Capturing carbon dioxide from industry, power plants, or air, then using it or storing it underground

Carbon Capture

Carbon capture refers to technologies that separate carbon dioxide from industrial exhaust, power generation, fuel production, or sometimes directly from the air. Captured CO2 can be compressed, transported, used in products, or stored deep underground. It can help cut some hard-to-abate emissions, but it also raises questions about cost, energy use, storage integrity, equity, and fossil fuel lock-in.

Main target

Carbon capture focuses on separating CO2 before it reaches the atmosphere or after it is already there

Storage option

Geologic storage injects compressed CO2 into deep rock formations for long-term isolation

Important limit

Carbon capture is not a substitute for reducing energy waste and replacing high-emission fuels

Industrial carbon capture equipment at the Heidelberg Materials Brevik cement plant in Norway. — Carbon capture projects separate CO2 from industrial gases before it is transported for use or storage.View image on original site

What it is

Carbon capture is a family of technologies for separating carbon dioxide from gas streams or air. The captured CO2 is then compressed and either used or stored. Most current projects focus on large industrial sources where CO2 is concentrated, such as cement, steel, chemicals, hydrogen, ammonia, natural gas processing, or power generation.

Capture methods

Capture can happen before combustion, after combustion, or through industrial process separation. Some systems use solvents, solid sorbents, membranes, mineral reactions, or cryogenic methods. Direct air capture removes CO2 from ambient air, where it is much more dilute, so it usually requires more energy per tonne captured.

Transport and compression

Captured CO2 is often dried, purified, and compressed into a dense fluid for transport. It can move by pipeline, ship, truck, or rail, depending on distance and scale. Transport systems require safety rules, monitoring, emergency planning, and public trust because concentrated CO2 can be hazardous if released in confined or low-lying areas.

Geologic storage

Carbon storage usually means injecting CO2 deep underground into suitable formations such as saline aquifers or depleted oil and gas reservoirs. Good storage sites need porous rock, a sealing layer above, monitoring, pressure management, and long-term stewardship. The goal is to keep CO2 isolated from the atmosphere for very long periods.

Utilization

Captured CO2 can be used in products or processes, including synthetic fuels, chemicals, concrete curing, mineralization, greenhouses, or enhanced oil recovery. Utilization is not automatically climate-positive. The benefit depends on energy sources, product lifetime, whether CO2 is re-released, and what activity is displaced.

Where it may help

Carbon capture may be most useful where emissions are difficult to avoid quickly, such as cement process emissions, some chemical production, waste-to-energy plants, and existing industrial clusters. It may also support carbon dioxide removal if paired with biomass or direct air capture and durable storage.

Risks and criticism

Critics warn that carbon capture can be expensive, energy-intensive, overpromised, or used to justify continued fossil fuel expansion. Projects can fail to capture expected amounts, and communities may face pipeline or storage risks. Strong policy needs transparent accounting, monitoring, liability, environmental justice, and comparison with cleaner alternatives.

Why it matters

Carbon capture matters because climate goals require rapid emissions cuts, and some emissions are harder to eliminate than others. It is a tool, not a cure-all. Understanding how capture, transport, use, and storage work helps people judge when carbon capture reduces real climate risk and when it distracts from deeper change.

Key concepts

CCS: carbon capture and storage, where captured CO2 is stored for long-term isolation.
CCUS: carbon capture, utilization, and storage, including uses of captured CO2.
Point-source capture: capturing CO2 from a concentrated source such as a plant or factory.
Direct air capture: removing CO2 from ambient air rather than an exhaust stream.
Monitoring, reporting, and verification: systems used to track captured, transported, and stored CO2.

Project chain

Capture separates CO2 from exhaust, process gas, or air.
Conditioning removes impurities and prepares CO2 for transport.
Compression turns CO2 into a dense fluid for efficient movement.
Transport moves CO2 to a use site or storage site.
Storage injects CO2 underground and monitors the site over time.

Common misconceptions

Carbon capture does not remove all pollution from a facility; it focuses mainly on CO2.
Captured CO2 is not automatically permanent unless it is stored durably or locked in long-lived products.
Direct air capture is different from capturing CO2 at a smokestack because air contains much less CO2.
Using CO2 for enhanced oil recovery can undermine climate benefits if it enables more fossil fuel use.
Carbon capture cannot replace efficiency, renewable energy, electrification, conservation, and lower material demand.

Open questions

Which sectors should get priority for limited carbon capture capacity?
How can policies prevent carbon capture from extending avoidable fossil fuel use?
Who is responsible for monitoring and liability after CO2 is stored underground?
How can communities influence pipeline routes, storage sites, and risk management?
How should climate accounting compare captured CO2, avoided emissions, and carbon dioxide removal?