Carbyon’s Breakthrough in Direct Air Capture: Ten Times Better Technique for CO2 Removal

Carbyon received $1 million in prize money last April. The idea of ​​the start-up from Eindhoven was named one of the fifteen most promising ideas to reduce CO₂ to remove from the air. The award was great for publicity, the XPrize Foundation’s global innovation contests are prestigious, and tech billionaire Elon Musk funded this edition. But it was also uncomfortable.

“The idea had not yet been proven. Far from it”, laughs Hans de Neve, inventor and founder of Carbyon. “We had been trying to prove it for four years, nothing worked. It was still no more than a good idea.”

A breakthrough followed two months after the prize money. And now there has been a demonstration installation in Eindhoven for several weeks. De Neve now dares to say with confidence that his technique is ten times better than CO₂ from the outside air than existing techniques for direct air capture (DAC). “I think this could form the basis for a whole new generation of DAC technologies.”

Viewed with skepticism

CO₂ filtering from the outside air is difficult. Of every million particles in the air, only 420 are CO₂. It is captured by letting air flow past filters where the CO₂particles stick to it. When the filters are full, they are heated, causing the CO₂ releases and can be removed. Passing so much air and heating the filters takes a lot of energy – a reason why many people view these types of technologies with skepticism.

For Elon Musk, the high energy consumption (and therefore the high price) was the reason to ask the XPrize organization to organize a competition. Because suppose there is a way to generate a lot of CO with little energy₂ out of the air, then the climate may be salvageable and a range of possibilities will open up. Making cheap green kerosene, for example.

Carbyon’s technology works roughly the same as existing technologies, but faster. It’s in the filter. The adhesive layer of Carbyon is only one atom thick. As a result, it is saturated in a few minutes and empty again in a few seconds. Other techniques have a thicker adhesive layer, in which the CO₂ has to penetrate and that takes time. Heating also costs less energy with Carbyon. The thin layer heats up by energizing the filter, others require hot steam.

The idea for the thin layer was born when De Neve was still working at TNO. “I am a semiconductor physicist. At TNO I worked on thin film materials for solar panels. These are also applied in layers of one atom. I followed the domain of CO₂capture has been with interest for some time. At a certain point we thought that it should also be possible to filter materials for CO₂capture as thin as the thin films on solar panels.”

As large a surface as possible

It started in 2018 with experiments in a lab at TNO. “We thought quite quickly that we had it done,” says De Neve. “That is why I dared to take the step in 2019 to leave TNO and start Carbyon. But when I asked TNO for the latest results after a while, my former colleagues said: ‘Sorry, Hans, the previous results turned out to be incorrect measurements. It’s not working at all yet.’ That was a difficult moment.”

The difficulty lies in the porous material, on which applying a super thin layer turned out to be more complicated than on a flat solar panel.

“That porous material is necessary because you want to have as large a surface as possible, then you can absorb the most CO₂ on lost. Because the layer is so thin, it is quickly saturated,” says De Neve. Activated carbon is a suitable carrier, black powder that a layman may know as Norit. “One gram of activated carbon has a surface area of ​​3,000 square meters.”

I think three quarters of these powders do nothing at all

Hans de Neve Carbyon

The reacting layer, which consists of amines or potassium carbonate, is applied to the carbon using various processes. Atomic layer deposition is the most important of these. “You expose the carrier material to a gas and atoms from that gas settle on the carrier,” says De Neve. “The chemical process is self-limiting, in principle the layer does not get thicker than one atom. This is where it differs from classic vapor deposition technology.”

“But such a porous carrier material also has a disadvantage: the openings are only one nanometer wide,” says De Neve. “One nanometer, that’s a few atomic layers. They silt up very quickly, and that’s what happened all the time. Then the filter will not work, because the air where the CO₂ in it can no longer pass.”

Four years of trying followed. With different variants of the carrier material, different substances for the adhesive layer and different ways of applying the layer. Carbyon does not have an extensive lab, so De Neve sought collaboration with TNO and universities in Antwerp, Eindhoven and Twente.

Nothing at all

“A lot of work is done at universities direct air capturemore to CO₂ capture in flue gases. The general picture is still that DAC is unfeasible, I was told that from all sides when I started this,” says De Neve. “So we mainly work with researchers in the field of thin-film technology or certain chemistry. We went to collect puzzle pieces from the various universities.”

At Carbyon itself there are two test setups to test the filter materials. They are both one meter by one meter and two meters high. Behind a glass door, a variety of cabinets can be seen that are connected to each other and to a mass spectrometer via tubes wrapped in leucoplast. A lot of wires go to measuring equipment. Air is supplied from bottles to control the composition, temperature and humidity. On a table next to it, two bins full of jars of black powder, all variants of the filter material.

“Here we send air through the filter material and then we use the mass spectrometer to see what has happened to the air. How much CO₂ there has disappeared”, says De Neve. “I think that three-quarters of these powders do nothing at all. There are only a few that work.”

Further filter to 100 percent CO₂ others can do very well

Hans de Neve Carbyon

If the filter material works, the mass spectrometer shows a graph in an s-shape. The air would briefly be free of CO₂ should be, and when the filter is full, it shoots back up. “But we never saw that shape,” says De Neve. “Keep trying, I kept saying. The day we did see a careful s’je was really great, I still remember that phone call I got from the lab. We have already improved the result five times, but that first time was really a goosebumps moment.”

Now a demonstration installation is shining in a room further on. It was delivered at the beginning of April. Thick pipes run outside, but it does work with outside air. It is not switched on yet, a colleague of De Neve is working outside. The heart of the reactor is 30 by 30 by 30 centimeters in size. It takes 1 to 3 kilograms of filter material. The block can be seen at the front with the power supply to heat the filter material after saturation to remove the CO₂ to take out.

This relatively small thing has to produce 2 tons of CO per year₂ will be removed, with a (sustainably generated) energy consumption of 2,500 to 3,000 kilowatt hours per tonne. (Compare: the emission of a passenger car is 3.3 tons of CO₂ per year and ten solar panels generate about 3,000 kWh per year in the Netherlands). “If we can demonstrate that this works, then we have completely proven the original idea from 2018,” says De Neve.

The gas that leaves the installation consists of 60 to 70 percent CO₂, the rest is water, nitrogen and oxygen. “Then we have come from a concentration of 0.04 percent,” says De Neve. “That is really the hardest step. Further filter to 100 percent CO₂ others can do very well. We focus on getting it off the air.”

We aim for a cost price of 50 dollars per ton of CO₂

Hans de Neve Carbyon

The final installation that De Neve has in mind is many times larger. “It consists of 20 of these types of modules next to and above each other. A column of 2 or 3 meters in diameter, 5 or 6 meters high. We opt for modules like this and not one large reactor because everything has to go fast. If you make it big, inertia in the mechanical parts would hinder the speed.”

In terms of collection capacity, such a large installation comes close to what other major players in the field of direct air capture can now. Climeworks, a Swiss company, will commission an installation in Iceland in 2021 with a capacity of 4,000 tons per year. A new installation is in preparation, with an intended capacity of 36,000 tonnes per year.

Cost is crucial

“If we build an installation of a similar size to the existing installation of Climeworks, we could absorb 40,000 tons,” says De Neve. “The cost of the installation would be about the same, so our cost is ten times lower. Ultimately, we are aiming for a cost price of USD 50 per ton of CO₂.”

That cost is crucial. CO₂ from the air can serve as a raw material for sustainable kerosene, for example, but that only happens if it is available simply and cheaply. “The aviation industry is very interested in this direct air capture. Availability of CO₂ is still a bottleneck for making sustainable kerosene,” says De Neve. “As long as it costs $500 a ton, no one is going to make fuels with it. If it can be done for 100 dollars, it can be done.”

If it has just been taken out of the air with a lot of effort, it will happily fly back into the air. Why the CO₂ not store underground, as Climeworks does in Iceland? “Of course we are doing this to save the climate, not to support the aviation industry,” says De Neve. “But the first step is to replace fossil fuels with circular fuels. You can’t fly across the ocean with batteries, and people will continue to fly. Once you have replaced fossil fuels, you can use CO₂ storage and hopefully the share of CO₂ return to the air. I always say: first the tap must be turned off, only then does it make sense to start mopping.”