Carbon capture systems could become less expensive and more compact by using a mist of electrically charged droplets.
Capturing carbon dioxide from industrial facilities like power plants is seen as an important way to tackle climate change, but carbon capture technology is expensive. at the Massachusetts Institute of Technology and his colleagues devised a way to slash the price of the technology and make the devices smaller by fundamentally redesigning them.
They envision a system in which flue gas enters a container filled with a mist of microscopic droplets of potassium hydroxide. The CO2 in the gas reacts with these droplets to form water and potassium carbonate. These droplets then move to another part of the carbon capture device where there is a high electric voltage, so they become charged. The charged droplets are then attracted to a so-called collector electrode. In the final step of the process, the researchers envision the droplets being removed from the electrode, processed to remove CO2 and then reused.
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Current carbon capture systems are bulkier. They typically involve passing flue gas through towers filled with layers of metal mesh that are soaked with liquids that react with CO2. To capture the most CO2, the area where this reaction can happen must be maximised. This means using many mesh layers, which then necessitates towers up to 40 metres in height and 20 metres in diameter.
In a presentation at the California, Rufer said that based on a scaled-down prototype he and his colleagues tested in the lab, they estimate that their design could be 95 per cent efficient at capturing carbon dioxide, while measuring less than 4 metres long. This is because the surface area of the droplets in even a small volume of mist is vast, maximising the area for reactions more efficiently than using solid meshes.
Rufer said that their analysis also showed that the approach would reduce capital costs of adding carbon capture to power plants by about 2.6 times compared with current technology.
鈥淔or a typical plant you are looking at something that鈥檚 going to cost three quarters of a billion dollars, so anything that you can do to bring the cost down is going to help. And this is a really unique design鈥� says at Pacific Northwest National Laboratory in Washington state. However, using mists may present new challenges when making the devices large enough for actual power plants, he says.
at Cornell University in New York says that most existing carbon capture technology can be traced back to the 1930s, so a fully new design like using an electrically charged mist is exciting 鈥� even if some details of its practical application still need to be worked out.
