Water. Desalination + reuse
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32 In Site September 2016 Water. desalination + reuse Latecomer Mascara shakes it up 5 Mascara president Marc Vergnet made an impact in water supply when in 1974 he invented a hand pump design that today supplies water to more than 50 million people, through 100,000 water points worldwide. "I retired and decided to set up a new company to try to make desalination only with the sun and without a battery," he says. Solar desalination system Osmosun was born, and has been welcomed by Masdar Clean Energy as a late addition to its pilot series on energy efficient desalination. The inital aim of Vergnet's new technology was to supply remote island communities with water. As well as the installation at Ghantoot, in September 2016, a new 80 m3/d project in Bora Bora, in French Polynesia in the South Pacific, is in sight, and there are ambitions for installations in Fiji, Vanuatu, and in the Indian Ocean, Rodrigues Island. "I have a dream to produce fresh water in Cape Verde, an island country in the Atlantic Ocean off the coast of West Africa," says Vergnet. The Ghantoot demonstration project is for a 40 m3/d unit, using a solar photovoltaic generator capable of producing peak power of 30 kilowatts, working eight to 10 hours a day. "It cannot work during night because we have no battery, no storage," says Vergnet. "It's the first time in the world that such desalination works. Many people have been working on this possibility, but nobody found it before us. The water in United Arab Emirates is 43 grams of salt a litre concentration, and we will produce fresh water at less than 20 grams a litre," he says. While many other solar desalination technologies exist on the market and in development, so far Osmosun is the only one that does not rely on energy storage. "Storage is expensive. When you store one kilowatt hour, it costs €0.8 ($0.9), and you need generally three to six kilowatts for one cubic meter, so you will pay, just for storage, €3 or €4 (£3.3 to $4.4) for one cubic metre of water," Vergnet says. The new system is unlike others because it can operate without constant energy. "Nobody has tested a system where the power at the beginning of the day is zero, it increases, and when the cloud is near the energy falls down 80 per cent, and then the cloud goes. Nobody knows how to work an RO system with this very variable energy, and we have succeeded with a very simple and reliable system," says Vergnet. When the sun begins to shine at the start of the day, the system starts up, and in the evening it stops, protecting and regenerating the membranes in fresh water. It uses smart technology to smooth pressure variations during operation, and the company claims it is able to produce potable water at an energy consumption rate of 2.5 kilowatt hours per cubic metre, assuming seawater with salinity of 35 grams a litre. "The key here is that it doesn't need electricity and it works without batteries, which is a very interesting aspect, because if you are very remote and very far from main activities, then battery replacement is always costly, tricky, and they need to be serviced. If you are really remote, then this system may be ideal because it can operate on its own without the need for specialist maintenance," says Dr Alexander Ritschel, head of technology, Masdar Clean Energy. "That's what we are trying to prove here, so it will be very interesting if it is successful. Also, it will not use any chemicals. If it works, it will be a great success. No chemicals, no batteries, no electricity, and we can still produce drinking water, just out of the sun." Inventor of water technologies Marc Vergnet adjusts the controls on Osmosun, his new solar-powered reverse osmosis desalination system that does not use batteries or energy storage, chemicals, or grid sup- plies of electricity. The system will be installed in Ghantoot as part of Masdar Clean Energy's pilot series, in September 2016. Vergnet previously invented a successful hand pump design. 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 0 10 20 30 40 50 60 70 Recovery (per cent) kWh/m Osmosun plant Conventional plant Small scale solar desal Unconventional Operating at a recovery rate signifi- cantly reduces energy consump- tion and enables desalination to occur from solar power without a battery.