Direct Air Capture technology: extracting water and CO2 from the ambient air

The idea of Direct Air Capture - DAC for short - is not new. Two and a half decades ago, in 1999 to be precise, Klaus Lackner, a German physicist working in the USA, first proposed extracting carbon dioxide from the ambient air. The incessant rise in CO2 emissions caused by human activity and the resulting increase in global temperatures have brought direct air capture technology increasingly into focus in the fight against global warming in recent years. The first DAC plants already exist, for example in Switzerland, Iceland and the USA. However, the technology is still in the development stage - and the results achieved are still quite limited and very cost- and energy-intensive.

A new approach to direct air capture

What must a DAC process fulfill so that it can really be rolled out everywhere globally? Where are the weaknesses in the existing systems? And above all: what can be done better?

With questions like these in mind, the Obrist engineers sat down with the German chemist Prof. Robert Schlögl, former director of the Fritz Haber Institute, the Max Planck Institute for Chemical Energy Conversion and now President of the Alexander von Humboldt Foundation, analyzed existing systems and looked for new approaches. In doing so, they always had the principle of company founder Frank Obrist in mind: it must not only be different, but better. In line with this principle, the industrial group from Lustenau in Austria is already on different areas actively involved.

"Our analyses showed that the system must be feasible with cheap materials that are available everywhere and at all times. It must also be a continuous process - without constant switching on and off. The system must work with thermal energy at comparatively low temperatures and, of course, it must function in the Earth's sun belt, where electricity is available. The process must also be stable and scalable. We have found a solution that offers us a number of advantages over our competitors," explains Frank Obrist. 

Extracting not only CO2 but also water directly from the air

Keyword sunbelt: One of the Obrist team's basic requirements was not only to extract pure CO2 from the air, but also water - even in the driest conditions. This is an enormously important factor, which also represents a significant advantage over the competition, according to Obrist. Due to their design, conventional systems constantly release water into the environment as a result of their chemical process. It is easy to understand why this is fatal in desert regions. Obrist DAC, on the other hand, can actively extract water during the process.

Higher energy consumption, but very manageable costs

A comparison of the energy requirements of the Obrist DAC with the systems of other manufacturers shows that the energy consumption of the Obrist solution is around 20 to 50 percent higher than that of the competition. However, the Obrist technology can be operated in the Earth's sun belt and therefore with comparatively affordable energy - less than 1 cent/kWh. Another advantage over competitors whose concepts are not designed for this. Obrist technology also requires heaps of thermal energy for certain process sequences. However, the Obrist engineers have calculated that a large proportion of the thermal energy can be recovered as waste heat from the methanol synthesis. In combination with the use of solar thermal energy, the costs are significantly reduced once again. The costs of building the plant are also lowwww.obrist.atSince Obrist DAC does not work with high pressures, the system can be built quite simply from plastic and therefore in more remote areas of the world. The first test plant, which demonstrates the process under laboratory conditions, is in operation in Lindau on Lake Constance. 

Source and further information: www.obrist.at