[HN Gopher] Desalination Can Beat Out Batteries for Excess Energy
___________________________________________________________________
Desalination Can Beat Out Batteries for Excess Energy
Author : Brajeshwar
Score : 55 points
Date : 2023-12-18 17:11 UTC (5 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| somethoughts wrote:
| Is the idea to use excess solar power to desalinate salt water
| instead of mine crypto currency? At a high level that seems
| smart.
|
| It seems like the general idea is to build out excess capacity on
| the desalinization side and run the desalinization plant at less
| than full throughput during peak consumer demand (i.e. peak of
| the duck curve?).
| mdale wrote:
| Lol. Almost like making drinking water and water that can be
| used to grow food is a better use of energy than boiling a
| small ocean of water on math designed to create artificial
| scarcity :)
| dragontamer wrote:
| The opposite.
|
| The various policies we have are for Aluminum Smelting plants,
| Desal, and other heavy-electricity industries to use excess
| solar (or nuclear) power during peak-energy times, and to turn
| off during peak-usage times to help balance the grid.
|
| On an individual level, we might be able to even do this for
| air-conditioning, washing machines, or car-charging (if you
| have a PHEV or EV).
|
| Cryptocoins then perverted the models we created to earn money
| from this through mining (using energy during peak-energy and
| turning off during peak-usage). But the "intent" for those laws
| has always been for industry and/or individual grid-level
| issues.
|
| --------------
|
| For low-utilization machines (ex: washing machines and dryers),
| this makes perfect sense. The main issue is that for high-
| utilization machines (ie: all industry wishes to run at 100%,
| rather than 80% or 50%), you end up doubling or more the cost
| of CapEx.
|
| Ex: You'll need twice as many Desal plants if they only operate
| during the most efficient 50% of times during the week. Which
| might be worthwhile, but you have to run the math. Every hour
| these plants are shutdown for power-saving purposes is an hour
| that they are sitting away / depreciating.
| vlovich123 wrote:
| I can't imagine that's how industries could actually run. I
| think they can benefit from cheaper costs to absorb excess
| electricity or reduce capacity slightly when it gets too
| expensive, but shutting down an aluminum smelting plant seems
| like a non-starter as they need to run constantly 24/7 and
| require long startup/shutdown times. Same goes for desal -
| you're not going to economically produce sufficient amounts
| of water just trying to time the energy grid.
|
| https://www.reddit.com/r/AskEngineers/comments/3g78nj/are_al.
| ..
| dragontamer wrote:
| I agree.
|
| Nonetheless, some industry are willing to give it a test to
| see how feasible it is.
|
| https://www.lightmetalage.com/news/industry-
| news/smelting/tr...
|
| > "We have reinvented the electrolysis process for the
| production of aluminium. For the first time, we will be
| able to vary the energy supply during operation
| significantly. This will allow us to react to changes in
| the electricity supply, which will benefit the power supply
| to households in Essen," says Philipp Schluter, CEO of
| TRIMET. "As an aluminium producer, we are naturally an
| energy-intensive company. As such, however, we are also a
| valuable partner for the energy revolution."
|
| > The EUR36 million trial installation converted a total of
| 120 furnaces in hall one of its Essen plant, which will be
| able to consume either 25% more or 25% less energy for up
| to 48 hours. The energy requirement can also be reduced to
| zero for up to an hour, if necessary. This means up to
| 2,000 megawatt hours of electricity can be stored for use
| in the energy revolution.
|
| -----------
|
| It requires new smelters, new software, new engineers. Its
| all very expensive. But it might be worthwhile. Just don't
| go like... crazy... with the idea right? There's downsides,
| but the upsides are immense. Keep an eye on the costs and
| practicality, and give it a test. It might be worthwhile.
|
| That's my outlook anyway. Maybe Aluminum specifically is
| run too close to 100% utilization to be useful (we do have
| a very predictable amount of Aluminum...), but maybe other
| industries have a more start/stop and feast/famine kind of
| setup that would benefit from off-hours automation for
| energy price optimizations and/or even grid-tie
| stabilization.
|
| But there are _real_ Aluminum plants giving this idea a
| test. So this isn't "vaporware" or even "theoretical". This
| is a real test occurring today.
|
| -------------
|
| We have to ask ourselves: is a 2GW-hr battery the best
| thing to build? What if Aluminum-smelters could instead
| vary their load by +/- 25% with this new
| software/manufacturing mechanism? What costs more, the 2GW-
| hr battery or this software + manufacturing change to
| Aluminum plants?
|
| In both cases, we get 2GW-hrs of "energy storage". EDIT:
| IE, varying your load each day is a form of energy storage
| that should be considered by members of society. It may
| very well be cheaper to achieve 2GW-hrs of virtual energy
| storage by upgrading industry, rather than trying to build
| impossibly huge amounts of Li-ion batteries.
| vlovich123 wrote:
| Varying load by +/- 25% is neat but that doesn't solve
| the "I need energy at night" problem for solar. You
| either need batteries or wind (but even wind is risky
| because you're screwed during windless nights).
|
| All these other ideas are worth exploring and I'm 100% in
| favor of them, but the only path to decarbonizing the
| grid is nuclear & I'm so frustrated by all the solar
| absolutists that think renewables can power 100% of the
| grid by 2050 just because solar panel costs are dropping.
| We'd get much closer to net 0 if we were building fission
| plants aggressively (cue all the solar proponents
| claiming it's too expensive or unsafe even when it really
| isn't and solar costs are intentionally calculated in a
| misleading fashion to ignore the buildout needed for
| energy storage or altering unrelated industries to make
| solar more attractive).
| matthewdgreen wrote:
| When the grid transition began in the 2000s the hope was
| that solar prices, storage and nuclear would all see
| massive cost declines that made a fast transition
| possible. This has occurred for solar PV. It's reasonably
| plausible that it will also occur for storage, given the
| huge incentives and rapid increase in manufacturing
| efficiencies. It has not happened at all for nuclear and
| there's currently nothing on the horizon that gives much
| hope this will change by the 2050/60 time frame. Even
| China, which is blasting away at nuclear, predicts it
| will only be 18% of their generation by 2060 (and that's
| likely optimistic.)
| vlovich123 wrote:
| Yeah, nuclear is hard because it was strangled in the
| crib for 50 years and it's hard to make up that ground on
| time scales for net 0. It still remains the better bet
| for decarbonizing the grid and all the other neat ideas
| seem mostly like party tricks and nothing more. I think
| China in particular is interesting because there's a good
| chance that they're building enough capacity that their
| costs start to decrease & they become the world leader in
| fission plants. Specifically interested in what they're
| doing with MSR designs because they should be much much
| cheaper than traditional HWR designs. But yes, it's going
| to take us a minute to rebuild and restart our fission
| know-how as a species. It's also telling that China is
| building a heck of a lot of fossil plants (natural gas &
| coal) in addition to lots of solar. That's because they
| have a lot of electrification to do (they have a massive
| rural population & they also have much more
| transportation that needs to electrify to use grid
| power). Solar is a fine companion to handle daytime peak
| growth (which is why they're reaching TW scale with
| solar) but that baseload growth remains a problem which
| is why they're building so many fossil fuel and nuclear
| plants.
| matthewdgreen wrote:
| I don't want to re-litigate the "fission didn't fail
| economically, it was killed" perspective (which I find
| unconvincing: people have proven they'll put up with much
| more dangerous things if they're profitable.) But we need
| to replace the entire global fossil fuel industry in
| 20-30 years, and the only possible way to do that is with
| energy sources that can be mass-produced in a factory
| with all the scale and efficiency improvements and
| virtuous cost and production flywheel that entails. Solar
| and wind are on this trajectory. Storage is plausibly on
| an earlier stage of this trajectory. Nuclear might get
| onto this trajectory through modular reactors, but those
| don't exist and are at the "maybe" research stage with
| huge questions still unanswered. By contrast, commercial
| battery deployment and production is economical and
| projected to hit 6.5TWh by 2030.
|
| As a related datapoint on "party tricks", China built
| more solar and wind _in the first nine months of 2023_
| than all 26 nuclear reactors it has under construction.
| They're likely to build even more next year. The need for
| baseload is a valid point, but the trajectories of
| renewables vs. non-modular nuclear are so different that
| it's hard to see nuclear catching up enough to make a
| difference.
| vlovich123 wrote:
| Given that China is building out more coal plants than
| all other countries combined, I think that's telling
| about the efficacy of renewables to achieve net 0.
| They're targeting 2030 for peak CO2 emissions because
| they're trying to cheaply electrify as much of their
| population as possible as quickly as possible because the
| CO2 reduction efforts that will dominate 2050-2100 will
| impose significant economic growth challenges & China
| wants to make sure they're in a more stable position to
| compete with the West.
|
| Yes, China is building a huge amount of solar capacity,
| but AFAICT it's all about absorbing peak growth as they
| add more consumers of electricity. Baseline growth
| remains a huge problem and China is solving that with a
| mix of nuclear and fossil fuels. I fully expect China
| will continue to ramp up nuclear as they get better at
| it.
|
| And EVs are a huge iceberg problem for the electric grid
| as they currently don't run off the grid and represents a
| massive amount of energy consumption that will be added
| to the grid. On top of that they consume a huge amount of
| battery production which means there's not that much left
| over for grid scale batteries. We also have no existence
| proof of economical grid scale batteries at any
| meaningful scale. You also have to overbuild your solar
| by quite a bit so that you can charge the battery up when
| the sun is shining to time-shift that excess capacity
| into the night.
|
| Solar is fine and it's not a knock against it, but
| there's simply no trajectory to reach net 0 CO2 emissions
| and you will end up with a hybrid grid. 18% nuclear would
| represent a huge CO2 reduction because all that capacity
| would otherwise be fossil fuels (because the alternative
| is not building batteries because that tech doesn't exist
| yet). MSRs are a neat party trick but honestly I think
| China's approach of SMRs is a far safer bet in terms of
| being a massive cost reduction, safer, and use waaay less
| water & are far less of a research project. My hunch is
| that they're also standardizing their nuclear plant
| designs to keep costs in check. Keep in mind that France
| is 90% fossil fuel free in their grid even though nuclear
| only represents ~60% of energy produced.
|
| I haven't read anywhere that fission failed due to
| economics - it has always been price competitive with
| fossil fuels. It's the regulatory burdens & concerns
| about safety (some valid, most not) that strangled its
| growth. Do you have any links suggesting nuclear
| construction is uneconomical?
| matthewdgreen wrote:
| The latest estimates are that China's emissions will peak
| next year and then enter a structural decline [1]. The
| 2030 number is generally viewed to be obsolete now
| (that's how fast things are moving.) This is even with
| the new coal capacity they're building, which they're
| structuring to be "idled" (through government payments
| not to generate.) They're also building large amounts of
| solar capacity in the west and in deserts, with
| continent-scale HVDC interconnects.
|
| Right now the (global) goal isn't 100% renewable energy,
| and it won't be even by 2030 or 2040: a grid that's
| 70-80% renewable with 20-30% average fossil emissions
| will be a massive improvement and will keep us on track
| for decarbonization. The interesting question is whether
| battery storage will decrease in price fast enough to
| deliver that remaining fraction, or whether we'll have to
| build the remaining 20% with fission by 2050/60.
| Batteries are already economical enough that we have 5GW
| deployed in CA for infra-day time shifting. It seems like
| an incredibly long bet to imagjne that after _three more
| decades_ of technological and manufacturing improvements
| their cost won't have dropped enough to make them a
| viable competitor for nuclear. For my own part I wish I
| could take the other side of that bet, since I think it
| would be a good one. But we'll have to wait and see.
|
| [1] https://www.carbonbrief.org/analysis-chinas-
| emissions-set-to...
| breischl wrote:
| >we might be able to even do this for air-conditioning,
| washing machines, or car-charging (if you have a PHEV or EV).
|
| No _might_ about it, this currently happens for A/C, and is
| just getting going for car charging (see EV Managed Charging
| as a category).
|
| Also some functions of commercial/industrial facilities that
| can be ramped more easily, eg shut off half of the hallway
| lighting in an office building. I think I recall things like
| rock crushers being turned off, but I might be misremembering
| that.
| __MatrixMan__ wrote:
| Unfortunately, solar panels get less efficient when hot,
| which is when your AC demand increases.
|
| Ideally you could offset this by having people who aren't
| well positioned for panels do energy storage: Buy in the
| morning, sell back in the afternoon. Practically I don't
| think the utility companies are going to cut them in on a
| big enough part of the profits to incentivize them to do
| so.
| breischl wrote:
| Sorry I stated my original point poorly, and it wasn't
| exactly what you were saying. My bad.
|
| Demand response for A/C tends to look more like pre-
| cooling before the hottest hours, then reduce demand
| during the hottest hours. So it's not about shifting
| demand towards maximum production, but rather shifting
| demand away from the demand peak (aka, peak shaving). So
| it's similar but a little different.
|
| >Practically I don't think the utility companies are
| going to cut them in on a big enough part of the profits
| to incentivize them to do so.
|
| The commercial version of what I stated in the previous
| paragraph (ie, demand response/peak shaving) empirically
| already happens, and has non-trivial dollars attached to
| it. Again, maybe not exactly what you're talking about,
| but it rhymes.
| duckmysick wrote:
| > Unfortunately, solar panels get less efficient when
| hot,
|
| Less efficient by what factor?
| edent wrote:
| Based on my experience - about 12%. See
| https://shkspr.mobi/blog/2022/07/solar-efficiency-and-
| high-t...
|
| That will depend heavily on local conditions, type of
| panel, etc.
|
| Significant, but not devastating.
| duckmysick wrote:
| That's pretty cool! 10% was my educated guess. It's good
| to have some data points.
|
| Would you say the same holds across months? Say, would
| cooler May have better production than hotter July? Or is
| July still ahead because of more sunshine hours,
| offsetting the hot inefficiencies?
| edent wrote:
| It really depends on the weather. You can see my monthly
| generation at https://pvoutput.org/aggregate.jsp?id=83962
| &sid=74451&v=0&t=...
|
| Sometimes May beats July, sometimes it doesn't.
|
| If you're interested, I have released all my panels' data
| at https://gitlab.com/edent/solar-data/
| Neikius wrote:
| I don't remember the numbers but I did watch this YouTube
| video where a guy strapped on some fans to a solar panel
| and actually got a better yield fan usage included.
| F-W-M wrote:
| Energy costs vary not only over the day but per quarter hour
| in each hour, e.g. during the morning the last quarter is
| cheaper than the first for each hour. So you don't
| necessarily have to shut down the machines, maybe you can
| just move the most energy expensive phase into another
| quarter.
|
| If you are brewing beer you have times where you have to heat
| it and times where it needs to sit at a given temperature.
| Try to optimize the process to heat during cheaper quarter
| hours.
| patall wrote:
| You assume that it is all linear which it may not be. Osmosis
| at power P may produce X litres of water per time unit while
| osmosis at power 4P may produce only 2X litres per time unit.
| And thus be viable only when the electricity price is N times
| lower.
| BiteCode_dev wrote:
| Consuming energy productively > storing it?
|
| Well, yeah...
| tantalor wrote:
| What's the difference
| vlovich123 wrote:
| Storing it lets you feed back that energy at a different time
| (e.g. night) but requires a lot of expensive hardware (i.e.
| batteries) + you have to deal with losses involved with
| storing & retrieving that energy. Consuming it directly
| doesn't require batteries and desal plants are cheaper than
| battery plants + going to be fewer losses.
|
| It's a stupid comparison though because the point of
| batteries is to get to net 0 and desal plants don't help with
| that. But it's not a great sign for renewables achieving net
| 0 at the grid level that a process that is so energy
| intensive for getting so little water out is a better use of
| electricity than batteries.
| jeffbee wrote:
| Desal plants _do_ help by giving renewables something
| economically valuable to do in the spring when energy
| output is being wasted.
| vlovich123 wrote:
| Only because you have to overbuild more solar capacity
| than you need to with nuclear/hydro/fossil fuel plants
| which have a more reliable method of operation.
| toast0 wrote:
| If you live somewhere that desal is the way you get your
| drinking / irrigation water, it makes sense that rather
| than storing energy to run desal continuously you can run
| desal intermittently and store water.
|
| You already need infrastructure to store fresh water for
| later use, and storing water for later use is relatively
| low loss (depending on the scale --- outdoor reservoirs can
| have a lot of loss). There's always a question of capital
| costs, of course: does it make more sense to have a higher
| capacity plant with a lower duty cycle where the duty cycle
| that uses mostly off-peak priced energy, or a lower
| capacity plant with a higher duty cycle which uses on-peak
| priced energy much of the time.
|
| Most energy consumers don't care about getting to net 0,
| they want to pay less for energy, if energy is a large part
| of their input costs.
|
| Intermittent operations do help get to net 0 though --- if
| all energy intensive uses could handle intermittent
| operations, it allows for more intermittent generation. It
| certainly doesn't get you all the way though; there's lots
| of uses that won't work well without continuous energy.
| vlovich123 wrote:
| If you read the article, this take actually is not true
| if you have a grid powered fully by renewables. It only
| makes sense when you have a hybrid grid where baseload is
| powered by fossil fuels and the arbitrage difference
| makes desal attractive. Note that a nuclear grid doesn't
| have this problem & it has enough capacity to reliably
| power everything + continuously run desal. To run desal
| off of solar requires a much larger capacity installed
| because you have to make up the lack of 24/7 operation
| with excess capacity whereas something like nuclear can
| make up the production gap due to smaller excess capacity
| by running 24/7.
| governmentdude wrote:
| Another good use is making hydrogen for ammonia.
| brilee wrote:
| https://www.moderndescartes.com/essays/factobattery/ I looked at
| a variety of these ideas and most of them are bad. Desalination
| is another one I looked at quickly (did not add it to the blog
| post), but I recall it being at least 10-100x more expensive than
| just buying batteries.
| cogman10 wrote:
| I think the desal math changes a bit because it also produces a
| product beyond just batteries. For particularly arid or water
| poor locations where you need desal anyways, seems like this
| could be a win (think islands or the middle east).
|
| That said, you'd probably still want batteries to supply power
| to things like a desal plant when water levels are low.
| thelastgallon wrote:
| The lifetime of a Li plant is just 10 years? Batteries lose a
| bit of capacity at 10 years, maybe still have 80 - 90%
| capacity. These can run for decades.
| vlovich123 wrote:
| > New research shows that hybrid energy grids that rely on a mix
| of renewable and fossil fuel energy are up to the task, so long
| as the timing of freshwater production is right. In some
| situations, it may even be more financially and energy efficient
| to put that generated energy toward desalination rather than
| store it in batteries for use later.
|
| And this is why I remain skeptical of renewables as base load
| energy. The only carbon free base load energy tech remains
| nuclear which is also perfectly capable of performing desal
| during off-peak times.
| tmoertel wrote:
| Geothermal also works for carbon-free base load, and newer
| drilling techniques made it viable in areas without high
| surface heat.
| barbazoo wrote:
| > And this is why I remain skeptical of renewables as base load
| energy.
|
| Someone should tell countries like Germany then \s
|
| https://www.reuters.com/business/sustainable-business/german...
| himinlomax wrote:
| Germany is currently producing nearly half of their
| electricyt from coal and gas right now.
|
| https://app.electricitymaps.com/zone/DE
| tsimionescu wrote:
| Yes, someone really should. Germany is currently one of, if
| not the, worse polluters in the EU, by far. Compare it to
| France, which produces most of its electricity from nuclear
| power, and thus produces almost half the CO2.
| barbazoo wrote:
| First sentence from the linked article:
|
| > Germany aims to fulfill all its electricity needs with
| supplies from renewable sources by 2035
| tsimionescu wrote:
| Aiming is easy. Achieving your aims is an entirely
| different problem.
|
| Given their track record, it seems more plausible that
| they'll close down wind turbines and replace them with
| more coal, like their "green" government has been doing
| with nuclear.
| ProjectArcturis wrote:
| Somebody always wants to tout nuclear, even when that's not the
| topic at hand. Nuclear is equally unsuitable to solar as a
| stand-alone energy source. Nuclear energy is produced
| constantly throughout the day, and would not match the daytime
| peaks in electricity consumption.
|
| Anyway, this article is discussing one of many new ways that
| power usage can be shifted around during the day, which makes
| solar able to provide a LARGER share of our overall energy.
| vlovich123 wrote:
| No, this article is saying that if you have a hybrid grid of
| fossil fuels & solar, desal is a cheaper application than
| storing in batteries & using solar power banked in batteries
| at night. If you have a full renewable grid, that advantage
| disappears. That's because the price differential comes from
| arbitrage & that price differential makes desal cheaper than
| building capacity.
|
| I bring up nuclear whenever there's a discussion of grid
| energy to provide a reality check that solar is not able to
| get us to net 0 by 2050 in any way regardless of clever new
| ideas. By contrast nuclear actually does have that capability
| and it's not purely theoretical nor "hey what if we
| productionized some new hypothetical theoretical idea at
| massive scale and ignore all unintended side effects" - we
| have plenty of existence proof that nuclear is a drop-in
| replacement for fossil fuels & thus actually very quickly
| reduces the need for them in the grid energy mix whereas no
| such existence proof really exists for renewables (yes -
| someone brought up Denmark but that's not a repeatable
| situation because they are one of the windiest places on
| earth and wind doesn't have the same critical downsides that
| solar does for grid power).
| ProjectArcturis wrote:
| >very quickly Vogtle 3 just came online in July, 17 years
| after the initial application was filed. Unit 4 hasn't come
| online yet. They're going to cost more than double the
| initial estimate.
|
| I just don't get the fascination with a power source that
| is so much more expensive and slower to bring online.
| laurencerowe wrote:
| Unfortunately nuclear is now horribly expensive to build so
| we're just not going to build that much of it. By contrast
| renewables (and batteries) are getting cheaper and cheaper so
| we are building lots of them.
|
| In 2022 Denmark generated 62% (+12% from 2021) of its
| electricity from renewables (excluding biomass which seems
| suspect to me) while France generated 63% (-5% from 2021) from
| Nuclear.
|
| I think you can make a case that nuclear is competitive for
| 100% carbon free grids (though by the time it's built batteries
| will have gotten far cheaper.) But it seems clear that
| renewables are by far the cheapest and quickest way to get to
| ~80% carbon free grids.
| vlovich123 wrote:
| Yes yes. Renewable proponents really love trotting out costs
| while ignoring the only reason costs have gone up is because
| we significantly ramped down our nuclear production efforts.
| Same would happen if we did that for solar. But that's a
| choice we get to make. Also nuclear construction costs are
| particularly outsized in the US where regulations are
| intentionally constructed to strangle it. Japan, China, and
| Europe build it much more cheaply.
|
| Existing heavy water reactors could be built more cheaply
| than they are now. And MSR/thorium designs are a step
| function cheaper beyond that because they generate even less
| waste, don't need expensive fail-safe mechanisms because it's
| inheritently physically impossible to melt down, and don't
| need water to cool down which is both a cost savings & avoids
| the issue of warming waters due to global warming impacting
| the ability for reactors to run at times.
|
| China has already started building MSR designs and it sucks
| that the DOE is dragging their feet in approving these
| designs & focusing instead on SMR designs. The regulatory
| capture of the US beuracracy by fossil fuel companies is a
| huge problem.
|
| > it seems clear that renewables are by far the cheapest and
| quickest way to get to 80% carbon free grids
|
| Got any existence proof for this claim? We're building
| renewables as fast as we can and countries seem to generally
| tap out at ~20% ammortized across the year and are growing
| extremely slowly (~1% each year). By comparison France runs
| 90% carbon free and that's because of their nuclear grid.
| Batteries will decrease over time but we still don't yet know
| what grid-scale renewable base load looks like & I don't
| think that 80% number is correct considering that baseload is
| 30-40% of maximum load (i.e. best case peak without batteries
| is 60-70%). But all the solar proponents also seem to ignore
| a major headwind for solar which is that while we build out
| more & more capacity, our energy demands grow faster than
| that. We've electrified 2% of consumer cars, 0% of trucks, 0%
| of ships, 0% of airplanes. Electrifying cars is going to add
| an insane amount of demands on the grid & solar can't keep up
| (batteries either). And yes, there's the argument of using
| batteries in EVs to do the grid balancing but we don't
| actually have that tech & 0 regulations requiring it meaning
| that in 2035 which is the target when ostensibly we stop
| creating new ICE cars, we still won't have that ability.
|
| Building out nuclear capacity is still by far the quickest &
| cheapest option to not only convert our existing energy to
| carbon free but also to keep up with ever growing demands.
| Remember - the more capacity you build, the cheaper it gets
| per MW. Also, nuclear is way more land efficient than solar
| which is a separate unrelated discussion but also relevant.
| Again, my argument is not to stop solar investments but to
| remove all the regulatory and bueracratic roadblocks that
| inhibit nuclear fission so that those companies can compete
| fairly.
|
| Denmark is an absolute best case because they are
| geographically advantaged for wind. Wind is much more
| resilient and cheaper than solar but is also more geography
| dependent. Fission can be installed anywhere.
| DelaneyM wrote:
| It's fascinating that this is a paper - we did the math about 20
| years ago and have been using excess electricity for desalination
| in Cayman ever since.
| jmyeet wrote:
| We love rediscovering things and writing papers [1].
|
| [1]: https://fliptomato.wordpress.com/2007/03/19/medical-
| research...
| thechao wrote:
| Texas tried to do this in the early 2000s; we even built a
| bunch of desalination plants (here's a comment about this I
| made recently):
| https://news.ycombinator.com/item?id=38422172#38424191
|
| Long-story-short (based on my experience with these
| chuckleheads): it was killed because the current political
| establishment didn't own the desalination plants, so there was
| no way they could _personally_ profit off of them; they own oil
| /gas/fracking & ERCOT.
| passwordoops wrote:
| Sadly that's just about true for most things, whether it's
| city state or federal. God forbid Congress tries to tackle
| the health care industrial complex, it might hit their
| portfolio!
| datadrivenangel wrote:
| Really impressive simulation of using fresh-water storage tanks
| as energy storage in regions that use desalination.
|
| The cost of overbuilding desalination capacity is non-zero
| though, and energy is only about ~1/3rd of the typical cost for a
| cubic meter of water overall depending on the plant, so the
| marginal savings may not be as big as we would like here.
| p1mrx wrote:
| > this economic efficiency "mostly vanishes" under scenarios with
| 100 percent renewable grids, says Conejo, because the cost of
| producing electricity is similar throughout the day.
|
| I don't understand this statement. Shouldn't the cost of
| _consuming_ electricity vary as the supply of renewables changes
| throughout the day?
| Animats wrote:
| If you only run the desalination plant when energy is cheap,
| plant cost per liter of water goes up. May or may not be a win.
| Probably a win for small, isolated plants, say for powering and
| watering a small island. Large grid-connected plants, don't know.
| thelastgallon wrote:
| Water probably isn't grid connected like electricity. Nor does
| the supply need to perfectly match the demand every second.
| There is quite a bit of water storage in the system.
|
| There might be pumps, in addition to just gravity assisted
| transportation of water. When energy is cheap, we can do both
| desalinate + transport.
| cperciva wrote:
| You're missing the point. If you need 24 m^3/day of fresh
| water, you can have a desalination plant producing 1 m^3/hour
| and a water tank to match supply to demand. But if you only
| want to run the plant for 3 hours/day when electricity is
| cheap, you now need a plant which can produce 8 m^3/hour.
|
| There's a tradeoff -- spending more building the desalination
| plant makes it possible to run at a lower duty cycle so you
| can spend less on the electricity.
| laurencerowe wrote:
| But mainland desalination plants are connected to the
| electricity grid.
|
| The problem with only running them part of the time is that
| the fixed capital and other operational costs of the plant
| are now split over a smaller amount of water produced so that
| water is more expensive than if you ran the plant all the
| time paying more for electricity at other times of the day.
| morepork wrote:
| There is certainly a trade off there, does the cheaper
| electricity compensate for the fact that you need to add
| say 20% extra capacity and the accompanying costs to your
| desalination plants as they will now be idle during low
| renewable production/times of high electricity costs.
| dragontamer wrote:
| All water infrastructure in mainland America is stored in large
| reservoirs / lakes and/or water-towers for future use.
|
| If it takes 1GW-hr to make I dunno, a billion gallons of water
| or whatever, then it might be cheaper to store a billion-
| gallons of water + build a 2nd desal plant rather than trying
| to build a 1GW-hr Li-ion battery.
|
| That's the real question that's being discussed here. What's
| cheaper? Additional Desal plants + water storage? Or Giant-
| batteries?
|
| Presumably, pumped-hydro is off the table (which is true in
| some geographies). Pumped-hydro is an effective form of GW-hr
| sized energy storage but is somewhat frustrating at how limited
| the geography can be for it in practice.
| bryanlarsen wrote:
| I don't think the geography at the Ludington pumped hydro
| storage plant is particularly uncommon.
|
| https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power.
| ..
| jimnotgym wrote:
| If you electrolyze seawater, to make hydrogen when the grid is
| over producing...and then you burn it to produce electricity when
| the grid is in need....can you capture the waste water from the
| exhaust... and call the entire process desalination?
| loufe wrote:
| The energy conversion losses in the cycle you describe are
| enormous.
| thsksbd wrote:
| Not enormous, but not insignificant either.
| thsksbd wrote:
| I worked on this a little bit. You still need to energetically
| pay the entropic cost of separating salt from water, and the
| kinetic over-potential (on the electrodes). Also these cells
| hate running in reverse. Ruins their lifespan. Overall it is
| still not viable.
|
| Your idea to use it to iron out the economics, though, might
| have some merit if the price fluctuations are high enough
| (which is what motivated us to begin with)
| thelastgallon wrote:
| Also, we can charge EVs. Grid connected batteries may or may not
| use the energy, but EVs will use some portion of it every day,
| and can be charged again the next day when there is excess
| energy.
|
| Power price goes negative +200M times/year, just in the US and it
| is increase. It would be wonderful to get paid for charging EV.
| Tesla Electric customers report making as much as $150 a day[1].
| Car batteries are bigger than powerwall, EV owners can make quite
| a bit of money by participating in VPP (Virtual Power Plant).
|
| (1) https://electrek.co/2023/07/05/tesla-electric-customers-
| repo...
| sandworm101 wrote:
| It would take a great many discounted electric bills to justify
| the extra wear on the batteries that would result from the
| extra daily charge/discharges.
| led76 wrote:
| I'm not sure it would have much of an adverse impact. Driving
| the car is constantly charging / discharging it (regen
| braking).
|
| I think it's more about how deep the cycles go -- just don't
| let the grid drain below like 30-40% battery and it likely
| would have no meaningful impact long term.
| sandworm101 wrote:
| I'm not sure it a totally rational thing. This is
| effectively putting more miles on your battery, an item
| that costs tens of thousands of dollars to replace, if even
| possible years after purchase. There would have to be a
| substantial compensation for such use even if it only
| degraded the lifetime a few percent.
|
| But at such a compensation level, one could probably just
| purchase deep cycle lead acid marine batteries. They could
| sit in one's basement charging/discharging at a much lower
| cost than the lithiums in a car.
| thelastgallon wrote:
| The price of batteries has declined by 97% in the last
| three decades:https://ourworldindata.org/battery-price-
| decline. And it continues to go down! The chart ends at
| 2018, $181/KWH. 2024 forecast is $94/KWH (half of 2018
| price), 2030 forecast is $62/KWH. Thats just Lithium Ion.
| Newer chemistries are even cheaper. CATL first-generation
| cells (Sodium Ion) cost $77 per kWh, expected to drop to
| $40/KWH.[1]
|
| Current estimate for a battery replacement is 4K - 20K.
| With energy storage's learning curve, this will be soon
| under $3K.
|
| 1)https://www.nextbigfuture.com/2022/12/catl-will-mix-
| cheaper-...
|
| https://about.bnef.com/blog/behind-scenes-take-lithium-
| ion-b...
| gnicholas wrote:
| > _Driving the car is constantly charging / discharging it
| (regen braking)._
|
| My understanding is that the impact on battery longevity
| relates to the rate at which it is being
| charged/discharged. Accelerating and regenerative braking
| are small potatoes compared to charging over a typical
| level 2 system, I would think.
| _ihaque wrote:
| Level 2? Certainly not.
|
| A typical L2 charger will provide in the range of 6-10kW
| (AC, marginally less ends up going to the battery after
| conversion losses). 10kW is only 13hp; forget
| acceleration - the car draws more than that at highway
| speeds.
|
| (You can come at this result another way too - an L2
| charge may take 6-10hr to refill the battery from empty.
| But the car would not be able to drive 6-10hr at highway
| speed starting at 100% charge! So the L2 must be
| delivering less power than the car consumes at cruising
| speed.)
| gwbas1c wrote:
| When people plug in their cars:
|
| 1: They expect them to start charging.
|
| 2: They expect them be charged when they return.
|
| Please don't let your imagination run away with schemes like
| this. The incentives might be nice, but they'll only attract
| people who understand them and are in a situation to take
| advantage of them.
| bryanlarsen wrote:
| I dispute that. Ontario Ultra-low-overnight rates let me
| charge my car overnight for $2 or during peak periods for
| $25. Not too many people are going to ignore savings like
| that.
|
| I just tell my car to make sure it's charged & warmed by 7AM
| and it takes care of the rest.
|
| If I had the opportunity to join VPP I'd just tell it to make
| sure that it was at 80% at 7AM and never below 50% any other
| time.
| edent wrote:
| I think every EV I've driven has a charging timer - so I've
| been able to say "only charge overnight when prices are
| cheaper". Some have "Be charged to 100% by this time" so they
| can pick and choose when to start charging.
|
| Please don't let your lack of experience run away concocting
| scenarios which don't exist.
| thelastgallon wrote:
| Your assumption is there is no electricity at home or work,
| only at charging stations far away.
|
| But, we have electricity anywhere we have a building. In
| fact, thats the first utility thats hooked up before anything
| is even built. Now, we can think of charging an EV anytime it
| is parked. Residential garages have a 240V dryer outlet (or
| in the laundry room next to garage). That outlet can be used
| or an additional outlet can be added.
|
| Cars are parked 22 - 23 hours a day. They can charge anytime
| they are parked.
| breischl wrote:
| This seems like a special case of the general concept that
| matching electricity demand to supply is important, and whereas a
| fossil fueled grid has enough dispatchable power sources to match
| supply to demand, a renewable-powered grid has to instead match
| demand to supply (at least to a much greater degree).
|
| So it's interesting, although at some point it seems unnecessary
| to enumerate that this same concept applies to every possible
| source of electricity demand.
| AtlasBarfed wrote:
| I get this is useful for a huge overload of wind or solar power,
| but this doesn't address base load and offpeak generation usage.
|
| The headline reeks of oil/gas companies pushing an agenda to keep
| gas turbine a critical part of the baseload infrastructure and
| keep grid storage from developing.
| gwbas1c wrote:
| > freshwater tanks are cheaper than electrical batteries, it
| seems appropriate to fully exploit the ability of tanks to
| displace energy production/consumption, and then, if needed, to
| use electrical batteries for the same purpose
|
| What about the cost of additional desalination equipment needed
| to take advantage of energy peaks? In a situation like this, is
| extra desalination equipment needed when renewable energy peaks?
| Or, do current desalination systems have periods where the
| equipment is idle?
___________________________________________________________________
(page generated 2023-12-18 23:02 UTC)