USA - A real-life water and wind laboratory

Researchers seeking to make the ocean's salty brine drinkable using wind power will spend the next year using the town of Hull as a case study to help other water-needy, windswept coastal areas filter freshwater from the sea. With one wind turbine already spinning, another to be installed in January, and a third offshore turbine being considered, Hull is an ideal laboratory for modeling a desalination plant that runs off a combination of renewable energy and the electric grid, according to James Manwell, director of the Renewable Energy Research Laboratory at the University of Massachusetts at Amherst. Manwell's research group received a $100,000 grant from the US Bureau of Reclamation this month to study the feasibility and economics of such a desalination plant, a technology that requires huge amounts of energy.
Hull has long depended on water piped in from wells in Hingham, at a cost of roughly $8 per 1,000 gallons, giving it among the highest water rates in the region. With the average family consuming nearly 71,000 gallons of water last year, officials said, Hull hopes that a wind-powered desalination system would both reduce water costs and give the town more control over its supply. Developing a plant to purify seawater would also give the town control over one of wind power's biggest drawbacks: inconsistency. ''At certain times of the day or the year, [the wind turbines] would be producing too much electricity, and the town would sell it into the grid. Other times, when the wind isn't blowing, they're going to be buying electricity," said Manwell. A wind-powered desalination plant would act like a battery. If the turbines were producing more energy than was needed, the town could route the excess power to the desalination plant, building up Hull's freshwater supply, instead of selling it to the electric grid at a typically discounted price.

"It's kind of like storing energy," said Thomas Burns, vice chairman of the Water Resources Committee, which last month hired engineering firm Wright-Pierce to examine the costs, technology, and ideal placement of a desalination plant. The committee hopes to have "a comprehensive package of how desalination can benefit the town, how it can potentially reduce our costs, and supply us with a steady source of water" ready for consideration by Town Meeting this spring. Other communities south of Boston are studying desalination, to defray high water costs or supplement scarce supplies as their populations continue to grow. According to a report by regional planning councils, for every 10,000 new people in the region, about 710,000 more gallons of water are consumed each day. Braintree set aside $75,000 for a study on the feasibility of a desalting plant last year. And Peter Fairbanks, on the board of directors of Aquaria LLC, which is working to build a desalination plant along the tidal Taunton River in Dighton for perennially water-scarce Brockton, said his company's project is clearing the last few hurdles before construction.

But critics say that desalination plants, which are common in parched areas such as the Middle East and the Caribbean, are a troubling trend for New England - a rain-rich region that receives almost 4 feet of precipitation each year. "There isn't a single municipality in Eastern Massachusetts that should be having problems with water supply. There's plenty of water everywhere - we're running into problems because we're overusing water, we're exporting it out [in sewage systems and street drains] as we pave the region," said Christopher Kilian, who directs the Clean Water and Healthy Forests Program at the Conservation Law Foundation. However, Burns said that Hull, a peninsula surrounded by saltwater, has long lacked an adequate supply of fresh groundwater. Even 50 years ago, 95 percent of the town's drinking water was piped in from Hingham. As the need for potable water grows across the region, desalination becomes increasingly attractive. "Water consumption is increasing all the time in the South Shore, with development, with the train, with the [South Weymouth] Naval Air Station. This would give the community of Hull greater control over the resource," Burns said.

Manwell, the UMass researcher, said his study will also give insight into how to best combine renewable energy sources and electricity from the grid to produce the cheapest, most efficient system for purifying water in locations with similar resources. Already, desalination that uses wind power coupled with diesel-powered generating systems have helped Greece produce water, but the new model would help balance the need for electricity and clean water with the fickle nature of gusting winds, he said. By next fall, Manwell said, he and his team hope to develop a model that can be tested against reality in Hull, and that will eventually help island nations and coastal communities across the world - "wherever anybody has wind and not much freshwater."