Two new studies have outlined novel ways to capture small amounts of carbon, and which could be scalable for larger applications. In one study, investigators developed a system that uses bacterial cells to remove carbon from flue gases emitted in chimneys, and convert that carbon for other uses directly. In another report, scientists have created a type of ceramic material with bacterial cells inside that can detect low levels of formaldehyde in the air, or capture small amounts of carbon.
In this work, which was reported in Advanced Materials, scientists used 3D printed structures that could be stacked and can stand on their own. These spiral, ceramic structures carried pits of varying sizes, from about 20 to 130 micrometers. The smaller pits gave bacterial cells a home in the structure while the larger pits moved nutrients to the bacteria. By placing the structures into a solution, the bacterial cells could survive for long periods. The researchers determined that the bacteria could live for up to two weeks in this system.
By using different types of bacteria, the researchers were able to modify the structure for different purposes. For example, Esherichia coli bacteria was used to detect formaldehyde while photosynthetic cyanobacteria were shown to remove amounts of carbon dioxide from the air.
In an unrelated study reported in Nature Communications, scientists were also able to use bacteria to take carbon being emitted from a chimney, and convert it into a solid that can be stored. In one type carbon capture method, chemicals are used to remove carbon dioxide from flue gases, but instead of being processed with may additional steps, the researchers aimed to streamline this technology, and reuse the carbon directly in the carbon circuit.
Carbon dioxide within flue gases that are emitted from industrial chimneys are a major contributor to climate change. This carbon dioxide is also especially difficult to remove, the researchers noted, because it is mixed with other gases. It usually takes intense heat to isolate the carbon from other chemicals, making the entire process energy intensive and expensive.
But bacteria can absorb the carbon dioxide, and metabolize it, which also converts that carbon into other things. Bacteria might create methane in this process, for example, which could be then be directly applied. The bacterial cells also function at much lower temperatures than the heat-intensive processes that usually isolate carbon from flue gases. One drawback the researchers acknowledge is the need for hydrogen, which is required by bacterial cells and limits the expansion of this method.
However, there are potential solutions to that and other challenges. "We already have a wide range of different reactors to test—it's primarily a question of putting the system together correctly," said graduate student and study co-author Amalie Kirstine Hessellund Nielsen.
Sources: Advanced Materials, Aarhus University, Nature Communications