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Comment by FilterJoe | Hacker News Reader

With all the talk of water running out in CA and the world, I am wondering why desalination is not part of the conversation. According to Wikipedia:

"Supplying all domestic water by sea water desalination would increase the United States' energy consumption by around 10%, about the amount of energy used by domestic refrigerators."

Is this true? If so, why isn't desalination happening on a massive scale in CA?

http://en.wikipedia.org/wiki/Desalination#Considerations_and...

EDIT: The Wikipedia sentence I quoted was not clearly written. It should have said "supplying all household water" not "supplying all domestic water." Far more water is used by farming.

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It is part of the conversation. There was just an NPR Forum segment about it yesterday or so. There are articles about it sometimes (e.g., http://www.mercurynews.com/science/ci_25859513/nations-large...). This solution often ends up not being pursued because it's extremely expensive and energy intensive not only to desalinate but to then pump the water to where it needs to go, and you also have waste product to deal with. So in many cases it has been decided that other avenues, like conservation, are more economical.

Simple: cost

As long as it is cheaper to exploit an existing clean water source than to spend the energy, and invest in the massive and in some cases unproven tech and engineering infrastructure to build desalination plants, then that's what will happen.

It's unfortunate, because the cost to future generations, or the biosphere doesn't calculate into our current economic system, and most of the commercial infrastructure is aligned against re-calibration of that kind, because it would cost them dearly.

http://www.technologyreview.com/featuredstory/534996/megasca...

$0.58/m3 seems pretty cheap to me.

I live in Florid; we have a large desal plant here as part of our water supply. It took years to get it working well, along with a few lawsuits; they're not easy, or cheap, but well worth it.

http://www.tampabaywater.org/tampa-bay-seawater-desalination...

This was the follow-up piece to that "California will have no water in a year" post.

http://www.latimes.com/local/california/la-me-0320-drought-e...

That is talking about the water you use in your household. But that is a tiny faction of all water used in total. Industry and farming absolutely dwarf household consumption.

A ton of water is used to grow Alfafia. There is no way it's profitable if you had to desalinate it first.

More realistically, California stops growing alfalfa and stops raising beef cattle altogether. That would free up enough water to water every lawn across the state.

Well, we should consider moving away from lawns too. They are the largest crop grown in the US.

http://scienceline.org/2011/07/lawns-vs-crops-in-the-contine...

I was just looking into a fake lawn for my next house, but you don't recoup the cost for 7 years. The builder has been putting in smaller lawns in the front, so we'll likely put a small one back and be smart about watering it (not in the middle of the day, properly position sprinklers etc.). Or we'll xeriscape it

The cost to build desalination plants to service millions of residents would be BILLIONS. Tens of Billions. Money that is available, just being spent on other things...

We built one in Sydney a few years back. It cost nearly 2 Billion, and it now sits idle at a cost of around half a million per day

I guess we'll be laughing in 15 years though

http://en.wikipedia.org/wiki/Sydney_Desalination_Plant

The issue is the waste... the salt that's left over. What happens to it? In the Persian Gulf (I think...) they have basically killed everything in the water from the abundance of salt that's been put back into the sea water.[1]

There is a theory that if we continue making the Gulf warmer by putting so much salt in, it could be a catalyst for plunging the world into an ice age. Who knows if that's true.

Already here in New Zealand we are exporting some of our fresh water to very rich people over in Saudi Arabia and neighboring countries. Can't link the source, it was a court news article about some guy who assaulted someone. He was exporting prime NZ lambs, and water tankers...

A previous comment I made, with quote from National Geographic about this: https://news.ycombinator.com/item?id=2094701

[1] http://gulfnews.com/news/uae/environment/waste-dump-threaten...

The salt was in the water to begin with. If you read that reference that you posted, you'll see that the problem is the waste chemicals (not salt), and the increase in temperature of the water. It's plausible that they could filter out the waste chemicals, but I'm not sure about the heat.

Yeah, you're right that salt is in the water already and isn't technically waste. I just called it that because as a 'left over', it feels like it's waste.

However... it doesn't mean much that salt is in the water already. You're taking the water out, but leaving all the salt. That can't be good at all.

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