Carbon capture, utilization, and storage (CCUS) is a set of technologies that pull carbon dioxide out of industrial exhaust or the open atmosphere, then either lock it away underground or convert it into useful products. The system has four linked stages: capturing CO2, transporting it, storing it deep underground, or utilizing it commercially. As of early 2025, facilities worldwide can capture just over 50 million metric tons of CO2 per year, a figure that would need to grow roughly 150-fold to reach the 7.6 billion metric tons the International Energy Agency says is needed by 2050 to hit net-zero emissions targets.
How CO2 Gets Captured
The capture stage separates carbon dioxide from other gases, most often at the smokestack of a power plant, cement factory, or steel mill. There are two broad strategies: absorption, where a liquid solvent dissolves the CO2, and adsorption, where a solid material grabs CO2 molecules onto its surface. In both cases, the mechanism can be physical (relying on weak molecular forces) or chemical (forming actual bonds with the CO2).
The most widely used chemical approach runs exhaust gas through a liquid amine solution. The amines react with CO2 to form stable compounds, effectively pulling it out of the gas stream. The solution is then heated to release a concentrated stream of CO2 and recycle the solvent. Physical absorption works differently: it relies on high pressure to dissolve CO2 into a solvent, following the principle that more gas dissolves as pressure increases. This approach works best when the exhaust stream already contains a high concentration of CO2.
A third, less mature option is direct air capture, which pulls CO2 straight from the atmosphere rather than from a smokestack. Because the atmosphere contains far less CO2 than industrial exhaust, direct air capture requires moving enormous volumes of air and is significantly more expensive.
Transporting Captured CO2
Once captured, the CO2 needs to travel from its source to a storage site or a facility that can use it. Pipelines are the workhorse for large volumes over short to medium distances. Inside a pipeline, CO2 is compressed into a supercritical state, a dense fluid that flows efficiently. For smaller volumes or longer distances, shipping becomes more cost-effective. CO2 transported by ship is chilled into a liquid, typically kept around negative 30°C at about 15 times atmospheric pressure, borrowing techniques from the food-grade CO2 industry. Trucks and rail cars can also move liquid CO2 in tanks, though these are practical only for modest quantities.
Where CO2 Gets Stored Underground
Geological storage means injecting CO2 deep underground into rock formations that can trap it permanently. The most common options are deep saline aquifers (porous rock saturated with saltwater), depleted oil and gas reservoirs, unminable coal seams, and basalt formations. A suitable site needs a thick, continuous cap rock with very low permeability sitting above the storage layer, acting like a seal that prevents CO2 from migrating upward. Engineers also look for formations free of active faults, fractures, or subsidence zones, since cracks in the rock are one of the main pathways for potential leakage.
Most storage targets sit at depths below 800 meters, where pressure keeps the CO2 in a dense, liquid-like state that takes up less space. Site selection involves evaluating storage capacity, sealing safety, economic feasibility, and environmental stability. Once injection begins, operators monitor the site using a combination of pressure sensors, surface deformation tracking, gas flux measurements, and sampling to detect any CO2 migration. Leakage through faults remains one of the most studied risks, and the permeability of those faults over time is a key factor in long-term safety assessments.
Utilization: Turning CO2 Into Products
Rather than burying all captured CO2, some of it can be put to commercial use. The largest application today is enhanced oil recovery, where CO2 is injected into aging oil fields to push out crude that conventional pumping can’t reach. The CO2 dissolves into the oil, making it less viscous and easier to extract. A portion of the injected CO2 stays trapped underground in the process, giving enhanced oil recovery a dual role as both utilization and partial storage.
Beyond oil fields, captured CO2 can be used as a raw material in building products like concrete, in chemical manufacturing, in carbonated beverages, and in producing synthetic fuels. These applications are growing but still account for a small fraction of total captured volumes. The climate benefit depends on how long the CO2 stays locked in the product. CO2 mineralized into concrete is essentially stored permanently, while CO2 used in a synthetic fuel gets released again when that fuel is burned.
What It Costs
Capture is by far the most expensive link in the chain, and costs vary dramatically by industry. In natural gas processing, ammonia production, and ethanol manufacturing, where the exhaust stream is already rich in CO2, capture runs roughly $15 to $35 per metric ton. For power plants, cement kilns, and steel mills, where CO2 is more diluted in the exhaust, costs jump to roughly $50 to $120 per metric ton. Economies of scale matter: larger plants with higher exhaust volumes tend to fall toward the lower end of their cost range.
These numbers explain why CCUS has been slow to scale. Without a carbon price, tax credit, or regulatory requirement that makes emitting CO2 more expensive than capturing it, most facilities have little financial incentive to install capture equipment. Policy tools like the 45Q tax credit in the United States, which pays operators per ton of CO2 stored or utilized, are designed to close that gap.
The Scale Challenge
Global capture capacity crossed 50 million metric tons in early 2025. That sounds substantial, but global energy-related CO2 emissions exceed 37 billion metric tons per year. The IEA’s net-zero pathway calls for 7.6 billion metric tons of capture capacity by 2050, split across fossil fuel and industrial processes (860 million tons), bioenergy paired with capture (570 million tons), direct air capture (630 million tons), and other sources making up the remainder.
Reaching those numbers requires not just more capture facilities but also a massive buildout of pipeline and shipping infrastructure to move CO2, along with thorough geological surveys to identify and certify enough storage sites. Each component depends on the others: a capture plant is useless without transport, and transport is useless without a verified storage site or a buyer for the CO2. This interdependence is one of the main reasons projects stall. Coordinating investment across the entire chain, often involving different companies and regulatory jurisdictions, remains one of the biggest practical hurdles.