What is direct air capture (DAC)?

Quick Answer: Direct air capture (DAC) is a technology that removes carbon dioxide directly from the atmosphere using chemical processes, then stores or uses the captured CO2. Unlike nature-based carbon removal methods such as planting trees, DAC uses engineered systems to extract CO2 from ambient air at any location. It is one of the few carbon removal approaches capable of producing permanent, verifiable reductions in atmospheric CO2 concentrations.

What is direct air capture?

Direct air capture is a carbon dioxide removal technology that pulls CO2 out of the surrounding air using large fans and chemical sorbents or solvents. The process is distinct from point-source carbon capture, which intercepts emissions at a specific industrial source like a power plant or factory. DAC works on the ambient air around us, meaning it can, in principle, operate almost anywhere.

The CO2 in our atmosphere is highly dilute, making up roughly 0.04% of the air we breathe. That low concentration is what makes DAC technically demanding: systems need to process enormous volumes of air to extract meaningful quantities of CO2.

How does direct air capture work?

Most DAC systems follow the same basic sequence: draw in air, separate the CO2, concentrate it, then store or use it.

The separation step is where the main technical approaches diverge.

Solid DAC (S-DAC) passes air over a solid sorbent material that binds CO2 at its surface. Once the material is saturated, changing the temperature and pressure conditions releases a concentrated stream of pure CO2. The system then regenerates the sorbent and the cycle repeats. This temperature swing requires significant energy input.

Liquid DAC (L-DAC) exposes air to an alkaline liquid solution, typically potassium hydroxide. The CO2 reacts with the solution to form carbonate salts; heating these at high temperatures releases concentrated CO2. This method is also energy-intensive, but the underlying chemistry is well understood and has been used in industrial settings for decades.

Once captured, the CO2 has two main destinations:

• Geological storage: operators compress and inject the CO2 deep underground into porous rock formations, where it mineralises over time, permanently removing it from the atmosphere. This combination is often called Direct Air Carbon Capture and Storage (DACCS).
• Utilisation: the CO2 serves as a feedstock in industrial processes, including synthetic fuels, concrete production, and carbonated drinks. In most utilisation cases, the process eventually re-releases the CO2, so this does not constitute permanent removal.

Why does direct air capture matter for climate change mitigation?

The IPCC has stated with high confidence that meeting the Paris Agreement temperature goals requires carbon dioxide removal alongside deep emissions cuts. Scenarios that limit warming to 1.5°C require removing on the order of 100–1000 GtCO2 cumulatively over the course of this century, and DAC is one of the few approaches that can scale independently of land availability.

It is location-flexible. Developers can site plants near geological storage sites or renewable energy sources, rather than being constrained by geography in the way that forests or wetlands are.

It is measurable. Because DAC is an engineered process, operators can measure the volume of CO2 flowing through the system with precision. This makes monitoring, reporting, and verification (MRV) more straightforward than for many nature-based approaches, where carbon stocks are difficult to quantify and remain vulnerable to reversal through fire, disease, or land-use change.

It can deliver durable storage. When combined with geological storage, DAC can deliver carbon removal that is effectively permanent on human timescales, which is a significant advantage over biological storage methods.

These properties have made DAC a focus of both public investment and carbon credit markets. The US Department of Energy has committed over $3.5 billion to establishing regional DAC hubs, with the Department announcing a further $1.8 billion for a second tranche of projects.

What are the current limitations of direct air capture?

Cost is the most significant barrier. Current estimates put the cost of DAC at $152–$398 per tonne of CO2, depending on the technology and location. For DAC to play a major role in corporate decarbonisation strategies, most analysts agree costs need to fall below $100 per tonne. Research from MIT suggests solid sorbent DAC will reach $100–$400/tCO2 by 2050, while liquid solvent DAC will reach $100–$220/tCO2 in the same period, assuming continued investment and learning-by-doing effects.

Energy demand is the second major constraint. DAC is an energy-intensive process: current systems require between 1,500 and 2,500 kWh of energy per tonne of CO2 removed. If that energy comes from fossil fuel sources, it significantly reduces the net CO2 removal achieved. Integrating DAC with renewable energy is therefore a prerequisite for genuine climate benefit, not an optional add-on.

Water consumption is an emerging concern. DAC plants, particularly liquid-based systems, consume significant quantities of water, which raises questions about siting in water-stressed regions.

Scale remains the most daunting challenge. As of 2024, the global pipeline includes roughly 130 DAC plants operating or in development, with the largest (Climeworks' Mammoth facility in Iceland) removing approximately 36,000 tonnes of CO2 per year. Reaching gigaton-scale removal would require a many-thousand-fold increase in capacity, which demands sustained investment, policy support, and manufacturing scale-up.

How does direct air capture relate to carbon accounting and corporate climate targets?

For companies building science-based decarbonisation strategies, DAC is most relevant as a source of high-quality carbon credits for residual emissions that companies cannot eliminate through operational changes.

DAC-backed credits command higher prices than most nature-based offsets, but buyers generally consider them more credible than many offset types, though they currently carry a significant price premium. Understanding where DAC sits in the broader carbon removal picture matters for companies setting Science Based Targets, because the SBTi framework distinguishes between emissions reductions (which must be the primary focus) and carbon removals (which address residual emissions). DAC-backed credits, particularly those combined with geological storage, align well with the permanence requirements that credible net zero frameworks demand.

For companies working with Seedling to build a full-scope carbon footprint and decarbonisation plan, understanding the role of carbon removal technologies like DAC helps frame what a credible long-term strategy looks like: deep cuts first, high-quality removals for what remains.

The trajectory of DAC costs over the next decade will determine how accessible this technology becomes as a corporate climate tool. As manufacturing scales and policy support matures, analysts expect the gap between DAC's current price point and the cost of other removal methods to narrow considerably.