Extracting CO2 from ambient air is a daunting challenge, but it’s not impossible thanks to a number of recent technological developments, including the development of CO2 sorbent materials that can be desorbed at low temperatures.
Currently, the concentration of CO2 in the air is 0,04%. This is 250 times less than a 10% CO2 concentration in flue gases. So, extracting CO2 from ambient air would take only 2-3 times more energy than extracting it from a concentrated waste stream such as post-combustion.
The lower energy limit for extracting CO2 from air is 125 kWh per ton of CO2. However, real-world gas separation processes only achieve efficiencies up to 5%, which brings the energy required for CO2 capture from air closer to 2500 kWh per ton of CO2.
This is the stage where Carbyon comes in.
Carbyon designed a system to capture CO2 from the air by using a thin film originally developed for solar PV applications. The film is a porous structure with a large interior surface, which is coated with a solid state sorbent for CO2.
When we send air with a concentration of 0,04% CO2 through this thin film, all CO2 molecules stick to the sorbent at the interior of the porous structure, and CO2-free air comes out at the other side.
The CO2 molecules which stick to the film can easily be released again by heating up the sorbent, leveraging the advantages of solid state sorbents that can be regenerated at low temperatures.
This approach has two major advantages:
- The pressure drop of air going through the thin film is extremely low, which means the energy budget to move air across the active medium is much smaller than in conventional approaches
- The thermal mass of the thin film is very small, which means the thermal budget to regenerate the active medium is also much smaller compared to conventional approaches.
In this way, Carbyon drastically reduces the energy required to extract CO2 from ambient air, greatly reducing the costs of this process and making it economically viable.