The building industry has a significant climate footprint as one of the biggest industries on earth. To tackle it, microbes similar to corals are being developed to manufacture cement that is carbon neutral.
Considering that the construction industry has one of the greatest global carbon footprints, there is little to celebrate when new buildings are completed. Cement production in the industry alone released 2.9 billion tons of CO2 in 2021, or more than 7% of all CO2 emissions worldwide. As cement is heated, emissions happen because the release of CO2 occurs at high temperatures.
Making sustainably friendly cement
The solution to this issue is being worked on by postdoc Colleen Varaidzo Manyumwa and PhD candidate Chenxi Zhang, initially at the micro level. They were able to generate a particularly resilient species of bacterium to manufacture an enzyme with a highly desired characteristic by transferring genes from microorganisms into the bacteria. One of the key components of cement, limestone, or calcium carbonate, may be swiftly and effectively bound to CO2 by the enzyme.
"Ocean corals can also trap CO2 in the natural world, but the process can take a very long time. It merely takes a few minutes with our enzyme,“ says Manyumwa.
The research group is currently attempting to increase the production efficiency of the enzyme. They could potentially make carbon-neutral cement if they scale up their technology and apply it to industry. In order to ensure that the CO2 emitted is absorbed rather than seeping into the atmosphere, cement manufacturers are required to have a properly built bioreactor with the bacteria, also known as a cell factory.
The process will resemble a green circle in that the factory will release CO2 during heating, we will capture it in the bioreactor where it will bond to calcium carbonate, the factory will then reheat the calcium carbonate to create fresh cement, and we will once more capture the released CO2.
As the solution has only been tested in the lab, more tests and results are needed before the researchers can move to a true scale-up and make the assumption that they can produce cement that is carbon neutral.
Making the bacteria resilient enough to resist the harsh conditions and high temperatures they would encounter in the industry is the key problem. The potential is huge if the researchers, that also match with the goals of the global society, are successful with their endeavor.
"We have developed a solution that could prove to be quite beneficial for the building sector at first. Nevertheless, since our bacteria can produce calcium carbonate, they may also produce other carbonates that can be used, for instance, in the production of paper or in the pharmaceutical business. The potential is quite enormous, "Manyumwa says.
Despite the fact that there is still a long way to go from the laboratory microbes to the end result, he is inspired by the potential of his research.
The development of carbon-neutral cement through the use of microbial technology has the potential to significantly contribute to the achievement of the Sustainable Development Goals, particularly SDG 13 (Climate Action) and SDG 9 (Industry, Innovation and Infrastructure), by reducing carbon emissions and promoting sustainable infrastructure and innovation.