Recycling CO2 instead of emitting it into our atmosphere is one of the possible solutions to reduce our greenhouse gas emissions. But we need proof that this technology is industrially viable.
What if it was possible to recycle CO2? This is the innovative idea sought out by several researchers and start-ups around the world, including the French company Carboneo, created in December 2020. Their objective: to transform CO2 into CO (carbon monoxide) and oxygen. Carbon monoxide is a very useful molecule for the chemical industry, it could serve as a building block for new products or fuel.
An industrial pilot as early as 2025
The idea is to capture CO2 where it is concentrated, meaning on industrial sites such as cement or steel factories, or the chemical industry, and then to produce carbon monoxide. Afterwards, the CO can be reinjected into the industrial process or sold. The technical procedure is performed electrolytically (unlike a battery) and therefore consumes electricity. On one of the electrodes, the CO2 is reduced to CO, while on the other, water is oxidised to form oxygen.
Even though the concept is appealing, it will not be industrially viable right away. The proof-of-concept was provided in 2019 via an article in the journal Science1 published with Canadian researchers, but the challenge is now to upscale. With this goal in mind, Carboneo is joining the business incubator Accelair of Air Liquide, at Jouy-en-Josas (Yvelines, France). “Laboratory and medium-sized pilots are under development, and we plan to build an industrial pilot in 2025”, says Marc Robert, professor at the molecular electrochemistry laboratory of the Université de Paris (CNRS), and co-founder of Carboneo.
No rare metals
The advantage of the technology developed by Carboneo is its simplicity: the catalyst does not contain any rare metals, only abundant elements like iron, cobalt and carbon. The electrolyser operates at ambient temperature and pressure, and the electrolyte is water, which avoids pollution. Finally, forming the electrode is simple: the catalyst, mixed with carbon ink, is deposited on a paper-based electrode, which is dispersed when the ink evaporates.
The different pilots will have to show that the electrolyser also works at a larger scale, can remain stable for long periods , and that costs and maintenance are managed. It is a difficult task, because for the moment they only know how to transform a few milligrams of CO2 per hour. Whereas the objective is to reach a few dozen kilograms per hour in the pre-industrial pilot.
What energy and financial cost?
Nonetheless, recycling of CO2 is not a miracle solution. We cannot toss aside efforts to reduce CO2 emissions. To give a sense of scale, CO2 emissions due to industry (including the manufacturing industry, energy and waste processing) amounted to 133 million tons in 2019 in France2. But to recycle 1kg of CO2, you need between 4 and 7kWh of electricity depending on the performance of the electrolysers. Recycling all the CO2 emitted by the French industry would consume between 532 and 931 terawatthours (TWh), which is more than total French electricity production for that same year (537,7TWh)!
That being said, all solutions must be considered to reduce CO2 emissions in the atmosphere. The main question will be the cost of this technology. “Today, CO2 costs almost nothing: 50€/kg at most. But the carbon tax should triple by 2030, it will become expensive for industry” points out Marc Robert. Will that make the recycling of CO2 cost effective? The future of this technology will depend on policies around the price of carbon and emission reduction obligations.