Freshwater from the Seas
by L. Wedekind, Chief Editor,
IAEA Division of Public Information
IAEA, 6 August 2001Tapping the world's seas to produce freshwater for cities and towns takes energy, and countries are looking at nuclear electricity plants to provide it. India is among countries looking to couple a nuclear power plant to a desalination facility, working through international cooperative projects supported by the IAEA.
The technology of desalination -- or desalting seawater -- is not new. Over the past fifty years, its use has grown, particularly in the Middle East and North Africa, where freshwater is scarce. The facilities are energy intensive, and usually draw the steam or electricity they need from conventional fossil-fueled plants. But as environmental concerns grow over greenhouse gas emissions, other cleaner sources of energy are being sought.
The technology of coupling nuclear energy and desalination plants already has taken hold in Japan and Kazakhstan, where commercial facilities have been operating since the 1970s. India is seeking to expand the base of national and international experience through a demonstration plant it is building at Kalpakkam in the southeast of the country. Other countries involved in nuclear desalination projects include the Republic of Korea, Russian Federation, Pakistan, Iran, Egypt, Saudi Arabia, Indonesia, Morocco, Tunisia, Argentina, Canada, France, and China.
In 2002, the IAEA is planning an international symposium to review and update the global status of nuclear desalination. As more experience is gained and shared, the technology's use could help more countries meet rising demands for electricity and for freshwater. About two-thirds of the world's population is projected to face shortages of clean freshwater over the coming decades.
For more information, see "Freshwater from the Seas", a feature by T. Konishi and B.M. Misra in the latest edition of the IAEA Bulletin.
Another interesting invention that has never been implemented on a large scale was designed in 1931 by M. Achille Knapen. He succeeded in condensing and extracting water from warm air to irrigate fields and vineyards in southern France with what he called, an "air well" (See U.S. patent no. 1,816,592). Looking like a 40-foot concrete beehive, it was possible to produce as much as 6,000 gallons of water daily for every 1,000 square feet of condensing surface. An airwell can be built on practically any scale, and the wall materials can be concrete blocks, bricks or concentric hollow shells filled with sand or earth. A small airwell 12 feet high and 12 feet across with walls 2 feet thick can supply a generous output of daily water. It can be fitted with top and bottom air pipes, and a multitude of condensing plates on the inside. Warm air circulates and gives up moisture on the cool inside condensing plates angled downward toward a catch basin at the bottom were it is collected. Using scrap and local materials, makeshift air wells could help solve many water problems in drought ridden areas of the world, especially in Third World countries. """
What's great about these is that water vapor is one of the greatest "global warming" gasses. What could be better than to extract water vapor so that is usable by humans. Take it easy.