Until recently, turning a dry and hot desert into a green landscape might have sounded like a dream or a fairy tale. However, even in extremely dry and hot climates, the autonomous SAWER system can obtain water that can be used for human consumption, livestock watering or plant irrigation.
SAWER is used as a two-stage system, in which a desiccant is used in the first stage - a material that binds water vapor to its surface by adsorption. It removes the water content from the outdoor air and retains it on its surface. The dehumidified air is then led back into the outdoor environment.
At the same time, additional outdoor air with its natural water vapor content is sucked into the system, which is first heated to such a high temperature that it is possible to release water vapor from the surface of the desiccant and thereby moisten the desert air. Air at an elevated temperature can bind a larger amount of water vapor. Air that is significantly more humid than the outside air from the desert then arrives at the cooler. Thanks to this, the cooler can get much more water by condensation from the air.
The SAWER type unit uses a total outdoor air flow of 2000 m3/ha in a dry and hot desert environment (climate conditions of Riyadh) and produces an average of 100 liters of water per day in autonomous operation. If the device is connected to the network, the output is roughly doubled. In such an environment, the SAWER device has eight times higher water production compared to conventional purely condensing devices.
The main feature of the SAWER system is autonomous operation. The energy needs of the system are fully covered by solar energy (solar photothermal collectors, photovoltaic modules, heat and electrical energy storage). The by-product of the technological system is then hot water for showering and cold air for the building's air conditioning. It is therefore perfectly suited to areas where there is no infrastructure.
The SAWER facility consists of two container units. The production container contains a sorption unit, a water tank and a
potable water treatment plant. The production container can be connected to a three-phase electrical network and supply drinking
water separately. For autonomous operation, it is necessary to add an energy container that contains battery storage, heat
and cold accumulators and a solar roof built over both containers. By connecting the roof and containers, it is possible to
produce and deliver drinking water autonomously without connection to energy networks. The containers have external floor
plan dimensions of 2.4 x 6.0 m and a height of 2.9 m.
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Jiří F. Potužník came up with the idea of creating the SAWER system in February 2017 as part of the concept of the Czech Republic's participation in EXPO 2020 in Dubai, the central theme of which is harvesting water from the air and cultivating the desert into a fertile garden. In autumn 2017, the team of the University Center for Energy Efficient Buildings of the Czech Technical University led by Tomáš Matuška took over the professional development and implementation of the technology. Patents and licensing rights to the device therefore belong to this research institution.
In the summer of 2019, scientists from CTU UCEEB started trial operation of the system in the Sweihan desert in the United Arab Emirates. During six months of testing, they verified that SAWER can extract water from the air in a real desert environment, where it withstood high temperatures, fine sand and other adverse effects.
The knowledge gained during the test operation of the first prototype was used in the production of a more powerful device with a production capacity of 500 liters of water per day. In February 2020, this version of the SAWER system was sent on its way from the Bustěhrad laboratories of the Czech Technical University UCEEB to Dubai, where it will become part of the Czech Republic's pavilion at the World Expo EXPO 2020.
