7 ms·

As a person who has run through this particular loop once with local politics (Sunnyvale's northern border is the SF Bay which has former Morton Salt ponds in i

As a person who has run through this particular loop once with local politics (Sunnyvale's northern border is the SF Bay which has former Morton Salt ponds in it) what I ran into was two things, one that there wasn't a cost effective power solution for just desalination, and two, the players don't care about water to individuals (drinking water and what not) because there is absolutely no risk whatsoever in the bay area of not having "enough" of it. The political block that kills it is a combination of local pop saying "we don't want nuclear/cheap power in our back yard" and the folks farming the desert in the central valley saying "If you can't supply farms, why would you do it?" My hope is that one day, small scale nuclear power (sometimes called "modular nuclear power") will make this a reality.

BurningFrog 3y ago
Desalination seems ideal for cheap but unreliable energy like solar or wind. You just need a water reservoir to act as "battery".
- brilee 3y ago
  https://www.moderndescartes.com/essays/factobattery/ https://www.moderndescartes.com/essays/factobattery/ Using the above methodology, I ran numbers for a desalination factobattery and it's really bad, like two orders of magnitude more expensive than just buying a Li battery to buffer the unreliable energy and running desal 24/7.
  - ChuckMcM 3y ago
    This right here. Even low grade continual energy supply is better for desal.
  - BurningFrog 3y ago
    By "battery" here, I just mean a dam that holds a few days worth of fresh water.
    - brilee 3y ago
      I think you misunderstood the comment. I agree there has to be a buffer somewhere. You're arguing that we can get a free buffer by piping the water behind a reservoir, but the cost is that the very capital-expensive desalination plant will be idle half of the time. I'm proposing that the more economical option is to buy a lithium ion battery to buffer the renewables and run the desal plant 24/7. (You can still pipe the water behind a reservoir if you want)
      - tomrod 3y ago
        Even with battery degradation?
      - BurningFrog 3y ago
        I see. It's better to have a half as big plant running 24/7 with a battery. Thanks for educating me!
  - yodelshady 3y ago
    See: collapsing European industry, finally now even in Germany, due to thinking "demand-side response" was a good solution.
- schiffern 3y ago
  The problem, of course, is utilization. Amortized capital costs for desalination runs about 40%,[0] so if you "charge" for 12 hours and "discharge" for 12 hours then your facility doubles in size, so your desalination cost increase by (at least) 40%. This doesn't even account for added maintenance btw. If you charge for 6 hours (ie the solar peak) and discharge for 18 hours, you need a facility 4x as large, and your desalination costs increase by at least 160%. Desalination isn't 'free' energy storage. [0] https://www.advisian.com/en/global-perspectives/the-cost-of-desalination https://www.advisian.com/en/global-perspectives/the-cost-of-...
- lazide 3y ago
  Desalination plants do REALLY badly when run infrequently. All the salt water, brine, etc. creates absolute havoc when it sits for random period of time, and maintenance costs are already a huge part of opex for desal plants. Also, the concentrated brine is a real problem in any area that has regular sealife. Maybe not a big problem in the salt ponds already, but it will kill off anything normal.
  - ChuckMcM 3y ago
    Yeah, it isn't going to hurt the salt ponds. What is more, we did the math and found you could harvest more salt faster for less money when starting with a higher salinity brine which would be a win for Morton.
jojobas 3y ago
The smaller the reactor, the worse neutron efficiency gets, good old cubes and squares. Good practices also require as many hands/eyes for normal operation a GW class reactor as a 50MW one.
- ChuckMcM 3y ago
  At the time we were thinking NuScale type, see https://www.energy.gov/ne/advanced-small-modular-reactors-smrs https://www.energy.gov/ne/advanced-small-modular-reactors-sm... for efforts by DOE to make small modular reactors feasible in the US.
  - jojobas 3y ago
    >Advanced SMRs offer many advantages, such as relatively small physical footprints, reduced capital investment, ability to be sited in locations not possible for larger nuclear plants, and provisions for incremental power additions. SMRs also offer distinct safeguards, security and nonproliferation advantages. I studied in a tangent area and either I'm dumb or DOE had a lapse of reason that day. Having five reactors per site is going to be worse than two of equal installed power in almost every respect. USA is the fourth largest country in the world, how is reduced footprint even a consideration?
    - ChuckMcM 3y ago
      There is probably a literal ton (if you printed it out on 20# paper stock ;-)) of stuff written about how small modular reactors are a much better answer to deploying nuclear power than big LWRs. In the desal pitch the ability to scale them as needs scaled "quickly" as well as the ability to decomission them when they were done by picking the entire reactor complex up and transporting it off site were the primary selling points. If you're still interested you can start at the DOE site and follow those links, NuScale (https://www.nuscalepower.com/en https://www.nuscalepower.com/en) has a bunch of stuff to, they will send you white papers). Anyway, I doubt they are going to go anywhere before the first round of the climate apocalypse gives people the "You can either put in a nuclear power plant or you can all die, which do you want to do?" choice.
ChuckMcM 3y ago
FWIW there is a really fun "disruptive" desalination option that could work in places like Monterey Bay which is just dropping a really really long pipe down into the ocean that has the desalination membrane at the bottom of it. Top of the pipe is above the surface. Water pressure at depth drives water through the membrane and up the pipe. At the surface you just pump fresh water out of the pipe like an ordinary fresh water well. Maintenance is basically pulling the pipe up every couple of years and replacing the membrane which will become fouled over time, but generally it would be deep enough that it would not get barnacles and other mollusks on it.
- cgb223 3y ago
  On paper this sounds like a really obvious great idea Have we ever built a working prototype/plant that does this?
  - ChuckMcM 3y ago
    There was a startup pursuing a test setup using an oil derrick of Santa Barbara if I recall. These guys[1] were proposing a different system (basically providing fresh water to an underwater habitat) however the paper goes over the basics pretty effectively. [1] https://www.hindawi.com/journals/ijce/2021/8898472/ https://www.hindawi.com/journals/ijce/2021/8898472/
  - Baeocystin 3y ago
    It does sound clever at first glance. It caught me at first, too. The problem is, your fresh water is now several hundred feet below the surface. To raise it up to where you are, you need pumps to push up the same exact pressure differential that you got by putting the membrane so deep. And if you need to do that anyway, just use surface level water and pumps for ease of maintenance and access.
    - ChuckMcM 3y ago
      Have you seen a "wave" pump?
- 3y ago
abhibeckert 3y ago
> there wasn't a cost effective power solution for just desalination There absolutely is. All you need is a bunch of mirrors to direct the sun at a chamber filled with water. The water will evaporate, the expansion into steam creates significant pressure so you can run it through a turbine, and then once the steam cools down and liquifies again, it won't have any salt in it. It's not even remotely expensive. Mirrors are cheap. The turbines/etc are basically the same as a coal or gas power plant and mirrors are a hell of a lot cheaper than mining coal or gas. Also if you're boiling a usable quantity of water you'll be generating a lot of power, which is a handy byproduct (more valuable than the water to be honest). "Not in our back yard" is the real issue. The chamber is generally at the top of a tower, and even painted black all that sunlight focused onto it is very bright. People generally don't want a really bright object on top of a tower anywhere near them. I guess you could build a wall around it or something, but you'll still get complaints from aircraft/etc. Driving into the sunset or sunrise is annoying. Imagine if that was all day every day instead of just for 20 minutes or so. Having said that, if you're in a remote area to counter the NIMBY issue, and clean water is hard to find, then the system I've described is very effective and they are being used for cost competitive farming of cheap crops. Anyone who actually wants to desalinate seawater can do it. It's just that almost nobody wants to right now.
- eropple 3y ago
  This is really interesting; I of course know of salt retrieval via evaporation but I don't have a strong understanding of steam capture for pressure. How big a tower are we talking about for the steam volume necessary to turn a reasonably sized turbine?
  - aaronbwebber 3y ago
    Big. https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Pr...
    - bin_bash 3y ago
      isn't molten salt quite a bit different?

BurningFrog 3y ago

Desalination seems ideal for cheap but unreliable energy like solar or wind. You just need a water reservoir to act as "battery".

brilee 3y ago
https://www.moderndescartes.com/essays/factobattery/ https://www.moderndescartes.com/essays/factobattery/ Using the above methodology, I ran numbers for a desalination factobattery and it's really bad, like two orders of magnitude more expensive than just buying a Li battery to buffer the unreliable energy and running desal 24/7.
- ChuckMcM 3y ago
  This right here. Even low grade continual energy supply is better for desal.
- BurningFrog 3y ago
  By "battery" here, I just mean a dam that holds a few days worth of fresh water.
  - brilee 3y ago
    I think you misunderstood the comment. I agree there has to be a buffer somewhere. You're arguing that we can get a free buffer by piping the water behind a reservoir, but the cost is that the very capital-expensive desalination plant will be idle half of the time. I'm proposing that the more economical option is to buy a lithium ion battery to buffer the renewables and run the desal plant 24/7. (You can still pipe the water behind a reservoir if you want)
    - tomrod 3y ago
      Even with battery degradation?
    - BurningFrog 3y ago
      I see. It's better to have a half as big plant running 24/7 with a battery. Thanks for educating me!
- yodelshady 3y ago
  See: collapsing European industry, finally now even in Germany, due to thinking "demand-side response" was a good solution.
schiffern 3y ago
The problem, of course, is utilization. Amortized capital costs for desalination runs about 40%,[0] so if you "charge" for 12 hours and "discharge" for 12 hours then your facility doubles in size, so your desalination cost increase by (at least) 40%. This doesn't even account for added maintenance btw. If you charge for 6 hours (ie the solar peak) and discharge for 18 hours, you need a facility 4x as large, and your desalination costs increase by at least 160%. Desalination isn't 'free' energy storage. [0] https://www.advisian.com/en/global-perspectives/the-cost-of-desalination https://www.advisian.com/en/global-perspectives/the-cost-of-...
lazide 3y ago
Desalination plants do REALLY badly when run infrequently. All the salt water, brine, etc. creates absolute havoc when it sits for random period of time, and maintenance costs are already a huge part of opex for desal plants. Also, the concentrated brine is a real problem in any area that has regular sealife. Maybe not a big problem in the salt ponds already, but it will kill off anything normal.
- ChuckMcM 3y ago
  Yeah, it isn't going to hurt the salt ponds. What is more, we did the math and found you could harvest more salt faster for less money when starting with a higher salinity brine which would be a win for Morton.

jojobas 3y ago

The smaller the reactor, the worse neutron efficiency gets, good old cubes and squares. Good practices also require as many hands/eyes for normal operation a GW class reactor as a 50MW one.

ChuckMcM 3y ago
At the time we were thinking NuScale type, see https://www.energy.gov/ne/advanced-small-modular-reactors-smrs https://www.energy.gov/ne/advanced-small-modular-reactors-sm... for efforts by DOE to make small modular reactors feasible in the US.
- jojobas 3y ago
  >Advanced SMRs offer many advantages, such as relatively small physical footprints, reduced capital investment, ability to be sited in locations not possible for larger nuclear plants, and provisions for incremental power additions. SMRs also offer distinct safeguards, security and nonproliferation advantages. I studied in a tangent area and either I'm dumb or DOE had a lapse of reason that day. Having five reactors per site is going to be worse than two of equal installed power in almost every respect. USA is the fourth largest country in the world, how is reduced footprint even a consideration?
  - ChuckMcM 3y ago
    There is probably a literal ton (if you printed it out on 20# paper stock ;-)) of stuff written about how small modular reactors are a much better answer to deploying nuclear power than big LWRs. In the desal pitch the ability to scale them as needs scaled "quickly" as well as the ability to decomission them when they were done by picking the entire reactor complex up and transporting it off site were the primary selling points. If you're still interested you can start at the DOE site and follow those links, NuScale (https://www.nuscalepower.com/en https://www.nuscalepower.com/en) has a bunch of stuff to, they will send you white papers). Anyway, I doubt they are going to go anywhere before the first round of the climate apocalypse gives people the "You can either put in a nuclear power plant or you can all die, which do you want to do?" choice.

ChuckMcM 3y ago

FWIW there is a really fun "disruptive" desalination option that could work in places like Monterey Bay which is just dropping a really really long pipe down into the ocean that has the desalination membrane at the bottom of it. Top of the pipe is above the surface. Water pressure at depth drives water through the membrane and up the pipe. At the surface you just pump fresh water out of the pipe like an ordinary fresh water well. Maintenance is basically pulling the pipe up every couple of years and replacing the membrane which will become fouled over time, but generally it would be deep enough that it would not get barnacles and other mollusks on it.

cgb223 3y ago
On paper this sounds like a really obvious great idea Have we ever built a working prototype/plant that does this?
- ChuckMcM 3y ago
  There was a startup pursuing a test setup using an oil derrick of Santa Barbara if I recall. These guys[1] were proposing a different system (basically providing fresh water to an underwater habitat) however the paper goes over the basics pretty effectively. [1] https://www.hindawi.com/journals/ijce/2021/8898472/ https://www.hindawi.com/journals/ijce/2021/8898472/
- Baeocystin 3y ago
  It does sound clever at first glance. It caught me at first, too. The problem is, your fresh water is now several hundred feet below the surface. To raise it up to where you are, you need pumps to push up the same exact pressure differential that you got by putting the membrane so deep. And if you need to do that anyway, just use surface level water and pumps for ease of maintenance and access.
  - ChuckMcM 3y ago
    Have you seen a "wave" pump?
3y ago

abhibeckert 3y ago

> there wasn't a cost effective power solution for just desalination There absolutely is. All you need is a bunch of mirrors to direct the sun at a chamber filled with water. The water will evaporate, the expansion into steam creates significant pressure so you can run it through a turbine, and then once the steam cools down and liquifies again, it won't have any salt in it. It's not even remotely expensive. Mirrors are cheap. The turbines/etc are basically the same as a coal or gas power plant and mirrors are a hell of a lot cheaper than mining coal or gas. Also if you're boiling a usable quantity of water you'll be generating a lot of power, which is a handy byproduct (more valuable than the water to be honest). "Not in our back yard" is the real issue. The chamber is generally at the top of a tower, and even painted black all that sunlight focused onto it is very bright. People generally don't want a really bright object on top of a tower anywhere near them. I guess you could build a wall around it or something, but you'll still get complaints from aircraft/etc. Driving into the sunset or sunrise is annoying. Imagine if that was all day every day instead of just for 20 minutes or so. Having said that, if you're in a remote area to counter the NIMBY issue, and clean water is hard to find, then the system I've described is very effective and they are being used for cost competitive farming of cheap crops. Anyone who actually wants to desalinate seawater can do it. It's just that almost nobody wants to right now.

eropple 3y ago
This is really interesting; I of course know of salt retrieval via evaporation but I don't have a strong understanding of steam capture for pressure. How big a tower are we talking about for the steam volume necessary to turn a reasonably sized turbine?
- aaronbwebber 3y ago
  Big. https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Pr...
  - bin_bash 3y ago
    isn't molten salt quite a bit different?