In Depth: The 'miracle turbine' that can turn wind into water
French technology start-up Eole Water is on track to erect a wind turbine in the United Arab Emirates that can produce hundreds of litres of drinking water a day from the dry desert air.
Tests on a ground-mounted prototype of its water maker system (WMS), which began in October in Mussafah, on the outskirts of Abu Dhabi, have shown it to be capable of flowing 500-800 litres daily.
But Eole Water believes this volume can be tuned up to levels of well over 1,000 litres with a tower-top system, and the company has hopes of scaling up the technology for use by industry and off-grid communities.
“The process is based on the same experience you see after you have taken a shower and every surface is covered with condensation — we do the same with the WMS1000 but just on a much larger scale,” says Eole
Water marketing director Thibault Janin. “The prototype is not yet on a mast because we wanted to check that it could operate in difficult desert conditions first — and so far the results have been very good. And would be even better, of course, if it was placed in coastal or offshore areas where there is higher humidity and more wind.”
Eole chief executive Marc Parent dreamed up the concept in the 1990s while working as an engineer in the Caribbean, where he had been reducing his bottled water costs by siphoning the condensation from his air conditioner.
Janin says it was then a “short step” to refashion the technology as a wind-powered device by hooking it up to a turbine, creating a system that generated both power and potable water.
Along with the 1,000 litres of drinking water that will be produced per day, the turbine generates 30kW of electricity to flow the water to the storage tanks and power the purification system. Efficiency rates of 50% (of available water extracted from a given volume of air) have been reached with the prototype.
Under full-time development since May 2010, the technology has attracted huge interest among industrial players, and partnerships have been forged with about 40 companies, including Emerson, Siemens, Danfoss, Carel and Arcelor Mittal.
The water-generating turbine — which is the size of a standard 300-500kW model — features a 13-metre-diameter rotor set at a hub height of 24 metres. Its 12-tonne nacelle houses a direct-drive permanent-magnet generator protected by sand-shutters, cooling compressors, stainless-steel humidity condensers, an airflow regulator and a heat exchanger.
“This, we realise, is heavy and high for a system that produces one cubic metre [1,000 litres] of water a day. So you can imagine the size of the machine if it were producing 25 cubic metres — it would be the size of a large offshore wind turbine,” notes Janin.
“People in the Middle East are very much aware of the problem of water shortage, unlike us in the EU who use water freely without any thought of it running out.
“[In the Middle East] the interest is mainly in what the technology can do for remote communities and for its political influence — but of course if the technology is being used only on small projects it will not have the big, political impact.
“Still, [in Mussafah] we have shown that we can produce large volumes of water from air with 15-20% humidity, so this is a good proof of the technology.”
Janin points to OECD figures that suggest investment of $10bn a year is needed to halve the number of people in developing nations who do not have access to drinking water — which in turn could create an economic boost of $38bn in such areas.
“Water shortage is a real problem — 1.1 billion people in the world cannot get clean water, and 15,000 die every day due to diseases caused by drinking unsanitary water,” Janin says. “Politicians around the world understand this is something that will only get worse.
“But, with our system, we believe we have something that will help normal people have the means to do something to avert a crisis that could be only five or ten years off.”
To the naked eye, Eole Water’s WMS1000 looks like any mid-scale wind turbine. But its six-metre-long nacelle houses a system that can turn a day’s wind energy into as much as 2,000 litres of drinking water.
Wind drawn into the machine by air regulators through intake vents around the nose cone is heated by the turbine’s generator to become steam, then compressed, causing the moisture to collect like steam on a bathroom mirror. This moisture is then condensed, with the water cascading down pipes inside the turbine tower and into stainless steel tanks for final filtration and purification. Hot air is blown out of the nacelle by a heat exchanger and air extractor.
Early tests suggest that after a five-stage process, the water will meet the drinking-quality standards set by the World Health Organization.
The system needs seven-metre-per-second winds to begin water production.
Designed for baseline flow of 1,000 litres a day, the technology is calculated to be able to produce up to 2,000 litres daily in coastal areas or islands, and 500-800 litres in desert regions.
The surplus 30kW produced by the turbine powers the purification system.