An alliance of construction and property giants is hoping to kickstart development of greener concrete by pledging to buy only concrete with net-zero carbon emissions by mid-century.
A crucial material in cities and the built environment, concrete is responsible for 8 per cent of global CO2 emissions. Emissions from cement, the glue that holds concrete together, were .
Now a group of 17 companies, including , 听补苍诲听, have formed a coalition pledging that one-third of the concrete they use by 2025 will be a low-emission version, rising to one-half by 2030. They also intend to use only net-zero concrete by 2050. The group is modelled on previous initiatives for and that were designed to show there is market demand for lower carbon options.
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鈥淐oncrete is a huge part of global emissions. What we are aiming to do is put a really big collective demand signal there, which gives confidence to innovators, to investors. It鈥檚 about saying the market is coming for zero carbon solutions, and we鈥檙e ready to buy it,鈥� says at Climate Group, the non-profit organisation that has organised the campaign.
The problem with decarbonising concrete is there are currently no solutions on a large enough scale. The chemical process of making cement is inherently carbon-intensive and usually requires huge amounts of fossil fuel-powered heat. However, researchers and companies are making progress, such as and so less concrete is needed to build a given structure.
There are also efforts to develop technology to capture and store the carbon released when limestone is heated and crushed to make cement. Clarkson says there will be a role for carbon capture and storage (CCS), but downplays how big it will be: 鈥淐CS has not been proven yet, we don鈥檛 have it at scale. It comes into that kind of, 鈥榙on鈥檛 worry, we鈥檒l wave a magic wand鈥� sort of category.鈥�
of property developer Joseph Homes, one of the initiative鈥檚 founders, says in the short term people are looking to cut concrete emissions by using fly ash, a by-product of coal power stations, as a replacement for some of the cement in the concrete. But fly ash deposits are finite and declining, so innovations will be needed long term. He says volcanic ash may offer a fly ash alternative and points to start-ups such as California-based , which is using concrete to store CO2. 鈥淚t鈥檚 going to cost more in the short term,鈥� he says of buying low-carbon concrete, but he thinks some of that extra cost could be offset by design choices that use less of the material.
鈥淚 don鈥檛 think there are a huge number of direct alternatives to Ordinary Portland Cement [one of the most widely used type of cement],鈥� says at Imperial College London. He thinks focusing on developing carbon capture and storage to decarbonise the cement might be more sensible 鈥� although he adds that the initiative to lower emissions from concrete is 鈥渁 good idea in general鈥�.
Part of the alliance鈥檚 job will be to define what 鈥渘et-zero concrete鈥� means, as there is no universally accepted standard. Clarkson says she hopes the new initiative will be followed by similar alliances in China and India, where demand for concrete is high.
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