Innovation Pipeline

There’s a steep energy price to pay at most desalination plants. And the cost can make or break their feasibility, especially if located in a remote area with limited infrastructure.

Now researchers at the Fraunhofer Institute for Solar Energy Systems in Freiburg , Germany, have developed a small-scale solar-powered desalination system for areas of the developing world where drinking water is scarce.

The system features 6 square meters of thermal solar collectors, a photovoltaic module to drive a water pump and a desalination component. The unit produces about 120 liters (32 gallons) of fresh water a day at a cost of about 10 euros ($15 US) per 1,000 liters of water (264 gallons).

It works like this. Incoming saltwater is heated and guided through a microporous water-repellent membrane. A steam-pressure gradient is established between the hot and cold water sides of the system. This creates a temperature gradient that allows for the removal of salt from the water as the water vapor condenses and cools.

The research institute says test units have been running without problems in the Canary Islands and Jordan. Later this year Fraunhofer researchers plan to have their spinoff company, SolarSpring, marketing the units.

There are other devices like this one. One novel system was designed by the well-known inventor of the Segway, Dean Kamen. His Deka Research and Development group designed and built two devices, each about the size of a washing machine, that can provide power and clean water in rural villages. An estimated 1.1 billion people in the world don’t have access to clean drinking water and an estimated 1.6 billion don’t have electricity. The water purifier is able to generate 1,000 liters of clean water in a day. The power generator to drive the purification system runs on cow dung and is capable of generating a kilowatt of electricity.

The U.S. Bureau of Reclamation calls for reducing the cost of desalination technology by 50 to 80 percent by 2020. The minimum cost of turning seawater into potable water in the U.S. is around $3 per 1,000 gallons. At the upper end it costs the consumer $8 for every 1,000 gallons.

In terms of large-scale desalination systems, reverse osmosis is the preferred method for removing salt, according to industry players in a recent survey . Among the leaders in desalination water systems are GE Water, Siemens and Calgon Carbon.

Looking ahead, that same survey indicated that four in five water industry respondents predicted strong spending increases for water projects over the next six months. The top-ranking geographical regions for those projects were North America, Asia with the Middle East. Make no mistake, water issues are on the rise and that’s likely to spark more innovation and investment in labs and startups. –Lee Bruno