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Using Solar Heat to Create Clean Drinking Water

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Hello again iMechanica! My name is Ryan and I am the Founder of Mechanical Engineering HQ. I am writing today to share an interesting development in water sanitation technology. Scientists and engineers have developed a new solar powered water purifier that can create drinking water from wastewater and seawater. Read on to find out how they have achieved this!

Using Solar Heat to Create Clean Drinking Water

Solar heat has been used to develop an efficient membrane distillation technology that has the ability to create drinkable water from wastewater and seawater, by a group of researchers from the Korea Institute of Science and Technology (KIST). 

Membrane desalination technology means that the water is evaporated from seawater using thermal energy and is fed through a hydrophobic membrane that extracts water vapor from the seawater. The is a low-temperature process and requires relatively low energy, which makes it an environmentally friendly way to generate drinking water.

Solar energy is a renewable source of energy, and membrane distillation technology is powered by a heat source which in this case is solar heat. A solar absorber is used to collect solar light and therefore heat water. Solar absorbers in the past have had poor absorption performance and are only implemented in special areas with the right solar radiation conditions. The absorber needs to be physically large in size to obtain the necessary amount of solar radiation, the new technology solves these issues.

The new solar absorber is made up of thin layers of magnesium fluoride and titanium. It is manufactured using an electron-beam evaporator. It increases the water production and can absorb over 85% of the solar energy using a wavelength of 0.3 to 2.5 μm. The water is heated to temperatures over 80 degrees celsius.

Clean drinking water in a glass

When this heat was applied to the solar-driven membrane distillation, it created 4.78 L/m2 of drinkable water, this was made over 10 hours on a clear September day. This level of performance is significantly higher than its commercial solar-absorber predecessors, making it an invaluable product. The applications of such an efficient device are somewhat obvious with developing countries with water sanitation issues being those who would benefit the most from this technology.

 Another solution comes from the highly respected Massachusetts institute of Technology (MIT), U.S. They look to provide a simple solution to dirty water in places that lack reliable electricity but have access to seawater. Their device is cube-shaped, with multiple layers of solar evaporators and condensers piled one on top of another, surmounted with a layer of transparent insulation. Essentially it is a multi-layer solar still, similar to those used for centuries to make strong liquor and used today in many applications.

A solar still uses flat panels to absorb heat which it then transfers to a layer of water, which begins to evaporate. The vapor condenses on the next panel and the water is collected, while the heat from the vapor condensation is passed to the layer above.

The team stated that a system with a roughly one-square-meter solar collecting area could meet the daily drinking water needs of one person. In production, they think a system built to serve the needs of a family might be built for around $100.

These two solutions to dirty drinking water are an encouraging sign that one of the world’s most basic needs might be becoming more available to those who need it the most.

What do you think about this new water purifying technology? Let me know with a comment down below!

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