To curb the climate crisis, a lot of CO2 has to be taken out of the atmosphere. One approach comes from Karlsruhe, where high-tech raw materials are made from air – which are also in demand in industry.
It is the high-tech raw material carbon black that researchers at the Karlsruhe Institute of Technology (KIT) have literally produced from air. Using an apparatus, they suck climate-damaging CO2 out of the ambient air and produce carbon from it. Carbon Black is not everything, as Benjamin Dietrich from the KIT Institute of Thermal Process Engineering says. Depending on the temperature and pressure, graphite and graphene could also be produced – materials in high demand in industry.
Whether for the construction industry or the paint industry, for solar cells, touch screens, lithium-ion batteries, or car tires – the possible applications of these products are manifold. For example, the Association of the Mineral Paint Industry emphasizes the “excellent” UV protection and antistatic effect of carbon black, also known as industrial carbon black. In a study, the market research company Ceresana assumes that demand for carbon black alone will grow to more than 17 million tons per year worldwide by 2030.
Experiments with Temperatures between 900 and 1200 Degrees
In comparison, the half kilogram of carbon that the experimental plant at KIT produces from two kilograms of CO2 in an eight-hour working day seems rather puny, according to Dietrich. But the research team is only at the beginning: With different temperatures between 900 and 1200 degrees and different pressures, they are testing how they can influence the end products.
The whole thing works in a multi-stage process: With the help of a so-called adsorber, CO2 is separated from the air – this is called “direct air capture.” In the second step, carbon and oxygen are separated by chemical processes and form new bonds, resulting in methane and water. The methane contains the carbon, which is split off in a reactor with liquid tin. This process step is called pyrolysis.
In the project, called NECOC, the team is investigating how much energy is required and whether pollutants are produced as intermediate products, as Dietrich explains. Parts of the resulting hydrogen, for example, flow directly back into the methanation process. In the end, the process “only makes sense, of course” if the production of the necessary energy does not produce CO2, Dietrich admits – in other words, if renewable energies are used.
Purr: “A lot of potential”
This is also the view of Katja Purr, who heads the “Strategies and Scenarios for Climate Protection and Energy” department at the Federal Environment Agency: If renewable energies are used, the approach promises “a lot of potential for the future.”
According to Dietrich, it is also conceivable that emissions from the chemical industry, for example, could be purified using a standard scrubbing process and that the CO2 filtered out in this way could be fed directly into the second step of the NECOC process, i.e. methanation. However, this is not really the solution for the future, because the aim then is to work without fossil carbon sources as far as possible – keyword decarbonization. “Smokestacks must become fewer if we want to achieve the climate turnaround,” Purr also emphasizes.
The more pressing main problem is that there is too much climate-damaging CO2 in the nuclear sphere. That’s because carbon dioxide heats up the planet. The only way to get that out is through so-called negative emissions – that is, the removal of greenhouse gases, Purr makes clear. “We need negative emissions, there’s no way around it.”
Enormous amount needs to be taken out of atmosphere
However, a recent report by the Mercator Research Institute on Global Commons and Climate Change (MCC) found that the international community has a lot of catching up to do. Currently, only 0.002 gigatons (billion tons) of CO2 per year are being removed using new methods. In view of the climate targets, however, this figure would have to be 1,300 times higher by the middle of the century – averaged over various scenarios. To put this in perspective, global CO2 emissions last year were estimated at 40.6 gigatons.
Yet there are now several ways in which CO2 could be stored in huge quantities in the ground, for example, or even converted into stone. “Scientists believe that by capturing CO2 during the combustion of fossil fuels and then storing it underground, 65 to 80 percent of CO2 can be permanently kept out of the atmosphere,” the German Federal Environment Agency explains.
Carbon capture and storage is controversial
But the technology, known as carbon capture and storage, is controversial. It depends heavily on the subsurface, Purr explains. Close monitoring is needed to see that the CO2 really stays in the ground. In Germany, only research, testing and demonstration of such technologies is permitted.
In that respect, storing it in solid carbon, as with NECOC, may also be the safer option, Purr says. “This is the first time I’ve come across such an approach.” Dietrich of KIT also says the individual subprocesses have been developed and tested for some time. But, “The process network with its special challenges has been realized in this way for the first time worldwide, according to our current knowledge.” In addition, KIT occupies a leading position worldwide in liquid metal-based pyrolysis as an essential substep.
Greentech Process and CO2 Circular Economy
This fits in with current discussions: Because in the meantime, it is increasingly a matter of not only storing CO2, but reusing it. Shortly before Christmas, the German government decided to draw up a carbon management strategy this year. At a closed-door meeting in mid-January, the CDU’s federal executive board, for its part, spoke out in favor of a “genuine CO2 circular economy. Climate neutrality cannot be achieved by avoiding CO2 emissions alone.
However, NECOC is still in its infancy. The test plant, which KIT has built together with two companies, is constructed on a container scale. This is basic research. When asked when it could be used on a larger, relevant scale, Dietrich does not dare to make any predictions: “There are still some steps to be taken.
