What Is Carbon Capture and Storage?

Carbon capture and storage (CCS) is a suite of technologies designed to capture carbon dioxide (CO₂) emissions at their source — typically a power plant, steel mill, or cement factory — before they reach the atmosphere, and then transport and permanently store that CO₂ underground. It is one of the more technically complex and debated tools in the climate mitigation toolkit.

CCS is often distinguished from carbon removal or direct air capture (DAC), which pull CO₂ out of the ambient atmosphere rather than from a concentrated emission point source. Both approaches have a role in most comprehensive climate scenarios, but they operate on different scales and economics.

The Three Stages of CCS

Stage 1: Capture

CO₂ is separated from other gases at the point of emission. There are three primary methods:

  • Post-combustion capture: CO₂ is removed from flue gases after fuel is burned. This is the most widely applicable method and can be retrofitted to existing plants.
  • Pre-combustion capture: Fuel is partially oxidized to produce a mixture of hydrogen and CO₂ before combustion; the CO₂ is separated and the hydrogen is burned cleanly.
  • Oxyfuel combustion: Fuel is burned in pure oxygen rather than air, producing a flue gas of almost pure CO₂ that is easier to capture.

Stage 2: Transport

Once captured, CO₂ is compressed into a dense fluid state and transported — typically via pipeline, though ship transport is also possible — to a storage site. Infrastructure for CO₂ transport is an emerging industry, and building out pipeline networks at scale represents a significant capital investment.

Stage 3: Storage

CO₂ is injected deep underground into geological formations — typically depleted oil and gas reservoirs or deep saline aquifers — where it is expected to remain permanently trapped. Extensive monitoring is required to detect any leakage and to verify long-term containment.

Where CCS Fits in Climate Strategy

Most credible climate scenarios developed by bodies like the Intergovernmental Panel on Climate Change (IPCC) include CCS as a component of deep decarbonization, particularly for hard-to-abate sectors — industries where direct electrification is technically difficult or uneconomic in the near term. These include:

  • Cement production (process emissions from calcination)
  • Steel production (particularly blast furnace-based routes)
  • Chemical and fertilizer manufacturing
  • Waste-to-energy and biomass combustion (BECCS)

In these sectors, CCS may be one of the few realistic pathways to deep emission reductions without entirely restructuring industrial processes — though alternative approaches, including green hydrogen and electrification, are also being developed.

Criticisms and Limitations

CCS is not without controversy. Key concerns include:

  • Cost: Capture, transport, and storage remain expensive, and cost reductions have been slower than in solar or wind energy.
  • Energy penalty: The capture process itself requires significant energy, reducing the net output of any facility that uses it.
  • Storage permanence: While geological storage is considered reliable, long-term monitoring and liability for stored CO₂ remain open questions.
  • Moral hazard: Critics argue that CCS can be used to justify continued fossil fuel use rather than accelerating the transition away from it.
  • Scale: Current global CCS capacity captures a small fraction of what would be needed to meet climate targets; massive scale-up is required.

Current State of the Technology

Several commercial CCS projects are operational globally, including facilities in Norway, the United States, Canada, and Australia. Bioenergy with carbon capture and storage (BECCS) — burning biomass and capturing the resulting CO₂ — is also in pilot phases and is considered a form of carbon dioxide removal.

Government support through tax credits and direct investment has accelerated project development in recent years, though deployment remains well below the levels that many climate modelers suggest are needed.

The Bottom Line

Carbon capture and storage is neither a silver bullet nor a distraction — it is one tool among many in a complex decarbonization challenge. Its role is most defensible in hard-to-abate industrial sectors where alternatives are limited. Understanding how it works, what it costs, and where it can realistically be deployed is essential for any serious engagement with climate policy.