Imagine a machine that inhales the sky and exhales cleaner air, pulling carbon dioxide back out of the atmosphere. That is the promise of carbon capture: technologies that trap CO2 from power plants, factories or even the open air, and then store it underground or turn it into products. Advocates call it an essential tool for net zero; critics call it an expensive distraction from cutting emissions. The truth is more nuanced. Carbon capture works, physically, but whether it can scale fast enough and cheaply enough to matter is one of the most contested questions in climate policy.

The three flavours of capture

Carbon capture comes in distinct varieties aimed at different problems. Post-combustion capture scrubs CO2 from the exhaust of power plants and factories, typically using chemical solvents that bind CO2 and release it when heated. Pre-combustion approaches gasify fuel first and strip out carbon before burning. Then there is direct air capture, or DAC, which pulls CO2 straight from ambient air using giant fans and chemical filters. DAC is the most dramatic and the most difficult: CO2 is only 0.04 percent of air, so filtering it is like finding a particular grain of sand on a beach, and it takes enormous energy.

What happens to the CO2 afterwards

Captured carbon has to go somewhere. The main option is geological storage: compressing CO2 and injecting it into deep rock formations, depleted oil fields or saline aquifers, where it mineralises over time. Norway’s Sleipner project has stored about a million tonnes a year under the North Sea since 1996 without incident. The alternative is utilisation, turning CO2 into fuels, building materials, chemicals or even fizzy drinks. Utilisation is appealing but limited: most products eventually release the CO2 again, and the scale of potential demand is dwarfed by the scale of emissions.

The energy and cost problem

Capture is thermodynamically expensive. Separating a dilute gas takes energy, and early projects consumed so much power that they significantly raised the cost of electricity. Costs have fallen with experience, but capturing a tonne of CO2 still costs on the order of tens to over a hundred dollars depending on the source, with direct air capture at the expensive end. For capture to make economic sense, the carbon must be worth more captured than emitted, which requires strong carbon pricing or subsidies. Without that, most projects survive on enhanced oil recovery, using injected CO2 to squeeze more oil from wells, an irony not lost on critics.

Where capture genuinely helps

Dismissing capture entirely misses its real niches. Some emissions are genuinely hard to eliminate:

• Cement and steel production release CO2 from chemical reactions, not just fuel, with no easy alternative.
• Residual fossil use in sectors like aviation may need offsetting even in a decarbonised world.
• Carbon removal to draw down historical emissions will likely be needed to return to safer CO2 levels.

The moral hazard debate

The fiercest argument is not technical but political. Critics warn that promising future capture gives fossil fuel companies and governments an excuse to keep emitting today, betting on technology that may never scale. Proponents counter that refusing to develop capture guarantees failure in hard-to-abate sectors and on carbon removal. The IPCC’s pathways to 1.5 degrees all assume some carbon removal, but far less than what would be needed to offset continued high emissions. The emerging consensus: capture is a complement to deep emission cuts, never a substitute.

FAQs

Does carbon capture actually work? Yes, the chemistry and engineering are proven at industrial scale. The open questions are cost, energy use and how fast it can be deployed.

Is stored CO2 safe underground? Well-chosen geological storage appears secure for millennia, with monitoring in place, though regulation and long-term liability frameworks are still developing.

Can DAC solve climate change alone? No. Removing today’s 40 billion tonnes of annual CO2 with DAC would require staggering amounts of clean energy; emission cuts must do the heavy lifting.

Carbon capture is a real technology with real limits: useful, perhaps indispensable, in specific corners of the climate challenge, but no substitute for stopping emissions at the source. Like many climate tools, its value depends entirely on the honesty of the plan it serves.

Source: International Energy Agency