May 2, 2008
Desalination is the Solution to Water Shortages
By Conway, McKinley
With water shortages looming, it's time to commit to building seawater desalting plants. Prompt action can bring new rivers of freshwater and avert disasters. Desalination is likely to become one of the world's biggest industries. Growing communities and new industries must have dependable water supplies in order to prosper. If droughts, exhaustion of groundwater sources, decline of lake or river levels, or a combination of such factors threaten an area's water supply, siteseeking firms may look elsewhere, giving waterrich areas a competitive advantage.Certainly, water conservation programs should come first as a strategy for regions facing water problems. Many jurisdictions are already imposing wateruse limits. Other communities try drilling wells deeper and deeper until their aquifer is maxed out, or they propose to pipe water from distant streams. But such shortsighted strategies can do incalculable damage to the environment.
There is a better solution. Desalting systems have long proven effective in Kuwait, Bahrain, Qatar, the United Arab Emirates, Oman, and Saudi Arabia. Where once there were bleak villages on barren deserts there are now bright modern cities with treelined streets. There are homes with lush gardens. In the countryside there are productive farms.
The big desalting plant at Jubail, Saudi Arabia, is a model for the world. A pipeline carries a river of freshwater 200 miles inland to the capital city of Riyadh, and desalted seawater has given a large region an entirely new future filled with opportunities.
There are more than 7,000 desalination plants, mostly small ones, in operation worldwide. About twothirds are located in the Middle East, and others are scattered across islands in the Caribbean and elsewhere. Aruba's hightech water plant has for many years met the needs of a thriving tourist industry.
The largest plant in the United States is the pioneering $158million project of the Tampa Bay Water agency. The project was let to contract in 1999 and after overcoming some technical problems in its early years is now performing well and causing no significant environmental problems. But no U.S. water agency has yet undertaken a really big project comparable to those found along the Arabian Gulf.
A CHALLENGE FOR WATER OFFICIALS
The first obstacle is cost: Today's desalting plants are multibilliondollar projects, and it will take time for improving technology to bring the cost down. Timid government officials and politicians delay action for years, during which the cost of a plant and related distribution facilities may double or triple.
Fuel for desalination is a major challenge. Desalination plants in most nations don't have access to cheap oil as do plants in the Middle East. So planners of big new units in the western United States need to think of energy from wind and solar installations. Along the Florida coast, ocean energy could become important. The Gulf Stream is an enormous asset waiting to be used. Electric utilities that need cooling water may engage in joint ventures for such under takings.
Today, plans are under way in California for a seawater desalting plant to meet about onehalf of the water requirements of Santa Barbara. A group that includes Bechtel and several utilities has proposed to build a desalting plant near San Diego to produce 100 million gallons per day of potable water. A private developer has built a small plant on Catalina Island. North of San Francisco, Marin County is considering a seawater unit.
Texas, meanwhile, has built a $2million pilot plant at Brownsville to explore ideas for a $150million installation planned for 2010.
Coastal states obviously have a big advantage in coping with future water needs, and many cities sit at the ocean's edge or nearby. Inland cities are likely to face bigger problems, and, sooner than we think, it will be necessary to build pipelines to some of them. Right now, Las Vegas is planning a $2billion, 300mile pipeline to bring water from rural northeast Nevada counties to the city.
Booming Orlando, Florida, has been expecting to meet future water needs by piping water from the St. Johns and other rivers. However, this scheme is strongly opposed by ecologists. After the expensive environmental mistakes of the crossFlorida barge canal and manipulation of the Everglades, the state may be hesitant to approve any more drastic changes in natural flow patterns.
Thus, Orlando could be the first large inland city in Florida to resort to a seawater system, as difficult as that might be. There would be powerful opposition to building a large desalting plant at the nearest point on the East Coast, where it might conflict with the NASA launch complex at the Kennedy Space Center. An offshore site might work.
Even Atlanta, 300 miles from the ocean, may someday have to turn to seawater. Since the 1950s, when no one foresaw the possibility of longterm water shortages for Atlanta, a population explosion accompanied by an extended drought of unprecedented severity has lowered water levels drastically in Lake Lanier and Lake Allatoona- two huge reservoirs serving the area.
Clearly, planning and developing large numbers of seawater desalting plants will cause many problems, but the desalting plants that cause local problems may in the aggregate help against a huge global problem- the rise of sea levels due to the melting of ice in mountain ranges and at the poles.
Solar thermal desalination plant developed by the Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany, could help poor countries transform seawater or brackish water to pure drinking water for low cost. Unlike largescale industrial desalting plants with access to energy infrastructure, Fraunhofer's projects would be appropriate for small, rural areas with autonomous solar power supplies.
"Today's desalting plants are multibillion- dollar projects, and it will take time for improving technology to bring the cost down. Timid government officials and politicians delay action for years, during which the cost of a plant and related distribution facilities may double or triple."
About the Author
McKinley Conway is an engineer and founder of Conway Data Inc., a firm involved in research, publications, and telecommunications, specializing in futures studies, global megaprojects, and site selection. His address is Conway Data Inc., 6625 The Corners Parkway, Suite 200, Norcross, Georgia 30092. Web site www.conway.com.