Research project

Development of a compact system for independent and continuous solar sorptive water harvesting from the air in arid regions

Brief description

In the "AirWater" cooperation project, a compact, site-independent system is to be developed that operates without electricity and enables the continuous extraction of water from the air with minimal use of electrical power in arid regions.

According to the UN World Water Report 2020, some 2.2 billion people do not have access to safe drinking water. Consequently, about one sixth of the world's population is affected by severe water scarcity, especially in remote regions with arid and semi-humid climates. The water content of the air in the entire atmosphere is 13,000 km³, of which only the air layers close to the earth can be used, but this still offers great potential for the production of drinking water, as this source is accessible everywhere.

One way of harvesting water from the atmosphere and extracting it from the ambient air is condensation by radiation cooling against the cold of the night sky or direct condensation of water by an electrically operated cooling machine. Neither of these methods is suitable for arid areas due to the low water content of the air for drinking water production. These systems are associated either with a low yield (0.12 to a maximum of 3 l of water per square meter of collector surface or PV surface) compared to the relatively large equipment and financial expenditure required for this, or with a high energy input to cool the air adequately and then dissipate the enthalpy of condensation. The existing concepts for obtaining water by sorption and solar radiation can be operated mainly during the day and therefore only intermittently.

The innovation of this development is a continuous operation based on sorption and thermal cooling. This is made possible by a decoupled and only air based process.

The water contained in the air is obtained through a process which consists of adsorption, desorption and subsequent energy-efficient condensation. The cooling of the air with a water content of almost 70% allows the condensation of the water by cooling against the ambient temperature without the expenditure of electrical cooling energy. New high-performance sorption materials such as MOFs are used for the water extraction process.

Continuous operation of the plant is achieved by decoupling heat generation and desorption. The adsorption and desorption processes can run in parallel due to the use of at least 2 sorption beds, as one sorption bed can be used for each process. With the help of special vacuum tube air collectors, which produces at very high temperatures, it is used both for desorption and for charging the heat accumulator. The heat accumulator allows operation out of daylight hours and the entire process can run continuously.

The process is designed to obtain as much water as possible in a single cycle (adsorption, desorption and condensation). The goal is to provide water harvesting independent of an electricity connection in continuous operation (24h per day), in very arid areas.

System for drinking water production
System for drinking water production




01/2021 – 12/2023


Project Partners

HydroTec Gesellschaft für ökologischeVerfahrenstechnik GmbH
Roland‐Dorschner‐Straße 5
95100 Selb

Richter & Stegner Steuerungstechnik GmbH
Grün 34
95195 Röslau


This image shows Dr.-Ing. Henner Kerskes

Dr.-Ing. Henner Kerskes


Team Lead

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