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Glossary · Energy industry & energy transition

Direct Air Capture, DAC

Direct Air Capture DAC negative emissions Carbon dioxide removal CCS E-Fuels Climate neutrality

Direct Air Capture, DAC for short, refers to technical processes that capture carbon dioxide directly from ambient air. The captured CO₂ can then be stored geologically, bound mineralogically or used as a carbon source for products. This distinction is decisive for the climate balance. Permanent CO₂ removal only occurs if the carbon dioxide remains separated from the atmospheric carbon cycle over very long periods. When DAC is combined with permanent storage, this is referred to as DACCS (Direct Air Carbon Capture and Storage).

Operating principle and technical challenge

The central difficulty is the low CO₂ concentration of air. According to measurements by the US agency NOAA, the globally averaged CO₂ share in 2026 was around 426 ppm, or about 0.043 percent. The value fluctuates seasonally and rises by about 2 to 3 ppm every year. Exhaust gases from power plants, cement plants or industrial processes contain many times that amount. A DAC plant must therefore move very large volumes of air and extract the CO₂ from a highly dilute mixture. To put it vividly: for every million air molecules there are only a little over 400 CO₂ molecules.

Two families of processes are mainly used for this. Solid sorbents such as amine-coated filter materials bind the CO₂ on their surface. They are usually regenerated with low-temperature heat of around 100 °C and under vacuum. Liquid solutions, for example hydroxide-based ones, bind the CO₂ chemically. For these, the release takes place in a high-temperature step at several hundred degrees Celsius. In addition, moisture-driven or electrochemically driven processes are being developed. In all cases, the CO₂ is released again after uptake, concentrated, dried and compressed for transport, use or storage.

Energy and resource requirements

DAC is not a simple filter technology that runs on the side without significant effort. The plants need electricity for fans, pumps, controls and compression, and often additionally heat for regenerating the binding agents. An analysis by Harvard University's Belfer Center gives a practical energy requirement of about 5 to 15 GJ per tonne of CO₂, i.e. 1.4 to 4.2 MWh, including compression for transport and storage. Extrapolated, this means: one million tonnes of DACCS per year requires 1.4 to 4.2 TWh of low-emission energy. One billion tonnes would require 1,400 to 4,200 TWh, an order of magnitude comparable to the entire large-scale electricity generation of the USA in 2022.

In addition there are materials, sorbents with a limited lifetime, water and chemicals depending on the process, as well as land, maintenance and infrastructure for CO₂ transport and storage. The climate impact therefore depends not only on the quantity captured. It is also determined by the origin of the energy, the lifetime of the plant, the upstream chains of the materials and the permanence of storage. A complete life cycle assessment must distinguish gross capture from net removal. If a plant is operated with fossil-generated electricity, a large part of the removal, or even all of it, can be lost again.

Distinction from CCS, CCU and negative emissions

DAC is often confused with CCS. CCS stands for Carbon Capture and Storage, i.e. the capture and storage of CO₂. The CO₂ can come from industrial or power plant exhaust gases, from biogenic processes or from ambient air. DAC only describes the source of the capture, namely the air. Storage is a separate, downstream step. DAC without storage is not permanent CO₂ removal. CCS at point sources using fossil fuel can reduce emissions, but does not remove any CO₂ already present from the atmosphere. The umbrella term CCUS covers both storage and use. A related removal route is BECCS, in which biogenic CO₂ is captured and stored.

The term negative emissions is also narrower than many debates suggest. Negative emissions only arise if net CO₂ is removed from the atmosphere and stored permanently. EU Regulation 2024/3012 defines CO₂ removal as the anthropogenic removal of CO₂ from the atmosphere and its permanent storage in geological, terrestrial or oceanic reservoirs or in long-lived products. If DAC CO₂ is instead used for beverages, greenhouses or short-lived chemical products (CCU), it usually returns to the atmosphere soon. Such uses can replace fossil carbon, but as a rule they are not permanent removal.

This distinction is particularly important for e-fuels. Synthetic fuels such as methane, methanol, kerosene or diesel need a carbon source, and DAC can supply it. However, when burned, the previously captured CO₂ is released again. In terms of accounting, the cycle can be largely climate-neutral if hydrogen, electricity and process heat are provided with almost no emissions. But this does not create a CO₂ sink. DAC carbon in e-fuels shifts the carbon source from fossil to atmospheric, but does not permanently remove any CO₂ from the air.

Legal framework in the EU and Germany (as of November 2026)

  • EU: Regulation (EU) 2024/3012 of 27 November 2024 establishes a voluntary Union framework for the certification of permanent carbon removals, carbon farming and carbon storage in products. It has been in force since December 2024 and sets quality criteria such as quantification, additionality, long-term storage and sustainability.

  • EU methodology for DACCS: With Delegated Regulation (EU) 2026/285 of 3 February 2026, the Commission established certification methodologies for permanent carbon removals. This expressly includes direct air capture of CO₂ with storage (DACCS), alongside BECCS and biochar. Under this methodology, only permanent storage is certified as removal, not mere capture.

  • Emissions trading: Certification does not automatically mean that removal certificates are credited in the EU Emissions Trading System. Whether and how permanent removals are included there had not yet been conclusively regulated at the time of the sources evaluated here.

  • Germany: The amendment to the Carbon Dioxide Storage Act entered into force on 28 November 2025. Since then the act has been called the Carbon Dioxide Storage and Transport Act (KSpTG). It lifts the previous restriction to research and demonstration storage sites and comprehensively regulates the transport of CO₂ for the first time. This creates the legal prerequisites for storage and pipeline transport on a larger scale, including for CO₂ from DACCS. However, permits, infrastructure and storage sites still have to be created on a case-by-case basis.

Significance for the electricity system

For the electricity system, DAC is relevant above all because of its energy demand. Large DAC volumes would create additional electricity and heat demand. In a climate-neutral energy system, this demand must be met from renewable or otherwise low-emission sources. Otherwise new emissions offset part of the removal again. The decisive factor is therefore not only how much CO₂ a plant can capture. Equally important is when it needs electricity, what temperature level its heat must have, and whether waste heat, geothermal energy or heat pumps can supply this heat.

In an electricity system with a lot of wind and solar power, DAC plants could act as flexible consumers. To do so, they would have to increase their output when a lot of renewable electricity is available and throttle it when electricity is scarce. However, this flexibility is neither technically nor economically a given. Sorbents, process control, compressors, heat storage and CO₂ logistics determine how quickly and how strongly a plant can change its output. There is also an economic trade-off: plants with high investment costs pay off mainly with many operating hours. Frequent curtailment makes every tonne removed more expensive.

Orders of magnitude and misconceptions

A common misconception is to regard DAC as a later repair technology for today's emissions. The orders of magnitude argue against this. Global CO₂ emissions amount to many billions of tonnes per year. According to IEA evaluations, 18 DAC plants were in operation worldwide in 2022. Together they captured less than 10,000 tonnes of CO₂ per year. Newer plants are designed for several tens of thousands of tonnes, and projects in the range of hundreds of thousands up to one million tonnes are under construction or in planning. The capture actually achieved can be well below nominal capacity. Scaling up therefore means not only more modules, but also more energy, investment, storage sites, transport infrastructure and institutional oversight. Every tonne that is not emitted in the first place does not later have to be recovered with great effort from highly dilute air.

This does not mean that DAC would be superfluous. On the path to climate neutrality, residual emissions are expected to remain, for example from parts of agriculture, certain industrial processes, waste treatment or individual applications in transport. DAC with permanent storage can offset such emissions if the removal is permanent, verifiable and additional. The term residual emissions must not be expanded arbitrarily. It refers to emissions that remain after serious reduction, not those whose avoidance is politically inconvenient or expensive in the short term.

Economic assessment and site selection

How DAC should be assessed economically depends strongly on which service is paid for. Mere capture is not yet a permanent climate service. With storage, questions of liability, monitoring and certification over very long periods arise. With use, the duration of use and later release must be taken into account. A market for CO₂ removal therefore needs different rules than a market for avoided emissions. An avoided and a removed tonne can look the same in balance sheets, but are based on different technical chains with different risks.

The site is also important. Air is available everywhere, but in practice sites with affordable, low-emission energy, a suitable heat source, grid connection, sufficient water and access to CO₂ storage sites or transport routes have a clear advantage. In regions with scarce renewable electricity, DAC competes with electrification, hydrogen production and industry for the same resources.

Conclusion: DAC is a technical chain and not a mere balance sheet item. Capture, energy supply, compression, transport, storage, monitoring and legal responsibility belong together and must be assessed jointly. Direct Air Capture can become important as a building block for offsetting hard-to-avoid residual emissions. As a substitute for emission reduction, efficiency, electrification and the expansion of renewable energy, DAC is overestimated.

Sources

Related glossary entries

Edited by eCMS on 11.11.2026 19:07

© 2026 Erik Schmidt. All rights reserved. Quotations with a link to the source are welcome.