Drawing drinking water from desert air
Turning a dry and hot desert into a green landscape has until recently been a matter of dreams or fairy tales. The autonomous unit S.A.W.E.R. generates drinking water in the dry hot climate which can be used for consumption and feeding livestock.
The unit works using the principle of adsorption and desorption of air humidity. Its main part is the sorption unit with a desiccant exchanger that allows for dehumidification even of air with low content of water vapor that can be found in desert conditions. The unit takes the outside air in, dehumidifies it and returns the dehumidified air into the outside environment.
Afterwards, significantly smaller stream of air is heated to a high temperature, withdraws accumulated humidity from the desiccant, and becomes considerably more humid. High humidity from the air then condenses on the built-in cooler in the unit as liquid water. This way, it is also possible to get water in desert conditions where ordinary condensing coolers do not produce any.
The S.A.W.E.R. type unit uses the total flow rate of outside air of 2000 m3/h and its average daily production is 100 liters in the dry and hot desert environment (climatic conditions of Riyadh) in autonomous operation. If the unit is connected to network, its production is approximately double. In such environment, the S.A.W.E.R. unit production of water, as compared to ordinary condensation-only units, about eight times higher.
The S.A.W.E.R. unit can be operated in a totally autonomous way without the need of energy from external sources. The energy for its operation is taken from the local environment: electric energy for powering the cooling unit and fans is taken from photovoltaic panels, heat for heating the air is taken from solar thermal collectors, and cold for pre-cooling the air is taken from combined photovoltaic/thermal collectors used for cooling in the nighttime. The operation is complemented with the energy storage in the form of battery repository and heat and cold storage tanks. Therefore, the S.A.W.E.R. unit is suitable for areas without any infrastructure at all.
The S.A.W.E.R. autonomous unit consists of two containers – production and energy. The production container comprises the sorption unit, water reservoir, and a plant for treatment of the drinking water. The production container can be connected to three-phase electric network and the water can be produced without energy container. For autonomous operation, it is necessary to add the energy container which comprises the battery repository, storage tanks for heat and cold, and the solar roof constructed over both containers. By connecting the roof with the containers, it is possible to produce and supply the drinking water autonomously without a connection to energy grid. The outside dimensions of the containers in the top view are 2.4 × 6.0 m and the height is 2.9 m.
The latest news
Scientists from the University Centre for Energy-Efficient Buildings of the CTU launched the S.A.W.E.R. system in United Arab Emirates in summer 2019. The testing of the system will run in the Sweihan desert in UAE for about six months so that data from operation in extreme summer conditions as well as in autumn and winter are available. During this time, the creators led by Tomáš Matuška want to check how S.A.W.E.R. stands the test in the real desert environment where it will have to resist high temperatures, fine sand and other unfavorable influences.
UCEEB technical project management team
- Tomáš Matuška – Energy Concept
- Vladimír Zmrhal – Air Handling Technology
- Bořivoj Šourek – Design and Construction
- Petr Wolf – Photovoltaics and Battery
- Pavel Pelán – Control and Monitoring
Czech oasis at the Expo 2020 in Dubai
Experience gained from the test operation will be used by engineers when designing the device for the Czech pavilion at EXPO 2020 in Dubai where it should be installed next year.
This unit with the production capacity of 500 litres of water per day that uses the same technology as the container version is designed as a part of the pavilion technology and it will irrigate the oasis growing from the sand around the pavilion. More about EXPO 2020
Materials and prospects