[Veserv]

Or maybe the unsustainable depletion of groundwater for the purpose of growing alfalfa is only viable in very niche areas without heavy subsidies?

The number they are quoting is 0.41 $/m^3. Per capita water withdrawals (including agriculture) in the US were ~1200 m^3 in 2015 [1]. That means the cost per person to convert all residential, industrial, and agricultural to desalination is only ~480 $/(person * year). Or approximately 6/1000 of US GDP. Even if we assigned all of that cost to agriculture and food, all that would mean is that the average person's food budget would increase by ~480 $/year. That is sizeable, but not even slightest bit infeasible. If we really needed to we could just assign 3% of the US federal government budget to preventing death by starvation and thirst by achieving full water independence.

Desalinated water is only uneconomical in comparison to unsustainable groundwater depletion. On a absolute basis it is very affordable and would not constitute a material problem for the US or any other developed country.

[1] https://www.statista.com/statistics/263156/water-consumption...

[Retric]

Subsidies is arguable as groundwater isn’t necessarily useful unless you pump it out. How much to value that finite resource isn’t obvious but letting it run out is a self correcting problem.

Anyway your numbers aren’t even close. Water needs to reach people not simply exist. Groundwater depletion really isn’t a thing in the east cost, it’s mostly a thing west of the Mississippi and mostly at fairly high elevations.

To offset water withdrawals of people living 2km above sea level that 1200 m^3 of sea water would need 6480 kWh before consideration inefficiencies. For much of the Midwest you’re spending more on pumping than desalination, but you also need pipes etc.

[Veserv]

Oh geez, 6840 kWh. At 0.10 $/kWh that is ~700 $. Added onto the 480 $ that would increase the costs to nearly 8% of the US budget. If it takes a 8% increase in the government budget, I prefer dying of starvation and thirst, said nobody ever.

I am being a little flippant here. Transitioning to a desalinated water economy is a gigantic megaproject. I am not including the costs needed to add all the transport infrastructure, but we also do not need to convert over 100%. We only need desalination where we are consuming water in excess of water renewal rates. And if you need excess water you will need to move your business to where water resources are cheap. That or your business and people die of no water. I know what I prefer. Luckily, highly productive farmland which consumes the vast majority of the water is generally on flat, low elevation ground where transport costs will be low.

Desalination is a viable solution. Are there challenges? Sure. Can you do it without any sacrifices and without changing your lifestyle at all? Probably not. But if your alternative is insufficient freshwater resources desalination can solve that economically at scale at a modest cost and with relatively minor sacrifices.

[Retric]

Except this isn’t about drinking water its just agriculture and not even agriculture used inside the US.

Spending 8% of the US budget to subsidize exports would be lunacy. Ban Alpha exports from California largely solves the problem within the state as does a host of other possibilities like say charging a fee for using an aquifer.

Anyway it’s a self correcting problem, when farms can’t pump out water they will shut down reducing water use. The US is such a massive exporter that none of this will be noticed by US consumers.

[Veserv]

Then don’t do that. You are the one who brought up alfalfa, the classic example of a low value good being subsidized by unsustainable and flagrant water usage, as evidence that desalination is not viable.

I pointed out how even if we decided to support and subsidize the moronic use cases the US can still easily support a desalinated water economy if we had to.

In actuality, if we moved to bulk desalination we would see a reconfiguration of water usage to higher value usage since water would be immensely more expensive. However, despite being much more expensive, even if we massively overestimate water usage by including water wasteful export crops, desalination still ends up being viable including the usage that would almost certainly disappear if they did not get to defray their depletion externalities.

Massive overestimate comes out reasonable. Therefore correct estimate will also come out reasonable.

[Retric]

Simply introducing vastly more expensive desalinated water isn’t going to get people to use it when they can just pump more water from aquifers.

You need to fix the underlying issues or nothing changes. But by fixing those issues there’s no niche for desalination.

Desalination is a solution in search of a problem, not a useful tool here.

[concordDance]

> If it takes a 8% increase in the government budget, I prefer dying of starvation and thirst, said nobody ever

This seems like a false dichotomy.

[concordDance]

You're forgetting to take into account transport costs.

Want to pump that cubic meter of water 100 km inland and the energy cost alone will be over $1/m^3. Ignoring pumps, piping, maintenence, land purchasing, cabling, planning permission, etc etc.