To pray water using a solar water heater

Italian engineers have succeeded in developing an innovative and cost-effective technology used to desalinate seawater into drinking water, while directly utilizing the sun's heat

According to the estimate of the Food and Agriculture Organization of the United Nations (FAO), by 2025 almost two billion people will not be able to get a sufficient amount of drinking water to meet all their daily needs. One of the possible solutions to this problem is desalination, i.e. - converting seawater into potable water. At the same time, the removal of salt from seawater requires the use of ten to a thousand times greater energy than normal methods of supplying drinking water, that is - pumping water from streams or wells.
With this problem at their doorstep, a team of engineers from the Department of Energy at the University of Turin in Italy managed to invent a new prototype designed to desalinate water in a sustainable and economical way, using only solar energy and in a more efficient manner. Compared to previous solutions, the innovative technology is able, in practice, to double the amount of water produced within a given amount of solar energy, and it may be even more effective in the future after further experiments and developments. The research findings have long been published in the scientific journal Nature Sustainability.

The working principle of the innovative technology is very simple: "Inspired by plants, which conduct water from their roots to their leaves by capillarity as well as transpiration, our floating device is able to collect sea water with the help of a cheap porous material, thereby avoiding the need to use in expensive and cumbersome pumps. In the next step, the collected seawater is heated by solar energy, which causes the salt to separate from the evaporated water. The process can be further optimized by introducing membranes between the polluted water and the drinking water, this in order to prevent their re-mixing, similar to a number of plants that are able to survive in marine environments (for example, a mangrove plant)," explain the main researchers. While normal 'active' desalination technologies require the use of expensive mechanical or electrical components (for example, pumps or control and monitoring systems) while staffing the positions of dedicated technicians and maintenance personnel who are experts in the method, the desalination method proposed by the researchers is based on a process that occurs spontaneously without the assistance of any equipment , and therefore can be considered a 'tolerable' technology. All these facts make the device cheap and simple to install and maintain. These characteristics are especially important in those coastal areas whose residents suffer from a permanent shortage of drinking water and have not yet received central infrastructures and investments in them.

To date, a recognized disadvantage of 'tolerable' technologies within desalination methods has been their low energy efficiency compared to 'active' methods. The researchers overcame this drawback thanks to their creativity: "While previous studies focused on the desire to maximize the absorption of solar energy, we shifted the focus to more efficient management of the thermal energy collected from the sun. In this way, we were able to achieve record values ​​in terms of labor utilization of up to 20 liters per day of drinking water produced per square meter of area exposed to sunlight. The reason for this increase in efficiency lies in the recycling of the solar heat during several successive evaporation processes, within the concept of "doing more with less".

After developing the prototype for more than two years and testing it in practice at sea, engineers say this technology could have a positive impact on isolated coastal areas with little drinking water, but abundant solar energy, especially in developing countries. In addition, the technology is particularly suitable for the supply of safe and economical drinking water in emergency situations, for example, in areas that experienced flooding, floods or tsunamis and were then isolated for days or weeks and cut off from the electricity grid and water supply. Another conceivable application for this technology is floating greenhouses for growing food, an especially interesting option in densely populated areas. The researchers are now looking for collaborations with industry parties to make their prototype more sustainable, suitable for industry and versatile.
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