Octavia relies on an amine absorption method similar to the one used by other DAC plants around the world, but its project stands apart—having been tailored to suit the local climate and run on more than 80% thermal energy. OCTAVIA CARBON
Hannah Wanjau, an engineer at the company, explained how it works: Fans draw air from the outside across the filter, causing carbon dioxide (which is acidic) to react with the basic amine and form a carbonate salt. When that mixture is heated inside a vacuum to 80 to 100 °C, the CO 2 is released, now as a gas, and collected in a special chamber, while the amine can be reused for the next round of carbon capture.
The amine absorption method has been used in other DAC plants around the world, including those operated by Climeworks, but Octavia’s project stands apart on several key fronts. Wanjau explained that its technology is tailored to suit the local climate; the company has adjusted the length of time for absorption and the temperature for CO 2 release, making it a potential model for other countries in the tropics.
And then there’s its energy source: The device operates on more than 80% thermal energy, which in the field will consist of the extra geothermal energy that the power plants don’t convert into electricity. This energy is typically released into the atmosphere, but it will be channeled instead to Octavia’s machines. What’s more, the device’s modular design can fit inside a shipping container, allowing the company to easily deploy dozens of these units once the demand is there, Mutheu told me.
This technology is being tested in the field in Gilgil, where Mutheu told me the company is “continuing to capture and condition CO₂ as part of our ongoing operations and testing cycles.” (She declined to provide specific data or results at this stage.)
Once the CO 2 is captured, it will be heated and pressurized. Then it will be pumped to a nearby storage facility operated by Cella, where the company will inject the gas into fissures underground. The region’s special geology again offers an advantage: Much of the rock found underground here is basalt, a volcanic mineral that contains high concentrations of calcium and magnesium ions. They react with carbon dioxide to form substances like calcite, dolomite, and magnesite, locking the carbon atoms away in the form of solid minerals.
This process is more durable than other forms of carbon storage, making it potentially more attractive to buyers of carbon credits, says Pattison, the Cella CEO. Non-geologic carbon mitigation methods, such as cookstove replacement programs or nature-based solutions like tree planting, have recently been rocked by revelations of fraud or exaggeration. The money for Cella’s pilot, which will see the injection of 200 tons of CO 2 this year, has come mainly from the Frontier advance market commitment, under which a group of companies including Stripe, Google, Shopify, Meta, and others has collectively pledged to spend $1 billion on carbon removal by 2030.
The modular design of Octavia's device can fit inside a shipping container, allowing the company to easily deploy dozens of these units once demand is there. OCTAVIA CARBON
These projects have already opened up possibilities for young Kenyans like Wanjau. She told me there were not a lot of opportunities for aspiring mechanical engineers like her to design and test their own devices; many of her classmates were working for construction or oil companies, or were unemployed. But almost immediately after graduation, Wanjau began working for Octavia.
“I’m happy that I’m trying to solve a problem that’s a real-world issue,” she told me. “Not many people in Africa get a chance to do that.”