We've already seen a number of technologies developed for capturing carbon dioxide emissions from smokestacks or other sources, but many of them have a limitation – in order to reclaim the captured CO2 for disposal, a considerable amount of energy is needed. Now, however, scientists at the University of California, Berkeley have developed a new carbon-capture material that requires far less energy in order to give up its payload.
The material is a type of metal-organic framework (MOF), which are composites made from metal and organic compounds. In this case, the metal is either magnesium or manganese (depending on the application) and the organic compounds are nitrogen-based diamines.
Like other MOFs, it has a porous structure featuring microscopic parallel channels.
When the correct temperature and pressure are maintained, CO2 molecules in air passing through those channels bind with the material. The process gets more effective as the filtration process continues, as subsequent molecules bind with those that are already trapped in the MOF.
The temperature at which it works can range from room temperature to over 100 ºF (38 ºC) depending on how the diamines are synthesized, while the required pressure varies with the type of metal used. Once the material is saturated, it can be made to release the CO2 molecules simply by heating it to a temperature that's a total of 50 ºC (90 ºF) warmer than the temperature at which they were captured.
By contrast, many power plants currently utilize a carbon-capture technique in which flue gases are filtered by being bubbled through water containing amines (of which diamines are one type), the CO2 molecules binding with them. In order to subsequently release the captured CO2 from the amines, however, the water has to be heated to a temperature of 120 to 150 ºC (250 to 300 ºF). According to the university, the whole process can sometimes consume up to 30 percent of the power generated at the plant.
Plans now call for the material to be tested in a pilot study at a power plant. Lead scientist Prof. Jeffrey Long also hopes that it could be used to purify the air in submarines, or even aboard the International Space Station.
A paper on the research was recently published in the journal Nature.
Source: UC Berkeley
