C2I 2025 Energy Winner: Carbon Capture For Sustainable Construction

This pioneering project combined direct air capture with technology to sequester CO2 in carbon-negative building aggregates.

Project: World-first integration of direct air capture for building materials production
Partners: Mission Zero Technologies with OCO Technology and Optimus

For several years, OCO Technology has been transforming various forms of waste into building aggregates using a proprietary process known as Accelerated Carbonation Technology (ACT), which relies on a secure supply of CO2. Now, at an OCO facility in Norfolk, a first-of-its kind experiment is taking place that combines ACT with an innovative direct air capture (DAC) technology, courtesy of London-based startup Mission Zero Technologies (MZT). Together, the two integrated circular practices are delivering a new class of carbon negative building aggregates that could help transform the construction sector’s environmental impact.

“At OCO Technology we've been pioneering the capture of carbon dioxide into industrial wastes to create what we call a manufactured limestone that's used in the construction sector,” said Graham Cooper, UK managing director at OCO Technology.

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“What we're now doing with Mission Zero is we're trying to incorporate CO2 from the atmosphere around us into our carbon negative building materials.”

The Engineer first heard about the project when it visited MZT’s Bethnal Green labs in 2024, along with an explainer on how the company’s DAC works. Instead of heat, MZT’s process uses electricity to release captured CO2 from its liquid solvent. This electrochemical approach makes MZT’s technology one of the most cost effective and efficient DAC platforms around, as well as allowing direct integration with renewables.

“If you look at the total energy consumption, the engineering complexity, and therefore the implied cost of direct air capture, it usually comes from how you get the CO2 back from whatever medium you captured it in,” Nick Chadwick, co-founder and CEO of Mission Zero Technologies, told The Engineer. “And we’re able to selectively extract and regenerate the CO2 using just electricity.”

While efficiency is crucial, finding commercial pathways for captured CO2 is ultimately what will drive the DAC market forward, according to Chadwick.

“If you can find ways to utilise CO2, then you can actually change the narrative on that and provide alternative pathways for carbon-based products to make our relationship with carbon more sustainable,” Chadwick told The Engineer.

MZT is exploring a range of applications for utilisation of captured CO2, including a project with The University of Sheffield Translational Energy Research Centre (TERC) to produce sustainable aviation fuel (SAF), and a collaboration with Canadian company Deep Sky to permanently sequester CO2 in rock, creating carbon credits. However, its collaboration with OCO perhaps offers the most promising commercial route forward, transforming waste and atmospheric CO2 into essential building materials with embedded carbon sequestration.

“The building materials industry represents 37 per cent of total yearly global emissions, but the world around us is made from carbon-based products,” said Chadwick. “What if we could turn the CO2 in the air all around us into the building materials we use every day?”

Funded by the Department for Energy Security and Net Zero (DESNZ) through its Direct Air Capture and Greenhouse Gas Removal Innovation Programme, the project saw MZT working with OCO and engineering consultants Optimus to design and install a bespoke DAC system at OCO’s Wretham plant in west Norfolk. Previously, OCO had relied exclusively on biogenic supplies of CO2, sourced from regional anaerobic digestion and fermentation plants. The new system, in operation since May 2025, provides an on-site, on-demand source of sustainable CO2 to supplement that existing supply.

If you can find ways to utilise CO2, then you can actually change the narrative

Nick Chadwick

The DAC system seamlessly integrates with OCO’s production processes via a direct pipeline connected to a buffer tank. OCO then combines the captured CO2 with recycled incineration residues from its ACT process to create carbon-negative limestone, which in turn can be used to decarbonise building materials like concrete and asphalt. The plant can capture up to 250 tonnes of atmospheric CO2 per year. Alongside the resultant building aggregates, the project also unlocks a secondary revenue source in the form of high-quality carbon removal credits.

For OCO, the collaboration marks a step towards complete independence and security of supply for its CO2. While the availability of biogenic CO2 is highly regionally specific, DAC can be sited virtually anywhere. This opens up possibilities for OCO to expand its footprint without constraints, while at the same time boosting self-sufficiency and enhancing the environmental credentials of its end product.

“With this technology, one of the things that we can build is business resilience,” said Cooper. “Collocating the production of CO2 to one of our sites, which could be anywhere in the world, means that we have a more reliable supply chain, but also a more sustainable source of CO2.”

According to MZT, speed and scalability were also pivotal to the project’s success. This was underpinned by a modular approach to design, simple utilities, and the use of mature components backed by international supply chains. A nimble engineering approach brought by Optimus also helped in enabling this novel technology to move from concept to pilot stage much faster than traditional projects.

Throughout the project, MZT and OCO fostered proactive collaboration, working as part of a consortium from initial design through to delivery over three years. This included mutually attending HAZOP processes for clear integration of the process and alignment on all safety-related considerations, securing buy-in on all major design components, and fully aligning with OCO’s standards for the direct integration.

OCO and MZT both co-reviewed and approved the pipeline design for integrating the two technologies, with personnel from both teams working closely on-site to confirm this. MZT and OCO held weekly meetings across the project’s lifespan to ensure consistent and clear communication. An agreed sign-in and safety process for both of sites ensured inter-company compliance and consistent management for site visitors, and both companies co-hosted multiple site tours spanning both facilities to showcase the pioneering technology.

“The future of sustainable construction is here,” said Cooper.

“What this project does is not only demonstrate the scalability of direct air capture, but it represents a huge breakthrough in sustainable building materials.”