Ocean Water Desalination
Ocean water covers 71% of our planet and a significant percentage of humans all over the world live within 30 miles of an ocean. That factor coupled with rising global populations makes ocean water desalination an increasingly necessary measure to provide clean water for our daily living. In arid areas such as the Middle East, desalination has been the only option for providing water for human consumption and irrigation. Saudi Arabia derives 70% of its potable water from desalination plants near the ocean, and other countries around the world are looking to ocean water desalination to meet their water needs for the future.
How does Ocean Water Desalination Work?
There are two methods that are used to desalinize water in large quantities:
Distillation is a desalination process where the water is heated to boiling and the steam is condensed to produce water with a much lower concentration of salt and other impurities. This allows the water to be filtered more thoroughly through less costly methods.
Reverse Osmosis involves using pressure to force ocean water through a permeable membrane with pores small enough to restrict salt, minerals, and other impurities, but large enough for water molecules to pass through.
Ocean Water Desalination Problems
There are several problems that arise from ocean water desalination which, until recent years, have confined most of the desalination plants to the most arid regions of the earth.
Costs of ocean water desalination are two to four times as much as other water sources which may be the single biggest reason why most of the world has been slow to develop the technology.
Energy concerns are another factor as it requires an enormous amount of energy to create the pressure needed to force seawater through reverse osmosis membranes. Even with current technologies, an estimated 33-50% of a desalination plant�s operating costs go to energy.
Location is a concern because proposed desalination plants in Florida and California are slated to be located right next to older, inefficient power plants for easy access to energy and to share the same water intakes. This may lead to higher concentrations of pollutants in nearby air and water.
Environmental Impact is perhaps the biggest problem of all. Ocean water intakes suck in vast quantities of plankton, fish eggs, fish larva, and small fish and remove them from the ecosystem. This causes a collapse in the estuaries that act as nurseries for a wide portion of marine life. Also, the salty brine that is removed from the water is typically dumped back into the ocean resulting in much higher salt concentration which creates ecological dead zones.
Summary
Due to dwindling freshwater sources and increasing population density, we can expect desalination plants to appear on the coasts of our continents in even greater numbers to meet the future demands for clean drinking water. But unless new technologies allow ocean water to be desalinated without such a devastating impact on our environment, the costs will be much greater than any currency can measure.