快猫短视频s are exploring whether a legacy of the UK鈥檚 polluting industrial past, the dozens of slag heaps that dot the country, could chart the way to a cleaner future by slowing climate change.
Since the industrial revolution, about half of the country鈥檚 slag 鈥� a stony by-product of making iron and steel 鈥� has been used as a construction material. But the other half is an unseen and unused potential resource, with in heaps, many now grassed over.
at Heriot-Watt University in Edinburgh, UK, is leading a team seeking to find out if those heaps can be used to help the UK achieve its climate goal of removing lots of carbon dioxide from the atmosphere. As an alkaline material, slag can react with CO2 in the air and lock it away in solid minerals, offering a long-term form of carbon storage.
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Two questions need answering : how much carbon could be stored and how to do it? To find out, Renforth and his colleagues in 2019, extracting about 1000 kilograms of slag to measure how much CO2 it was absorbing. The answer: not much.
鈥淵ou might think that that鈥檚 a disappointing result. But actually it鈥檚 quite a positive result [because we can improve it]. We have produced slag for a really long time. There鈥檚 evidence now that those legacy deposits could become a resource for CO2 removal,鈥� says Renforth. Along with other experts on , he is looking at ways to manipulate how much CO2 the slag absorbs.
One of the issues he found at the former steelworks was that the slag was simply not being fed enough CO2. One way to remedy that would be direct air capture machines akin to those being used by Swiss firm Climeworks in Iceland. Such devices could direct the CO2 they trap into slag, which would act as a storage medium like basalt rock does in Iceland. An alternative would be distributing the slag in engineered heaps above ground so that it is exposed to more atmospheric CO2 and therefore absorbs more from the air.
Exactly how either idea would work in practice is still being thrashed out, but Renforth has estimated there is the potential to cumulatively capture between 60 and 140 million tonnes of CO2, equivalent to up to a third of one year of . 鈥淪o maybe this could make an important contribution, but not a massive one鈥�, to UK CO2 removals, he says.
The idea might be attractive to the UK government, which has pledged to 鈥渓evel up鈥� regions that lag other areas economically, as most of the slag is in deindustrialised communities, largely in the north of England. Cumbria in north-west England is a hotspot. 鈥淭hat obviously has a lot of interesting political aspects to it. If you wanted to exploit that resource, you need to invest quite a lot into those communities,鈥� says Renforth.
Globally, there is much more potential for slag: Renforth estimates it could absorb around 200 million tonnes of CO2 a year. Stacked with all other alkaline industrial by-products, including those produced by making lime and cement, the number jumps to a billion tonnes a year, a symbolic but important threshold for large-scale CO2 removal.
