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.
