CO2 Capture – A worthwhile goal or pointless?

27-09-2021 |   |  By Robin Mitchell

Recently, Iceland unveiled the world’s largest carbon capture and storage system to help reduce the overall amount of CO2 in the atmosphere. How does carbon capture work, what is Iceland planning to do, and is carbon capture a pointless effort?

How does carbon capture work?

The idea behind carbon capture is to remove excess carbon dioxide from the atmosphere with the idea that reducing the levels of CO2 will help to slow down the greenhouse effect. However, removing CO2 from the atmosphere is no small feat and can require large amounts of energy to do so efficiently.

Since the industrial revolution, the amount of CO2 in the atmosphere has risen from 300ppm to 400ppm. While this is a significant increase, 400ppm translates to only 0.4% of the atmospheric contents. As such, any system that tries to extract CO2 from the air would be doing so from a very dilute source, and therefore difficult to do so efficiently.

Multiple technologies exist for removing CO2 from the air, with some of the more common forms including chemical absorption, mechanical storage, and cryogenics. Chemical absorption can use materials such as calcium oxide that bond with CO2 to form a byproduct stored underground or in containers. Cryogenic extraction methods turn air into a liquid, and since different gasses cool at different temperatures, they can be used to remove CO2.

Trying to extract CO2 from the air itself is somewhat of a complex, tedious, and expensive task due to the low concentration of CO2 in the air. This is why many carbon capture technologies try to place themselves at the source of CO2, such as the chimney of a power station. Filters are already installed to reduce particulates entering the atmosphere, such as dust, soot, and volatile compounds, and CO2 capture technology would be highly efficient at such locations.

Iceland unveils world’s largest CO2 capture system

Recently, Iceland unveiled its Orca CO2 capture system, boasted as the world’s largest yearly capacity of 4000 tones. The system is a direct-air capture device meaning that it cleans the air immediately around it, and this air is mixed with water which traps the CO2. This water is then pumped underground, where it mineralises over a period of two years, essentially turning the CO2 into rock.

The Orca system is not only able to extract CO2 directly from the air, but it has also been designed with modularity in mind, and each Orca system is housed in a rectangular stackable form. Furthermore, to ensure that the system is efficient as possible, it has been placed next to a geothermal plant so that all energy used by the system is sourced renewably.

Is carbon capture worth it?

While it would seem to Orca that direct carbon capture from the atmosphere is a worthwhile project, some factors need to be considered. The first is that such a system requires energy. Considering that renewable energy is currently limited, diverting it all to try and remove CO2 is somewhat counterintuitive; create renewable energy to remove CO2 produced by burning fossil fuels to produce energy. In this scenario, the CO2 could be entirely eliminated by simply replacing a non-renewable power station with a renewable one.

The second factor to consider is that carbon capture is most efficient when capturing at the source. Such a system may be better used if placed next to power stations and directly connected to chimneys. Trying to capture CO2 from Iceland, where CO2 is already produced in minimum quantities, is an odd experiment to run.

The third factor that needs to be considered is that such technologies could encourage other countries to produce more CO2. Simply put, if one nation devotes itself to removing CO2 from the air, another nation could increase its CO2 output knowing that someone else will remove it.

CO2 capture is a noble idea, and doing so at the source of CO2 production does make sense. However, such technologies need to be examined on their energy efficiency, how much CO2 they remove, and how much energy they consume to do so. Trying to remove CO2 from the atmosphere when the original power source of the extraction system could just replace the CO2 source is counterintuitive and virtue signalling.


By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.

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