Carbon capture and storage (CCS)
Technologies that separate CO2 from flue gas or process streams, compress it, and inject it into deep geological formations for permanent storage.
CCS has three stages: capture, transport (pipeline or ship) and storage in saline aquifers or depleted oil and gas fields, typically at depths below 800 m where CO2 is supercritical. Capture routes:
- Post-combustion: amine solvents (e.g. MEA) scrub flue gas with 4–15% CO2; regeneration needs about 2.5–3.5 GJ of heat per tonne CO2.
- Pre-combustion: fuel is reformed to syngas and CO2 removed before combustion, as in blue hydrogen.
- Oxy-fuel: combustion in pure oxygen gives a nearly pure CO2 stream.
Capture costs are lowest for concentrated streams: gas processing and ethanol fermentation USD 15–35/t CO2, versus USD 50–120/t for power and cement (IEA). Global operational capture capacity was about 50 Mt CO2 per year in 2024–2025 (Global CCS Institute), well under 0.2% of emissions, with much of it used for enhanced oil recovery. Norway's Sleipner project has stored about 1 Mt per year since 1996. Real-world capture rates have often fallen short of 90%, and lifecycle studies must account for upstream methane leakage.
Related terms
All terms →- Direct air capture (DAC)
Engineered systems that extract CO2 directly from ambient air using chemical sorbents or solvents, producing a concentrated stream for storage or use.
- Blue hydrogen
Hydrogen produced from natural gas by reforming, with most of the resulting CO2 captured and permanently stored.
- Net zero
A state in which anthropogenic greenhouse gas emissions are balanced by anthropogenic removals over a specified period, so net additions to the atmosphere are zero.
- Combined-cycle gas turbine (CCGT)
A power plant that runs a gas turbine and uses its hot exhaust to raise steam for a second, steam turbine, reaching electrical efficiencies of 55–64%.
- Methane leakage
Unintended release of methane from oil, gas and coal supply chains through leaks, venting and incomplete flaring, often expressed as a percentage of gas produced.