These capsules are tiny, but they promise to have a big impact in the fight against climate change.
Using the same baking soda found in most grocery stores, scientists from Lawrence Livermore National Laboratory, along with colleagues from Harvard University and the University of Illinois at Urbana-Champaign, have created a significant advance in carbon dioxide capture.
The team developed a new way to capture carbon by encapsulating a sodium carbonate solution in a shell made of a material similar to that of a silicone spatula. The capsules keep the liquid contained inside the core, and allow the CO2 gas to pass into the shell. The CO2 then reacts with the sodium bicarbonate (the main ingredient in baking soda,) where it is trapped before it can enter the atmosphere.
To date, microcapsules have been used for controlled delivery and release in pharmaceuticals, food flavoring, cosmetics, agriculture and more, but this is the first demonstration of using this approach for carbon capture.
This technology has a number of benefits over current methods. The sodium bicarbonate solution is more environmentally friendly than the caustic solutions used today. It can be mined domestically rather than being made in a complex chemical process. The microcapsules only react with the gas of interest (in this case CO2). And encapsulation dramatically increases absorption compared to traditional carbon capture techniques because the tiny beads mean more surface area for interacting with the CO2. Finally, baking soda can be reused forever, whereas current solutions break down in months or years.
The technique is not meant to be a short-term solution to carbon capture, but a broad, sustainable approach. The new process can be designed to work with coal or natural gas-fired power plants, as well as in industrial processes like steel and cement production. After filling, the capsules are removed from the flue gas and heated to remove the now-pure carbon dioxide gas. At that point it can be reused, like for enhanced oil recovery, or compressed and stored underground.
“We think the microcapsule technology provides a new way to make carbon capture efficient with fewer environmental issues,” said Roger Aines, part of the research team from Lawrence Livermore. “Capturing the world’s carbon emissions is a huge task. We need technology that can be applied to many kinds of carbon dioxide sources with the public’s full confidence in its safety and sustainability.”
The encapsulation process was developed as one of the Department of Energy’s inaugural Advanced Research Projects Agency-Energy (ARPA-E) carbon capture projects. Livermore scientists are now working on with the National Energy Technology Laboratory (NETL) on a way to incorporate the microcapsules into existing power plants and industrial facilities.