Carbon Capture Plants Scale Up in Iceland

The fight against climate change recently took a concrete step forward in Iceland. In May 2024, a Swiss company named Climeworks switched on “Mammoth,” the world’s largest direct air capture and storage plant. Located on a dormant volcano, this facility represents a massive leap in technology designed to suck carbon dioxide directly out of the atmosphere and lock it away permanently.

What Is the Mammoth Facility?

Mammoth is the second commercial direct air capture (DAC) plant constructed by Climeworks in Iceland. It sits on the Hellisheiði lava plateau, adjacent to its smaller predecessor, “Orca.” While Orca, which opened in 2021, was a proof of concept with a capacity of 4,000 tons of CO2 per year, Mammoth is designed to operate at an industrial scale.

Once fully operational, Mammoth will have the capacity to capture 36,000 tons of CO2 annually. To put that number in perspective, that is roughly equivalent to taking 7,800 gas-powered cars off the road for a year. The facility consists of 72 collector containers stacked in a V-shape, making it nine times larger than the Orca plant.

How the Technology Works

The process involves two distinct phases: capture and storage. Climeworks handles the capture, while their Icelandic partner, Carbfix, handles the storage. Here is the step-by-step process of how the facility turns air pollution into rock.

Phase 1: Direct Air Capture

The Mammoth plant looks like a large industrial ventilation system. It uses giant fans to draw ambient air into collector containers. Inside these collectors, the air passes over specialized filters filled with a solid sorbent material. This material acts like a sponge that chemically binds with carbon dioxide.

Once the filters are fully saturated with CO2, the fans shut down and the collector closes. The system heats the interior to approximately 100 degrees Celsius (212 degrees Fahrenheit) using geothermal energy supplied by the nearby ON Power geothermal plant. This heat releases the concentrated CO2 from the filters so it can be collected.

Phase 2: Mineralization (The Carbfix Method)

This is where the geography of Iceland becomes essential. Once Climeworks has gathered the concentrated gas, they hand it over to Carbfix.

  1. Dissolving: Carbfix dissolves the CO2 in large amounts of water. The result is essentially highly pressurized soda water.
  2. Injection: This sparkling water is pumped deep underground (about 700 to 2,000 meters) into basaltic rock formations.
  3. Solidification: Basalt is rich in metals like calcium, magnesium, and iron. When the acidic CO2 water hits the basalt, a chemical reaction occurs. The CO2 reacts with these metals and turns into solid carbonate minerals, such as calcite.

Unlike other forms of carbon storage that pump gas into empty oil wells (where it could theoretically leak), this process turns the carbon into stone in under two years. It is permanent and safe.

The Economics of Scrubbing the Sky

While the technology is scientifically sound, the economics remain the biggest hurdle. Direct air capture is currently one of the most expensive ways to reduce carbon. While Climeworks does not publicly disclose the exact cost per ton for Mammoth, industry estimates place the current cost of DAC between $600 and $1,000 per ton of CO2 captured.

For this technology to be viable in the global fight against climate change, experts believe the cost needs to drop to $100 per ton. Climeworks aims to reach this price point by 2050 through economies of scale and technological improvements.

Who pays for this now? Climeworks relies on voluntary carbon markets. Major corporations purchase carbon removal credits to offset their own emissions. High-profile clients include:

  • Microsoft
  • Stripe
  • Shopify
  • Swiss Re
  • JP Morgan Chase

These companies pay a premium now to help fund the development of the technology, hoping it will become cheaper and more available in the future.

Why Iceland Is the Perfect Laboratory

Iceland offers a unique combination of factors that make it the ideal launchpad for this technology.

  • Geology: The island is largely made of porous basalt rock, which is required for the Carbfix mineralization process. This rock type is found in about 5% of the continents and most of the ocean floor, but it is easily accessible in Iceland.
  • Energy: Carbon capture is energy-intensive. If you use coal-generated electricity to run the fans, you create more CO2 than you capture. Iceland provides abundant, renewable geothermal energy. The Hellisheiði Power Station provides the heat and electricity Mammoth needs without adding new emissions to the atmosphere.
  • Water: The Carbfix process requires 25 tons of water for every ton of CO2 injected. Iceland has significant freshwater resources to support the current scale of operations.

Expanding Beyond Mammoth

Mammoth is a milestone, but Climeworks views it as just the beginning. The company has a “megaton” roadmap, aiming to capture one million tons of CO2 annually by 2030 and one billion tons (a gigaton) by 2050.

To achieve this, they are looking beyond Iceland. The United States government recently selected Climeworks to participate in three massive DAC hubs in America. One notable project, “Project Cypress” in Louisiana, has received funding from the U.S. Department of Energy (DOE) as part of a $3.5 billion investment in carbon removal. Unlike Iceland, the U.S. projects will likely use different storage methods, such as injecting the gas into deep saline aquifers, as basalt is not as readily available in those specific locations.

Frequently Asked Questions

Is the storage method safe? Yes. The Carbfix method mimics natural processes but accelerates them. Once the CO2 mineralizes into calcite (stone), it cannot leak back into the atmosphere. It becomes a permanent part of the geological record.

Can this technology solve climate change on its own? No. Scientists and the IPCC agree that DAC is necessary to remove “historical emissions” already in the air, but it cannot replace reducing current emissions. We emit roughly 37 billion tons of CO2 per year. Mammoth captures 36,000 tons. We cannot build plants fast enough to offset current burning; we must stop burning fossil fuels and use DAC to clean up the excess.

Does the plant run 24⁄7? Yes, the Mammoth facility is designed to run continuously. However, the efficiency of the fans and filters can vary slightly depending on extreme weather conditions, though the geothermal energy supply remains constant.

How much water does it use? The process is water-intensive. It takes roughly 25 tons of water to store 1 ton of CO2. However, Carbfix has developed methods to circulate and reuse water, and in some locations, seawater can be used for the mineralization process.