Interesting zeolite solar power system

Water molecules are a ubiquitous substance on the planet. However, according to the United Nations, more than 2 billion people do not have access to safe drinking water and more than 2.3 billion people, or 30% of the world's population, do not have enough to eat all year round.

Researchers at the Royal Abdullah University of Science and Technology (KAUST) in Saudi Arabia have developed a system that uses waste heat from solar panels to extract liquid water from the water vapour in the air. The system is a self-sustaining system that combines water/power generation/crop production. The results of the study are published in the 1 March 2022 issue of the journal Cell Reports Physical Sciences.

Solar energy is known to be inefficient, with less than 20% of the solar energy hitting the solar panels being converted into electricity. The remainder becomes waste heat generated during the power generation process, further reducing the efficiency of the electricity generated.

The research team has developed a system that uses this waste heat to produce water. The system uses hydrogels, which the research team has been working on for some time. Zeolites are highly hygroscopic, porous structures with interconnected polymeric structures that can store large amounts of water molecules inside. Zeolites do not require very high temperatures to release water. The waste heat released by the solar panels is only about 50 degrees Celsius above the air temperature, but this is sufficient to release water molecules from the hydrogel.

The system developed can be switched between two modes. One is the cooling mode, in which the hydrogel is always exposed to the outside air. At night, the hydrogel absorbs water vapour from the air and the next day, when the sun comes out, the waste heat from the solar panels releases the water vapour. Using thermal energy to cool solar panels and increase power generation efficiency.

In crop production mode, the hydrogel is only exposed to the atmosphere at night and sealed during the day. The water molecules collected at night evaporate and condense in the chamber during the day, producing liquid water. This water can be used as irrigation water for crop growing facilities.

In a three-month demonstration experiment, the solar panels increased their power production in cooling mode by up to 9.9 per cent. In addition, the water obtained in the crop production mode can be used to grow crops such as cabbage. The electricity generated by the solar panels is not used for water production or plant growth.

The system can produce two important resources, water and electricity, at the same time, potentially contributing to the water/energy/food nexus. However, the researchers say that the LDCs need sufficient funds to purchase high-tech solutions at this stage. While figuring out how to install them at low cost, they are seeking support from governments and NGOs, but the future is uncertain.