Capturing CO2 from the air has just got a major boost

2 November 2019

Here’s the thing about CO2 emissions: in order to keep manmade climate change in check, it won’t suffice simply to reduce our emissions. We’ll also have to sequester much of the carbon already in the atmosphere.

One simple way of doing so is to plant trees as forests and plants are great at naturally sequestering carbon. Then there are scientific attempts under way to capture and store atmospheric carbon. As part of that effort, researchers at MIT in the United States have built a special battery that absorbs carbon dioxide from the air and repurposes the gas, in its purified form, for useful applications.

The battery is equipped with stacks of electrodes coated with a compound called polyanthraquinone, which is composited with carbon nanotubes. The electrodes react well with CO2 molecules even when the gas is in low concentrations.

During charging an electrochemical reaction occurs the surface of each stack while a reverse reaction takes place during discharge, which helps power the system that operates at room temperature and with normal air pressure. During the process the battery purifies carbon dioxide, which can then be used in industrial applications.

At some soft-drink bottling plants, the scientists explain, “fossil fuel is burned to generate the carbon dioxide needed to give the drinks their fizz. Similarly, some farmers burn natural gas to produce carbon dioxide to feed their plants in greenhouses.”

Their new system, they say, could eliminate that need for fossil fuels in these applications and in the process take the greenhouse gas right out of the air. The purified CO2 thus gained could either be compressed and stored underground or else made into fuel.

“The greatest advantage of this technology over most other carbon capture or carbon absorbing technologies is the binary nature of the adsorbent’s affinity to carbon dioxide,” explains Sahag Voskian, who conceived of the system. The details of the system are explained in a new study.

“This binary affinity [of the electrodes in it] allows capture of carbon dioxide from any concentration, including 400 parts per million, and allows its release into any carrier stream, including 100 percent CO2,” Voskian says.

The scientist describes the system’s process of capturing and releasing carbon dioxide as “revolutionary” because it takes place at ambient conditions without the need for thermal, pressure, or chemical input. “It’s just these very thin sheets, with both surfaces active, that can be stacked in a box and connected to a source of electricity,” Voskian notes.

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