De-salinization side effects

Rethinking desalination

(Hat tip to
The Issue.)

Last month saw the release of a UN report that paints a very bleak picture of how humans are shepherding natural resources on the planet. One of the greatest causes for concern is our use of fresh water, without which life is impossible.
Demands for fresh water come from both agriculture and drinking, with agriculture currently using almost 70 percent of global fresh water. The world’s population is estimated to grow to nine billion within 50 years, meaning we’re going to need to double the amount of fresh water for agriculture in order to feed everyone, according to the UN. Although desalination is often pointed to as the answer to this problem, a new paper published in Science suggests we are going to need to think again.
Israel is a world leader in desalination; this desert nation recently opened the world’s largest desalination plant at Ashkelon, which produces 100,000,000 m3 of desalinized water each year by reverse osmosis. The massive scale of the plant also makes its product the cheapest so far, with production costs below $0.55/m3.
Unfortunately, it seems that what passes for fresh water for drinking isn’t good enough to be used for agriculture. Israeli farmers have discovered that although Na+ and Cl- have been removed, so too has Mg2+, essential for plant growth. As if that weren’t bad enough, boron concentrations have increased. Although boron poses no threat to human health, most crops aren’t so lucky.
Last but not least, the altered ion balance in the desalinized water results in water that is less buffered, meaning that the pipes that carry it corrode faster. Although none of these problems are insurmountable, they will all result in greater costs, and in regions where millions already live below the poverty line, that’s not a good thing.

I realize these technical problems in all probability can be compensated for through engineering. I also remember the promises of the ‘Green Revolution’ of bounty without unintended or ignored consequences. Projects small scale often obscure major flaws because we did not know what to look for or consider important. If farmers missed this aspect, what chance us cityboys and girls? After all, some still want to drain the Great Lakes to subsidize other locations, without even considering the huge expense of moving water from one river to another in the same watershed.

With water at about $120 a foot acre or $1.50 cents per 1000 gal.(sewerage is $4.50 per 1000 gal.), de-salination is about 4-5 times the cost of current kinds of prices in the US. If unsubsidized by governments, prices go up considerably.

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