Direct air carbon capture: the biggest plant and what it means for climate

01How direct air capture technology works

Direct air capture (DAC) is the use of chemical or physical processes to extract carbon dioxide directly from the ambient air. If the extracted CO2 is then sequestered in safe long-term storage, the overall process is called direct air carbon capture and sequestration (DACCS), achieving carbon dioxide removal. Systems that engage in such a process

Direct air capture, or DAC, uses large fans to push ambient air through a chemical sorbent that binds carbon dioxide. Once the sorbent is saturated, it is heated to release the concentrated CO2, which is then compressed for storage or use. The two dominant approaches are liquid solvents, which use a chemical solution to absorb CO2, and solid sorbents, which use filter-like materials that capture CO2 on their surface.

The chemistry is not new. Industrial processes have captured CO2 from concentrated gas streams for decades. The difficulty with direct air capture is that atmospheric CO2 is extremely dilute, about 420 parts per million. That means a DAC plant must process enormous volumes of air to capture a meaningful amount of carbon, which is why the energy demand is so high.

02The worlds biggest DAC plant and its capacity

The Mammoth plant in Iceland, operated by Climeworks, is currently the largest operational direct air capture facility. It has a designed capacity of 36,000 metric tons of CO2 per year when fully built out. The captured CO2 is mixed with water and injected into basaltic rock formations, where it mineralizes into solid stone over a period of years through a process called carbonation.

Even at full capacity, Mammoth captures a tiny fraction of the roughly 40 billion metric tons of CO2 humanity emits annually. The plant demonstrates that the technology works at industrial scale, but it also shows the magnitude of the scaling challenge. Replacing one year of global emissions would require over a million plants of similar size, which is why cost and energy efficiency improvements are critical.

03The energy requirements of carbon capture

Direct air capture is energy intensive. Capturing one ton of CO2 from the atmosphere requires significant thermal energy to release the CO2 from the sorbent and electrical energy to power fans and compressors. Estimates range from 1,500 to 3,000 kilowatt-hours per ton depending on the technology and the heat source.

If that energy comes from fossil fuels, the net carbon removal is reduced or eliminated. This is why the location of DAC plants matters. Iceland uses geothermal energy, which is both renewable and provides the low-temperature heat the sorbent regeneration process needs. Locating plants where clean energy is abundant and cheap is essential for DAC to deliver real net removal.

The energy penalty also means that DAC competes with other uses for clean electricity. A gigawatt of renewable power used for DAC could instead displace fossil fuel generation on the grid, which may remove more CO2 per dollar than using it for direct air capture. This trade-off is central to the debate about where DAC fits in climate strategy.

04Cost per ton of CO2 removed

The current cost of direct air capture is estimated at $600 to $1,000 per ton of CO2. This is far higher than other carbon removal methods like afforestation or soil carbon sequestration, which can cost under $100 per ton. The industry target is to bring DAC costs below $100 per ton by 2030 through economies of scale, improved sorbents, and cheaper renewable energy.

Cost reduction is plausible but not guaranteed. The cost curve for DAC depends on factors that are difficult to predict: sorbent longevity, energy prices, plant utilization rates, and the cost of capital for large infrastructure projects. Some projections show costs falling to $200-300 per ton by 2030, which is still expensive but potentially viable if carbon prices or credits rise accordingly.

05Where captured carbon goes

Carbon dioxide removal (CDR) is a process in which carbon dioxide is removed from Earth's atmosphere by deliberate human activities and durably stored in geological, terrestrial, or marine reservoirs, or in products. This process is also known as carbon removal, greenhouse gas removal or negative em

Captured CO2 can be stored permanently underground or used in products. Geological storage injects compressed CO2 into deep rock formations, often depleted oil and gas reservoirs or deep saline aquifers, where it is trapped under impermeable cap rock. In Iceland, the Carbfix process dissolves CO2 in water and injects it into basalt, where it mineralizes into carbonate rock within years.

Some DAC plants sell captured CO2 for use in synthetic fuels, building materials, or carbonated beverages. However, if the CO2 is used in products that release it back into the atmosphere, the removal is temporary. Permanent storage, not utilization, is what makes DAC a climate mitigation tool rather than an industrial process.

06How DAC fits into climate strategy

Climate change mitigation, also called decarbonisation, is an action to limit the greenhouse gases in the atmosphere that cause climate change. Climate change mitigation actions include conserving energy and replacing fossil fuels with clean energy sources. Secondary mitigation strategies include ch

Climate models that limit warming to 1.5 or 2 degrees Celsius typically include significant carbon dioxide removal alongside emissions reductions. DAC is one option in the removal portfolio, alongside nature-based approaches like reforestation and technological approaches like bioenergy with carbon capture and storage. Each approach has different costs, permanence, and land requirements.

The appeal of DAC is that it does not compete for arable land, can be located anywhere with clean energy, and offers permanent storage if the captured CO2 is mineralized or injected into suitable geology. The disadvantage is cost and energy demand. No single removal method is likely to scale to the tens of gigatons per year that climate models require, so a portfolio approach is expected.

07What scaling DAC requires

Scaling DAC from thousands of tons to gigatons per year requires solving several interlocking problems. Sorbent materials need to become more durable and energy efficient. Plant designs need to be standardized and factory-built rather than custom-engineered. Clean energy supply must expand to meet the additional demand. And the financing structure, whether through carbon markets, government procurement, or corporate climate commitments, must provide reliable revenue.

The Department of Energy has set a goal of deploying DAC at a cost below $100 per ton and has funded regional DAC hubs to build infrastructure. The European Union is also investing in carbon removal technologies. Government procurement can create early demand that helps the industry scale, similar to the role public procurement played in solar and wind energy development.

The timeline is compressed. To reach the removal volumes that climate scenarios assume for mid-century, DAC capacity needs to grow by orders of magnitude in the coming decades. Whether the technology can follow a cost curve similar to solar panels, which fell by roughly 90 percent over a decade, is one of the most important open questions in climate technology.