Drinking Water from Solar Power

MASSACHUSETTS INSTITUTE OF TECHNOLOGY, MA, USA. A portable solar-powered desalination system may be an innovative and effective solution to the world’s declining fresh water reserves. Using sustainable solar power, this novel system is an inexpensive way of converting salt water into drinking water that can be used worldwide.

MIT researchers teamed up with Jain Irrigation Systems, a US-based manufacturing company, in developing this system. It works by utilizing solar panels to charge a cache of batteries that power an electrodialysis machine. This machine removes the salt from the water and makes it drinkable.

Solar-powered desalination plants are expensive to build, run and maintain. This made it an impractical solution to water shortages. The main success factor of this innovation is the electrodialysis process. It runs by passing a stream of water between two oppositely-charged electrodes. Since the salt that is dissolved in water consists of negative and positive ions, the electrodes pull the ions out of the water, thus, leaving the fresher water at the center of the flow. The freshwater stream is separated from the increasingly salty ones by a series of membranes.

Reverse osmosis and electrodialysis require the use of membranes. It is in the electrodialysis system that membranes are exposed to lower pressures. Thus, they can be cleared of salt build-up with the use of reversing the electrical polarity. The MIT system can convert 90% of the saltwater fed into the apparatus into potable water. This is an immense improvement compared to the 40 – 60% conversion from reverse-osmosis systems.

The MIT portable desalination system is cost-effective, energy efficient and environmentally sustainable. It is currently being tested in rural communities and has been set up as irrigation systems in small farms. This system has the potential to double the recoverable water in an environment where water is lacking.

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