The direct capture of CO₂ from ambient air is considered a key future technology for climate protection. However, a new study shows that the choice of location and weather conditions have a major impact on efficiency and costs. For the first time, researchers from Jülich have calculated where such systems would be viable in Germany – and where they would not.
Each citizen in Germany is currently responsible for an average of around ten tonnes of CO₂ emissions per year. That is roughly equivalent to the emissions from four round-trip transatlantic flights between Frankfurt and New York, or the amount that 500 trees can absorb during one year of growth. In view of Germany’s ambitious climate targets, which aim to achieve greenhouse gas neutrality by 2045, there is a growing focus on new technologies that actively remove CO₂ from the atmosphere. One of these technologies is direct air capture (DAC).
The Jülich Research Centre (Forschungszentrum Jülich) is currently researching DAC – from the materials, components and systems through to their integration into energy infrastructure and climate protection strategies. Scientists at Jülich have now conducted the first comprehensive study of how weather and location influence the economic viability and energy consumption of such DAC systems. The results show that local conditions have a significant impact on efficiency and costs in some cases, meaning that a blanket rollout of DAC across the country would make little economic sense.
All methods are highly energy-intensive
DAC systems draw in large volumes of air, extract CO₂, and store it for a long time – for example, in underground storage sites. “Two technologies are considered particularly promising,” explains lead author Henrik Wenzel from Jülich Systems Analysis: “One is the solid sorbent-based adsorption process (LT-DAC), which requires comparatively low temperatures of around 110°C to regenerate the filter materials, and the other is the liquid solution-based absorption process (HT-DAC), which requires higher temperatures of around 900°C. However, both methods are energy-intensive, which is why their integration into a renewable energy system must be carefully planned.”
In their study, the researchers calculated how the temperature, humidity and the potential for wind and solar energy impact the performance and costs of DAC systems for all 11,000 German municipalities. They used a high-resolution model that simulates the interaction between weather, the renewable energy supply, and DAC system operation on an hourly basis. There was a focus on stand-alone systems, which operate completely independently of the power grid using locally generated wind or solar power.
Between 200 and 1,000 euros per tonne
The results reveal striking differences: the energy demand of DAC systems in Germany can fluctuate over the course of the year by more than 100%, primarily due to temperature variations and differing humidity levels. “Even within a single day, the energy demand of DAC systems can vary by up to 80%,” says Wenzel. “Particularly high humidity significantly increases the energy consumption of LT-DAC systems, whereas HT-DAC systems benefit from it.” The potential for wind and solar energy also plays a pivotal role as these types of energy can supply the systems at a cost-effective level.
The most economically viable sites are located in northern Germany, where wind energy is particularly abundant. “However, low costs can also be achieved in other regions of Germany with good solar and wind energy locations, as a combination of these energy sources can efficiently cover the fluctuating energy requirements of DAC systems,” explains Wenzel. Depending on the location and technology, the costs for extracting CO₂ in 2045 could vary between just under 200 and over 1,000 euros per tonne. “Which of the two examined DAC methods is respectively more cost-effective depends on the regions under consideration and their location and weather conditions,” explains co-author Thomas Schöb. “Both methods should therefore continue to be developed to ensure that sufficient capacity is available.”
Not a free pass to continue emitting CO₂
The researchers stress that DAC can be a valuable lever for climate protection – but only when deployed in regions where weather and energy conditions complement each other optimally. “Our study shows that the location is crucial if we want to efficiently remove CO₂ from the air,” explains Schöb. “It is essential to analyse regional weather conditions and energy potential in detail to ensure cost-efficient and sensible use.”
Even if technologies such as DAC alone will not be enough to neutralise Germany’s current carbon footprint (around 10 t per capita), they can – when used strategically – help offset unavoidable residual emissions. However, the study also makes it clear that such solutions are not a free pass to continue emitting CO₂. They require a great deal of energy, are costly, and must be carefully planned. Measures to avoid emissions therefore remain the most important lever for effective climate protection.
Source: Jülich Research Centre (Forschungszentrum Jülich)
