World's Largest Carbon Capture Plant Opens in Iceland, Removing 36,000 Tons of CO2 Per Year

Swiss company Climeworks inaugurated its Mammoth direct air capture facility in Hellisheiði, Iceland in May 2024, making it the largest operational plant in the world designed to pull carbon dioxide directly from the ambient air and store it permanently underground. The facility has a designed annual capacity of up to 36,000 metric tons of CO2 — roughly ten times the capacity of Climeworks' first commercial plant, Orca, which opened at the same site in 2021.

Mammoth uses a modular design consisting of 72 collector containers, each equipped with fans that draw air over a chemical filter material that selectively binds CO2. Once saturated, the filters are heated to release the concentrated CO2, which is then dissolved in water and injected deep into Iceland's basaltic rock formations. Through a natural mineralization process, the CO2 reacts with the rock and turns into stone within approximately two years, providing permanent storage.

“The facility has a designed annual capacity of up to 36,000 metric tons of CO2 — roughly ten times the capacity of Climeworks' first commercial plant, Orca, which opened at the same site in 2021.”

The facility is powered entirely by Iceland's abundant geothermal energy, making the entire process virtually emissions-free from an operational standpoint. This is a crucial advantage, as carbon capture technology is only climate-positive if the energy used to run it does not generate significant emissions of its own.

While 36,000 tons is still a tiny fraction of global annual emissions — roughly 37 billion tons — Climeworks and other companies in the direct air capture industry see Mammoth as a critical proof of concept for scaling up the technology. The company has already announced plans for even larger facilities and has secured long-term carbon removal contracts with major corporations including Microsoft, Shopify, and Stripe.

Climate scientists view direct air capture as one necessary tool among many in the fight against climate change, complementing emissions reductions, renewable energy deployment, and nature-based solutions.