Berkeley Lab researchers are exploring technologies for direct air capture with promising potential to bring the cost reduction and large-scale adoption the industry needs to realize meaningful carbon removals.
Using seed money through a program known as the Laboratory Directed Research and Development Program, Berkeley Lab is funding an array of emerging technologies to remove and sequester carbon dioxide from the atmosphere. The Lab calls it the Carbon Negative Initiative which is its own effort to scale gigaton carbon removal.
The project includes an electrochemical approach to direct air capture. What is different in the approach is allowing the entire carbon capture process to run on renewable energy which eliminates the need for a thermal process.
Normally a thermal approach is used for the regeneration of the CO2 absorbent. That approach requires very high heat, around 800 degrees Celsius which is one of the main reasons why the direct air capture process costs that much.
On the back of a rough calculation, the researchers have estimated that if all goes well, the system can cost in the range of $100 per ton of CO2 captured. That is assuming they find ideal, cost-effective cell materials. Current costs of the technology fall in the range of $200 – $600 per ton of CO2 captured.
There are several challenges that also need to be addressed to allow for a lower cost. The first is the design of the electrochemical cell. The cell needs to be stable and robust to lead to energy efficiency that would lead to getting costs low.
The second requirement is the membrane. It isolates the two electrodes of the cell from each other, otherwise, the hydrogen and CO2 would get mixed up, and they’re needed as pure streams. Researchers currently use Nafion which has great performance but is expensive and therefore impractical at a large scale.
The third challenge is finding a great catalyst for the bicarbonate to CO2 reaction which means having a high reaction rate when a small voltage to the electrode surface is supplied.
According to Bryan McCloskey – a Berkeley Lab scientist, the team is confident that they will be able to make the proposed scheme work. “It’s just a matter of, do we get to that $100 per ton CO2, or is it somewhere closer to $1,000 per ton, which would not make it competitive?”, he added.
Even though there are still issues to be solved, the proposed direct air capture approach from the Berkeley Lab is showing proof to be less energy-intensive than systems currently in use and therefore, lower in cost. Optimization is one of the fastest ways that could accelerate the large-scale deployment of the technology.