Carbon Capture, Utilisation and Storage (CCUS): Technologies and Industrial Applications

 Carbon dioxide (CO2) emissions from industrial processes remain a critical challenge in achieving net-zero targets. Carbon Capture, Utilisation and Storage (CCUS) technology offers a pathway to reduce, capture, and either utilise or permanently sequester CO2 from point sources such as refineries, ammonia plants, cement facilities, and power generation units.

Fundamentals of CCUS

CCUS comprises three integrated stages: capture, utilisation or storage. Capture technologies include post-combustion capture (removing CO2 from flue gases), pre-combustion capture (converting fuel before combustion), and oxy-fuel combustion (burning fuel in pure oxygen). Maturity levels vary, with post-combustion capture being commercially established while emerging technologies like direct air capture (DAC) remain in pilot phases.

Capture Cost and Energy Requirements

Post-combustion capture typically costs $40-60 per tonne of CO2 for industrial sources. Energy requirements range from 3-4 GJ per tonne for solid sorbent systems to 2-3 GJ for solvent-based approaches. This energy intensity necessitates coupling with low-carbon electricity or renewable sources for net-zero alignment.

Industrial Applications

Refineries and Ammonia: Hydrogen production in ammonia synthesis generates CO2-rich shift gas; capturing 90%+ of CO2 is technically feasible. Global ammonia production (170+ million tonnes annually) represents a significant decarbonisation opportunity where CCUS could reduce emissions by 200+ million tonnes CO2 annually.

Cement and Steel: These heavy industries produce process-related CO2 from calcium carbonate decomposition, unrelated to fuel combustion. CCUS is among few mitigation pathways; emerging oxyfuel calcination and low-calcium clinker formulations show promise.

CO2 Utilisation Routes

Underground Utilisation: Enhanced Oil Recovery (EOR) remains the largest CO2 utilisation outlet globally (~150 million tonnes/year), though raising sustainability questions due to continued fossil fuel extraction.

Chemical Utilisation: CO2 as feedstock for methanol synthesis, urea production, and polycarbonate manufacturing is gaining traction. Methanol-from-CO2 offers circular benefits if coupled with green hydrogen. Current volumes remain modest (< 5 million tonnes/year) but show 15-20% annual growth.

Mineralisation: Permanent sequestration through CO2 mineralisation (converting to carbonates) offers non-reversible storage but faces scaling and cost challenges ($100-200/tonne).

Geological Storage

Permanent CO2 sequestration in depleted oil/gas fields, saline aquifers, and unmineable coal seams offers long-term storage stability. The Sleipner field (Norway) and Gorgon project (Australia) demonstrate multi-decade operational readiness. Storage capacity is estimated at 1,000+ gigatonnes globally, far exceeding near-term capture volumes.

Policy and Economics

CCUS projects require supportive policy: carbon pricing (making abatement economically attractive), tax credits, and government-backed storage liability frameworks. India's CO2 utilisation policy (2022) and similar frameworks globally are beginning to enable CCUS deployment.

Future Research Directions

Advanced sorbent and membrane materials targeting <$30/tonne capture costs; modular, digitally-enabled CCUS units for distributed deployment; and integration of CCUS with renewable energy systems for zero-carbon chemical production.

Keywords: CCUS, carbon capture, CO2 utilisation, geological storage, net-zero, decarbonisation, ammonia, refinery emissions, mineralisation, enhanced oil recovery