A couple of nits to pick here.
Nit#1 you do not have to pump water over a mountain range to get from sea level to the Central Valley.
Cite: the Sacramento River Delta. Stockton which is in the San Joaquin Valley is a deep water sea port. Freighters as a rule don’t climb mountains worth a damn.
So you plumb the water up the delta.
Nit#2 Los Angeles has been pumping water up and over the Tehachapi Mountains from the California Aqueduct for years. Desal water for use in LA and you can turn those pumps off and have more water for use in the SJ Valley.
While I agree with your basic premise, that desalination, done properly, is not a realistic solution, I ask you this: if some form of vapor distillation method is used, for example, nuclear steam generation, would you not be left with steam/vapor, which would require somewhat less energy to carry it to altitude, where it could be condensed into liquid water and run into the valley, perhaps also generating more electricity? Can you guesstimate or calculate what the secondary energy requirement of transporting water vapor to 1000m would be, as compared to liquid water?
That aside, the other issue is the very desal itself. The steam/vapor distillation process leaves you with very pure water. Humans and crops are not exactly fond of really pure water, we need to have something like .1‰ salinity, most plants are happy with about 5 times that much, so if desal is to be practical, at some point we have to drizzle a little bit of the left-over brine back into the water supply, which becomes an added expense.
How far do you think the vapor would get before it condenses? (Unless you intend to keep heating it.)
Anyway the current desal state of the art of not steam/vapor distillate but reverse osmosis using pressure to force water through tiny holes that salt cannot fit through. According to an article in today’s NYT this technological advances has halved the energy cost (and they mention the fit with renewable energy as well).
Finally you seem to be ignoring Rick’s point: this water gets used locally allowing less to be pumped there and more therefore available for other uses closer to the source.
Still desal remains energy intense (and guess what, producing energy, including with nuclear, uses lots of water); the more that can be accomplished by better fresh water management strategies the better.
Yeah; I wonder if any plants are built with this in mind. They could be used as load-levelers.
If your production is intermittent, you need more core reverse osmosis units so that the peak rate is higher than the average rate (so that they can cover idle times). However, some parts of the system only need to be sized for average production–the intakes and brine outputs, for instance, which can be buffered with local pools or tanks. Same with pre- and post-treatment units, which I’d expect use minimal power.
Seems like doubling peak capacity for the energy-intensive units would cost much less than double for the whole plant; perhaps only 25-50% more. But I really don’t know what the expensive parts are.
Does anyone know if forward osmosis is being used anywhere commercially for drinking water or irrigation? The wiki article doesn’t have an energy breakdown. I haven’t talked with the guys who developed it (refs 13-14) in a while, but they paint such a shiny halo on it it’s hard to know what’s real.
The advantage is it requires relatively low-grade heat and minimal electrical power. So you could even hook it up after a combined cycle plant’s ORC, not that we’re seeing much of that.
Very interesting documentary. How many remember today that L.A. once sent 600 cops to the Owens Valley to thwart residents who were dynamiting its aqueduct?
Actually it is a national problem. Immigration to the U.S., in general, has tapered off since the Great Recession, but over the past generation it has been a big driver of national population growth, especially in the Southwest. As the economy improves I expect immigration will pick up again. If we’re going to have large scale immigration as a national policy, then perhaps more of the newcomers should settle where the water is, rather than in our driest region.
80% of the California water use is by agriculture. Agriculture makes up 2% of the California economy. We don’t have a population problem vis a vis water. We have a failure to apply ordinary market pricing to a scarce resource.
14% of CA water use goes to alfalfa, some of which is exported. 7% goes to rice. Neither is a high margin crop. Eliminate both and they won’t be missed. Together they use more water than residential and urban areas do.
The politics of all of this is difficult. Very. But we don’t really require nuclear powered de-salinization plants, relocated icebergs, or errant asteroids. We just need to treat water as if it was, you know, scarce.
Or adopt fusion power. I can get behind that. DSeid: In practice de-salinization will play a role. But recall that those plants are expensive (as in $1 billion), so leaving them at half capacity isn’t good. I understand that Australia has a number of shuttered plants, because they became too expensive to run after the rains returned.
Fresno has been on the front lines of this fight for decades.
Restrictions on car washing, lawn watering, etc with hefty fines and aggressive enforcement. We actually have water dept people running around and citing people for watering during restricted times. There are tons of billboards, commercials, and other signage promoting water conservation. I am surprised we have not seen any of the “if its yellow” kind of stuff. I just recently started doing that myself as I can see where skipping a few flushes a day x 700,000 people adds up in a hurry.
It has actually hit crisis levels in at least one town. Porterville, CA has had several city well bottom out to where there is no functional water service to some parts of the town. The city has set up large tanks for residents to tap off of for bathing and clothes washing.
Its an old article but it is an ongoing and growing problem.
That was my post #18 in this thread. What a difference the month of May made. Our local meteorologist, Ken Johnson, summed it up best, we replaced one natural disaster (extreme drought) with another natural disaster (flooding). Now all of our major lakes are 100% filled up, and have been going over the spillway for some three weeks, and will continue to do so for a good while longer. They said this is enough water to last our area for at least the next 10 years, even if we didn’t receive another drop of rain.
Here is water data for TX on what percentage its lake levels are at.
This cite is a figure I have been hearing a bit lately, which says that TX for the month of May received 35 trillion gallons of water. That’s enough to cover the entire state a depth of 8”, they said.
It has certainly turned the mood of this town around for the better, despite the flooding, hail, tornadoes, etc, we’ll gladly take it.
I wouldn’t be surprised if some California towns started trying similar programs.
I read something the other day about a California restaurant setting up some sort of an air compressor to use to pre-clean dishes before putting them in a dishwasher, and that it saved tons of water.
