Carbon Capture Technology: Removing CO₂ From the Atmosphere

Even with aggressive emissions reductions, the IPCC concludes that reaching net-zero by 2050 requires actively removing CO₂ already in the atmosphere. Carbon capture, utilisation, and storage (CCUS) encompasses a family of technologies designed to do exactly that — and it's rapidly moving from laboratory concept to industrial deployment as a criticalclimate solution.

Types of Carbon Capture

Carbon capture technologies fall into three broad categories:

• Point-source capture: Capturing CO₂ from large emitters (power plants, cement factories, steel mills) before it enters the atmosphere
• Direct air capture (DAC): Extracting CO₂ directly from ambient air, regardless of the original emission source
• Enhanced natural processes: Accelerating natural carbon removal through enhanced weathering, ocean alkalinity, and biochar

How Direct Air Capture Works

DAC facilities use chemical sorbents or solvents to selectively bind CO₂ from air (which contains only ~420 ppm CO₂ — making extraction energy-intensive). The captured CO₂ is then released through heating, compressed, and either stored underground permanently or used in products. Companies leading DAC include Climeworks (solid sorbent, Iceland), Carbon Engineering (liquid solvent, now part of Occidental Petroleum), and Global Thermostat. Climeworks' Mammoth plant, operational since 2024, captures 36,000 tonnes of CO₂ annually — significant, but still tiny compared to the 40 billion tonnes emitted globally each year.

Point-Source Capture

Capturing CO₂ from industrial flue gases is more energy-efficient than DAC because concentrations are much higher (10-30% vs. 0.04%). Post-combustion capture using amine solvents is the most mature technology, deployed at scale in facilities like Boundary Dam (Canada) and Petra Nova (US). Pre-combustion capture and oxy-fuel combustion offer higher capture rates but require new plant designs. Point-source capture is essential for hard-to-abate sectors where renewable energy alone can't eliminate emissions — cement, steel, and chemical production.

Carbon Storage

Captured CO₂ must be permanently stored. Geological storage injects compressed CO₂ into deep saline aquifers, depleted oil and gas reservoirs, or basalt formations. In Iceland, the CarbFix project dissolves CO₂ in water and injects it into basalt, where it mineralises into rock within two years — providing effectively permanent storage. The global geological storage capacity is estimated at over 10,000 gigatonnes — far exceeding likely need.

Carbon Utilisation

Rather than just storing captured CO₂, utilisation converts it into products: synthetic fuels (combined with green hydrogen), building materials (CO₂-cured concrete), chemicals (methanol, polymers), and carbonated beverages. While utilisation creates economic value, not all pathways provide permanent storage — synthetic fuels release their CO₂ when burned. Only mineralisation in building materials offers both utilisation and permanent sequestration.

Costs and Economics

Cost remains CCUS's biggest challenge. Point-source capture costs $40-120 per tonne of CO₂ depending on the source concentration. DAC costs $400-1,000 per tonne, though Climeworks targets $200-300 by 2030 and under $100 by 2040. For comparison, the EU carbon price is ~€80/tonne. As carbon prices rise and capture costs fall, CCUS becomes economically viable. Government incentives like the US 45Q tax credit ($180/tonne for DAC) are accelerating deployment — connecting tocarbon market mechanisms.

The Scale Challenge

Current global CCUS capacity is approximately 45 million tonnes of CO₂ per year. The IEA estimates that 6-10 billion tonnes of annual capture is needed by 2050 for net-zero scenarios — a 150-fold increase. Achieving this requires massive investment in capture facilities, CO₂ transport infrastructure (pipelines, ships), and storage site development. The energy required is also substantial — DAC at scale could consume 10% of global electricity production, underscoring the need for abundantrenewable energy.

Criticisms and Risks

Critics argue that CCUS provides a lifeline for fossil fuel industries, delaying the transition to renewables. "Moral hazard" — the idea that the promise of future carbon removal reduces urgency to cut emissions today — is a legitimate concern. Storage permanence, while geologically sound, requires long-term monitoring. And the energy penalty of capture (15-30% of a power plant's output) reduces overall system efficiency. The scientific consensus is clear: CCUS is a complement to, not a substitute for, rapid emissions reduction.

The Road Ahead

The CCUS pipeline is expanding rapidly. Over 200 new projects are in development globally, with expected investment exceeding $100 billion by 2030. Innovation in sorbent chemistry, modular capture units, and ocean-based approaches promises to reduce costs further. Whether CCUS fulfils its potential depends on sustained policy support, honest accounting of its limitations, and integration into a comprehensive climate strategy that prioritises emissions avoidance first, then removal of what remains.