New Carbon Capture Method is the Best of Both Worlds

Researchers have developed a new way to capture carbon that is the best of both worlds, for it is both cost-effective and energy-efficient, a new study describes.

Carbon capture is a process by which waste carbon dioxide (CO2) released by factories and power plants is collected and stored away, in order to reduce global carbon emissions. And with greenhouse gas levels hitting a record high in 2013, refining this process could prove extremely useful in the future.

There are two major ways of carbon capture today: one using powder-like solid materials which "stick" to CO2, and one using liquids that absorb it. Despite their potential environmental and energy benefits, current carbon capture strategies entail exorbitant costs because of engineering demands, cost and overall energy-efficiency.

But a team of scientists from Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, UC Berkley and Beijing have combined the two conventional methods to create a new approach that incorporates the best of both worlds. They developed a "slurry" that, as a liquid, can be implemented easily on a large scale, while maintaining the lower costs and energy efficiency of a solid carbon-capturing material.

The breakthrough method is described in the journal Nature Communications.

Typical carbon capture methods use liquid amine solutions, which can absorb CO2 from the atmosphere using two columns, one for capturing CO2 and one for releasing it from the liquid. But this process, called "regeneration," uses up a lot of energy since CO2 is so tightly bonded to the amine molecules.

So, an alternative is using solid materials called "metal-organic frameworks" (MOFs) - fine powders whose particles are made up of metal atoms that are connected into a 3-D structure. Using MOFs may cost less, but it has high engineering demands given that it requires the transportation of solids.

"Imagine trying to walk with a plateful of baby powder. It's going to go everywhere, and it's very difficult to control," Berend Smit of EPFL explained in a press release.

The solution? A material called ZIF-8 and the liquid glycerol. ZIF-8 has chemical and thermal stability, which is important for repeated regeneration cycles. It also has extremely narrow pores, smaller than those of the glycerol molecules, which makes it very efficient at capturing carbon.

Because it combines the low cost and efficiency of nano-porous materials with the ease of a liquid-based separation process, the slurry proves to be a success, and will soon be tested in real-life situations.