As the urgency of combating climate change intensifies, carbon capture technology has emerged as one of the most debated tools in the climate mitigation arsenal. The concept is straightforward: capture carbon dioxide before it enters the atmosphere, or remove it after it has accumulated, and store it permanently underground or convert it into useful products. Proponents argue that carbon capture is essential for reaching net-zero emissions, particularly in hard-to-decarbonize industries. Critics worry that it offers fossil fuel companies a lifeline while diverting investment from renewable energy. Understanding the science, economics, and real-world performance of carbon capture is key for evaluating its role in our climate future.
How Carbon Capture Works
Carbon capture technology encompasses three main approaches, each targeting CO2 at different stages. Point-source capture removes CO2 from large emission sources like power plants, cement factories, and steel mills before it reaches the atmosphere. Direct air capture (DAC) extracts CO2 directly from ambient air, regardless of where it was emitted. Finally, carbon dioxide removal through natural processes, enhanced weathering, ocean alkalinity enhancement, and biomass carbon removal, supplements technological approaches.
The most mature technology is post-combustion capture using chemical solvents. Flue gas from industrial processes is passed through a solution, typically amine-based, that selectively binds with CO2. The CO2-rich solvent is then heated to release concentrated CO2 for compression and storage, while the regenerated solvent is recycled. The underlying chemistry of these reactions has been well understood for decades, but optimizing the process for efficiency and cost remains an active area of research.
Pre-combustion capture converts fossil fuels into hydrogen and CO2 before burning. The fuel is first converted to a synthesis gas (syngas) through steam reforming or partial oxidation, then a water-gas shift reaction converts carbon monoxide to CO2, which is separated. The resulting hydrogen can be burned cleanly or used in fuel cells. Oxy-fuel combustion, a third approach, burns fuel in pure oxygen rather than air, producing a concentrated CO2 stream that is easier to capture.
Direct Air Capture: Pulling CO2 from Thin Air
Direct air capture represents a fundamentally different approach, extracting CO2 from the atmosphere at its current concentration of approximately 425 parts per million. This is thermodynamically challenging because atmospheric CO2 is roughly 300 times more dilute than in power plant flue gas, requiring proportionally more energy to concentrate.
Two main DAC technologies have reached commercial demonstration. Climeworks, based in Switzerland, uses solid sorbent filters that bind CO2 at ambient temperatures and release it when heated to 80-100°C. Carbon Engineering (now part of Occidental Petroleum), founded in Calgary, Alberta, uses a liquid potassium hydroxide solution to capture CO2, which is then processed through a series of chemical reactions to produce concentrated CO2 and regenerate the capture solution.
The world’s largest DAC facility, Mammoth, opened in Iceland in 2024 with capacity to capture 36,000 tonnes of CO2 per year. While impressive as a demonstration, this represents a tiny fraction of global emissions exceeding 37 billion tonnes annually. Scaling DAC to climate-relevant levels will require enormous expansion, though nanomaterial innovations in sorbent design are improving capture efficiency and reducing energy requirements.
Carbon Storage: Keeping CO2 Underground
Once captured, CO2 must be permanently stored to achieve climate benefits. Geological sequestration injects compressed CO2 into deep underground rock formations, typically depleted oil and gas reservoirs, deep saline aquifers, or unmineable coal seams. At depths exceeding 800 meters, CO2 reaches a supercritical state where it is dense like a liquid but flows like a gas, enabling efficient storage.
Multiple trapping mechanisms ensure permanence. Physical trapping below impermeable caprock prevents upward migration. Residual trapping locks CO2 in pore spaces through capillary forces. Solubility trapping dissolves CO2 in formation water over centuries. Mineral trapping, the most permanent mechanism, converts CO2 into stable carbonate minerals through reaction with calcium and magnesium silicates, essentially turning CO2 to stone over thousands of years.
The Sleipner project in Norway has safely stored over 20 million tonnes of CO2 in a saline aquifer beneath the North Sea since 1996, demonstrating that geological storage can be secure and long-lasting. Canada’s Quest project in Alberta and the Weyburn-Midale project in Saskatchewan are among the world’s largest onshore CO2 storage operations, providing decades of monitoring data confirming storage integrity.
Carbon Utilization: Turning CO2 into Products
Rather than simply storing captured CO2, carbon utilization (or CCU) converts it into valuable products. Current commercial applications include enhanced oil recovery (EOR), where injected CO2 increases petroleum extraction from aging wells, a practice critics note is counterproductive from a climate perspective, as it enables more fossil fuel production.
More promising applications include synthesizing carbon-neutral fuels by combining captured CO2 with green hydrogen produced from renewable electricity. These synthetic fuels could decarbonize aviation, shipping, and other transportation modes that are difficult to electrify. CO2 can also be mineralized into construction materials, concrete, aggregite, and building blocks, permanently locking carbon into the built environment.
Canadian company CarbonCure Technologies injects captured CO2 into fresh concrete during mixing. The CO2 reacts with calcium ions to form calcium carbonate nanoparticles that actually strengthen the concrete while permanently mineralizing the carbon. This process has been adopted by hundreds of concrete producers across North America, demonstrating that carbon utilization can be commercially viable today.
Economics and Energy Costs
Cost remains carbon capture’s greatest challenge. Point-source capture from concentrated industrial streams costs $50-120 per tonne of CO2, competitive with carbon prices in some jurisdictions but above many current carbon tax levels. Direct air capture is significantly more expensive at $250-600 per tonne, though costs are falling rapidly with technological improvements and manufacturing scale.
The energy penalty is substantial. Current post-combustion capture systems consume 25-40% of a power plant’s output to run the capture process, significantly reducing net electricity generation. This parasitic energy load is a key reason why building new renewable energy capacity is generally more cost-effective for power generation than retrofitting fossil fuel plants with carbon capture.
Government policy is driving investment. The US Inflation Reduction Act’s 45Q tax credit offers $85 per tonne for permanent geological storage and $180 per tonne for direct air capture, levels that make many projects economically viable. Canada’s federal carbon price, rising to $170 per tonne by 2030, creates a strong financial incentive for industrial carbon capture. Alberta’s Carbon Trunk Line, one of the world’s largest CO2 pipelines, connects industrial emitters to storage sites, creating shared infrastructure that reduces costs for individual facilities.
Where Carbon Capture Makes Sense
The strongest case for carbon capture exists in industries where CO2 emissions are inherent to the chemical process, not just the energy source. Cement manufacturing, for example, produces roughly 60% of its CO2 from the calcination of limestone, a chemical reaction that occurs regardless of the heat source. Steel production using blast furnaces, chemical manufacturing, and certain industrial processes face similar fundamental challenges. These sectors account for approximately 25% of global CO2 emissions and have few alternatives to carbon capture for deep decarbonization.
Carbon capture also makes sense for producing blue hydrogen from natural gas, provided capture rates exceed 90% and methane leakage throughout the supply chain is minimized. However, as clean energy technologies like electrolysis powered by renewables or fusion become cheaper, green hydrogen may ultimately prove more economical.
DAC serves a unique role by addressing legacy emissions, CO2 already in the atmosphere. Since the atmosphere is well-mixed, DAC facilities can be located anywhere with access to clean energy and geological storage, rather than being tied to emission sources. This flexibility enables optimal siting where renewable energy is abundant and storage geology is favorable.
Canada’s Role in Carbon Capture
Canada has emerged as a global leader in carbon capture, driven by its oil and gas industry expertise, favorable geology, strong policy support, and growing cleantech sector. The Alberta Carbon Trunk Line, Boundary Dam project in Saskatchewan (the world’s first coal plant with carbon capture), and the Quest project at the Scotford Upgrader represent pioneering Canadian contributions to the field.
The federal government’s $15 billion investment tax credit for CCUS, combined with provincial incentives and carbon pricing, has catalyzed a wave of new project announcements. The proposed Pathways Alliance, a consortium of Canada’s six largest oil sands companies, plans one of the world’s largest CCS networks in northern Alberta. Indigenous communities are increasingly engaged as partners and stakeholders in these developments, recognizing both economic opportunities and environmental responsibilities.
A Realistic Assessment
Carbon capture technology is neither a silver bullet nor a distraction, it is a necessary component of a comprehensive climate strategy. The Intergovernmental Panel on Climate Change includes carbon capture in virtually all scenarios that limit warming to 1.5°C or 2°C. AI-driven optimization of capture processes, new sorbent materials, and modular plant designs are driving costs down on a trajectory similar to the early years of solar energy.
The most important insight may be that different climate solutions serve different purposes. Renewables and electric vehicles can decarbonize electricity and light transportation. Carbon capture is essential for heavy industry and legacy emissions. Neither alone is sufficient; both are necessary. The scale of the climate challenge demands deploying every effective tool available, and carbon capture, despite its limitations, has earned its place in that toolkit.
