TechFEATURE

CCUS and CCS Explained: How Captured CO2 Gets Stored Underground

林紀旭 James LinEditor-in-Chief
Published · Updated
Carbon capture and storage (CCS) removes CO2 from industrial sources and stores it underground instead of releasing it to the atmosphere, per the Global CCS Institute. The U.S. Department of Energy (DOE) says the broader CCUS process — decades old and already used across cement, steel, hydrogen, and fertilizer production — either reuses or stores captured CO2 via EPA-regulated Class VI wells. The Congressional Research Service (CRS) identifies cost as the primary barrier to scaling the technology further.

What Are CCUS and CCS, and How Do They Work?

Carbon capture and storage (CCS) captures carbon dioxide from industry and stores it safely underground rather than releasing it into the atmosphereCITE:E1. The Global CCS Institute defines the process specifically around industrial capture followed by secure underground storageCITE:E1. The U.S. Department of Energy (DOE) describes a related, broader process — carbon capture, utilization and storage (CCUS), also called carbon capture, utilization and sequestration — which captures CO2 emissions from sources such as coal-fired power plants and either reuses or stores the captured gas so it does not enter the atmosphereCITE:E2. The distinction between the two terms is whether the captured CO2 is only stored (CCS) or also given a second use (CCUS)CITE:E1CITE:E2.

How Long Has Carbon Capture Technology Been in Use?

Carbon capture is a decades-old process, according to the DOECITE:E3. The DOE states that this established process captures CO2 emissions from industrial facilities and power plantsCITE:E3, indicating the underlying capture technology is not new even as deployment scale remains a live policy question.

Which Industries Use Carbon Capture Technology?

The DOE identifies eight application areas for carbon capture technology: ethanol, natural gas processing, gasification, fertilizer, hydrogen, cement, steel, and pulp and paper productionCITE:E4. This range spans both energy-sector processes, such as natural gas processing and gasification, and heavy industrial manufacturing, such as cement and steel — sectors frequently described as hard to decarbonize by other meansCITE:E4.

How Is CO2 Stored Underground for the Long Term?

The U.S. Environmental Protection Agency (EPA) regulates Class VI wells, which are used to inject carbon dioxide into deep rock formationsCITE:E5. The EPA calls this long-term underground storage method geologic sequestration (GS)CITE:E5. This is the storage step that both the CCS process described by the Global CCS InstituteCITE:E1 and the CCUS process described by the DOECITE:E2 rely on when captured CO2 is stored rather than reused.

What Is the Main Barrier to Wider Deployment?

The U.S. Congressional Research Service (CRS) reports broad agreement that CCS construction and operating costs would need to decrease before the technologies could be widely deployedCITE:E6. The CRS frames cost reduction as a precondition for scaling, rather than a technical capability gapCITE:E6.

What This Means

The evidence points to a gap between technical maturity and deployment scale. The capture process itself is decades oldCITE:E3 and already applied across eight distinct industrial categories, including cement and steelCITE:E4, while the storage step — geologic sequestration via EPA-regulated Class VI wellsCITE:E5 — is a defined, regulated pathway. Yet the CRS points specifically to cost, not technology readiness, as the condition that must change before broader deployment can occurCITE:E6. Read together, the DOE and Global CCS Institute descriptions of an established, multi-industry processCITE:E1CITE:E2CITE:E3CITE:E4 sit alongside a CRS assessment that scaling is currently constrained by economics rather than engineeringCITE:E6.

📊 Evidence

FAQ

What Are CCUS and CCS, and How Do They Work?

Carbon capture and storage (CCS) captures carbon dioxide from industry and stores it safely underground rather than releasing it into the atmosphereCITE:E1.

How Long Has Carbon Capture Technology Been in Use?

Carbon capture is a decades-old process, according to the DOECITE:E3.

Which Industries Use Carbon Capture Technology?

The DOE identifies eight application areas for carbon capture technology: ethanol, natural gas processing, gasification, fertilizer, hydrogen, cement, steel, an…

How Is CO2 Stored Underground for the Long Term?

The U.S. Environmental Protection Agency (EPA) regulates Class VI wells, which are used to inject carbon dioxide into deep rock formationsCITE:E5.

📎 Sources

  1. globalccsinstitute.com
  2. energy.gov
  3. energy.gov
  4. epa.gov
  5. everycrsreport.com

Related data

Author's Take林紀旭 James Lin

The notable gap here isn't technical: a decades-old capture process already serves eight industrial categories from cement to hydrogen, and the storage pathway — Class VI wells performing geologic sequestration — is a defined, regulated mechanism. What CRS flags instead is cost: construction and operating expenses need to fall before wider deployment is feasible. That reframes the deployment question as an economics problem layered on top of working engineering, not an unsolved capture or storage challenge. The metric worth watching going forward is whether CCS construction and operating cost trends move in the direction CRS says is required — since that is the specific precondition CRS names, rather than any further capture-rate or storage-capacity breakthrough.

林紀旭 James LinEditor-in-Chief

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