Cleantech Develop Kiln for Limestone-based Direct Air Capture

A CARBON removal company based in the US and UK has harnessed the “natural chemistry of limestone” to launch a large-scale demonstration kiln capable of capturing over 2,000 t/y of CO₂.

Origen’s lime production system reverses the traditional calcination process – converting limestone into lime, then using it to capture atmospheric CO₂ and reform into limestone through carbonation or mineralisation.

Lime is an inorganic material used across a range of industries, including steel, glass and construction. Origen says its kiln offers the sector a zero-emission production system tailored for direct air capture (DAC).

Standing more than seven storeys tall, the kiln is now undergoing commissioning at the Energy & Environmental Research Center (EERC) in North Dakota, US.

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How it works

The kiln marks the first step in Origen’s DAC system, which drives off CO₂ from limestone to produce lime and a pure CO₂ stream, later transported for permanent storage.

Later stages of the system involve processing the lime to maximise its capacity for CO₂ removal, then using an air contactor to capture atmospheric CO₂ by reacting it with the lime – converting it back into limestone, which is fed back into the kiln.

Origen’s DAC system features an oxy-fuel flash calciner design that enables fuel flexibility. Because DAC is energy-intensive, the system avoids renewable access bottlenecks by capturing all emissions from its fuel source, allowing it to operate on natural gas, renewable natural gas (RNG), biogas or hydrogen.

Origen states: “Because our system is primarily thermal, it avoids competing for scarce renewable power needed elsewhere and is well-positioned to benefit as alternative fuels like RNG and hydrogen mature.”

Commercial scale

With the kiln now online, Origen is set to commission its proprietary air contactor at EERC, designed to extract CO₂ directly from the atmosphere to complete the DAC cycle.

The company will begin integrated system testing with limestone in the coming months. Origen is also preparing for the first commercial deployment of its technology at the Pelican DAC Hub in southern Louisiana. In partnership with Shell, Mitsubishi, and others, Origen is conducting front-end design work for a system expected to remove around 25,000 t/y of CO₂ in its initial rollout. This project is slated to come online in 2029.