Carbon capture technology explained: can it actually save us?

01How direct air capture works

Direct air capture (DAC) extracts CO2 directly from atmospheric air. The concentration of CO2 in ambient air is roughly 420 parts per million — about 0.04% — which means capturing a tonne of CO2 requires processing roughly 1,800 tonnes of air. This dilution is the fundamental engineering challenge.

Two dominant approaches exist. Liquid solvent systems pass air through a chemical solution (typically potassium hydroxide) that absorbs CO2, then heat the solution to release concentrated CO2 for storage or use. Solid sorbent systems use filter-like materials that bind CO2 at ambient temperature and release it when heated. Each has different energy profiles and costs.

The captured CO2 must then go somewhere. Options include underground geological storage (sequestration), use in synthetic fuels or building materials, or enhanced oil recovery. The storage pathway is the one most relevant to climate goals, but it requires suitable geology and infrastructure that does not yet exist at scale.

02The energy cost of removing CO2

Thermodynamics is unforgiving. CO2 is the end product of combustion — the most stable, low-energy form of carbon. Reversing that process requires energy input equal to or greater than what was released when the CO2 was produced. This is why carbon capture is inherently energy-intensive.

A DAC plant requires heat (to release CO2 from the sorbent or solvent) and electricity (to power fans, compressors, and pumps). The energy demand is estimated at 1,500 to 2,500 kWh per tonne of CO2 captured. If that energy comes from fossil fuels, the net removal is reduced or eliminated. If it comes from renewables, it competes with other uses of clean energy.

The implication is that DAC cannot be a standalone climate solution — it must be paired with abundant clean energy. In practice, this means siting DAC plants where renewable electricity is cheap and plentiful, such as geothermal-rich Iceland or solar-rich regions. The economics improve with cheap energy but the thermodynamic floor remains.

03Current carbon capture facilities worldwide

Global operational carbon capture capacity is approximately 15 million tonnes of CO2 per year — less than 0.04% of the 40 billion tonnes emitted annually. The largest facilities are not DAC plants but point-source capture attached to industrial processes: natural gas processing, ethanol production, and hydrogen plants.

The Climeworks Orca plant in Iceland, the largest operational DAC facility, captures roughly 4,000 tonnes per year. The Mammoth facility, also by Climeworks, is under construction with a target of 36,000 tonnes annually. Carbon Engineering's partner plant in Texas aims for 500,000 tonnes per year when fully operational. These are meaningful steps but remain orders of magnitude below the gigatonne scale needed.

The gap between current capacity and climate-relevant deployment is enormous. The IEA estimates that carbon removal needs to reach roughly 1 billion tonnes per year by 2030 to align with a 1.5°C pathway. Achieving that would require building roughly 67,000 Orca-sized plants in the next five years — an implausible deployment rate.

04The economics cost per ton of CO2

Cost is the decisive variable. Current DAC costs range from $100 to over $600 per tonne of CO2, depending on technology and energy source. Point-source capture is cheaper — $40 to $120 per tonne — because the CO2 concentration is higher. But point-source capture only addresses emissions from specific facilities, not the atmosphere at large.

The target cost for climate-relevant DAC is widely cited as $100 per tonne, the level at which carbon removal becomes economically competitive with other climate interventions. No current technology reliably achieves this at scale. The cost trajectory is downward — driven by learning curves, economies of scale, and technology improvements — but the timeline to $100 is uncertain.

Government subsidies are bridging the gap. The US Inflation Reduction Act's 45Q tax credit pays up to $180 per tonne for DAC with geological storage, making some projects economically viable. The EU and UK are developing similar incentive frameworks. These subsidies are essential for early deployment but are not a long-term substitute for cost reduction.

05Storage and utilization options

Once captured, CO2 must be permanently stored or productively used. Geological sequestration — injecting CO2 into deep saline aquifers or depleted oil and gas fields — is the primary storage pathway. The IPCC estimates global geological storage capacity at 1,000 to 10,000 gigatonnes of CO2, far exceeding what is needed, but suitable sites must be individually characterised and permitted.

Utilisation pathways include converting CO2 into synthetic aviation fuel, concrete aggregate, or chemical feedstocks. These approaches have the advantage of generating revenue, partially offsetting capture costs. However, most utilisation pathways either re-release CO2 (synthetic fuels are burned) or have limited market scale (concrete can only absorb so much CO2).

The distinction matters for climate accounting. Only permanent storage — meaning millennia-scale retention — qualifies as genuine carbon removal. Utilisation that re-emits CO2 is carbon cycling, not carbon removal. This distinction is often blurred in corporate marketing, where captured CO2 used for enhanced oil recovery is presented as climate action.

06Carbon credits and market incentives

The voluntary carbon market has embraced carbon removal credits, and DAC credits command premium prices — $500 to $1,000 per tonne — because they represent genuine, permanent removal rather than avoided emissions. Microsoft, Stripe, and Frontier (a buyer consortium) have committed hundreds of millions to DAC credit purchases, effectively subsidising early-stage deployment.

The concern is integrity. The carbon credit market has a documented history of over-crediting — projects that claim more removal than they deliver. DAC credits are more verifiable than nature-based credits (trees can burn, soils can release carbon), but the market is small enough that verification standards are still maturing. The risk is that corporate demand for removal credits outpaces the supply of genuine removal, creating pressure to dilute standards.

Compliance markets — where governments mandate carbon removal — are emerging. The EU's Carbon Removal Certification Framework, proposed in 2022, aims to establish standards for carbon removal credits. If these standards are robust, they could channel significant capital toward DAC and other removal technologies. If they are weak, they could replicate the integrity problems of the voluntary market.

07Is carbon capture a distraction from emissions cuts

The most serious criticism of carbon capture is that it creates a moral hazard. If policymakers and industry believe that future carbon removal will offset continued emissions, they may underinvest in emissions reductions — the cheaper and more reliable climate strategy. The concern is not hypothetical: oil and gas companies prominently feature carbon capture in their net-zero plans while continuing to expand production.

The IPCC is explicit on this point. Carbon removal is necessary to achieve net zero — there are residual emissions from agriculture, aviation, and cement that cannot be eliminated with current technology — but it is not a substitute for rapid, deep emissions cuts. The agency's scenarios show that limiting warming to 1.5°C requires both aggressive decarbonisation and carbon removal, with removal playing a supporting rather than leading role.

The honest framing is that carbon capture is a complement to emissions cuts, not a replacement. It addresses the hard-to-decarbonise fraction of emissions and potentially reverses historical emissions later in the century. But if it is used to justify continued fossil fuel use, it becomes part of the problem rather than the solution. The technology is neutral; the policy framework that deploys it is not.