Pumped-storage hydroelectricity | Hacker News Reader

Pumped-storage hydroelectricity

en.wikipedia.org

92 pointsluu130 comments

I worked in the snowmaking industry at ski resorts for more than a decade before getting into tech. Many ski resorts have a snowmaking reservoir at elevation and a pumping system to fill it (usually off peak) and then use gravity to actually feed the snowmaking guns (at least partially). Almost every snowmaking manager (that I talked to) has had the idea at some point to try some sort of pumped hydro offset, but I'm unaware of anyone who has actually tried it. It would be fairly small scale (reservoirs can be ~20 million gallons, usually less) but it would be interesting to see the economics of it because the infrastructure is already there (pumps, pipes, reservoirs, etc). The systems generally even sit unused for 7-8 months of the year.

I think some of the challenges are that while most resorts have a fairly massive pumping system, it's usually geared towards slowly filling the reservoir, with the rest direct feeding the snow guns. Not many places have the need to fill a 20 million gallon reservoir in a couple of days.

There's also the probability that the head pressure's wouldn't work out. Gravity feeding from an upper reservoir near the top of a large mountain can result in thousands of PSI at the bottom if not passed through a series of pressure relief valves. I'd imagine ideally you would have to build a generating station and a new catch reservoir at the perfect elevation because if you are pumping a lot higher than needed the efficiency is going to drop significantly.

> I'd imagine ideally you would have to build a generating station and a new catch reservoir at the perfect elevation because if you are pumping a lot higher than needed the efficiency is going to drop significantly.

I don't think that's a concern. There's hydro plants with more than 6000' of head, leading to almost 3000 psi of pressure at the turbine and an exit velocity of the water jet of over 600 ft/s. From an engineering standpoint its totally manageable, and results in a highly efficient turbine.

> I think some of the challenges are that while most resorts have a fairly massive pumping system, it's usually geared towards slowly filling the reservoir, with the rest direct feeding the snow guns. Not many places have the need to fill a 20 million gallon reservoir in a couple of days.

Good news is that adding another pipe with its own pump/generator is relatively cheap. Bad news is that 20 million gallons is a relatively small reservoir for pumped hydro, and increasing that is expensive.

Still, seems like an easy and fast way to get some additional capacity online, especially in cases where a couple of megawatt of new solar get build in the vicinity of that damn...

The only problem of 3000 PSI is 99% of the snowmaking pipelines out there would instantly blow up at that pressure :)

You would also need to have PRVs anyways, because anything above about 700psi (900 if you are pushing it) is unusable/unsafe to use by the actual snowmakers and equipment. You also run soft 2" "fire" hose from a hydrant to a gun, and those are not rated for those pressures and the nozzles of the snow guns would wear out super quick as well (and the internal plumbing of the gun would probably blow up too).

You'd generally have a max of about 900 PSI and ideally much lower as most of these pipes are relatively old, have no maintenance (until they blow up and a quick patch is made) and were welded up by "Bob the maintenance guy"!

I suppose you could design a brand new system to be capable of such pressures when run in "generation" mode and still have some PRVs to keep it at a usable pressure during snowmaking operations.

If you pump up the hill, say to 3000PSI, then waste pressure on the way down: you lose said wasted energy.

Pumped Hydrogen Storage requires maintaining full pressure across the entire pipe. Which should be reasonable: the "fill up" pipe already needs to go from the bottom to top at full pressure. Reversing the flow should be enough.

The issue would be if the fill method was staged pumps.

> an exit velocity of the water jet of over 600 ft/s.

I’m completely unfamiliar with any of this stuff so please keep this in mind…

If that’s the exit velocity, shouldn’t the turbine it’s spinning be geared to give a bit more resistance?

Or is that the velocity of the water if its path is unimpeded?

Exit velocity is the nozzle exit speed. The water exists the nozzle and hits the turbine.

With that said, turbine efficiency is not strictly based on resistance. Rather it is about extraction of energy. In a few designs it looks like resistance, others it is about redirection: https://www.energy.gov/eere/water/types-hydropower-turbines

> exit velocity of the water jet of over 600 ft/s

What are the reasons not to set up secondary turbines / other mechanisms to capture that energy in turn?

Flims in Switzerland has a kind of hybrid scheme planned where they use a reservoir for both snowmaking and hydroelectricity.

https://www.wasserweltenflims.ch/wasser-in-flims/mehrzwecksp...

To what extent does it end up being "allow withdrawals for snowmaking" vs the thing being intended for snowmaking?

Well it's an enlargement of an existing snowmaking reservoir so I suspect it is the the latter. Probably part of a strategy to make the resort look eco-friendly.

Using google translate, it shows they are planning on upgrading the reservoir to 1 million cubic meters, which is about 264 million gallons from ~58 and that it will fill 3 times a year naturally, 4 times with pumps. 1/3 will be used to just keep the river flowing down the mountain, 1/3 for snowmaking and 1/3 for electrical generation.

Some extremely back of the napkin math (using ChatGPT) shows that if 1.33 million cubic meters of water per year were used at 1000psi (this is a huge assumption) to generate electricity, at the standard 80% efficiency you could do 2,030 MWh per year. A random search for the average price of electricity in Switzerland shows 0.154 euros per kWh, so it seems like this could potentially generate 312,620 euros (at consumer rates...) worth of electricity per year. Given that the idea of pumped hydro is to pump when electricity is cheap and then generate at peak demands...I'm not quite sure how to do that math!

Berkshire East is working on a micro pumped storage facility. Interestingly enough they’re already net producers of electricity.

https://berkshireeast.com/the-resort/100-renewable-energy

This map provides an interesting overview over the electricity sources used in Europe: https://app.electricitymaps.com/map

I found it very interesting that pumped hydro is contributing a small but not insignificant portion of energy in a lot of countries, including Germany and France.

Can anyone explain what's going on in America's western regions? My very naïve understanding is these places have giant deserts the size of some countries, shouldn't they be tripping over solar farms and have much lower carbon intensity?

They went full retard on politics and decided climate change isn't a thing. Or if it is, it is someone else's problem. "Look at the huge emissions of China and India - nevermind the CO2/Capita numbers that makes us the bad guy".

CO2/capita numbers matter from an assigning blame point of view, but physics doesn't care if a ton of CO2 is emitted by one person or ten people.

It's a bad argument to do nothing, but it's also not completely wrong. At this point we could turn off Europe and the USA and would still blow past 800ppm CO2 by 2100.

Would it work that way? A non-trivial portion of the emissions of those countries are caused by manufacturing products that are exported to the US and Europe

It would have some follow-on effect for a while due to shrinking the global economy but over time domestic demand in these countries and other places would pick up the slack.

But they can't pickup the slack if they are turned off. The east should not take the blame for emissions, when the majority of it is the proxy emission for the western consumption.

I meant the East would scale up consumption. The Chinese want cars and dishwashers and vacuum cleaners too, and I’m pretty bullish on air conditioning in India.

I think we overestimate how much is proxy emissions even now. Those are whole modern growing societies not just factories for us. Our view of climate change and carbon emission tends to be, like other things, very Euro-and-US centric and provincial.

What I’m saying is that if you turned us off you’d only delay the oncoming train, not stop it.

I think the chart doesn't show progress. California carbon fuel is mostly natural gas and those other states still burn a lot of coal. But much less than they used to 10 years ago. California started with a lower carbon intensity and pushed early on to move to renewables. But the other states are also moving that direction, just later and starting with high carbon footprint.

Probably helps California politically that 90% of it's natural gas is imported. vs locally produced coal. But Texas as reactionary conservative as it is isn't dragging it's feet either. (We hate that woke solar and wind. Enough to not make some money? Now you shut your mouth)

Worth noting inland western states are small population wise.

The right seems fairly interested in "space lasers" so perhaps if we just reframe solar to "space laser power" it'll help with acceptance? Very much tongue in cheek, however this has worked before. There's a company that collects old refrigerant that people have stored (mostly on farms and at mechanic shops). They specifically don't advertise it as recycling or a "green" initiative and instead promote it as a way to make some extra cash. There was a podcast about it a few years ago. I think it was this one https://gimletmedia.com/shows/howtosaveaplanet/kwhnz8b

Call it "large scale gravitationally confined fusion power," which is 100% accurate.

It's somewhat live, change it to monthly.

Also, cheap gas.

> I found it very interesting that pumped hydro is contributing a small but not insignificant portion of energy in a lot of countries, including Germany and France.

Is it really surprising? Pumped hydro is essentially massive batteries with fairly high rates of in and out flow, so they're really good both to smooth out production variability from renewables and to match / lead rates of consumption to relatively slow-following nukes.

The problem of pumped hydro is having suitable sites, I believe the US is still the only country to have built a completely artificial PHS facility with Taum Sauk.

A distributed approach to pumped hydro might make sense. Massive reservoirs are useful, but smaller systems could also offset fossil fuel use. There are already millions of water tanks across the world that store water for households and towns. Convert them to solar and add more for other small energy uses; build enough of them and the amount of power in aggregate will be significant. While these small storage tanks could only supply small amounts of electricity, they could be enough to power many applications, and perhaps using hydraulic actuators would increase the efficiency. For example, automatic doors could all be powered by stored water pumped by solar. Add a second storage tank below so the water is re-used instead of continually consuming fresh water. Windmills could do the pumping also. There are probably millions of applications for small energy storage systems like this. Divide and conquer is another approach to scaling, and small systems are not at all tied to having suitable sites for large reservoirs.

> A distributed approach to pumped hydro might make sense. [...] There are already millions of water tanks across the world that store water for households and towns.

It really doesn't. Let's ignore that most of those tanks are in active use and can't just be filled and emptied at will so you'd need a lot of additional hardware to do anything.

The fundamental issue of gravity energy storage is that it needs a lot of height or a lot of mass (ideally both): 1kg lifted 1 meter is a bit under 10j, which is nothing (it's 2-3 seconds of a led bulb). If you have a 5000L water tank on the ground an an other on the roof of a two-story house, let's say 7 meters between the two, that's a bit under 350000J, or 97Wh, which is a laptop's battery. And that's before accounting for inefficiencies in the pumps and generators, and friction losses in the ducts.

A good PHS site has an upper reservoir capacity of millions (usually tens thereof) of cubic meters, and at least 100m hydraulic head (some are close to 1000).

You'd need absolutely humongous water towers (we're talking taller than the tallest and larger than the largest) to get decent storage in distributed completely artificial contexts: the tala tank (https://en.wikipedia.org/wiki/Tala_tank) has 1.5MWh capacity. That's a dozen electric SUVs (à la Rivian), about 20 sedans if their batteries are not too large.

Moving, lifting, and storing water are things we're pretty good at, humanity has been doing that for literally thousands of years, if it was an easy way to store energy we'd have been doing it, a lot, for a longtime.

If people are interested in pumped hydro, Andrew Blakers et. al. from ANU have put together a global atlas of potential pumped hydro sites. They've got greenfield, brownfield, etc.

https://re100.eng.anu.edu.au/pumped_hydro_atlas/

That is already mentioned, in the fifth paragraph of the posted Wikipedia page (reference 8).

> Closed loop (off-river) pumped hydro storage has the smallest carbon emissions per unit of storage of all candidates for large-scale energy storage

Pumped-storage is a rather special approach as it feels almost like an extension of the natural water cycle.

Reducing the total footprint of the energy system (including all materials required for construction and ongoing maintenance) is an important part of the sustainability puzzle.

Ofcourse once you scale things to the gargantuan energy needs of modern civilization all sorts of minor "side-effects" may become important.

or, we should spend less electricity on AI, big data, and blockchains.

Even if we decided to stop all these and curtail datacenter power usage in other ways, decarbonising is certainly going to require increased electricity generation. Most oil and gas usage will be replaced with electrical alternatives. As the oil and gas burning applications are mostly quite inefficient, luckily we don't need to do 1:1 replacement of the chemical energy of fossil fuels. Still it seems unavoidable that in the future there will be more electricity generation rather than less.

They can be hugely political. Snowy 2.0 has tripled in price and has been a political weapon between coal, gas and renewable energy investment. It has pretty torrid engineering troubles with tunnel boring. It will be late coming onstream. Some argue the money could be better spent on renewable, batteries and poles and wires.

The Queensland proposal at Kidston has become a pawn between two parties and probably won't go ahead as large, if at all.

Queensland's existing PHES was operated by the coal generator to earn it money in coal, not to reduce pricing in bids by undercutting. The government had to structurally separate it out to get better bidding outcomes noting that it co-owns the coal power station concerned and liked the revenue side as it is.

Pumped hydro can be very useful in "black start" events.

Political is right. In NZ, the Onslow pumped hydro scheme was just cancelled by the incoming right wing-ish government, with no comprehensible rationale given [0]

> “On top of its $16 billion price tag, the Lake Onslow scheme would run into likely issues with consenting and it wouldn’t be delivered for at least another decade.

It will cost a lot and take a while. Duh. Show me the numbers. And govt can modify the consenting regime.

> “Industry experts warned that if the scheme went ahead it would have a chilling effect on the pipeline of renewable electricity generation New Zealand needs to reach our climate goals.

Please explain how something that can store renewable electricity has a chilling effect on renewables.

[0] https://www.beehive.govt.nz/release/lake-onslow-pumped-hydro...

By under bidding its energy against renewables, earned from gas and coal?

I don't entirely understand it either but the same reasoning is used by green opposition to snow2.0 to argue against it, a product of the turnbull LNP era government.

Damage to the national park during construction is the icing on the cake.

The Onslow pumped hydro scheme is estimated to store 4,000 – 11,000 GWh, with an estimated cost of $16 billion NZD (9.7 billion USD), and be delivered in (at least) 10 years time. Is that a cost of $881-2450 USD per kwhr?

I presume there is ample room for cost blowouts as well.

LiPo cells are currently costing about $110 to 130/kWh (USD), and trending downwards. Now large scale storage batteries are more than just the cells (Tesla megapacks are selling for 1.39M for 3.916 MW or about $410/kwhr), and cells probably wear out quicker than a dam, but it seems the Onslow scheme is not giving great bang for buck. The best you could say for it is that a lot of the spend would stay in NZ because a lot of the spend is in labour.

Am I missing something? Is my math wrong? It seems to me spending 16 billion becoming experts in assembling large scale batteries would be a better long term investment for NZ. And they can get access to the storage as it is build, instead of waiting 10 years.

https://www.mbie.govt.nz/dmsdocument/28349-identifying-poten...

https://pv-magazine-usa.com/2024/03/06/battery-prices-collap...

https://en.m.wikipedia.org/wiki/Tesla_Megapack

Your math is off by three orders of magnitude. The scale of the Onslow pumped hydro scheme is in billions of kWh, not in millions of kWh.

https://cdn.auckland.ac.nz/assets/business/about/our-researc...

Indeed the above puts it as having 8TWh storage capacity (and perhaps 1.2GW power). Longer duration storage, with low cost to hold the energy (which hopefully does not evaporate too much during the bountiful times).

Thanks for the correction. So this pumped hydro storage is at least 200x cheaper per kWh than current LiPo based solutions.

We already have massive storage in New Zealand - our existing hydro lakes.

What we need is solar installations. Reducing outflows is exactly the same as increasing storage.

AFAIK the problem is that regulations (plus the obligation to kowtow to maori interests) is preventing solar installations from going ahead. It isn't an issue of money, because I happen to know one private enterprise happy to invest half a billion to build out utility solar if they could get the necessary approvals. It isn't due to our conservative government - the same problem occurred under Labour+Greens. And our lakes when full can hold months of storage - in theory they would only need to spill for irrigation or ecological reasons or maybe during short flood periods.

> AFAIK the problem is that regulations (plus the obligation to kowtow to maori interests) is preventing solar installations from going ahead.

You'll have to be more specific than that dodgy statement, it kind of undermines your good point. What obligations are you referring to, outside the resource management regime, which is most definitely "regulations"?

I'm not involved with the project so I can't give you more than the vague impression I got as an outsider.

My general experience is that the NZ government tends to think big and blow money on wasteful initiatives while not identifying clearly advantageous initiatives and backing those (or otherwise encouraging the good stuff). That said, I have been pleasantly surprised with the broadband rollout (which helped during COVID).

Meanwhile your neighbours over here created a political foil in the shape of nuclear reactors and are coming in swinging for a presumptive election this year saying that is the way forward

The incoming government didn't cancel the scheme. They cancelled the investigation into the scheme which was due to report in late-2024 (I think).

The investigation would have covered other options as well.

They didn't save billions, they save a million and threw away the work done

There's definitely politics involved, but also the prices of solar, wind and batteries are and have been steadily falling.

One mental blindspot when comparing storage is to assume you need X amount of stored energy, but of course no-one wants stored energy, they just want energy.

Storing it only makes sense if you can't generate it for less so you need to compare against a portfolio of generation and short term storage. If you can't beat that on economics then you're useless, even if no other tech can beat you at your specific task of long duration storage.

Most pumped hydro is short-ish term storage and at full capacity runs from full to empty within 10-20 hours. And in a new development there's nothing really stopping you from putting in more pipes and generators so you can get the full energy out in half the time if that makes more economic sense.

Conceptually they are like batteries, just with the ability to scale max discharge rate and max capacity somewhat independently, a much lower cost per MWh stored, but high engineering complexity because each site needs a bespoke solution.

Of course there are some projects that just go for huge storage and few generators. Sometimes they serve another purpose and just have generators as a side benefit. And sometimes they don't make a lot of sense and seem to just be built that way to be more impressive

At least as of a year ago, pumped hydro was cost competitive with lithium ion batteries and filled the 10 hour niche. The other benefits are longer lifespan and domestic construction.

Lithium ion batteries filled the sub-10 hour niche.

But lithium ion battery costs will keep falling and pumped hydro costs won't fall or will increase alongside rising labour costs and gutted state capacity. So there could be a crossover point if it hasn't already happened.

> But lithium ion battery costs will keep falling

I question whether increased demand for grid scale batteries will create so much demand that lithium won't drop significantly any time soon.

I certainly hope i'm wrong.

The opposite may happen. Batteries follow a learning curve where the price drops exponentially in volume. High demand means a larger industry which means more scale benefits and cheaper prices.

Solar panels could be a comparison. Demand has been growing exponentially but this has actually pushed prices down because this demand drive the learning curve.

Or maybe the prices are being pushed down by the chinese government? I remember reading some news about how european governments are upset over this.

In general, I wonder how much do we really know when we talk about cause and effect in economics. We see prices going down. We attribute it to something. But without experiments, how can we be sure?

We see it in other goods like lightbulbs. Economies of scale is understood. The learning curve for solar/batteries has been stable for almost 50 years.

A small part of the price declines is due to subsidies from the Chinese government but I don't believe it's the best explanation for the 97% price drop.

But if you can answer the question "how much would batteries go up in price next year if China removed subsidies", I'd genuinely like to know the answer to that because it is important.

One risk is a war between the US and China, regardless of the subsidy question. So we should get good at domestic alternatives like compressed air and pumped hydro, and work towards our own manufacturing of batteries.

While that’s happening, we don’t for example see the Chinese pushing down the prices of nuclear in the same fashion, so it isn’t just that.

Grid storage is somewhat close to moving away from lithium. Sodium ion and iron batteries are in production and ramping up

Remember that energy and power are distinct quantities. A battery can easily match the power output of pumped hydro, but pumped hydro can exceed the energy storage of even the largest battery. The energy storage of pumped hydro is only limited by the size of the lakes, and lake size is only loosely linked to cost since the lake will potentially already exist. If a lake is artificial, volume increases non-linearly as a dam gets higher.

For example, the largest batteries can currently store about 3GWh of energy, but Snowy 2.0 will store abut 350GWh. Smaller pumped hydro schemes are typically 8GWh up.

Pumped hydro is suited for wind storage, and lithium ion is suited for solar storage, is a good approximation.

Snowy 2.0 with 2.2GW power and 350GWh energy will be great for multi-day wind surplus followed by multi-day dunkelflaute. But not as useful for solar, which is more stable, and where the droughts are seasonal in nature rather than weekly.

One worth mentioning in this context is the Western Sydney Pumped Hydro Project. It sounds like a no-brainer. It uses the existing Lake Burragorang (formed by Warragamba Dam) and an existing hole with infrastructure at the old Wollondilly Coal Washery, 400m above the lake and 3.1km from it. It will offer 8GWh of storage, close to Sydney, basically for the effort of digging a 3.5km tunnel and installing turbines.

https://www.waternsw.com.au/water-services/renewable-energy-...

To their credit, Sydney Water has a range of projects based on adding pumped hydro to exiting dams, of which the above is one. Total storage capacity of projects announced to date is 25GWh. They seem ideal for firming rooftop solar around Sydney/Newcastle/Wollongong.

https://www.waternsw.com.au/water-services/renewable-energy-...

The western sydney project is a no brainer. It’s being independently financed and run I think? Some mac banker saw and opportunity and ran with it

There are two incredibly common wrong assumptions made about pumped storage:

* It doesnt exist. Nobody says this outright of course but solar and wind skeptics often choose to "assume" that only more expensive lithium ion batteries can store power generated by solar or wind and "forget" about pumped hydro, being up to 3x cheaper.

* The geography for it is rare. The geography for hydroelectric dams which can also be used as pumped storage IS rare, because undammed dammable rivers are not common. However, for pumped storage it's not the case.

In both cases there are certain lobbies whom I think have a vested interest in perpetuating these false assumptions - the same way false assumptions about, say, wind turbines and bird deaths are perpetuated by people like Trump.

> the same way false assumptions about, say, wind turbines and bird deaths are perpetuated by people like Trump

I've not heard this one - what's it referring to?

https://www.newsweek.com/fact-check-are-thousands-bald-eagle...

Thanks for the link!

But, after reading the article, it seems that Trump's assumptions about bird killings were true? Apparently US windmills kill hundreds of thousands of birds every year. Among them hundreds of bald eagles. So over time that adds up to thousands.

The falsehood here is that only wind mills kill animals. Coal mines, especially strip and mountain removal mines kill plenty of wildlife. Oil refineries also do, as do turbines in hydro dams. There's no energy source we have that is zero impact.

I don't think that was a stated claim, though?

I've always felt it implied when this is discussed, but you are correct that it was not mentioned above. Wind turbines kill birds so wind farms are bad. But the alternative isn't that we just don't use less electricity. And Wind farms may kill more bald eagles than coal mines, but as a resident of an area where coal was king, I would disagree if anyone said they are less harmful overall.

There is a term for this type of comparison but it is escaping me right now.

> There is a term for this type of comparison but it is escaping me right now.

False Dichotomy?

> Wind turbines kill birds so wind farms are bad

I've read it more that "wind farms are not an unalloyed good", which counters something I do read.

In generaly, this example seems pretty weak. Trump might've exaggerated the number of this particular type of bird being killed, but by far more he massively underplayed the numbers of the total number of birds being killed by them. Seems as though people are reading a lot into this, when you could more easily read the opposite into it: Trump downplaying damage to non-bald eagles! Why!?

Yes, "wind farms are not an unalloyed good" seems like a great summary of the famously reasonable Donald Trump's take on Wind power, a subject he's kind of ambivalent about, but just wants a reasonable discussion of the facts with all context taken into account. And to immediately stop all offshore wind on day one of his potential next presidency.

> They say the noise causes cancer.

> If you have a windmill anywhere near your house, congratulations: Your house just went down 75% in value.

> The windmills are driving the whales crazy

> They shake, causing worms to come out of the soil. This is not a joke

> windmills are causing whales to die in numbers never seen before. No one does anything about that.

> If you love birds, you’d never want to walk under a windmill, because it’s a very sad, sad sight. It’s like a cemetery. We put a little statue for the poor birds.

Threw in a little bonus Putin quote there, see if you can spot it.

Now you have this little factoid, then what? Should we ban everything that kills more birds than wind turbines? Context-free facts like this with clear implications are akin to lying.

I have no idea what you are talking about. I'm a strong proponent of wind energy. But I also like birds. In my view of the world, we should search for solutions that let windmills kill less birds.

The fact that it was Trump who brought this up doesn't make it less true. At least not in my world.

I think it's rather the other way round. People who want to promote solar energy want to make it look as if the high volatility of this energy source can be simply solved with pumped storage, allegedly making it possible to get rid of coal and fission power plants, as well as natural gas power plants and biomass power plants etc. To this end they compare the cost of pumped storage merely to battery storage, which makes anything else look cheap. (Because batteries are so expensive.)

>I think it's rather the other way round. People who want to promote solar energy want to make it look as if the high volatility of this energy source can be simply solved with pumped storage

It can be solved with pumped storage and batteries:

https://reneweconomy.com.au/a-near-100-per-cent-renewables-g...

>To this end they compare the cost of pumped storage merely to battery storage, which makes anything else look cheap.

The cost of batteries, pumped storage and windgas do not compare favorably to natural gas.

They compared very favorably to nuclear power though. Nuclear power's costs eclipses the cost of solar and wind even when it is backed by windgas (which is more expensive than either):

https://theecologist.org/2016/feb/17/wind-power-windgas-chea...

Thank you for the link. I noticed a huge pro-nuclear sentiment in several places, Reddit, Lemmy, and sometimes here. It is an interesting energy source, but it has huge drawbacks compared to other energy sources. The price/time to build and operating costs are significant. Most current reactors need to be heavily subsidized with taxes to be competitive. Plus, of course, the waste challenge.

> I noticed a huge pro-nuclear sentiment in several places, Reddit, Lemmy, and sometimes here.

https://www.radiantenergygroup.com/reports/public-attitudes-...

  Across the 20 countries surveyed, 28% of survey respondents oppose the use of nuclear energy while 1.5x more (46%) support it.

> Nuclear power's costs eclipses the cost of solar and wind even when it is backed by windgas

We were talking about pumped storage, not "windgas".

Pumped storage is a cheaper form of storage than windgas and batteries.

Realistically we are comparing several stable energy sources here that can all be combined with highly volatile energy sources like solar and wind: Coal power, nuclear power, natural gas power, pumped-storage hydropower, power-to-gas [1], and batteries.

[1] https://en.wikipedia.org/wiki/Power-to-gas

Im comparing extremely cheap and green but volatile sources paired with storage with stable energy sources that are either polluting or expensive.

That is a biased comparison. Solar energy is infinitely expensive during the night (which is hardly "extremely cheap"), so you can only realistically compare it in combination with stable energy sources, like power plants or pumped-storage power. You have not shown that nuclear power and solar power are more expensive than pumped-storage hydropower and solar power.

>Solar energy is infinitely expensive during the night (which is hardly "extremely cheap"), so you can only realistically compare it in combination with stable energy sources, like power plants or pumped-storage power.

Yeah, or another more expensive form of storage windgas, which I did.

So did you not click on my link or what?

> You have not shown that nuclear power and solar power are more expensive than pumped-storage hydropower and solar power.

Never heard the term windgas before, very catchy. I wonder how cheap renewable electricy must be before it starts making economic sense going from water --> gasoline.

> Nuclear power's costs eclipses the cost of solar and wind even when it is backed by windgas

  This article is an edited version of a 'Wind power as an alternative to nuclear power from Hinkley Point C: A cost comparison', a report by Marie-Louise Heddrich, Thorsten Lenck and Carlos Perez Linkenheil, all of Energy Brainpool, commissioned by Greenpeace Energy. The evidence it furnishes is expected to be used as part of the legal case against HPC forthcoming in the European Court of Justice.

Incidentally the actual report can be found at https://green-planet-energy.de/fileadmin/docs/pressematerial...

Having skimmed the report I am not happy with the arguments within.

Is 60% efficiency for CCGTs in variable generation following mode realistic? 65% peak is possible in new CCGTs, by running continuously to keep the steam generating cycle going, however observed gas plant efficiency in the UK is just shy of 48% per DUKES data. https://www.gov.uk/government/statistics/electricity-chapter...

Is 71% efficiency of conversion from electricity to gas what is seen in industrial scale windgas installations? Are there many hundreds of MW windgas installations in 2024?

Where is the carbon coming from to turn into methane? Is there some sort of carbon capture going on (and shouldn't this be costed in)?

How much transmission build-out is required to support an additional 11.2GW of wind? How much does this cost given the low utilisation? Even if the electricity to gas plants are located within the wind farm, 11.2GW represents many square kilometers of land.

It is assumed that the methane network and storage are already there. The economics of storing the gas (also whether the gas can be taken out of the system at the same price and priority it is put in) is not addressed.

The study compares the price that will be paid for HPC power (including risk etc) with the cost of the components of the windgas system which is not the same as a company proposing and building the whole system (preparation, financing, risk etc).

> Is 60% efficiency for CCGTs in variable generation following mode realistic?

Level the output with batteries. And/or, if you have enough CC units, schedule them so each runs for a long time, then idles for a long time.

battery costs are falling incredibly fast, so maybe this whole conversation will be moot soon

Battery costs are coming down increasingly more slowly: https://assets.bbhub.io/professional/sites/24/fig1battery.pn...

Conveniently for you, that graph doesn't include 2024, when prices have collapsed very rapidly.

3 - even if not pumped, regular dams can be "saved" until they are full, saving the water for a not-windy nor sunshiny day.

I toured the Ludington Pumped Storage Plant when I was a child, in the early 70s, over 50 years ago! It was built on land that is as flat as a pancake, with the only geographical convenience being easy access to Lake Michigan. I am impressed to note that the Wikipedia article lists it sixth in its list of the five largest pump-storage plants in the world.

And yet batterystorage is about to overtake pumped hydro: https://reneweconomy.com.au/battery-storage-is-about-to-over...

Pumped hydro has been around for decades and was the goto solution for storing excess nuclear power in the sixties. So, there's a lot of it around. But it's barely growing. You can plonk down batteries just about anywhere. Engineering large water reservoirs for storing energy, is a bit more work; and not that cheap typically. And you do need the terrain to have some elevation differences. I.e. mountains.

Another wrong assumption about dams, whether for pumped storage or not: they're safe and environmentally friendly!

Hydroelectricity has killed several orders of magnitude more people than nuclear power, and it causes a lot more environmental damage too.

a thing I learned recently is that we are _already_ using hydroelectric power to balance out solar power - apparently with existing dams it's possible to dial down the flow in the daytime and dial it up at night. As more solar energy comes online, this becomes a natural consequence of energy markets

You are correct. It's most efficient to first stop hydro when there is cheaper renewable generation available, then if there is still excess then pump uphill into storage. It would be silly to have water going both up and down at the same time.

Hydro is extremely throttleable; most plants can go from 0 to 100% or vice versa in a couple of minutes.

Pumped water is used quite a lot here in South Africa to help handle peak load in the national grid. It's probably going to continue to play a huge role as we transition to more solar.

i'm only aware of the one supporting cape town. do we have more for the main grid?

Ingula Pumped Storage, KZN, 1,332MW

Drakensberg Pumped Storage, FS, 1,000MW

Palmiet Pumped Storage, WC, 400MW

Steenbras Pumped Storage, WC, 180MW

Steenbras is the only plant installed and maintained by City of Capetown, the rest are Eskom facilities (Its mentioned occasionally, by eskom, that load shedding continues over a weekend, or late evenings, to restore pumped storage for the week/productive hours)

https://en.wikipedia.org/wiki/List_of_power_stations_in_Sout...

I'll never forget the opportunity I had to visit the Helms Pumped Storage Plant. Driving directly into the side of the mountain and emerging into the generation facility was incredible. The shear size of the generators, the enormity piping, and the massive hunk of metal that are the turbine drives shafts left me reeling.

Each part is large beyond belief and the fact that it's not possible to view it in one piece only adds to the scale. Simply an feat of engineering.

NREL - National Renewable Energy Lab - interactive Pumped storage hydropower visualizer: https://maps.nrel.gov/psh

"Provides an effective way to view the national closed-loop Pumped Storage Hydropower (PSH) resource assessment and identify potential PSH sites while considering a wide array of possible technical and environmental specifications."

A few years ago there was a slew of articles about storing energy by lifting and stacking heavy blocks of concrete.

I have no idea how efficient those designs are compared to hydro storage but I imagine they solve a problem for regions where there is no suitable site for the water reservoir.

Haven't seen that concept in the news recently, maybe it didn't pan out?

https://spectrum.ieee.org/gravity-energy-storage-will-show-i...

https://www.wired.com/story/energy-vault-gravity-storage/

It appears Enel "plans" a gravity system in ERCOT (May 2024) https://www.pv-magazine.com/2024/05/22/enel-energy-vault-bui...

Physics isn't very kind to all these gravity-energy-storage ideas. You need very large objects and substantial height differences to store any meaningful amount of energy. While many ideas about new types of gravity-energy-storage are flaoting around, pumped hydro is the only gravity-storage technology that ever worked in practice.

And even pumped hydro isn't in a great spot. Batteries are essentially competing for the same market (intra-day storage, few hours, high round-trip efficiency), and improving fast.

Lat I checked it simply costs too much to build the lifting equipment and upkeep. It isn't economical because of the tower height.

Pumped hydro, assuming there isn't a huge excavation effort for the lake, is just some pipes and a turbine.

Is there a limit to the height (fall) needed to produce power? In other words does a drop of 500 feet produce the same power as a drop of 1000 feet? I assume there's a limit on how fast a turbine can spin and also a terminal velocity for water falling through a tunnel? Not sure if I am asking this right but for wind turbines for example 60 mph wind and 40 mph wind are the same, there's a limit on how quick those blades can spin.

You need stronger materials, but in general the more pressure the better.

There is a limit, but it is rather high. The big constraint is the steel cladding of the shafts --- those nearly vertical tunnels are all "armored", because normal rock would not resist the pressure. The company I work for has plants with 800m ~ 2400 feet height difference running, I know of slightly higher ones in the French/Swiss Alps. Up to 1km is doable with current engineering.

> In other words does a drop of 500 feet produce the same power as a drop of 1000 feet?

Because of "mgh", that halves the amount of energy you can store for a given reservoir size.

Easy where there is a lot of mountains (japan, Austria, France), harder in flat countries.

Interesting part of the article on electrolysis to use the lighter than air H2 instead of pumping water up. Smells a lot like over-engineering but seems fun !

Here is an insane video showing how difficult it can be to dig pumped storage tunnels: https://youtu.be/6AV2NcyX7pk

Would this also be 70-80% efficient on a smaller scale? Our land has a few meters elevation so I could create a 'pond' at the high end.

Probably about the same efficiency, but be aware the energy density for gravity storage is terrible.

Every cubic meter of water you raise by 1 meter, stores about enough to charge an iPhone 15 by 20%.

http://www.wolframalpha.com/input/?i=1000kg%20%2A%209.8m%2Fs...

I was getting ready to write an angry comment that you've got an error in your thinking / maths, because my intuition tells me that doesn't feel right.

I've run the numbers myself and am still in disbelief that raising 1,000 kg by 1 meter is the energy equivalent of an AA battery (= 20% iPhone 15 charge)

If it was any more than that, electric cars would not be able to drive up a mountain.

It’s also why if you’ve ever had a well, you discover how cheap it is to have your own water source compared to paying for municipal water. You just pay for the electricity to pump it up to your faucet, and the electricity to charge an AA battery is quite cheap.

I suspect most people have never had a well. One of the first indicators my family had about my grandmother's Alzheimer's was an Easter lunch in a small village, where she suggested the village was not connected to the water main and the residents probably still used wells — that was about 15 years ago when she was about 90.

Part of the justification for price difference between wells and municipal water also comes with guarantees from the latter about it being clean and free from contamination, and that they'll treat your waste water. How much this happens in practice… well (no pun intended), I'll leave that to news stories about Flint's flammable water and Thames Water's sewage discharges.

Where is this story based? Where I grew up, most small villages do have their own municipal wells, and there are even communities where every household has their own well.

Heck, even in my urban bay area neighborhood, I know of 3-4 people on my block with their own wells. I think it largely has more to do with when the neighborhoods were built than anything else.

South coast of the UK, Hampshire-Sussex border area.

I'm not at all sure what the law says about getting on the water main in the first place, but I believe it's not lawful to be disconnected even at your request.

just to be clear, are you talking about the village being connected to a larger water infrastructure, or specific residents and businesses in the village being connected to the village infrastructure?

I'd have to look up the exact network topology to even be able to distinguish between those two.

The rules are at the level of homes and the companies which supply them with water, of which there are a small number nationwide: https://en.wikipedia.org/wiki/United_Kingdom_water_companies

Places are not incorporated in the UK the way they are in the US, so "the village infrastructure" doesn't (so far as I know) even get well-defined, which makes it hard to make national laws that prevent it being disconnected from a wider network if that's what the suppliers want to do while supplying some particular house.

That's really interesting. In the US, it is common for water distribution to be managed at the level of town or city water districts. these may purchase water from larger scale state infrastructure, but will try to source water locally via wells where possible.

There are some cities where building codes require connection to the water grid for habitability, but this is much less common for unincorporated county land.

It's all fun until lightning strikes your wellhead, shorts out your well pump, and your insurance denies the claim. Then you discover there is a large capital cost to delivering water besides the electricity cost.

Sounds like there is a personal story in there somewhere. We have 5 wells, ranging from 20 to 300 ft, and I can confirm they are always a struggle to keep operational.

This is why pumped and all the other forms of gravity storage (cranes, trains etc) have low ROI unless you can make a really big reservoir with a minimum of work.

(Which is a little less than a AAA battery)

A little less than a AA battery. AAA rarely breaks past 1000mAh

I was looking for something like this. Thank you! Indeed not very interesting, it would take a lot of water and height to store for example 1 KWh.

The water: 1000 kg × 9.8 ms¯² × 1m = 9800 km m² s¯² = 9800 J

The "heavy duty" AA battery: 1.5 Ah × 1.5 V = 5400 As × 1.5 V = 8100 J

back-of-the-napkin it with `mgh`.

I'd kind of expect that it wouldn't scale down that far unless you plan on storing very little energy; by way of comparison our local PSHE has the same g as your land, but stores O(1e11) kg with an O(1e3) m vertical.

imagine if you could just park an icebergmountain on a small lake..all the power of a damed lake, none of the megastructure.

dabest

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