Is Desalination a Solution
to Growing Water Shortages?
Part One of Two
There is a growing number of new desalination plants planned and being built around the world to help address problems of fresh water shortages. Global output is still small at less than 0.1 percent of the world's drinking water. According to a recent report by Global Water Intelligence however, the desalination industry is expected to grow 140 percent over the next decade. About two-thirds of the world's desalinated water is currently produced in Saudi Arabia, Kuwait, and North Africa.
Populations are heavy in coastal areas, so the demand for desalination will grow as the need for improved clean water supplies grow and people see all that water nearby as a solution.
Singapore opened a sea water desalination plant in 2005 hoping it will meet at least 10% of its water needs. Israel introduced its first plant on the Mediterranean a couple of months ago that can process 87 million gallons of water a day. A sea water desalination plant in the Tampa Bay, Florida area opened in March. General Electric Co. has announced a contract to build a plant in South Africa. Texas is moving into desalination with a plant slated for construction in 2010. After a severe six-year drought in South Australia, one of the world's largest desalination plants is planned to supply water to Melbourne. That plant is expected to come on line in 2011. The US, Spain and China are turning to desalination. A push for Gulf of Mexico desalination began in 2002 after a study reported that hundreds of communities could face water shortages in the next 50 years.
Desalting water is expensive. Typical cost estimates run at about $650 for 326,000 gallons. That's enough for two homes for one year. To clean the same amount of fresh water costs about $200. The cost is this high because this is a very energy-intensive process. That means that as energy costs continue to rise, so will the cost of desalting the water. And of course there are all the implications to climate issues by introducing many large energy-intensive plants.
We should be very cautious about seeing desalination as a major solution to global water scarcity. A World Wildlife Fund report said in part: "Desalinating the sea is an expensive, energy intensive and greenhouse gas-emitting way to get water. It may have a place in the world's future freshwater supplies but regions still have cheaper, better and complementary ways to supply water that are less risky to the environment."
According to the report, since a growth in the energy intensive technology would increase emissions and damage coastal and river habitats, greater emphasis on managing existing supplies should be given before major new water projects are approved. New desalination plants, which are primarily located in coastal areas, should also be subject to tighter impact assessments to miminize damage to the marine environment. According to the study's authors, advances in technology should be applied to developing alternative 'manufactured water' systems, such as treating waste water.
The basic problem is that by taking sea water and producing fresh water, you are going to get a stream of fresh water, which is what you want, but you also produce a concentrated salt stream. Concerns about desalination plants also include that the intake process kills large number of aquatic life. A study of this impact in the USA from 1999 to 2000 reported a annual mortality of 55,000 invertebrates and 78,000 fish.
'Desalination plants....should only be constructed where they are found to meet a genuine need to increase water supply and are the best and least damaging method,' the WWF report said.
Gray Whales & Mexico
Some years ago, ESSA, a company backed by Mitsubishi's proposal to build a desalination plant in the primary nursery of the gray whales at Launa San Ignacio in Mexico - and the strong response - caused quite a stir. The RNDC said: "Besides putting the gray whale at risk - just a few years after its recovery from near-extinction - the factory also threatens numerous rare and endangered species in the surrounding International Biosphere Reserve."
Big mammals are often the lifeform that we humans can most readily relate to. However, the whales are probably the last species to be impacted by a desalination plant. The plant at San Ignazio showed 6000 gallons a second being pumped into 116 square miles of evaporation ponds. How many fish eggs, brine shrimp and other small life is sucked into this process and destoyed along the way? This endangers the balance of life in the area, and the local fishing industry.
Prior to San Ignacio, there was already a salt factory at Guerrero Negro, another calving lagoon. There are only 3 gray whales calving lagoons in total. At Guerrero Negro, a spill of toxic brine wastes caused the death of 94 endangered black sea turtles in December 1997. Scientists later observed another spill of more than 4 million gallons resulting in large fish kills.
But a story in Outside magazine in July 1999 reported that ESSA says when they started making salt there in the late 1950's, there were 250 gray whales migrating there. By 1999 there were over 1700. So the answer may be more elusive than obvious. During those years the whale was on the endangered list. That meant they were being protected elsewhere around the world at that time.
However, the campaign led by the NRDC, supported by fisherman, scientists, environmentalists and citizens led to Mitsubishi and the Mexican government abandoning their plans to build a desalination plant in this last undisturbed gray whale nursery and migratory bird refuge.
A reader writes:
"Talk about having the wrong end of the stick! Both the examples you use of "desalination plants in this last undisturbed gray whale nursery . . ." are actually salt evaporation projects (one planned in San Ignacio and canceled), the other very much in production in Guerrero Negro.
Evaporation produces salt - solid industrial salt, which is the purpose of the plant. Using these two examples as a result of the evils of desal for water production is ridiculous."
We're not sure what in the article this statement actual contradicts. We did note that one plant had been in operation and another plan was abandoned. But the key point, clearly made in both parts 1 and 2 of this article, is that we should be thoughtful about where we adopt desalination, and that we need to address ecological impacts.
continued in the next Waterfall..........
Click on Desalination Two.