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Desalination in Spain

Desalination in Spain

Canary Islands Renewable Energy

Researching methods to reduce energy use has long been a focus of the Canary Islands Institute of Technology (ITC), a research facility supported by the regional government of the Canary Islands. And scientists there are taking this one step further: they are producing freshwater from saltwater without using fossil fuels at all.

"Here, we have a great deal of sun, wind, and seawater. It is an excellent place to develop and test systems," said Gonzalo Piernavieja, ITC energy and water director. "It is also an ideal place to simulate conditions in many developing countries and to create systems and technologies to transfer to these countries, as is already happening."

The engineering involved in using renewable energy to power a desalination plant can be relatively simple: solar or wind generators can be hooked up to an existing utility grid, which then offsets the power demands of the desalination plant.

The challenge, however, in coupling desalination directly with renewable energy such as solar or wind power lies in the variability of renewable energy. Solar energy is plentiful when the sun shines and wind power only when the wind blows. Reverse osmosis is the most advanced technology to purify water, and batteries at times are included in the systems to keep power flowing and maximize production.

Researchers in the Canary Islands have spent the past decade developing stand-alone small plants that could provide water for approximately 100 to 300 families, about the size of a small village in a developing country. ITC projects are also carried out in conjunction with other international research institutes or companies.

On one Canary Island test site, photovoltaic panels are hooked up to a battery, which feeds a steady supply of electricity to the desalination plant. (ITC has a patent on this technology.) "But batteries aren't great because you have to replace them after, say, five to seven years, and then you have to dispose of them as well," says Piernavieja. "It's better to develop a system that needs no batteries in the first place."

Other solutions tested at the Canary Islands center make use of wind power. In one, a small wind-energy converter powers a seawater RO plant designed to operate even with the stops and starts of wind power. In another, a small wind farm creates a small stand-alone electricity grid that then feeds electricity to the desalination plant. A third plant uses biodiesel to power desalination.

The Canary island of El Hierro, which has 10,000 inhabitants, hopes to model the future of island living. ITC is involved in a project there in which eventually 100 percent of the island's energy needs will be served by renewable energy; that energy, through a grid, will also power desalination plants that supply all the island's drinking water and irrigation needs.
The ITC research group is one of only a handful focusing on developing and testing plants in which wind turbines directly power the desalination process without going through any grid.

Though all of these systems could be used in industrialized countries, the main goal of the ITC is to develop plants that could theoretically supply water to even a fraction of the billion people around the world in need of clean drinking water. "Many of these people live in areas that have abundant renewable energy resources and yet no electricity grid, and they may never be connected to a grid. This is the philosophy behind our research," says Piernavieja. For the next decade, he adds, the goal is to design and develop medium-sized systems for urban areas.

ITC research on coupling desalination with renewable energy is already being tested in the world outside the Canary Islands. The ITC has placed nine small desalination plants in Africa. There are four diesel-run systems supplying water to fishermen living within the boundaries of a national park called Banc D'Arguin in Mauritania. One solar-powered unit has been running for more than three years in the Tunisian village of Ksar Ghilene and four more were installed in rural Morocco last year.