In 1790, when Thomas Jefferson was Secretary of State, he held a bottle of “purified” seawater to his lips and drank. The water in the bottle tasted only slightly better than untreated salt water, but the potential of this discovery piqued his interest.
Desalination seemed a possible solution to a myriad of problems. Jefferson enthusiastically considered the implications of this water purification innovation for military applications as well as land settlement across America. And he assembled a team of experts to test the science. Unfortunately, it was a farce and Jefferson publicly exposed the fact that Jacob Isaacks had merely used an additive to neutralize the water’s salty taste. “Mr. Isaacks’ mixture does not facilitate the separation of seawater from its salt,” Jefferson stated in a 1791 affidavit.
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Today we are faced with a different sort of desalination dilemma. There is no question that contemporary purification technology is superb and proven highly effective. Over 18,000 plants worldwide produce nearly 23 billion gallons of water each day. Nor is there question that it could potentially supply the 1.1 billion people that lack access to clean water today. “At the moment, around 1% of the world’s population are dependent on desalinated water to meet their daily needs, but by 2025, the UN expects 14% of the world’s population to be encountering water scarcity,” predicts Christopher Gasson of Global Water Intelligence. Converting seawater to fresh, drinkable water seems like an obvious solution to our planet’s water crisis. Or is it?
Desalination is expensive—nearly twice as costly as treating rainwater or wastewater, Professor Raphael Semiat of Technion, the Israel Institute of Technology, in Haifa, told The Guardian. By his estimate, desalination costs at about $3 per cubic meter. Other researchers echo his sentiment, indicating that maintenance is also costly, an issue particularly crucial for developing nations in which NGOs often provide initial funding, but are unable to support running costs.
Desalination is also energy-intensive, requiring 3.5 kilowatt hours of electricity to desalinate 1 cubic meter of seawater, according to Semiat’s calculations—1.3 kWh to pump seawater to the plant and 2.2 kWh for the reverse osmosis process.
And then there are environmental issues, not only with regard to the withdrawal of large volumes of seawater and the marine organisms that may be damaged at intake points, but concerning the effect of saline-concentrated effluent water on the environment that it’s released into.
As the world’s population and global temperatures rise, pressure on our water resources increases. We’re experiencing a global water crisis while 97.5% of all of the earth’s water contains salt. What can be done to increase desalination technology’s efficiency and reduce costs?
Can desalination quench the world’s thirst?