ASK HN: Why are we not doing large scale desalination? | Hacker News Reader

ASK HN: Why are we not doing large scale desalination?

5 pointsThinkBeat8 comments

There are an ever-increasing stream of places, even just inm the US that is in severe shortage of water.

That is a local problem.

The Earth has an extreme abundance of water. 71% of the surface is covered with it and it is quite deep in places.

All added up about Thirteen Quintillion Five Hundred Ninety Quadrillionth liters of it.

There is no conceivable way we are running out of water anytime soon.

Water we have. People who desperately need it we have. The problem is that they are not the same location.

That is a solved problem for a lot of things people need.

Why are we not doing global scale desalination?

The pipelines could be constructed in a massiv parallel concurrent way. As long as you could keep the supplylines of construction material work.

Is the only thing holding it back the amount of enenrgy it would take to power it?

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It's not clear that desalination is the best approach. In California at least, 80% of our water goes to agriculture. And a big chunk of that is spent on growing alfalfa (and other fodder) for export to China and Saudi Arabia. We should consider whether that makes sense before investing billions into desal plants.

Many farms are still irrigated with sprayers. Israeli farmers have shown it's possible to maintain high yields and reduce water waste with drip irrigation and other techniques.

We can also do a lot more with water recycling. Wastewater can be cleaned enough for watering lawns and certain crops.

On the residential and commercial side, much of the water is spent on lawns and other decorative landscaping. How much of that do we really need?

Plus, most places that actually need water are well in inland. Pumping water uphill is expensive.

We are talking about an awfully high number of people right now. I was thinking on a global scale.

It's still true. Seawater is, rather by definition, at sea level. 99.999% of the Earth's surface is higher than that.

Energy use is a factor, but not the only one; this article has a concise list of why desalination isn't an easy answer to solving the earth's water needs... currently, anyway.

https://sciencing.com/advantages-disadvantages-desalination-...

Capital cost, operating cost, environmental cost, maybe real estate cost.

I believe that if it really comes to it, as in “the reservoirs are dry” and human survival depends on it, then desal will be done whether people want to argue about it or not.

That is more or less how much I was thinking about it.

I do think that we are nearing that stage. Of course, millions of people are already at that stage but they are apparently not worth it.

Since it will take time to build it out starting now would be sensible.

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