Global greenhouse gas emissions are still increasing in 2019. It’s important to achieve zero emissions as soon as possible to prevent global warming from reaching an irreversible point. In addition to reducing emissions from industrial activities, negative emission technology (the technology that captures and stores carbon from the atmosphere) plays an indispensable role in achieving mitigation targets.
In a study led by Zhu Liu, some common materials in our daily lives could achieve "negative emission," for instance, cement. Globally, the weathering process of cement materials have sequestered 16.5 billion tons of carbon dioxide from 1930 to 2013, which indicates that on a global scale, cement materials have a significant carbon uptake during their life cycle. It is estimated that the carbon uptake of cement in a 100 year life cycle can offset 40% of emissions released during the cement production process.
Although there is still a long way to go before achieving "zero emissions" for cement production, considering its energy intensive production process, some ideas to enhance cement's carbon uptake have emerged, such as increasing the surface of cement materials to speed up weathering. Another idea is that if we can increase the porosity of concrete without wreaking its structural strength, we can also enhance the carbon uptake. In addition, the reuse and recycling of cement materials will also increase its carbon uptake.
Zhu Liu's research on "Substantial Global Carbon Uptake by Cement Carbonation" was published in Nature Geoscience as the cover paper in 2016. It proposes the concept of "anthropogenic carbon sink," which is listed as one of the nine main carbon uptake processes by Nature.
Zhu Liu’s team is still looking for other materials, particularly those generated by human activity, with the potential to absorb carbon dioxide. Recent research by the team has found that replacing construction materials with wood can also achieve carbon uptake for the long term. Some of the cement-like artificial alkaline minerals, such as blast furnace slag, lime, and dust, can also be carbonized through the weathering processes, but the total amount of the absorption may not be as large as cement.
In addition to cement carbon uptake, Zhu Liu's research also focuses on providing more comprehensive and accurate global carbon data through interdisciplinary technology. These studies are of great significance to sustainable development and ecological construction.