (the tall smoking towers) and is redirected into the capture system by a network of ducts and pipes that channel the gas into an absorption tower, where the CO₂ is chemically captured.
5. Membrane Gas Separation
In membrane gas separation, carbon dioxide is separated from gas streams to either purify gases for industrial use (e.g. hydrogen production, biogas upgrading, or natural gas processing) or reduce emissions—capturing the CO₂ but letting the other gases (e.g. nitrogen, methane, or hydrogen) pass through.
Used at a range of emission-intensive sites, this method may not be the most effective, but does require no chemical solvents, operates continuously, and is more energy-efficient.
6. Carbon Capture and Conversion
Instead of storing carbon underground like CCS technology, Carbon Capture and Conversion (CCC) is about converting it and using it for products. If we’d captured carbon since the first power plant, we’d have enough carbon for billions of tonnes of fuel, plastics, and building materials.
Through CCC, the CO₂ goes through a chemical process using catalysts, electrochemical reactions, or biological systems to transform it into fuels, chemicals, or solid materials.
The end products can be used for a range of purposes from synthetic aviation fuel to carbon-infused concrete.
7. Bioenergy with Carbon Capture and Storage (BECCS)
Bioenergy with Carbon Capture and Storage (BECCS) combines bioenergy (BE) production with carbon capture and storage (CCS). Not only does this generate renewable energy, but it also actively removes CO₂, simultaneously addressing climate and energy goals.
This involves collecting biomass such as dedicated energy crops, agricultural residues, or wood, which absorb CO₂ during growth. It is then harvested and converted into bioenergy through burning (and sometimes gasification or fermentation), whereby it can be used to generate electricity or produce biofuels.
8. Chemical Looping
The process called chemical looping has been around since the 1800s, when it was initially developed for gas production and chemical processing. The process has been refined and adapted to reflect modern-day needs, and today looks like large interconnected reactors cycling metal oxides.
It’s successful in pilot-scale power plants and industrial applications, and can also generate clean hydrogen as a byproduct, used commonly for fuel cells, ammonia production, and industrial heating.
9. Cryogenic Carbon Capture (CCC)
Cryogenic carbon capture produces pure solid CO₂ in the form of dry ice. It gets flue gas from power plants, industrial facilities, or manufacturing plants, places it through a cooling system in very low temperatures, and freezes out the CO₂ as a solid.
The cubes are then either stored in underground geological formations or repurposed for carbonated beverages, dry ice blasting, synthetic fuels, or concrete curing.
10. Carbon Capture Using Nanotechnology
Carbon capture with nanotechnology uses nano-sized—meaning billionths of a metre in scale—materials such as metal-organic frameworks (MOFs), carbon nanotubes, and nanosponges to capture CO₂. This can involve powders, membranes, or coated surfaces, and results in clean, high-purity CO₂.
This method is highly efficient, cost-effective, and boasts faster reaction times. Still in its research stages, as the tech develops, the method should be a key tool for combatting global warming.
11. Carbon Sinks
Natural carbon sinks can include woodlands, wetlands, peatlands, forests, and even seagrass meadows. By absorbing more CO₂ than they emit, they naturally regulate the climate and reduce levels of carbon in the atmosphere.
Artificial carbon sinks could be carbon-storing concrete, mineralised CO₂, biochar fields, or a range of other innovative methods. These work by capturing CO₂, usually to be bound chemically, and stored long-term.
12. Saline Aquifers
Deep saline aquifers are underground formations of rock, i.e. porous rock layers 1-3 km underground, that are naturally filled with brine (saltwater).
This stores captured CO₂ from industrial emissions and coal-fired power plants long-term, as it is compressed by high pressure into a supercritical state and then injected into the aquifer. It dissolves and mineralises over time, leaving it permanently trapped.
13. Giant Air Filters
Similarly to DAC, giant air filter filtration systems remove CO₂ from the atmosphere. These are large box-like structures or metal towers that are placed in smog-heavy cities, or near emission-intensive industrial zones.
Giant air filters can turn smog into products, with some organisations even turning it into jewellery.
14. Ionic Liquids (A Capturing Carbon Technology of the Future)
Currently in the early stages, ionic liquids are being tested in lab research and pilot projects. It’s applied at industrial sites and power plants, whereby ionic liquid binds with CO₂ molecules, capturing them for storage or reuse.
If successful, ionic liquids could work well in DAC systems.
15. Post-Combustion Capture
Post-combustion carbon capture technologies include large capture units separating CO₂ from exhaust or flue gases, which could be used in coal-fired power plants and industrial processes.
It’s sold by companies like Shell, who have developed an ADIP-ULTRA solvent technology and applied this in projects like Canada’s Quest project which is successfully capturing CO₂.
16. Pre-Combustion Capture
Pre-combustion carbon capture differs from post-combustion as it is less developed, requiring new infrastructure.
Instead, it involves a gasification plant (i.e. coal or natural gas) transforming fuel into synthetic gas (syngas), then processing to separate hydrogen and CO₂. Hydrogen can then be used for energy, and the carbon is stored.
17. Oxy-Fuel Combustion Capture
Oxy-fuel carbon capture involves combustion chambers with oxygen instead of air. In these, fossil fuels are burned to produce concentrated streams of CO₂ emissions ready for capture.
This technique is still in its experimental phase and should offer a low-cost alternative for decarbonising industries.
While requiring new oxygen-built infrastructure, it can be considered more efficient than other energy-intensive methods.
18. Ocean Fertilisation
Ocean fertilisation is a geoengineering method where nutrients are fed into the ocean to encourage the growth of carbon-absorbing organisms such as phytoplankton.
Nutrients like iron make the phytoplankton grow, which can cause rapid growth. This is used primarily in nutrient-poor regions, in the early stages of development with pilots operating in the Southern Ocean and the Pacific.
19. Mineral Carbonation
In mineral carbonation, stable carbonate materials are formed when CO₂ reacts with minerals such as calcium or magnesium silicates that naturally occur. This chemically binds CO₂ into stable carbonate minerals, offering a permanent form of carbon sequestration and a durable, long-term solution.
CO₂ can be captured from industrial emissions or directly from the air, then reacted with crushed minerals either underground or in controlled facilities. Each ton of CO₂ mineralized can be measured in a straightforward way, leading to reliable and verifiable carbon credits.
The mineral carbonation can then be utilised for concrete or construction materials, where the carbon is locked in as part of the concrete’s structure.
20. Soil Carbon Sequestration
Soil carbon sequestration is the process of capturing and storing CO₂ in the form of SOC (soil organic carbon) or soil inorganic carbon (SIC).
For instance, polycultures involve growing multiple varieties of crops together, mimicking a natural environment and creating biodiverse ecosystems with complex structures and services, resilient to external challenges.
Polycultures are much more attractive to pollinators, leading to increased crop yield, reduced pest populations, and enhanced soil health able to support healthier, stronger wildlife. More dense wildlife equates to more carbon stored.
More Information
https://www.nationalgrid.com/stories/energy-explained/carbon-capture-technology-and-how-it-works
https://angeassociation.com/wp-content/uploads/2024/08/ANGEA-CCS-Whitepaper.pdf
https://www.globalccsinstitute.com/wp-content/uploads/2024/01/Global-Status-of-CCS-Report-1.pdf