Direct Air Capture and Geothermal Energy The Ultimate Carbon Negative Solution with Orca in Iceland as a Model for Future DAC Geothermal Carbon Removal Hubs
Direct air capture powered by geothermal is one of the few combinations that can credibly claim to be deeply carbon negative at scale.
Image : Direct air capture for fuel production
By pairing an energy‑hungry technology with round the clock low carbon baseload, it turns carbon removal from a theoretical idea into industrial infrastructure, and Climeworks’ Orca plant in Iceland is the clearest early example.
Direct Air Capture And Geothermal The Ultimate Carbon Negative Combo
Direct air capture is simple to describe and hard to do. The basic idea is to pull carbon dioxide out of ambient air and store it permanently underground. The problem is that air is a very dilute source of CO₂, so you have to move huge volumes of air through sorbent materials and then use heat and electricity to regenerate those sorbents. That makes DAC both capital intensive and energy hungry.
If the energy comes from fossil fuels, the climate value collapses. If the energy comes from intermittent renewables without storage, the plant runs at low utilisation, which kills the economics. Geothermal sidesteps both issues. It provides firm low carbon power and heat twenty four hours a day, and in some places it sits above geology that can mineralise CO₂ into solid rock. That is exactly the configuration Iceland uses today.
Why Direct Air Capture Needs The Right Energy Partner
DAC systems fall broadly into two categories. Some use liquid solvents. Others use solid sorbents. In both cases they need electricity to run fans and pumps, and heat to release CO₂ from the sorbent so it can be concentrated and stored. The thermodynamics are unforgiving. You are trying to reverse decades of emissions by processing a gas that makes up only about four hundred parts per million of the atmosphere.
That means power demand per ton captured is high. While exact numbers depend on technology and learning curves, studies and pilot plants suggest that capturing a ton of CO₂ can require on the order of one to several megawatt hours of energy when you combine electricity and heat.If that energy is fossil derived, a large fraction of the captured carbon is re emitted. If the plant runs only when the wind blows or the sun shines, expensive DAC equipment sits idle much of the time. In both cases, the cost per ton of durable removal increases and the net climate benefit shrinks.
This is why Climeworks and others emphasise that DAC must be matched with low carbon, high availability energy to make sense. Geothermal fits because it is dispatchable and low carbon, with lifecycle emissions measured at tens of grams of CO₂ equivalent per kilowatt hour rather than hundreds.And unlike many other firm low carbon sources, it often comes with co produced heat that can be used directly instead of converting everything into electricity.
Orca In Iceland How It Works
Orca, which came online in twenty twenty one, is widely described as the world’s first large scale commercial direct air capture and storage plant.It is located on a lava plateau about thirty minutes southeast of Reykjavik, adjacent to the Hellisheiði geothermal power plant operated by ON Power. The name Orca comes from an Icelandic word meaning energy.
The plant consists of eight modular collector units that look like oversized shipping containers. Each unit contains fans and solid sorbent filters that bind CO₂ when ambient air is drawn through them. Once the sorbent is saturated, the unit is closed, heated and evacuated to release the concentrated CO₂.Orca has a design capacity of up to four thousand tons of CO₂ per year at this stage, modest on a global scale but significant as an integrated demonstration of DAC plus storage.
Electricity from the geothermal plant runs the fans and controls. Low grade heat from the same plant regenerates the sorbent. The recovered CO₂ is then handed off to Carbfix, a local company that mixes the gas with water and injects the mixture into porous basalt formations nearby. In this rock, CO₂ reacts with minerals and turns into carbonate solids, effectively becoming part of the rock within a few years.
Independent reporting notes that one of Orca’s advantages is modularity. The collector containers were prefabricated, shipped to the site and assembled rapidly, allowing the plant to be designed and commissioned in roughly fifteen months.That modular approach is critical for scaling. It allows Climeworks to add capacity incrementally as customers sign long term removal contracts rather than having to build huge monolithic plants in a single step.
Why Orca Is Genuinely Carbon Negative
Many carbon capture projects have been criticised as greenwashing because they capture CO₂ from fossil plants and sell it for enhanced oil recovery or because the energy used in capture wipes out much of the benefit. Orca is different for two reasons.
First, the energy input is overwhelmingly geothermal. The Hellisheiði plant itself is powered by geothermal steam fields and supplies both electricity and heat, which have low lifecycle emissions. Climeworks has stated that for every hundred tons of CO₂ captured at Orca, at least ninety tons are stored permanently and less than ten tons are re emitted by the plant’s own energy consumption.[1][3][8] That gives the system a high net removal rate compared to fossil powered capture.
Second, the storage pathway is permanent on human timescales. Carbon that is dissolved in water and injected into basalt reacts with the rock to form stable carbonate minerals. Studies and monitoring data from the Carbfix project show that the majority of injected CO₂ mineralises within two years in the Hellisheiði reservoir.[4][9] That sharply reduces concerns about leakage that can accompany some forms of conventional CO₂ storage in sedimentary formations.
When you combine those two features, you get a plant that removes CO₂ from the global atmosphere and stores it in rock using mostly renewable energy. That is what people mean when they describe geothermal powered DAC as truly carbon negative. It is not perfect, but the direction of travel is clearly removing more than it adds.
Geothermal And DAC As A Template For Future Hubs
Orca is small relative to global emissions, but the design principles translate. In any region where geothermal resources and suitable rocks for storage coexist, you can imagine building integrated hubs where power plants, DAC units and storage infrastructure sit side by side. These hubs would function like the energy equivalents of industrial parks dedicated to carbon removal.
Iceland is ahead thanks to its geology and policy environment. It has abundant high temperature geothermal resources, accessible basalt formations and a national strategy that welcomes carbon removal projects. Climeworks’ next plant, Mammoth, is already under construction near Hellisheiði with a planned capacity of around thirty six thousand tons per year, an order of magnitude larger than Orca.That facility will use a similar combination of geothermal energy and mineral storage, but with more collector units and improved designs.
Other locations are being explored. Geothermal fields and basalt formations exist along many volcanic arcs, mid ocean ridges and continental rift zones. In theory, any such site with grid access and suitable permitting could host a geothermal DAC hub. Some studies suggest that pairing DAC with geothermal in these regions could deliver cost and emissions advantages over pairing with variable renewables alone because the utilisation of the capture equipment stays high.
These hubs would in some ways resemble classic oil fields. Instead of wells bringing hydrocarbons to the surface for combustion, they would host wells that inject captured carbon back underground. The economic logic would be similar too. Companies would invest in exploration to find the best combinations of heat and storage rock, secure long term contracts, and build out modular capacity over time.
Why Geothermal Is Uniquely Suited Among Renewables
It is worth asking why geothermal plays this role rather than other renewables. Solar and wind provide low cost energy, but they are variable. Hydro can be firm but is constrained by geography and environmental impacts. Nuclear is firm and low carbon but has different cost and siting issues and typically does not co produce large amounts of low grade heat.
Geothermal has several advantages for DAC. It offers high capacity factors, often above eighty percent, meaning the plant can run almost continuously.[4][6] It provides both electricity and heat, and DAC requires both. Low temperature heat is especially useful for regenerating solid sorbents without needing additional boilers or complex heat pumps. And geothermal plants can be built at scales that match the modular nature of DAC. You do not need gigawatt scale projects to start.
There is also a systems benefit. Geothermal can stabilise grids with high shares of variable renewables by providing flexible but firm output. If geothermal plants are sized slightly larger than grid demand, the excess can be routed into DAC units. That way, carbon removal becomes a controllable load that helps balance the system. Some analyses describe this as a symbiotic relationship where DAC acts as a flexible offtaker for geothermal heat and power that might otherwise be under utilised.
Economics And Policy The Road To Gigaton Scale
The biggest challenge for DAC plus geothermal is cost. Today, published costs for high quality DAC removal remain in the mid hundreds of dollars per ton, although companies expect learning curves to bring this down as plants scale.[5][3] Geothermal projects also require significant upfront capital for exploration and drilling. That means early projects rely heavily on supportive policies and buyers willing to pay a premium for durable removals.
Climeworks has secured multi year offtake agreements with companies like Microsoft and Stripe that want to lock in high integrity removals for their climate commitments.[5] These contracts provide predictable revenue streams that make financing Orca and Mammoth possible. At the same time, public funds and multilateral banks are exploring how to support carbon removal infrastructure, including DAC hubs, as part of broader climate strategies.
On the geothermal side, derisking tools like exploration funds, risk sharing schemes and blended finance can reduce capital costs and make more projects viable. As more geothermal capacity comes online, the marginal cost of directing part of that energy into DAC may fall. Over time, if carbon prices rise and removal becomes mandatory for some sectors, geothermal DAC hubs could shift from niche demonstration projects to core infrastructure in climate constrained economies.
Could Geothermal DAC Hubs Become The New Carbon Fields
If you extrapolate the Orca model over decades, you end up with a world where clusters of geothermal powered DAC plants dotted around the globe function as carbon removal fields. Some could sit in volcanic regions like Iceland, or parts of the western United States. Others might leverage lower temperature geothermal for heat coupled with grid electricity for the rest of the energy demand.
These hubs would share several features. They would have dedicated injection and monitoring wells. They would host modular DAC units that can be expanded as demand grows. They would be tied into global carbon markets and long term contracts, much like liquefied natural gas terminals and oil export hubs today. And they would employ many of the same skills and supply chains currently used in geothermal power, oil and gas drilling and industrial plant operation.
The analogy to oil fields is not just rhetorical. Oil fields are geographic concentrations of extraction capacity linked to pipelines and markets. Geothermal DAC hubs would be geographic concentrations of removal capacity linked to pipelines for money and carbon accounting. In both cases, the resource is underground. The difference is direction. One brings carbon up. The other sends it back down.
Why This Story Matters For Developers And Investors
For developers, the geothermal DAC story is an invitation to think beyond pure power sales. If you control a geothermal concession with good heat and suitable rock, your product might not just be electricity. It could be high integrity carbon removals sold to global buyers. That requires new business models, but the technical foundation is already visible in Iceland.
For investors, these projects offer exposure to two structural trends at once. The rise of firm low carbon power and the growth of carbon removal as a service. The risks are non trivial. Technology is evolving, policy is uncertain and costs are still high. But the strategic upside is significant. If gigaton scale carbon removal becomes a regulatory or market requirement, the entities that own and operate geothermal DAC hubs will occupy a crucial position in the climate economy.
For policymakers, the lesson from Orca is that integrated projects can be built today if the pieces align. Supportive permitting, clear rules for storage, collaboration between utilities and innovators and buyers willing to pay for removals. Those conditions are rare but not unique to Iceland. With the right frameworks, other countries could follow.
In sum, direct air capture plus geothermal is not a silver bullet. It is an early but concrete example of how to build truly carbon negative infrastructure. The Orca plant shows that when you combine a firm renewable with smart chemistry and the right geology, you can turn the abstract idea of removing carbon from the air into a physical facility that does it every day
The question now is how many Orcas the world will choose to build.
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