Carbon Capture, Utilisation and Storage

Carbon Capture, Utilisation and Storage (CCUS) refers to a suite of technologies that capture carbon dioxide (CO₂) emissions from large point sources—such as fossil fuel-based power plants, steel mills, and cement factories—or directly from the ambient air. Once captured, the CO₂ is either repurposed for industrial use or compressed and transported for permanent sequestration in deep geological formations. CCUS is recognized globally as a critical pathway for decarbonizing “hard-to-abate” industrial sectors where electrification is not currently technically or economically feasible.

The CCUS Value Chain

The CCUS process involves four distinct stages that must be integrated to achieve effective emissions reduction:

• • Capture: The separation of CO₂ from other gases. Common methods include:
    • Post-combustion: Capturing CO₂ from flue gas after fuel combustion using chemical solvents (e.g., amines).
    • Pre-combustion: Gasifying fuel (like coal) to produce a mixture of H₂ and CO₂, then separating CO₂ before combustion.
    • Oxy-fuel combustion: Burning fuel in pure oxygen instead of air, resulting in a flue gas composed primarily of CO₂ and water vapor, which is easily separated.
    • Direct Air Capture (DAC): Using advanced sorbents or solvents to extract CO₂ directly from the atmosphere.
  • Transport: Captured CO₂ is compressed (often to a supercritical state) and transported via high-pressure pipelines, ships, or trucks to storage or utilization sites.
  • Utilisation: Transforming captured CO₂ into commercial products or services. This includes manufacturing concrete, synthetic fuels, plastics, and chemicals, or using it for Enhanced Oil Recovery (EOR).
  • Storage (Sequestration): Injecting CO₂ into stable geological formations, such as depleted oil and gas fields, deep saline aquifers, or unmineable coal seams, where it is trapped under impermeable rock layers for centuries.

Role in Governance and Economy

CCUS serves several strategic functions in a modern energy economy:

• Decarbonizing Heavy Industry: Industries like cement, iron, and steel release CO₂ as a chemical by-product of manufacturing, not just from fuel combustion. CCUS is often the only available technology to mitigate these process emissions.
• Enabling Low-Carbon Hydrogen: “Blue hydrogen” is produced from natural gas using CCUS to capture the resulting emissions, providing a scalable, low-carbon alternative until green hydrogen (electrolysis) becomes fully competitive.
• Ensuring Grid Reliability: As power grids shift toward intermittent renewable sources (solar/wind), natural gas plants equipped with CCUS can provide reliable, low-carbon baseload power when renewable output is low.
• Circular Economy: Utilizing CO₂ as a feedstock for products creates economic value from waste, potentially offsetting the high capital costs associated with capture infrastructure.

Challenges to Large-Scale Implementation

• High Capital Expenditure (CAPEX): Building capture plants and transportation infrastructure requires massive upfront investment, which is often commercially risky without policy support.
• Energy Penalty: The capture process itself is energy-intensive, reducing the net efficiency of the industrial facility or power plant.
• Regulatory Gaps: There is a need for clear legal frameworks regarding long-term liability for stored CO₂ and international standards for transboundary transport.
• Public Perception: Concerns regarding the safety of underground CO₂ storage, such as the potential for leakage or induced seismicity, require transparent public engagement.

India’s Strategic Roadmap

Recognizing the necessity of CCUS for achieving Net-Zero by 2070, the Government of India, through NITI Aayog, has initiated steps to build a domestic CCUS ecosystem:

• Policy Framework: NITI Aayog has released frameworks aimed at outlining deployment mechanisms, safety standards, and incentives for private sector participation.
• Industrial Clusters: The focus is on establishing CCUS hubs near industrial clusters to share infrastructure (like transport pipelines), thereby reducing individual project costs.
• R&D and Capacity Building: Support for indigenous technology development to lower the cost of capture, which is currently a major barrier for Indian manufacturers.

Comparative Overview of Carbon Capture Methods