How capturing CO2 from APCr is helping to build a sustainable future

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Dr Peter Gunning, Head of Research & Development at O.C.O Technology, says the EfW sector offers huge potential when it comes to carbon capture. 

Image: O.C.O Technology's Dr Peter Gunning

2021 marks ten years since the Environment Agency granted ‘End of Waste’ approval to O.C.O Technology’s carbon negative aggregates, classifying them as a ‘product’ and underlining their production as a perfect example of the circular economy in action.

It was the first time a company in Europe had achieved such status for an APCr waste stream and since then, O.C.O has broken more barriers, becoming the first company in the world to successfully commercialise the Accelerated Carbonation Technology (ACT) process. 

In that decade, its technology has been expanded on a worldwide basis and its three UK operations in Avonmouth, Leeds and Suffolk now produce more than 450,000 tonnes of carbon negative aggregate a year for use in the construction and aggregates sector.

Dr Gunning explains more about the technologies involved: “To our knowledge, while there are some pilot schemes in place, no-one else is successfully operating on the same commercial scale as O.C.O and producing such large quantities of aggregate product.

“We take a wide range of industrial residues, including air pollution control residue (APCr) and, using our ACT process we mix them with waste CO2 gas before adding a blend of binders and fillers. That creates our carbon negative aggregate called Manufactured LimeStone – known as M-LS for short – and, because the process permanently captures more carbon dioxide (CO2) than is generated during the manufacturing process, the M-LS is uniquely carbon negative.”

In 2019, it was estimated that O.C.O’s M-LS BlockMix, specially formulated for use in concrete masonry blocks, was used in well over 25 million blocks – the equivalent to building more than 10,000 three-bedroom homes. Every tonne of M-LS used avoids the quarrying of 1.4 tonnes of natural aggregate. 

With a turnover in excess of £16 million, O.C.O has contracts to manage APCr from leading waste management and EfW operators, including Grundon Waste Management and Viridor, as well as the Ferrybridge Multifuel 2 (FM2) power station in Yorkshire operated by SSE. 

Carbon negative M-LS aggregate from O.C.O Technology is in demand as a sustainable building material

Last year it also expanded into handling biomass APCr, signing a contract with Tilbury Green Power (TGP), which wanted to find a circular economy solution for APCr from its waste wood powered renewable energy facility. 

Because biomass APCr has different characteristics to municipal waste EfW APCr, O.C.O’s in-house team of chemists spent time fine-tuning the process to make sure the biomass APCr could be successfully processed.

Dr Gunning continues: “No two materials are alike so we carried out rigorous tests, carefully honing the ‘recipe’ and processing conditions to achieve the right results, ensuring that the aggregate would be 100% compliant with the End of Waste specification. 

“The depth of our expertise and our experience means we can respond quickly and effectively to new challenges and guarantee our customers achieve the results they are looking for.”

Alongside APCr, Dr Gunning says the same technology can also potentially be applied to residues arising from the energy recovery, cement manufacture, metallurgical processes, paper production, power generation and many other sectors. This increases opportunities to boost the circular economy and increase diversion from landfill. 

“Using carbon dioxide to transform unwanted waste materials into new carbon negative products is a perfect example of the circular economy in action. It reduces the need for natural aggregates and above all, it enables significant volumes of CO2 to be taken out of the atmosphere – something we all need to work towards to improve the future sustainability of our planet,” he adds.

“I see the EfW and biomass sectors as having among the most important residues suitable for carbon capture and we already have the proven technology to show that APCr recycling works.  

“There is the potential to add much greater capacity to what we are doing now and to help deliver that goal I’d like to see more a more harmonised approach to End of Waste materials on a global scale.  

“While the EA has been ahead of the curve in its certification processes, that’s not necessarily the case worldwide and I would like to see more recognition of the benefits of this technology, both from a carbon capture and a sustainability perspective.”

Recently the company secured permit variations at all three of its operational facilities to enable it to handle different types of waste and increasing the range of materials authorised for processing. 

This has stood it in good stead for increased expansion on the global stage, with projects under way in both Australia and Japan.  

Mitsubishi Corporation recently named O.C.O as one of only four global companies to be part of its Green Concrete Consortium, with the goal of transforming CO2 into carbon negative concrete and aggregates, and work has already begun on a project to assess the potential for carbonating new waste materials, including slag waste from steel processing plants.

O.C.O Technology Ltd is a sponsor of the Energy from Waste Conference 2021. Find out more here and book your place here.

Energy from Waste

Editorial staff, Energy from Waste

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