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Comment by idiotsecant | Hacker News Reader

Obviously hydroelectricity is massively damaging to ecosystems. My day job includes designing hydroelectric control systems and even I can admit that. That's a big part of the reason that hydro is a non-starter in much of the western world, which is probably a reasonably good thing (although there are certainly some exceptions where hydro development seems like a no-brainer to me but I digress)

What's not so clear to me though, is why we aren't pumping (pun intentional) massive amounts of money into hydroelectric pumped storage. These systems are capable of storing massive amount of energy cheaply, safely, and (relative to other methods) efficiently. Every single pumped storage project gets mired in protracted legal battles and they are impossible to build. Our modern energy ecosystem requires more and more storage, and somehow we are under the illusion that we can get there with overgeneration of solar and hooking up batteries. We can't. We need storage and pumped storage is the only practical way to get there with current supply chains and technology.

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> We need storage and pumped storage is the only practical way to get there with current supply chains and technology.

This really cannot be enphasised enough - this is the only game in town. The solutions are needed yesterday, and must be built on a massive scale - there is no time for a 20 year R&D to production cycle of a miracle technology. Only hydro does not require any new minerals and mining.

The only other container that is even worth mentioning is conpressed gas, but it seems to have neither the capacity nor the efficiency of a large hydro deployment

> Only hydro does not require any new minerals and mining.

Why is mining a major obstacle, provided it is economical and the environmental costs are some orders of magnitude less than those of climate change?

The environmental costs of mining are extremely localized and that’s also generally where the permitting takes place.

New mining permits in the US are magnets for environmental review lawsuits.

Depending on the type of mine, getting a new one up and running can take 7-17 years, counting planning, permitting and the inevitable lawsuits.

Copper and nickel mine runoff can be extremely toxic, especially to aquatic wildlife and wetlands. Remediation isn't really feasible once the damage is done, so plenty of groups would rather outright ban certain rich deposits from being mined at all than take the risk.

How sensitive environments elsewhere in the world fare under mines that aren't subject to safety precautions in the US is apparently an "other people" problem.

Because lots of mined metals come either from 3rd world countries like Congo with no environmental protection laws or are mined in few places like Russia where a trade war can lead to shortages.

Hydro requires the most common mayerials like steel or concrete.

And, not even concrete.

But there are numerous other storage alternatives that also do not need any special materials. We don't know yet which ones will be cheapest.

Ontario recently started a pumped hydro facility in an abandoned mine, and it will hold ~400 MWh of power that can be charged or released over several days. Several other sites are in planning, including one that, if it goes forward, will hold 8000 MWh. That could run the entire city of Toronto for many hours.

Such facilities should allow Ontario to run on a mix of pure nuclear, hydro and wind. Currently about 15% of the electricity supply in the province is natural gas, used at peak times when demand exceeds the constant output of the nuclear/hydro base. At other times, their surplus is sold at a loss. More pumped storage will smooth this out.

The only other contender that is even worth mentioning is compressed gas, but it seems to have neither the capacity nor the efficiency of a large hydro deployment.

The largest pumped storage station in the US has a storage capacity of 24,000 MWh:

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

There's an underground hydrogen storage project underway in Delta, Utah with a capacity of 300,000 MWh:

https://www.powermag.com/massive-utah-hydrogen-storage-proje...

It would take 22 Deltas to overtake the world's largest pumped storage plant, a massive Chinese installation with 6.6 terawatt hours of storage capacity:

https://www.pv-magazine.com/2022/01/04/state-grid-of-china-s...

Still, potential underground hydrogen capacity is tremendous, amounting to thousands of terawatt hours in Europe alone:

https://www.preprints.org/manuscript/201910.0187/v1

How does the energy in underground hydrogen get utilized? Is the capacity the combustive energy, or only the energy from the gas pressure?

It's burned as fuel in a gas turbine to generate electricity. The process is similar to burning natural gas in turbines, but some equipment adjustments have to be made when running on hydrogen. The Delta project is starting with a 30/70 blend of hydrogen and natural gas, gradually stepping up to 100% hydrogen.

Siemens currently has turbines that can burn up to 75% hydrogen and is targeting 100% hydrogen by 2030:

https://www.siemens-energy.com/global/en/priorities/future-t...

General Electric has a variety of gas turbines, accepting 50% to 100% hydrogen in the fuel blend:

https://www.ge.com/gas-power/future-of-energy/hydrogen-fuele...

Mitsubishi claims to offer turbine operation on up to 100% hydrogen:

https://solutions.mhi.com/clean-fuels/hydrogen-gas-turbine/

Also used for direct industrial heat and as a feedstock!

Eg. the Hybrit project produces iron sponge with electrolyzed hydrogen. So the process becomes

> (electricity + H2O) + Fe3O4 [iron ore] => Fe + H2O

instead of the usual

> C [coke] + Fe3O4 => Fe + CO2

No it's mostly the chemical energy in the stored hydrogen, pressure is only a small part of it (though they might insert some expander turbine somewhere in there). Pretty similar to how you'd rate a natural gas storage facility.

It should be noted that the energy stored in the pressure of gas is zero. All the energy of an ideal gas is the kinetic energy (and rotational/vibrational energy) of its molecules, which is thermal energy. Internal energy of an ideal gas is independent of pressure.

What compressed gas storage does is (aside from combustion energy of a fuel gas) to provide not a store of energy, but a store of reduced entropy, enabling otherwise unusable amounts of heat to be converted to work.

The Delta facility is in its preliminary stages. It could be expanded by something like 50x that of current listed capacity.

You are confusing energy storage and fuel storage. I am talking about CAES, it uses electricity to compress air and feed that into a container, like a metal cylinder or caverns lined with impermeable material. When you need electricity, you release the air through a generator and produce electricity.

Hydroelectric, compressed air and batteries have round trip efficiency of ~80%.

https://www.sciencedirect.com/topics/engineering/compressed-...

The facility you linked produces and stores chemical fuel, and can't even convert it back into electricity. It is really easy to store insane quantity of fuel, just like we can store loads of oil.

The kicker is that production of Hydrogen and other e-fuelds is less than 50% efficient, and converting them back to electricity is another 50% loss. Compression for storage and transportation mean further losses. So the overall round-trip efficiency is expected to be about 25% or lower.

It is probably possible to build an economy based on e-fuels, and that's what many oil companies are pushing for. They are probably the only viable way to achieve seasonal storage. It's a different set of tradeoffs.

The facility you linked produces and stores chemical fuel, and can't even convert it back into electricity.

The project includes using Mitsubishi M501JAC combined-cycle gas turbines to turn the hydrogen back into electricity:

https://www.powermag.com/aces-deltas-giant-utah-salt-cavern-...

https://power.mhi.com/products/gasturbines/lineup/m501j

This turbine has a rated combined-cycle efficiency of 64%.

Production of hydrogen is more than 70% efficient in the best current commercial electrolyzers:

https://www.nrel.gov/docs/fy04osti/36705.pdf

Round-trip efficiency is much lower than 80%, but not as low as you have written here.

Industrial-scale electrolysers will soon be well over 90% efficient.

Any terms I can search to understand these advances? I seemed to remember learning that boring old electrolysis was around 30% efficient!

https://www.nature.com/articles/s41467-022-32652-y

Presuming I understood correctly.

Another system used a hydrogen-side electrode made of foamed metal immersed in water, where the surface area presented to the water was therefore very large, and the small pore size limited the hydrogen bubbles' interference with contact between water and electrode surface.

why are turbines used in place of potentially more efficient fule cells?

Cost. Fuel cells require quality manufactured membranes that also require regular maintenance and replacement. Getting volume with them is also a hard problem.

Thermochemical hydrogen offers the best prospect for hydrogen production if it can be worked out, because the whole-process efficiency from solar or nuclear heat can exceed the practical limits of water electrolysis. Most recent work focuses on the copper chloride process (which uses an electrolytic step) [1]. The best purely thermal cycle is sulfur-iodine, but running the process sustainably has yet to be achieved due to the corrosive nature of the intermediates.

1: https://www.sciencedirect.com/science/article/pii/S019689041...

Russians did that at some point in the 70s 80s. They pumped compressed air into some salt mines and that worked well until one of the mines sprung a leak and blew the mountain up

Such hydrogen storage facilities already exist, actually. But the hydrogen the store is produced via steam reformation which emits carbon. The big issue with hydrogen storage cheaply producing hydrogen without producing CO2.

There is in fact no such issue because literally no one is even considering producing hydrogen for energy storage in that way.

Then how is hydrogen going to be stored? Electrolysis remains either inefficient or expensive.

Storage method has exactly nothing to do with production method.

Electrolysis efficiency and expense are entirely sufficient to requirements for the hydrogen storage projects are, in fact, proceeding.

Inefficiency doesn't matter if you are storing curtailed energy.

If it makes more financial sense and uses less resources to overbuild solar 3x and curtail 60% of the energy than paying for fuel, then you have 2 units of energy you have already paid for spread out over 6-8hrs/day.

As long as using your $300/kw electrolyser at reduced duty cycle is cheaper and less resource intensive than mining and shipping gas, you do it.

I thought it was missing from the list...

https://en.wikipedia.org/wiki/Grand_Coulee_Dam#Irrigation

However it seems that the pumped storage I recall hearing about as a kid has an extremely low storage capacity and is more focused on irrigation.

The recent appearance of hydrogen energy storage has basically refuted this argument. We can now store all of the renewable energy we want. The only problem is the lack of awareness among environmentalists and engineers.

My limited understanding was that the electrolysis tech is not yet efficient enough at scale to make this feasible. Do you have links where I could read more about the cutting edge in hydrogen production? This is a very fascinating potential tool for solving the "we don't have enough batteries" problem with renewables.

The lack of awareness I am talking about also applies to electrolysis. The current state of electrolyzer technology is already good enough to do the job. Future advancements will make this a no-brainer. This is similar to the rise of photovoltaics a decade (which also caught many 'experts' by surprise).

Some recent advancements:

https://www.energymonitor.ai/tech/hydrogen/toshiba-claims-hy...

https://newatlas.com/energy/hysata-efficient-hydrogen-electr...

https://energynews.biz/idaho-national-lab-and-bloom-energy-p...

The problem with electrolysis was not its efficiency, the problem was capital cost of the electrolysers (so they could be paired effectively with intermittently overproducing renewables.) Efficiency was more of the concern when it was imagined expensive nuclear power would be driving electrolysers 24/7.

Hydrogen leaks like crazy and corrodes storage cannisters. It isnt especially practical.

The world produces and uses 700 cubic kilometers (at STP) of hydrogen annually. Hydrogen has been used on a mass scale industrially since the 1800s. The US has over 1000 miles of hydrogen pipelines.

There are obviously off the shelf components for dealing with hydrogen. This is not some hand wringing unsolved problem.

It can be used there are just better, cheaper options. Same for compressed air, molten salt, tidal power or a litany of other working tech that doesnt hit the right price/performance point.

Better cheaper options for seasonal leveling of a 100% renewable grid, or backing up the grid against rare prolonged renewable outages? Pray tell me about these.

> this is the only game in town.

There is another game in town. Emphasis on "is", as in present tense, not future. Natural gas power plants. They emit much, much less CO2 than coal. If we use them to only generate electricity when solar and wind are not enough, we end up with much lower emissions than what the trees remove from the atmosphere. We also end up needing to overbuild solar and wind by only about 30%, not by a factor of 3 or 4. The capital cost of maintaining the current, existing, natural gas power plants is basically zero. The capital cost of building new pumped storage is huge.

Here, let me do it for you. Lifting 1 kg to a height of 1 m requires about 10 Joules (more precisely 9.8, as every high school student hopefully knows). One billion kg, or one million tons is 10 giga-joule, or giga-watt-seconds. Increase to 360 million tons, and you get one GigaWatt-hour. One ton is one cubic meter of water, one million is a square of 1km2 area and 1m height, and 360 megatons is a square of horizontal width and length of 6 km and a height of 10 meters. A fairly big lake. Building an artificial one would qualify as a mega-project. It would cost multiple billions of dollars. It would be able to generate one gigawatt of power for one hour. Of course you'd raise it to a certain height, let's say 100 meters, and that would generate the 1GW of power for 4 days. If you have 100% efficiency. Which you don't have, because you lose energy both when you pump up, and when you let the water come down. Assuming an optimistic 25% overall round-trip efficiency, you get 1GW power for one day. If you want for one month, well, you multiply this by 30.

Or you can just keep around a 1GW natural gas power plant, and use it when you need it.

To explain the economics of pumped storage, you must first understand it.

Pumped storage round-trip efficiency is not, in fact, 25%, but routinely above 70%.

Nobody pumps water up just 10 meters. It is, instead, pumped (say) a thousand meters up to a reservoir commonly 10 meters deep. A 10m-deep reservoir needs only a cheap earthen dike. A dike is hardly a "megaproject", even if km long. Dikes are low tech.

The energy is extracted at the bottom end of a penstock. Each ton of water in a reservoir 1000m up stores 10MJ. One just 100x100x10 meters thus holds 100,000 tons, 1000 GJ, >270 MWh, 6 hours at ~40 MW.

Nobody needs 30 days' storage. If your hydro storage runs low, and local fuel tankage looks like it might, too, you order out for LNG or, soon, NH3 or LH2 from solar farms in the tropics.

Few would need or want a 1km x 1km reservoir. Smaller ones distributed where the power is needed are more useful.

An underground cavity, where it exists, can be used instead of a hilltop reservoir, or with one.

Burning NG once in a while is no big deal, but NH3 will be cheaper in the near future.

I concede the 70%. I agree with your calculations too.

But you also concede that you can use LNG from time to time. Which we can later switch to H2 or NH3.

Right now, all the natural gas power plants in the US produce about 12% of the total (gross) emissions. If we use these plants only when there's not enough electricity from solar, wind, hydro and nuclear, we'll reduce their emissions by a factor of 10.

What is the point in building thousands of reservoirs then? To reduce that 1% to 0%. Which we'd reduce anyway once H2 or NH3 become cheap and abundant enough?

By the way, the EIA made a handy comparison table for various power plants [1].

A "combustion turbine - industrial frame" is by far the plant with the cheapest capital cost, only $785/kW. Conventional hydro is listed at $3083/kw, with a fine print footnote that this cost is the least expensive plant that could be built in the Northeast (where the geography permits).

So, the cheapest possible conventional hydro is 4 times more expensive than an brand new natural gas power plant. My point is, we don't need a brand new one. We can just keep existing ones (and we don't even need to keep them all).

[1] https://www.eia.gov/outlooks/aeo/assumptions/pdf/table_8.2.p...

> Right now, all the natural gas power plants in the US produce about 12% of the total (gross) emissions. If we use these plants only when there's not enough electricity from solar, wind, hydro and nuclear, we'll reduce their emissions by a factor of 10.

Concluding that we'd only need 2% of the current emissions from this is a bit misleading. The overwhelming majority of emissions currently don't come from electricity and the only way to replace many of them is via electrifying them.

Some can be turned into opportunistic loads, but there will still be a major need for 4-100 hour storage in addition to the seasonal storage (which will be largely achieved via hydrogen or ammonia).

Off river PHES seems to currently be cheaper than other storage, but chemical batteries have a lot of other advantages and may become cheaper.

It also has at least one advantage over conventional hydro in that sites can have a lot more head. This allows the power room to be a lot smaller, and there are many brown field sites where one or both reservoirs are mostly complete (which may make it cheaper in spite of needing two reservoirs).

It's hardly 'the only game in town' though, and it's unclear whether the gap between 'batteries have much lower cost per watt' and 'ammonia has much lower cost per joule in storage' is big eough that 'a hole has zero long run cost' the marginal efficiency gain over electrolysis is worth it.

Let's say you want to reduce emissions by the equivalent of a 1GW natural gas power station.

Option 1: Build enough solar and wind to replace the electricity generated by the power station; in fact overbuild by let's say 30%. You can afford that because solar and wind are cheap. And then build pumped storage to be able to add an extra 300 MW for a few weeks, when you need that. Decommission the natural gas power station.

Option 2: Don't build the pumped hydro. Build instead twice as much solar and wind as in Option 1 above (for less money than in Option 1, because pumped storage is so expensive compared to solar and wind). When they can't provide 2 GW of electricity, fire up on natural gas power station to make up the deficit. Decommission one natural gas and keep one in partial use. Achieve more emissions reductions for less money.

Which option do you choose?

And, costs for everything are shifting throughout, with new technologies appearing randomly. The right answer today might be wrong tomorrow.

My point is that pumped hydro is hardly being built, but battery storage is growing very fast even at much higher costs (due to the other advantages). Step zero is, as always, build wind and solar but once you reach step one (and some places have) pumped hydro is hardly 'the only game in town', and it's not even obvious if it will remain a good option even if you have an excellent site.

Battery storage being built today is, correctly, almost all for shifting afternoon collection to evening usage, where batteries are best suited by their unlimited charge and discharge wattage, and their high cost per MWh stored matters least.

For storage beyond 4 hours, other considerations become important, particularly cost per MWh stored. You still need to extract plenty of wattage, but charge rate matters less. So, you need big or many turbines, but pumps can be slower. And, of course, retrofitting the many existing reservoirs is cheapest, so you do that before building anew.

Fuel storage similarly takes advantage of existing combined-cycle turbines, which are being adapted to burn a gradually increasing fraction of hydrogen. It remains to be seen whether they can be made to burn ammonia directly, or if the ammonia must first release its hydrogen. Stored fuel has the great advantage that it can be shipped, bought, and sold.

Most of the value in pumped hydro storage, as for chemical batteries, is in load-shifting, particularly from daily collection to evening load. You use it every day, so opex should be minimal.

For tertiary, occasional use, efficiency doesn't matter much, and other considerations dominate. Gas and steam turbines need expensive periodic maintenance after operating for some period, so you avoid running them too much. Fuel costs money, too. (Unless you synthesized it yourself; but what you burn you cannot sell.) But storing liquid fuel is cheap. Shipping it, too.

Transmission lines complicate choices, in large part because they go both ways, and because must be scheduled long in advance to maximize usage because they cost a lot to build. The power they carry might be free at the source.

Pumped hydro has 70-80% efficiency. I just looked up the number for a local one (smallish, ~180MW) and it claims 77% It operates on a weekly cycle, pumping up at night and weekends.

You do need a hill to build one, though. But you don't need Putin.

Obviously hydroelectricity is massively damaging to ecosystems

False.

A river is not a static thing. Nor a lake. Rivers, lakes, swamps, bodies of water change over thousands, and even hundreds of years.

A lake today, is a river tomorrow, and vice versa. Terrain erodes, shifts, rivers dry up, or appear from nothing.

Go back in time, in 10k increments, and see how a local area changes.

To claim that a hydroelectric dam is massively damaging, is not valid, not even remotely. A dam does not destroy ecosystems, it changes them. One disappears, another appears.

And considering that some beaver dams can be seen from space, and dwarf the size of our dams, the idea that daming a river, is unnatural, is absurd!

This ridiculous mantra that dams are bad, needs to end. It needs to end, now.

If we embraced dams, we could entirely wean off of hydrocarbons, and move to h2 generation, using existing pipelines in North America.

And no, the absurd assertion that h2 is hard to store and use, is not valid either.

I swear, there is so little logic to the environmental movement.

Everything is bad, everything terrible, and so we are left with te worst outcome possible.

I assume that the problem, like global anthropogenic climate change, isn't change in and of itself, it's change faster than biological systems can adapt to or evolve for – resulting in mass extinction events or radical losses of biodiversity.

I strongly disagree. When humans alter the natural environment, it’s inherently destructive. Even if a new environment arises in its place, we have destroyed what was there before.

That said, the environmental destruction is worth it when it comes to hydroelectric power.

I think the comment above argues that every change that happens in nature is a destruction of what was there before, and that that's an inherently natural process, whether humans are responsible or not.

You're right - building a dam and waiting for a thousand years will result in a new stable ecosystem with biodiversity comparable to the original. The problem is that natural systems need 'settling time' to adapt to changing conditions. The immediate impact in dams is a dramatic drop in biodiversity, that's not even a controversial claim. It's great that the ecosystem will rebound after I'm dead but I don't think that's what most people are concerned about. Deforestation and desertification of formerly healthy riparian ecosystems isn't a trivial concern. Not all 'changes' in nature are equally beneficial to humans.

When I was in school for power systems planning the the accepted notion was that pumped hydro storage is cool and great, but like hydropower, it is extremely geographically dependent, and we have basically developed all of the places where it would work (at least in the US), or at least, by order of magnitude, there are not enough remaining untapped hydro-related resources to make a dent in projected storage demand. Is that a wrong understanding?

Entirely wrong. All pumped storage requires is a big high spot and a big low spot*. Take a look at this, for example:

https://www.gordonbuttepumpedstorage.com/

There are a lot of good pumped storage sites out there.

*exaggeration, but close enough.

Unfortunately that rules out a lot of the US Midwest, where coal is a huge source of electricity generation.

That's the US wind belt - the Texas panhandle north to Canada, and east into Illinois.[1]

[1] https://www.kgou.org/energy/2013-09-03/oklahomas-wind-energy...

> All pumped storage requires is a big high spot and a big low spot

I think that's what the GP meant by "extremely geographically dependent." Finding a 1,000 ft height difference (using the Gordon Butte Project as an example) between reservoirs will be really challenging in huge swaths of the United States and elsewhere.

It also needs to be near a natural source of water, near population centres and is preferably not a pretty national park.

Dinorwig power station [0] is in the middle of a national park. A pretty one, even.

[0] https://en.wikipedia.org/wiki/Dinorwig_Power_Station

Yes, and add you can see it's already been developed - for over 60 years. That's not to say more can't be developed, but the rate of new development has been pretty low, and the prevailing belief was that this was the result of all of the best resources being used up.

...and even then they built it mostly inside the mountain, next to an old slate quarry. Which is going to help national park acceptability but not the unit cost of construction I suspect.

Doesn't need to be near population center. The majority of the energy I've used in my life comes from a dam over a thousand kilometres from where I live.

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

There are many possibilities globally. 1000 feet is not needed.

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

It is ridiculously uneconomical to create the volume for pumped storage. For context, with 100 meters of pressure head, you'd need 25,000 olympic swimming pools worth of water to store 12 hours of electricity from a 1 GW electric plant with 70% roundtrip efficiency. At a cost of $216/cubic yard of excavation, that's over $17 Billion. If you can make 3 cents per kwh profit buying at low times and selling at high, it would take 129 years to cover just the costs of digging the hole at the high spot. Then you need to dig another hole of the same size at the low spot so you can reuse the water.

There are really only 3 options - dam up a watershed so you can get a huge volume without much structure, build your resevoir on top of a mountain so you can get much larger pressure head and thus require less volume, or reuse a hole you were digging anyways such as an open pit mine. In all three cases you are heavily constrained by geography.

It is a good thing then that nature has already done the excavation for us by providing high and low spots.

Yep, now we just need to excavate the reservoirs on those high and low spots, a mere 100% of the work required.

This is nonsense. We have lakes already. We don’t dig two giant holes in rock. Look at real work pumped storage costs.

That's the "geographically dependent" part.

Except, not.

Lakes aren't geographically dependent?

Don't need any lakes.

Mind the thread context.

"This is nonsense. We have lakes already."

Maybe you could read up, instead of guessing.

Dikes are a technology older than writing.

I am curious where the 216/yd cost comes from. I had a rock driveway put in at 10/yd, and I assume the stone was excavated from somewhere.

Usually the rock is waste from excavation. When buying it you pay the cost of transport, group that did the excavation might have even paid for the rock to be removed.

Excavating a circle of area A costs O(A). Building a wall around a circle of area A costs O(A^0.5).

I think you'll find the attached link is project currently in development that does exactly what you're saying is economically impossible. It clearly is not impossible to build a relatively shallow dikes on top of a butte.

Yes, that is the whole concept.

The question is, is this something that has been re-evaluated? Are there more site locations available than previously thought? Have the economics changed significantly? Was this a known-wrong assumption 15 years ago? Has the public perception changed re: the environmental costs vs benefits of this land use?

I would much rather we build a bunch of pumped hydro than a bunch of chemical batteries, on the belief that it is a much more sustainable technology. But I have seen a lot of online discussion about pumped hydro that treat siting, operational, economic, and land use concerns as if they don't exist, when often they are the primary reasons these projects don't get built.

It is not "more sustainable". It is just, likely, cheaper.

Siting, operational, and land use concerns for pumped hydro are, generally, trivial. If one site is bad, another is good. There is absolutely no shortage of sites, so only the best need be even considered.

It's geographically dependent if built on rivers. Beyond rivers the possibilities expand enormously.

> Obviously hydroelectricity is massively damaging to ecosystems.

The whole of the human race is massively damaging to ecosystems. That bit isn't in doubt. The question is as to whether the benefits outweigh the costs. And naturally, humans get to be judge and jury on the matter. But hey, do you want to be able to get to work, afford that iPhone, or not?

What are you saying? Are you asking if the benefits of the human race outweigh the costs? Or of hydroelectricity? If it's the latter, I think OP clearly said that in his opinion hydro is a "no-brainer" in a minority of cases.

My view is that hydro and fission are proven tech, so I am in favour of them. I am sceptical about solar and especially wind, which I suspect are feelgood solutions that are easy sells politically, ignore economics, and may consequently be more harmful than the things they were intended to replace.

Having gotten that out of the way, my post was more intended to be along the lines of a curmudgeonly cynical sideswipe at political processes. Getting hydro schemes approved seems a lot like getting bypass routes approved. There's always going to be otters, pandas, or whatever going to be on the short end of the stick. In one interview of a route's detractors, I saw a Downs Syndrome girl shown on the telly. The route would go near the home where she was housed, and would consequently "get confused". I was sitting there, thinking to myself, "holy shit, talk about cynical manipulation. She doesn't even know she's on here."

So my post was more of a criticism against the detractors of such schemes, who I think favour emotional over a more sober analysis. It's too easy to sloganeer about "Won't someone pleeease think of the children".

In the end, there's no definitively right or wrong answer, of course. It's up to society to weight the benefits and costs. There's always trade-offs. Sometimes the trade-offs can be black-and-white, sometimes they are shades of grey.

Since you’re in the industry I’m interested in your perspective on this report from Lawrence Berkeley lab on integrated battery storage for wind/solar projects: https://emp.lbl.gov/hybrid

It seems to me that high capacity integrated battery projects are being built in large numbers, and they are much closer to cost-competitive than I would have though from the general sentiment in the press/HN comments. Obviously they are more expensive than raw solar but still in a price range to be competitive with NatGas OpEx in the next few decades. If that’s true then we might not need to fight the environmental battles on pumped storage (which for the record I do agree could be used more).

Too little, too late unfortunately. The amount of storage available from these projects is tiny and even though it's accelerating it's not accelerating at nearly the level required for the physics of a primary renewable grid to work. Chemical storage of energy is expensive and requires a long supply chain. It's huge that the costs are trending in a favorable direction and maybe eventually we can do all our load balancing that way but we don't need results 15 years from now, we need them yesterday.

Is this supported by the report though? We have yet to build most of the solar we need, and IIUC almost half of new solar is now being built with storage:

> At the close of 2021, there were more than 670 GW of solar plants in the nation’s queues; 285 GW (~42%) of this capacity was proposed as a hybrid, most typically pairing PV with battery storage (PV+storage represented nearly 90% of all hybrid capacity in the queues).

This is the surprising fact for me from that report. Of course, “built with some storage” is not the same as “built with 100% storage” but the report shows the distribution is not terrible, with ranges of 50-100% storage being built. (With %age being something like “daily maximum variance from demand curve” but I don’t understand exactly how this is computed).

My impression is that most "PV+storage" plants have storage enough to handle uneven loads and production rates on maybe hour timescales during the day. The storage required to provide overnight supply, though, is much larger, not to mention that required to handle seasonal variance in PV production. It seems hard to imagine batteries would provide that, but for that maybe the most cost-effective option is to just size the PV capacity for the worst-case season.

Given the evolution in PV cost, maybe it will be cheaper to size PV production to worst-case days rather than size it for an average day+storage? You'd still need sufficient storage for overnight consumption, obviously.

I previously shared your impression but this report seems to suggest otherwise; see p24 in particular:

> • Battery:PV capacity ratio always at 100% in HI; lower on the mainland (but increasing over time—see bottom right graph) • Storage duration ranges from 2-8 hours; 50 of the 61 plants have 4-hour duration (other 11 are 5x2 hr, 1x3.7 hr, 4x5 hr, and 1x8 hr)

And there are some detailed case-studies that give other examples too:

The first one (Pine Grove substation) gives a sort of "emergency button" to provide 12 hours of load relief, when they call it in. This seems like it's basically just shaving off extra load that occurs on particularly busy days (~40/year), it's not solving the core demand-curve mismatch. (It looks like the batteries function as essentially very-short-term demand smoothing/arbitrage when they are not being called in).

The second one (Wheatridge) is 4H of 30MW (~10% of the power of the whole facility); I don't have a feel for whether this is closer to the full demand-curve mismatch.

Edit to add: There's actually another case study that might be even better, Slate PV + storage plant in CA, which is ~50% power for 4 hours, which is very substantial.

I think you're right that you can't store much energy overnight -- but that's not really required I believe. My understanding is that if you have a mix of solar and wind in your grid, you tend to be fine overnight since it's always windy somewhere at night. The challenge for solar&wind is supplying the afternoon/early-evening peak.

Previously you'd conceptually have "baseload" which is sized at the daily minimum, and then "peakers" (or these days just rapid-dispatch gas) which are turned on as needed to supply the daily peaks. With solar this isn't an option; the supply curve is fixed. So you either have to massively overbuild to have enough generation to meet the demand peaks, or have some way of shifting the peak solar generation (midday) to the right, to match the peak utilization. So I think your storage ends up needing to look more like "store 25% of the midday generation to be used by 6pm" (numbers made up for the sake of example). Which seems to be the OOM that these projects from the report are achieving.

PV paired with wind is actually a lot more stable than either one individually because their outputs anticorrelate with each other.

A surprising amount of demand can be shifted with real time pricing, too.

Right now storage is almost irrelevant since deployed solar/wind capacity rarely reaches 100% of demand.

You need 2 weeks of storage.

https://energytransition.org/2017/07/germanys-worse-case-sce...

You don't use batteries to cover that worst-case scenario.

If you want to eliminate Carbon emissions, you do. The electricity supply network is always built for overcapacity or else bad things happen with frequency and device damage

This says 5 hours to get to 99%:

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

Windgas is actually pretty suitable for that last 1%. It may be 50% efficient to produce but it's easy to store large quantities of gas for long periods for those dark/still spells.

Counterintuitively that 1% of electricity generated from windgas will among be the most expensive "green" electricity but it will probably still be cheaper than nuclear power:

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

"almost half of new solar is now being built with storage:"

I very strongly doubt this, storage is very expensive.

Again, this is quoting from the report I linked up-thread: https://emp.lbl.gov/hybrid. (Linked PDF with lots more detail: https://emp.lbl.gov/sites/default/files/hybrid_plant_trackin...)

> Data on plants under development from the interconnection queues of all seven ISOs/RTOs plus 35 individual utilities suggest that these hybridization trends are likely to continue. At the close of 2021, there were more than 670 GW of solar plants in the nation’s queues; 285 GW (~42%) of this capacity was proposed as a hybrid,

Perhaps I'm mis-interpreting this (not my field), and it's plausible I suppose that these projects won't get approved uniformly. I'd be happy to get more clarity on this if the report is actually saying something different. (I acknowledge my original phrasing could have been better, the way I wrote it suggests "solar that has just been built" vs. "solar that is currently planned to be built". But I don't think that's the source of your surprise, it's surprising because batteries are supposed to be uneconomical any time soon.)

Anyway, if I'm interpreting this correctly it seems like quite big news; I certainly shared your priors/skepticism on battery storage prior to stumbling across this report.

storage isn't measured in watts, which is a unit of power, it is measure watt-hours, witch are units of energy.

PV should enable distributed power generation. I'm not saying grid storage, grid generation, and grid hydro isn't needed, but home solar should be a strong focus of policy.

The cost differentials are basically all down to labor, which is generally locally captured.

The "long supply chain" of batteries isn't true. We don't need cobalt or nickel for grid. Sodium Ion is going into mass production in China, and LFP is topping 200 wh/kg. Hell,you don't need cobalt or nickel for EVs anymore, a 300-400 mile car should be easily doable with the current state of the art LFP, and 200-300 doable with sodium ion.

Hydro storage is very very efficient (thanks to all the engineering that went into hydro dams), I think it's in the 90%+ for efficiency. It definitely should be a major part of our energy plans, but this thread makes it seem like it's the only practical way, and uses pumped hydrogen as a straw man competitor.

We need grid wind, gridsolar, geothermal, keep the nuclear, hydro, home solar, home storage, chemical batteries ... all of it. But the cost profile of wind/solar is already better than natural gas turbine, and I'm hoping wind/solar+batteries will pass everything in 5 years with sodium ion, but I don't have numbers on that.

This two weeks storage is ridiculous. With good home solar buildout, that is not needed.

You say ridiculous, and then Texas gets snowed in...

No one technology is accelerating fast enough. But I think battery storage has amazing potential for scalability. It is very suitable for mass production in a factory and produces small components that are relatively fungible. Battery storage sites can be built anywhere, require little civils works, have tiny environmental impact and are very quick to install. And they have the benefit of research and production for cell phones and cars. Massive scalability is hard to predict in advance but is definitely possible. Look at how many billions of arm chips are shipped every year.

We definitely do need pumped storage. Although big civil engineering projects tend to be slow and expensive in most developed economies. And how much of the world actually had the right terrain? My guess is that we will see a few massive projects at one end of a HVDC link rather than scaling up.

Lots of smaller projects work better than a few monsters.

There is absolutely no shortage of terrain suitable for pumped hydro storage. The smaller the project is, the easier it is to find a good item for it.

> If that’s true then we might not need to fight the environmental battles on pumped storage (which for the record I do agree could be used more).

Are pumped storage environmental battles really that much less of an obstacle than those for solar, wind, or transmission line installations?

Based on the number of pumped hydro vs solar projects I see approved in the US, I’d say so. We are building LOTS of solar. Not much (any?) pumped hydro.

The US has plenty of land that it could use for pumped storage if it didn’t care about the environment. (See, Hetch Hetchy in CA). AIUI it’s (justified) concern about environmental impact that holds this technology back.

We are not building much storage because it would be stupid to spend on storage that we have not spare renewable generating capacity to charge up. After we have plenty, then we will need storage, and will build it then.

For Japan, many pumped storages have been built to store energy generated by nuclear plant mainly at night. Now few nuclear plants running but many PVs are deployed, so it stores energy at noon. It's reversed but anyway it's useful!

Storage is always useful. At issue is where money is better spent, right now.

For nuclear era, it was easier to pay cost for storage because same operator built both nuclear plant and pumped storage. Even if operator isn't same, there are only few nuclear operator in the grid so easier to talk. For PV (or say electricity deregulation) era, it will be a bit difficult since PVs are deployed by small operators or individuals. Great market mechanism or govt regulation is needed.

California quietly added 3GW of batteries in the last three years to shift mid day solar to the evening. I think part of the quietly bit is locating them at mothballed natural gas peaking plants. Advantage the power infrastructure is there and no use change permits needed.

Before that, they attached pumps and ponds at the bottom of penstocks leading to reservoirs in the Sierra Nevada mountains that were built decades ago.

And these battery-based storage are also exploding in more frequency.

https://techcrunch.com/2022/09/20/pge-says-tesla-battery-was...

I think the main reason is that not everybody has the geography conducive for pumped Hydro.

Here in Kansas we have a ton of wind energy production and we’re lucky enough to have a nuclear reactor as well. It’d really be nice to store that, but we have no mountains. We have a rolling plain in the middle of the state but even the highest/lowest delta is like 200-300 ft (I made that number up).

You are spot on. Mt. Oread has 191 ft of prominence.

There's even a paper on it "Kansas Is Flatter Than a Pancake": https://www.usu.edu/geo/geomorph/kansas.html

Can you create an underground reservoir, say from an expired oil field, that is of sufficient capacity to create a pumped hydro system in concert with a ground-level reservoir?

We do have a ton of salt caverns actually, many centrally located (Hutchison, Ks if you’re interested. Great air and space museum there too oddly enough)

Unfortunately, water has the nasty habit of dissolving salt. As the Lake Peigneur Disaster taught us, mixing the two is generally a really bad idea.

That's how they create the salt caverns in fact: they pump hot water below impermeable limestone formations that were created when Kansas was an ocean 290 million years ago during the the Permian period. They use seismographs to watch the cavern formation and steerable drill bits to shape the formation.

Still need a place to keep all the water after you pump it out of the cave.

We call that a "pond".

In theory, yes. But I do not believe an oil field would be suitable.

Hydro relies on a pressure difference. This means you want the turbine located at the lower reservoir, which is going to be tricky with an oil well. Oil fields are not a hole filled with oil but instead are just porous rock, which greatly limits the flow rate you can achieve from a single well. Oil fields are already pressurized, so you'd actually need to put in energy to get water in there.

And of course you'd be contaminating the water with oil and gas, which makes the upper reservoir a bit of an issue.

Sounds like oil fields are better suited to compressed gas storage. I wonder if salt caverns would work though? To solve the pump location issue, you could perhaps pump down air to get the water to come up.

No need to think only within your own state borders. Germany has lots of wind farms and not much pump storage potential as well, they just send their surplus energy south to Austria for storage. Kansas could easily do the same with Colorado - ofc they would have to build more facilities first (afaik).

We export power all over the Southwest Power Pool actually! SPP even trades with ERCOT when we can and help them out if they're short. Kansas is quite green, with about 65% coming from renewables (Mainly wind, then nuclear), but we're too far north for Solar to be {wildly profitable|cost effective}, and wind doesn't blow all the time. Given our climate, with temps as low as -32f in the winter, and 105f in the summer, that unfortunately means we can't rely on renewables 100%. The only practical choice is coal and gas, which isn't my preference, but that's where we're at. I'd love to have a second nuclear plant somewhere in the state.

Ironically Colorado is a very hard partner to trade with. The major consumer (Denver) is in the center of the state. The entire eastern half is an empty plain and the western half of Kansas is a slightly less empty plain. From population center Kansas City to Denver is about 600miles, make energy trade a little impractical. They make a ton of their own wind energy on their open plain, and they were late adopters; they learned a lot from Kansas's expensive mistakes on wind power.

> but we're too far north for Solar to be {wildly profitable|cost effective}

If land is not overly expensive, then vertical bifacial solar can be quite viable. With snow or a light non-vegetated surface you should expect around 15% capacity factor in the worst month at 40 degrees and it will be skewed heavily towards morning/evening and slightly toward cloudy days compared to monofacial.

Doesn't get rid of the fossil fuels on its own, but should be cheap enough to displace most coal that remains after wind at a significant profit.

Today I learned that the high point in Kansas is 4039 feet above sea level, and was marked by a plaque that states "ON THIS SITE IN 1897 NOTHING HAPPENED" until 2015 when the plaque was stolen.

Totally agree on pumped power storage capacity being needed. But those are massive infrastructure projects. Erecting a damn, to store the potential energy is bound to meet resistance.

Alternative solution: Build Lots of pressure-piston, that are stable standing on its own. Basically, a pillar of ice, coated in insulation, standing upon a small lake that provides water at pressure. If additional energy is needed after the extraction, heat is added to the system and the lake replenishes, while the piston shrinks. If energy needs to be stored, additional water is pumped on top and frozen.

If additional heat reservoirs are nearby or something in need of coolant is nearby, additional heatpump like bonuses should be findable.

Similar concepts have been explored: https://energypost.eu/gravity-batteries-any-nation-can-do-it... but they need massive construction efforts.

Instead of having the building up storage provide its own structure, with little more then a concrete base and some grain silo walls. https://i.imgur.com/iCg9LzY.png

The piston sealing the under pressure water, could be archieved via "onion" layers, steps leading down, taking up a part of the pressure, until it drops to "holding back by atmosphere" on the outmost layer.

Pumped-hydro need not, in fact be any sort of "massive infrastructure project".

Forgive me my lack of understanding of the englisch language, but I do not understand the distinction you make.

Hydroelectricity: Is this power you obtain by placing turbines behind a huge concrete wall of a large river? If so, how is the scenario of building a large concrete dam in the mountains where water is pumped up a hill to covert it into kinetic energy any more better?

I understand that hydroelectricity is used to supply the basic power need, say 80% and a water reservoir with turbines to cover power peak needs.

Because you're not disrupting a river's flow and natural ecosystem, you only utilize the watershed some more during the initial filling period. After that, it's a closed system separate from the river ecosystem where only evaporation causes leakage.

That ship has already sailed as most power producing dams have been around for long time. Removing them would destroy the (now natural) ecosystem they have created. Plus dams have way more benefits to us than the extremely clean energy they produce - not just store.

This is the first time I've seen a claim that dams create ecosystems that we should worry about destroying. As far as I know, they disrupt fish and animal migrations, reduce natural carbon sinks, reduce biodiversity, and block sediment from providing nutrients downstream.

Is there any source saying dams create healthy natural ecosystems? A necessary evil I can kind of see, but a net positive for ecosystems? That seems doubtful.

I don’t know. I suspect the bias is towards the pre-dam ecosystem so it might be challenging to rationally compare them.

Certainly an ecosystem will grow up around nearly any situation.

there are many human ecosystems living below the dam though. Removing the dam means removing entire towns downstream in some cases.

That is not, in fact, true. Almost all dams have a river flowing below them, where it always did.

A very few places use all of the inflow for irrigation.

Yup my opinion only. To me water is life and if you let it flow to the ocean where it’s only use is to dilute saltwater you’ve wasted a precious natural resource.

Dams does not save any water except the initial filling. Their inflow and outflow match over a seasonal cycle.

Also, they tend to cost water instead: the larger surface area increases the amount "lost" to evaporation.

Perhaps. I suppose that would depend on size and depth of the reservoir and the makeup of the river. Also without a dam the water would be traveling the river mostly during the cold wet season with little evap. So yeah likely so. But in the end the cost would be lost saltwater. Probably a benefit for those that are worried about sea levels.

Yup that’s simplistically true. The difference though they do allow you to choose when it gets released. Around where I live that allows irrigation of crops during the summer months. That water does not go into the ocean. Also around here many of the municipalities draw water downstream from the dam as well. A portion of that travels through the sewer systems, gets purified then dropped back into the river.

This is not the case, removing dams still can come with huge benefits to the ecosystems those dams disrupted: https://www.mercurynews.com/2019/05/08/four-years-after-cali...

Read the article. Sounds like in that instance it was a good choice to remove the dam and had a good outcome. Well based on the information presented anyhow. Also I’m not sure if the main justification for removal pencils out for me. Yes some fish - 123 so far - were able to reproduce further upstream by 7 miles. What would have happened if the dam was still in place? Breed just below the dam? Do the fish really care where they do the deed or lay their eggs? Can’t believe that would be very true. Heck when I was their age I was pretty happy to do the deed and wasn’t too too awful concerned where it was at either. :D

No. First off, most dams silt up, not only not of being use in storing water but also not in creating power. Second, once they silt up, whatever ecosystem there is also destroyed and artificially created ecosystems are never natural and usually are bad for local fish populations. Artificial lakes can also host a number of non-native fish and are not any benefit to the native species that should be living there. Also, dams also block the migration paths of native fish.

Just think of this way, dams have a life span and for the most part, most of them in US have hit the end of their life spans and should be removed. They serve no purpose to anyone.

Right. Storing water for 50M+ people and generating enormous quantities of electricity. No use at all.

This is a pretty incomplete understanding of the issue, there are plenty of dams where silting is not an issue at all and will serve their purpose for centuries if properly maintained. There are also dams where silting is a regular problem. A so called 'sediment bypass' is often a feature of these dams, where water is pulled from the base of the dam through a bypass to clear out silting.

It all depends on the natural hydraulic dynamics of the dam - some are better placed than others.

We are, in fact, demolishing dams at an increasing rate.

Dams very commonly destroy fisheries worth far more than any value the dam can deliver.

I think the idea is to start pumping up water at existing hydroelectric power plants.

If you do this using wind or solar power the dam becomes a giant battery you charge.

Where does this extra water come from?

It’s just borrowed

Hydro power work by water flowing down turbines from a higher body of water to a lower.

So you can typically pump the lower water back up, using wind or solar power.

Wouldn't this mean the downstream would have no water flowing through it?

Pumped hydro can be built entirely off rivers. There's a plan to put a reservoir for one on top of a mesa in the desert in Arizona, for example.

What does the location of the reservoir matter? If you're taking a river and pumping it up on top of somewhere (a mesa in your example) aren't you going to cause the river to basically run dry everywhere downstream of where your pump is?

There's no river at the bottom, either. I thought the "desert" part would make that clear, but I guess it had to be said.

Water in this system is part of the capital cost (charging it up when you start), then a minor maintenance cost (replacing evaporation). Otherwise, unlike primary hydro, there is no large constant flow out of the system, and no need to be on a river.

The water lost to evaporation is at least an order of magnitude less than water evaporated from a nuclear plant of the same levelized power.

Wouldn't you need two reservoirs in that case? Otherwise where is the water being drained down to take advantage of the potential energy?

Yes, of course. Off-river pumped hydro involves two reservoirs.

I think the confusion is a couple of comments up you said "There's a plan to put a reservoir for one on top of a mesa in the desert in Arizona" which is really confusing since of course they're planning to put a pair of reservoirs for one in the desert in Arizona. I guess only one is on top of the mesa though.

So at that point why use a river? Couldn't you just use ocean water? It's comparatively "free" and we aren't going to run out anytime soon.

With a high enough plateau near an ocean, that should work.

I think those places are really rare though.

You need a reservoir to store that water downstream as well, it can't just be a river

Ya, this is how they do it. Eg see https://en.wikipedia.org/wiki/Dry_Falls_Dam

Pumped hydro is burning energy to pump energy into a (usually artificial) reservoir.

Then, later, allowing that filled reservoir to drain through a hydroelectric plant and generate electricity.

This solves 2 major problems, compared to alternatives.

1) The scaling costs (with respect to energy storage capacity / volume) are extremely low. E.g. instead of building twice as much battery, you're just consuming additional empty space behind the dam.

2) There is no time-cost to storing energy in pumped hydro, which affords great flexibility in when it's stored and when it's extracted. E.g. stored on a bright day when the wind is blowing, extracted at night when there's no wind.

In essence, it turns spikey supply and demand patterns into more constant ones, which are cheaper and more efficient to service.

> I understand that hydroelectricity is used to supply the basic power need, say 80% and a water reservoir with turbines to cover power peak needs

This seems like you either didn't understand what pumped storage is, or you've confused several related technologies.

A typical pumped storage scheme goes like this: We find a mountain with a high lake and a low lake. We dam the high lake so that its natural outflow (perhaps to the low lake) ceases. We dig tunnels between the lakes, and we put an electric pump/ turbine in the tunnels.

When we put electricity into the pump, water from the low lake is pumped up to the high lake (until it gets too full and we stop). This stores energy. When we let the water down the pipe through the turbine instead, the same water flows from the high lake down to the low lake, giving slightly less electricity via the turbine.

Unlike the conventional hydro electric power plant this is not really producing electricity, it is storing it, hence the words "pumped storage". We can use this to move electricity in time, which otherwise has to be done very expensively with batteries.

For example, when it's windy in the middle of the night in the UK, the French and Belgians buy some of our cheap electricity, and the stored power hydro facilities in Wales and Scotland also use that electricity to pump water up to their top lakes. The next afternoon, when peak electricity usage occurs as the sun goes down and people begin cooking evening meals, the pumped storage releases the water, making electricity it can sell at peak prices. In the UK the pumped storage plants are privately owned, so they benefit financially from this arbitrage.

Do you know the efficiency of using pumped storage? In other words, for every MW of electricity used to pump the water up the hill, how much do you get back in power generation when the water flows back down through a turbine? You will lose a bit of water to evaporation during this process, but it should be fairly negligible. Also all reservoirs lose some water by leakage into the ground. How does the efficiency compare to various battery storage techniques?

Batteries can get up to 95%+ efficiency, pumped hydro up to 85% efficiency so batteries win out in pure energy efficiency. However, when you take into account the economic efficiency then pumped hydro usually comes out very favorable. Battery prices have been falling rapidly over the last few decades, but simply damming up a mid-sized valley can store such a ginormous amount of water that is it hard to compete.

I would imagine energy density to be a bigger shortcoming (gravitational acceleration times height difference) -- especially for typically accessible height differences. Eg for 500m this is something like an order of magnitude lower than chemical batteries (which are themselves presumably at least an order of magnitude lower than gasoline). This would mean that we need reservoirs to be much larger than equivalent chemical batteries.

> simply damming up a mid-sized valley can store such a ginormous amount of water that is it hard to compete.

I would love to see an analysis of whether it is feasible to build enough such large scale reservoirs (and how many we would need) to store an order one fraction of the daily energy needs. (at city/country/world levels)

> This would mean that we need reservoirs to be much larger than equivalent chemical batteries.

Yes we know. It is still cheaper on a cost-per-kwh basis than batteries, by a significant margin.

> I would love to see an analysis of whether it is feasible to build enough such large scale reservoirs (and how many we would need) to store an order one fraction of the daily energy needs. (at city/country/world levels)

No it is not, there are not enough suitable sites in most places in the world to make this work for world levels. That said, it is entirely up in the air if there would be enough mineable lithium to make batteries for similar amounts of storage.

Efficient electrical energy storage at scale is currently unsolved.

I quite like what this startup is thinking. https://www.energybank.nz/. For offshore wind energy storage.

This Energy Bank system could possibly be practical.

Unlike "Energy Vault" (NRGV), a purely fraudulent investment scam. Energy technologies seem to be favorites of frauds (fusion especially so). It seems like nothing is so obviously nonsensical as to attract the attention of regulators.

There are, in fact, far more than enough suitable sites to store as much energy as we could ever care to store. Hydro power generation needs a watershed, but storage really needs only a hill.

But there are lots of different storage technologies, and costs are falling fast, so pumped hydro may be undercut in places.

Lake volume is just that: it's volume, plus the dam, times two for the lower reservoir. Battery storage facilities however mostly consist of maintenance access, scaffolding, temperature control and fire suppression, we don't just dump cells on a big heap and call it an energy storage solution. Pumped hydro is doing fine in density, particularly since we rarely think in volume for large facilities, we think in acres, and nobody would build a battery facility vertically stacked.

Lets take a pumped hydro I know of, https://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_.... It's 5,370,000 m^3 of water, 3600 MW·h for 8 hours to empty, 28,800 MW total. Cubic meter of water weighs 1,000 kg aka a metric ton. So 5,370,000 Metric tons of water.

Looking at https://energetechsolar.com/1mwh-500v-800v-battery-energy-st..., they're around .88 LB / AH, so 880,000 LB/MWh. 399,161 KG / MWh. 11,179,036,800, or 11,179,036 Metric tons of batteries. I don't know what the breakdown is but global lithium production was 100,000 metric tons in 2021, which is off by 2 oom.

My math may be wrong, and you do have losses of water from evaporation, but with pumped you can go up and down. But that's 11 million metric tons of lithium and other metals. Water falls from the sky (in most places still). Lithium has to be refined. You can recharge the battery, you can reload the water or pump it the other way. Tomsauk is mostly concrete and water (by volume). You do need almost a mountain for that head, or a mine. Concrete breaks down over time and can be maintained,. Batteries wear out as well but can be rebuilt. Water seems the easiest of the things to replace currently. The only things I can think of that are easier are provably gasses and maybe salt or rock.

This is all napkin math, and I may have missed a decimal some places. But they seem within the same order of magnitude for efficiency. But is it even possible to build batteries that big?

Of course when they got greedy with Tomsauk they ruind a great natural area. I'd love to be corrected on my math and assumptions.

If this still builds a dam, doesn't this have the same environmental concerns as any hydro project? Or is there something that makes this less of a concern?

Ideally you don’t build a dam.

Niagara Falls sits between Lake Erie into Lake Ontario. Which is the perfect location to use pumped hydro because all you need to build is a pipe between them and put a turbine inside the pipe. If you have excess energy pump water up from Lake Ontario to Lake Erie, and when you need power run that in reverse to generate electricity.

Move enough water and the water level on each lake will change, but 6 inches (15cm) isn’t going to change anything of note and that represents an insane amount of energy. Something like 500 GWh if I remember correctly. Unfortunately that’s literally the best case in the US, nothing else even comes close.

The scenario you've described still begs the question though. It seems the only difference between traditional hydroelectricity and pumped storage is how much you disrupt the natural flow from Lake Erie to Lake Ontario. The hard limit is when the Niagara Falls run dry. Anything more than that is basically spending electricity to create a treadmill for fish, which may be the environmentally responsible thing but we should be clear about that. And since fish probably cannot jump up Niagara Falls, it's probably more like spending electricity to run a really large water display for tourists and the occasional person who wants to go over in a barrel. But maybe that electricity use doesn't matter if we're getting more than we need from solar during sunny days, and just need predicable storage for nights and cloudy days.

I would think the stronger argument for pumped storage would be in a place where the high level of water did not naturally exist, and so the only way it gets up there is by pumping. But perhaps this still destroys too much of an ecosystem even if it's not a river ecosystem.

We let stuff migrate upriver years ago when they added a lock system back in 1829. At this point any environmental harm from connecting these lakes has already happened generations ago well before we where born. https://en.wikipedia.org/wiki/Welland_Canal

Anyway, the amount of water flowing over Niagara Falls is currently regulated hourly by treaty with excess flows above that level used to generate hydroelectricity. 100,000 cubic feet per second (2,800 m3/s) of water flowing over the falls, and during the night and off-tourist season there must be 50,000 cubic feet per second (1,400 m3/s) of water flowing over the falls. That excess is generally 50-70% of the rivers total, making the falls arguably just a really large and extremely expensive water feature used to attract tourism. https://en.wikipedia.org/wiki/List_of_Niagara_Falls_hydroele...

Adding a separate pumped hydro system really can be treated as an independent entity because we don’t just control the falls we can even turn it off when needed. https://www.dailymail.co.uk/news/article-1338793/Niagara-Fal...

Connecting two bodies of water for the occasional organism that wants to pass through is a distinct thing from disconnecting two bodies of water for say large numbers of fish that would otherwise swim up a river. The latter is a usual criticism of hydro power, which seems like it doesn't apply to Niagara because it's such a big waterfall.

I wasn't aware of the treaty, that makes sense.

The link about turning off the American side of the falls doesn't really support the implication that there is enough hydroelectric capacity to use up the entire flow of the river. The simplest explanation is that the flow was diverted over to the Canadian falls.

I assume they sent the water over the Canadian side simply due to the treaty. That said, they have excess capacity to handle blocking 1/2 the flow over Niagara Falls every night, but even doing nothing was still a non issue.

If you assume they blocked 1/2 the flow (1,400 m3/s) and didn’t use it for anything. That would still take 21 days to raise water level of Lake Erie by 1cm.

Pumped storage can also be used with existing hydro stations, just have a reservoir at the bottom to save water that can be pumped back up to the top of the dam. See https://www.nwcouncil.org/sites/default/files/MarkJones_1.pd... for the one at grand coulee.

California has dozens of hydro power reservoirs high up in its Sierra Nevada range, many built a century ago, with penstocks down to power stations far below. The penstocks have lately been fitted with pumps to push water back up.

Pumped storage does not, in fact, depend on finding conveniently placed lakes.

That is cheapest, but building a dike for a reservoir works fine too. A conveniently placed box canyon may need a dike only at one end.

> This seems like you either didn't understand what pumped storage is, or you've confused several related technologies.

What adds to the confusion is that Germans - OP used a common typo that hints at his native language - casually use "water power" ("Wasserkraft") both for hydroelectric dams ("Wasserkraftwerk") and pumped storage ("Pumpspeicherkraftwerk"). It's one of these fascinating little insights in how different languages form different train of thoughts.

I'm curious, what was the typo? The grammar hinted at German, but that's all I can see.

"englisch language" ... that the English 'sh' is pronounced almost identical to the German 'sch' is a common source for error.

Think of pumped storage like a battery: In areas with a lot of solar, pumped storage runs when there is a lot of daylight to store the energy for nighttime use. Pumps run when the sun is out, turbines run at night.

Or the opposite in areas with wind/nuclear. Pump it up during the night when demand and prices are low, then run turbines during day when demand and prices are higher. Arbitrage.

We certainly can use solar, wind & batteries to eliminate fossil fuels from our electricity system. Estimates are that we'd need about 300TWh of batteries, which is on the edge of feasible. Pumped storage would be a lot cheaper, though.

Oh great, only 300TWH of batteries! Let's put in the P.O.! Who is supplying those, again?

300TWh of batteries per decade is a lot easier than 90 million barrels of oil per day yet somehow we manage to do the latter.

At current battery prices of $132/kwh and oil at $88/barrel, 300 TWh of batteries per decade is actually 40% more expensive than 90 million barrels of oil per day.

Damn, we are that close. We are using expensive, high-density batteries meant for electronics and transportation for stationary storage. CATL is already claiming $40-$50/kwh for sodium ion batteries that begin production next year. In five years there will be even more grid-targeting battery solutions on the market at low price points.

From a practical business perspective, the falling prices of batteries may not be ideal from an investor's perspective. If I buy $100M of batteries and the price drops 50% in five years, I just "lost" 50 million dollars. You'd have to be at a point where the proceeds to storage exceed the depreciation of the product in order to pencil out, I think. So a lot of storage that could be built probably won't be built until the technology war shakes out.

>CATL is already claiming $40-$50/kwh for sodium ion batteries that begin production next year.

Tried to look this up, but didn't find anything. Where's that?

To be fair they stated it in the most roundabout way (40%-50% cheaper than LFP batteries) and with no time horizon. I think I got that from reports on their recent shareholder meeting but I will have to look it up better.

Its not like you can easily sign a PO for a pumped storage site either. Large scale civil engineering is still difficult in most places. And surely it requires lots of survey and design work.

With batteries you can design the site, get consents and order battery units off the peg in under a year.

And what percentage of the immense quantity of batteries would need replacing each year?

They're currently rated for 20 years of usable life, so you'd replace 5% of them a year. They're supposedly 95%+ recyclable, it's just not currently economically viable to do so since only cobalt and nickel are cheaper to reuse than to newly mine.

Any source for the 20 years?

A project I had a colleague working on where the batteries are critical to preventing blackouts since they will result in mothballing of other infrastructure indicated the utility was budgeting for a 5 year lifespan on the batteries.

It's what Tesla puts on their front page marketing[1].

But if you want more detailed breakout, there's this[2] report that you can dig through which states:

> A range of cycle estimates was provided throughout the literature for lithium-ion of up to nearly 6,000 cycles with lower DOD (DiOrio et al., 2015; Greenspon, 2017). The analysis conducted here estimates that lithium-ion LFP can typically provide 2,000 cycles at 80% DOD, while NMC systems provide 1,200 cycles for the same DOD, due to positive electrode dissolution and associated increased capacity loss at the negative electrode. In the next phase, more detailed cycle life data for LFP and NMC chemistries will be obtained. For example, based on 70% capacity at end of life, lithium-ion batteries have demonstrated a cycle life of approximately 8,000 cycles at 80% DOD (R. B. Wright & Motloch, 2001). The calendar life of lithium-ion batteries ranges with some stating > 5 years or as high as 20 years (R. B. Wright & Motloch, 2001) and others in the range of 5-15 years (Dubarry, Qin, & Brooker, 2018). This report estimates a 10-year calendar life at 80% DOD, also assuming 5% of that time will also be allocated to downtime. A cycle life of 2,000 cycles for LFP and 1,200 for NMC is assumed with a 5% increase in total cycles each by 2030.

So with the right chemistry, assuming one cycle a day, assuming 70% depth of discharge is acceptable, 8000 cycles is 21.9 years.

[1] https://www.tesla.com/megapack

[2] https://www.pnnl.gov/sites/default/files/media/file/Final%20...

Why doesn't hydroelectric pumped storage have the same obvious and massive ecosystem damage as hydroelectric when it is hydro electric + the environmental damage caused by producing solar panels or wind turbines?

The difference is because hydroelectric generation depends on currently existing rivers, damming them and turning them into electricity sources has to change the natural ecosystem in the river.

For pumped storage, we can essentially build it anywhere there is an elevation change. So we can avoid harming river ecosystems where they naturally exist and create pipes and tanks where it would be the least damaging to the ecosystem

Pumped Hydro doesn't have to be built on a river - you just need a pair of reservoirs that you can fill and transfer water between. This obviously destroys the ecosystem of the valley you use, but at least you're not impacting river water temperatures/sedimentation/fish spawning/etc.

It does not, in fact, need to destroy any ecosystem.

No matter where you put the few cubic kilometers of water that pumped hydro requires, you need to put it somewhere. The ecosystem of that place will then be displaced or destroyed.

It does not need more than the tiniest fraction of a cubic km of water.

A reservoir can increase scarce habitat for migratory birds, which is commonly much more valuable than your typical bald hilltop.

> It does not need more than the tiniest fraction of a cubic km of water.

One cubic km is one billion tons. Each ton is ~10kJ per meter lifted, and let's assume you can separate your reservoirs by 100m vertically.

That would give a total system capacity of 1e9 tons x 1e5 J/(ton x meter) x 1e3 meters, or 1e17 Joules.

A kilowatt hour is 3.6e6 Joules, so this gives us ~3e10 KWh. If we're imperfect in reclaiming that energy, we'll actually end up with 1-2e10 KWh.

US annual electricity consumption was ~4e12 KWh/year in 2018 (or ~1e10 KWh/day), so a 1km^3 * 100m installation is probably larger than required to provide a backup for replacing our entire electrical generation infrastructure with intermittent sources 99.9% of the time. Not by a huge amount though! Less than an order of magnitude, IMO.

> A reservoir can increase scarce habitat for migratory birds, which is commonly much more valuable than your typical bald hilltop.

How much is the level going to fluctuate on a daily basis, though? Does it really form useful habitat?

There are plenty of hills much more than 100m high. People will favor using the best places for it.

Efficiency of pumped hydro is always better than 70%, round-trip, and commonly better than 85%.

There is no reason to put all your storage in one place, and great reasons not to. A site moving 0.0001 km³ is useful for utility-scale storage. Of course, pumped hydro will be only one storage method among many.

Birds mostly use the top of the water. Probably, the lower pond is easiest to tailor for multiple use, but "floatovoltaics" are probably better in the upper one.

Check the one near Cape Town, Steenbras Dam. It is a set of two small dams near Cpt that uses a pumped storage scheme. It is currently used to provide load-shedding relieve during the day (cause the state owned entity Eskom is a failure).

So basically, during the daytime, they generate power from it and then at night the pump the water back to the upper dam. As far as I know its been working without any problems. And since the dams are fairly natural and small, and right by the coast (so very little downstream effects), it seems a bit more sustainable. The only wish would be for these mountain ranges to have multiple geographies like this so we can have multiple small pumped storage schemes with as little as possible negatives.

Is there a reason why you wouldn't combine pumped hydro with a diverted fraction of a natural river? You get the ability to store electricity along with some pure generation capacity while still allowing the river to mostly flow unimpeded. You're already building the generation capacity, and this allows you to generate some electricity 24/7 if the need arises. It seems feasible to divert a fraction of a river's flow, provided you work with natural, seasonally fluctuating flow rates, and not severely disturb wildlife. i.e. distribute the diversion plumbing over a mile of the river course.

> Obviously hydroelectricity is massively damaging to ecosystems.

Can you elaborate? To me it always seemed like we're basically replacing a river with a lake, which doesn't seem so bad. Sure, it requires adjustment to a new equilibrium, but why is the dam lake ecosystem strictly worse than the river one?

Genuinely curious, it always seemed to me that the discussion around hydropower seemed to focus solely on what is lost from the river ecosystem, without discussing what might be gained by a lake ecosystem.

For example, salmon migrate from the ocean to their spawning grounds in river beds. They have to go up over dams on special fish ladders. Most don't make it. Sockeye salmon were almost completely wiped out but are starting to bounce back. This also affects other species like bears which depend on these salmon runs before hibernation.

changing the flow characteristics of a river is a massively disruptive event, not just for the species in the water but also the animals that rely on tertiary characteristics and effects of that river. It changes the erosion patterns and sediment carrying capacity of the stream, it changes the seasonal flows that ecosystems have come to rely on, it changes nutrient transport, changes water temperature, changes oxygen content, and a million other things that make the stream less compatible with certain species and more compatible for others. Best case this results in loss of biodiversity, worst case it results in spread of invasive species that have even further impacts on an even wider swatch of the ecosystem. It doesn't make the ecosystem go away, it just changes it to a less settled one - generally when that happens the complexity of the ecosystem goes down until natural selection can catch back up and everything adapts to fill the same niches again, which is not a fast process.

It's hugely disruptive to ecosystems.

> hydroelectricity is massively damaging to ecosystems

Sure, but compare it with the alternatives. Oil and gas are obviously very destructive of ecosystems. But so are lots of renewables.

Here's what a silicon mine looks like (used to make solar panels): https://www.mining.com/wp-content/uploads/2016/02/anglogold-...

Here's a lithium mine (used to make batteries): https://assets.telecomtv.com/assets/telecomtv/open-cast-mine...

Here's a uranium mine (used for nuclear energy): https://energyeducation.ca/wiki/images/8/82/Openpit.jpg

Compared to these, the habitat displacement from hydro seems very mild. There simply is no energy source that is harmless.

For uranium, there is 510 million square km of surface area on earth, what's the issue with "destroying" (a lot of the mines are in pretty uninhabitable places) a few sq km out of 510 million to power the human race?

Your second picture is a coal mine. Most lithium is produced via evaporative pools. Same process as salt.

Thanks -- I thought it was Sonora Lithium Mine in Mexico, but it's actually Oyu Tolgoi mine in Mongolia. It primarily mines copper and gold, not lithium (or coal). However, they both look very similar, being open-pit mines.

Its also that most of the best sites for hydropower have already been heavily developed. Countries like Egypt, Canada, and Norway have massive amounts of hydro because it was obviously a good deal since the late 19th century. In western Canada, there is a big debate about the Site C dam site which is not just destructive but based on unstable rock.

In my region of the US, hydro use to power a lot of manufacturing until electricity came in. Canals were built for power, leaving the rivers flow naturally. But these canals are in dis-repair. To me, why not refurb these canals to provide power. There is plenty of water and plenty of places like this in the area.

Is that the case for all Hydro? Or only for specific types of Hydro applications?

I am curious to understand the different technologies. I am also asking because in the end every kind of power generation will have some effect on the ecosystems. It's always a question of trade-offs.

River ecosystems are really complex and far-reaching. It's about more than just fish swimming upstream to spawn.

Hydroelectric dams destroy these ecosystems completely. Yes, you can build bypass channels for fish, but that's just a part of the system and the channels don't work properly in many cases.

The good news is, that's starting to happen (in some places). A 5GW and 2GW pumped hydro station - both state owned infrastructure - have just been announced for the area I grew up: https://qldhydro.com.au.

Here in Australia we apparently have a virtually limitless supply of sites that are very well suited to "off-river pumped hydro", and yet there doesn't seem to be any action on this front.

I find this extra surprising because we also desperately need better fresh water management for other reasons, not least of which being our country's tendency to alternate between drought and flood.

There must be some reason we're not doing it, but I can't for the life of me figure it out. It seems to tick a lot of boxes:

- Powered by intermittent renewables, and can even be collocated

- Helps with fresh water management

- Easily to parallelize construction

- Can be operated in a federated way and replaced/upgraded/maintained piecemeal

- Requires only technology that is already extremely well-understood

- Relatively cheap

- Relatively clean

- Quick and easy to turn on/off

There is no "action" because it would be actively stupid to build storage you have not spare renewable generation capacity to charge up. The money is, instead, correctly spent on generation capacity that actually displaces CO2 output.

Storage will be built out later.

It is not yet clear which kinds of storage are cheapest, because the costs of many are still falling fast. By the time we have a use for storage, it will be cheaper and we will know which to build.

Australia is constructing the Snowy River 2 pumped hydro setup.

Initial cost estimate was $AU 3 Bn, it's now headed toward $AU 6 Bn plus a connector that could also cost billions.

https://reneweconomy.com.au/snowy-2-0-hit-by-another-blow-ou...

I really don't think we have a "virtually limitless supply of sites" here in Australia - in fact I would suggest the opposite. It's a really flat continent.

I'm more familiar with the southeast, so I can't speak for Queensland, but areas that have both good rainfall and high topological relief, already have a lot of damn construction (and associated destruction of wilderness).

There's the Snowy Mountains scheme of course (which has drained dry the Snowy River of Banjo Patterson's day) and also the lesser known Shoalhaven Scheme, and in Tasmania practically every river except the Franklin is dammed.

What are you talking about?

Tasmania has had significant hydro since 1895, is currently 80% hydro powered and is 100% renewable (and aiming for 200%, to increase green supply to the mainland).

I've wondered for a while if we couldn't build a pipeline between the ocean and the Salton Sea in SoCal and store quite a bit of energy that way. The Salton Sea is already kind of a wasteland so at least use it for something.

What is the difference in meters? If not much, the effort of building will not be counterweighted by the energy storage capacity.

AFAIK salton sea is pretty much at sea level?

It's 72 meters below, but it's not very big, and once it's full you'll have to wait for the water to evaporate away, I assume?

If it could be made a permanent bay of the ocean, that might make the area less of a disaster. But it seems real hard...

If it's below then the answer is no, so that answers my question. :) I was assuming it would be above sea level since it's inland.

Actually all.you need is a height difference, the direction doesn't matter. 72 meters is the limiting factor here.

I think the reason is, pumped hydro competes with fossil fuels as a storage mechanism, and it's very hard to compete with fossil fuels as a storage mechanism on economic terms. In terms of clean tech, it's probably still the best in pure economics, but batteries are currently getting more attention because Tesla found that by bundling its batteries with wheels and motors it can sell them as luxury goods. That circumvented the need to store energy cheaper than fossil fuels, but it's obviously hard to do anything similar with pumped hydro storage.

Agreed we need hydroelectric pumped storage - what is a typical efficiency number for that? I'd think its super inefficient, but not sure what the numbers should be.

> The round-trip energy efficiency of PSH varies between 70%–80%, with some sources claiming up to 87%.

For me, that sounds like quite good, given the capacity possibilities. We can always build tiered storage, with smaller, but more efficient tiers (e.g. batteries) used first and PSH when that's filled up or exhausted.

Wow I actually was expecting more like 10-20%.

Turbines and pumps can be surprisingly elegant and efficient when built well.

My impression as a layperson is that the economic feasibility of pumped hydro is very location-dependent, and our electrical grid isn't so fungible that storage in one region can meaningfully store energy generated in another region. Is my understanding correct? And if so, how do we tackle that?

Pumped hydro is very dependent on location. But the supply of energy would not need to be. Electricity grids and DC interconnectors work really well. Having a few massive sites spread across a continent could work well.

Pumped hydro is not, in fact, very dependent on location. You just need a hill. There are a lot of hills.

Even places without hills often have deep underground cavities, which also serve.

It gets worse once we remember that electricity can be transported, but the damage stays mostly in place.

My hypothesis is that market-driven electricity production simply doesn't handle this correctly. Planification would probably work better, but that's not politically accepted.

The lead times are too long on power plants. It takes years of permitting and studies and then years of procurement and construction for large projects.

Why is hydroelectricity massively damaging while hydro pumped storage is great?

One destroys an ecosystem and fishery. The other moves water between ponds.

Never understood that to be honest.. we can today build quite excellent tunnels that are crossable for fishes.

https://www.youtube.com/watch?v=j_B5bZvCdJY

Just make it go to almost the same depth and you dont even loose water..

A dam is not the same as an aquarium. True experience is that dams destroy fisheries and drive extinctions. Almost always, the fishery had produced overwhelmingly more value than the dam.

Grand Coulee Dam should be demolished, but won't be.

what about artificial hydro ? make a big large raised water retention thing with generators.. it will take space but not harm existing natural spaces. Even in europe there's a lot of unused land.

Pumped hydro needs to be truely massive scale, both in the amount of water (read: lots of depth AND surface area), and the height differential between the two reservoirs. To make it cost feasible we really need very favourable natural geography. Building such structures ourselves would be astronomically expensive.

Pumped hydro does not, in fact, need "lots of depth". 10m is typical, for which cheap earthen dikes suffice.

It does not, in fact, need "very favourable natural geography". It needs an elevation difference, something found almost everywhere, Holland and Kansas excepted. Kansas has deep underground cavities, which also suffice.

Building dikes is cheap and low tech. Dikes predate written language.

On the depth thing, I really only meant to mean you need lots and lots of water. You could have a shallow basis, and take over a huge area of land, or or smaller amount of land if you have deeper water. Deeper also allows for less evaporation, less land area.

Perhaps your and my definitions of favourable geography are different. You need a water source, due to evaporation, you need a big resovoir at elevation, and another lower. If you don't want to build it all yourself you need valleys that you can close off at one end. You need ground that is not permeable, so the water you have stays where you want it.

Perhaps I am misreading you, but you seem a bit agitated with your in fact writing style. We're all friends here. I am not anti pumped storage. Far from it. If you can make it work economically, it's a great solution. It will definitely be part of the mix. But there's reasons it's not being rolled out everywhere, and a lot of this is due to cost and unfavorable geography.

You don't need a "huge area of land", under any circumstance. Even a football pitch is big enough for useful storage. Permeability is a thing that is controllable. Since there are so very many hills, only the most favorable sites need be considered.

The main reason it is not being rolled out much is that it is not time yet to roll it out. You need enough spare renewable generating capacity to charge it from, first, which we are very far from, most places. In the meantime the right place to spend is on generating capacity. Later, we will know better which storage methods are best.

I'm assuming you understand that my statements have a implicit "from an economic pov" when I argue about the practicality of pumped hydro storage, and you're arguing that it is economical to do pumped hydro on a small scale.

My understanding is that it only becomes competitive with other options at a very large scale. A 10 m deep football sized reservoir, at an altitude of 1km above the generator would have approx 13Mwh of energy storage at 100% efficiency (if my math is correct). Battery prices are around $140 per kWh, so a 13 Mwh battery installation is going to be in the vicinity of 2 million dollars.

I would love to see some costs involved in building two man made ten meter deep football field size dams, a large 1km length (it will be quite a lot longer due to it running on a slope) with all the required engineering to run it down a steep incline. The add to that the and generating equipment, and pumps.

Once you've done that, we could compare the operating costs of the two options.

Agreed, cost matters. While costs of the parts of a pumped hydro system are well-known, which of those parts need to be built for a given installation vary, as do their scale, but most importantly the costs of competing storage media, which are in many cases falling fast.

As for nukes, stable costs make them proportionally less competitive by the day, in the face of cheapening competition.

Check the one near Cape Town. It can run for up to 12 hours with two "small" dams and the altitudes for the dams are ~100m & ~350m respectively, connected by water tunnels & 4 turbines. It is located in the mountains, right next to the coast (which I think minimizes negatives further).

The the size and rainfall season matters for how long they can run. Cape Town has a winter-rain season that runs from roughly May to September.

This one? Looks interesting.

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

The capacity of the smaller of the two dams is 3,560 megalitres. I think a 1km X 350m X 10m deep is this capacity. So "small" is fairly subjective term, but you are right that it is not gargantuan. It is still not going to be easy to place such a setup just anywhere, but I'm willing to admit my statements may have been a little too much.

I would be interested in how much it cost to build and run to obtain the 180mwh capacity. A similarly size gridscale battery would cost in the vicinity of 40-60 million USD (using the $140 per kWh cost, numbers are is hard to find for the supporting equipment and installation costs).

There is probably an inflection point where pumped storage becomes more economical than batteries. With land and labour costs so different from lace to place what makes sense in certain areas, is probably not economical in others.

https://www.morningbrew.com/series/battery-tech-for-evs-and-...

Wind and solar energy also destroy ecosystems, but we don't stop using them. Dams may be more harmful, though.

What's your definition of destroy and do you have any examples of ecosystems that were destroyed by wind and solar?

Cutting down large swathes of forest and building over the habitats of endangered species happen for both. Solar and wind farms both need large land clearances in areas that have a lot of their respective kind of energy, which animals also use.

Solar farms do best in deserts, which tend to be habitats for species that like extreme conditions. Several of them have been blocked in recent years. There was a recent huge solar project that was planned to cover most of the land area that an endangered desert tortoise inhabits.

https://www.reuters.com/article/us-solar/exclusive-sierra-cl...

https://news.bloomberglaw.com/environment-and-energy/massive...

Aside from the large swathes of forest that have to be cut down for wind farms, birds of prey tend to fly into the blades of wind turbines. These are also often endangered species. The fish and wildlife survey estimates 140,000-500,000 bird deaths at wind farms per year, with most of these being birds of prey which have low birth rates and high conservation value (many endangered species). In contrast, cats kill billions of birds per year, but they are common small birds, not endangered predator species.

In addition, something like 800,000 bats are killed by wind turbines.

https://wildlife.onlinelibrary.wiley.com/doi/abs/10.1002/wsb...

The solution, for solar, is obviously installations on top of human structures, like roofs and roads (but not on the road surface, which is silly). For wind, there isn't a good solution that doesn't hurt predator bird populations.

Pretty much any human activity affects the ecosystem of animals and plants. It's a matter of weighing the pro's and the cons.

You link to an article from 2010, I don't exactly know which plant you refer to but I did find that a solar plant (Ivanpah) was built around that time and this was done by taking into account the tortoise territory. They decided not to build where the tortoise territory was. There is also recent work being done by environmentalists to help guide solar panel placement in the Mojave desert. https://medium.com/wild-without-end/the-tortoise-and-the-sol...

> These are also often endangered species. The fish and wildlife survey estimates 140,000-500,000 bird deaths at wind farms per year, with most of these being birds of prey which have low birth rates and high conservation value (many endangered species).

The article you linked mentions 573k birds and 80k being birds of prey, that's 14% and not "most". It also mentions there is a need for better measuring methods, it's a bit old now so they likely have gotten better at it too. This is an area of active research so efforts to reduce birds collisions are being worked on.

At the end of the day, the real issue is "NIMBY".

Solar - sure we will protest that:

https://barrie.ctvnews.ca/solar-project-demonstration-in-tay...

Wind - yep... people will protest that:

https://toronto.ctvnews.ca/ontario-wind-power-opponents-prot...

Nuclear? Of course:

https://globalnews.ca/news/4298298/protesters-rally-pickerin...

So.. when those people go home, what do they think powers the lights?

Different people protest each thing. The only thing nobody is protesting is natural gas, which is green in Germany.

This is not true. People protest against everything, gas is no exception. https://www.cbc.ca/news/world/germany-lng-energy-crisis-1.65...

> why we aren't pumping (pun intentional) massive amounts of money into hydroelectric pumped storage

Because energy storage is currently not a problem, and consequently not profitable.

Unless you have some very bold organization to invest on things that today make negative marginal profit on any scale, or a government rushing into the solution of tomorrow's problem with today's money, you won't see any action.

It will certainly turn into a problem at some point (I expect it on this decade already). But even when it happens, it's not clear what kind of storage will be successful; and pumped hydro has a bunch of competitive issues due to its geographic limitations.

> Because energy storage is currently not a problem

Yes it is. It's one part of the solution to fluctuations in electricity production (renewables: wind, solar) and consumption (day / night, warm / cold).

In a grid, at all time, the production has to match the consumption perfectly. You can make the frequency vary a bit to make up for fluctuations, but only so much before damaging things. Storage helps with a production higher than consumption and then with a higher consumption later.

Good storage makes grids more flexible and ideally lower the need for electricity production, and costs.

I agree with the rest of your comment though.

> Yes it is. It's one part of the solution to fluctuations in electricity production (renewables: wind, solar) and consumption (day / night, warm / cold).

It both is and isn't a problem, depending on your time scale, and opinions about how we should bridge the variations in supply and demand.

Today, on the short timescale (subsecond) this need is called frequency regulation, and we mostly do that with so-called "peaker plants", essentially natural gas turbines that run constantly and feed power onto the grid at subsecond notice.

This is a very expensive source of supply (easily 5x the median wholesale rates) because the natural gas is mostly wasted (not to mention the very high CO2 emissions: ~600g/kWh produced [1]).

Therefore, there are a lot of companies working toward solutions to this, that don't involve burning fuel, either by building stationary storage, or by aggregating negative demand, thereby participating in a very expensive electricity market with a low-marginal cost solution. In short, this is where the money is today.

The next level for storage is not yet a problem, but will be: storing excess renewable energy supply between different parts of the day or week. The value of this service to the climate is massive, but the economic value of this is not enough to justify the cost of Lithium batteries. To support this use case, we need batteries or other storage media that are 10-100x less expensive than Lithium batteries.

There are many candidate storage technologies for this use case, from pumped hydro to metal-air batteries, to compressed air energy storage, but no clear winners yet.

1. Estimated based on a rough average of .65tons/MWh for CA peaker plants from: https://www.psehealthyenergy.org/wp-content/uploads/2020/05/...

> Because energy storage is currently not a problem, and consequently not profitable.

All the big pumped storage in the UK is owned by for-profit companies.

Are they making the big money from running school tours? Maybe the gift shop? I don't think so.

In the UK they can buy 1.5GWh of electricity for say £75000 on a windy Sunday night and then sell say 1.2GWh (pumped storage is maybe 80% efficient) for £200000 on Monday afternoon. That's a £125 000 profit in under a day. And this wouldn't be their best case it's just a pretty good day although there are always worse days because doing this well involves predicting weather and other factors so as to judge when to buy and sell.

They're not going to become the next Apple doing this, but it's a healthy business.

Dinorwig isn't profitable due to energy arbitrage, at least not within 4 decades of construction. It does also get paid for maintaining a permanent on-call capacity for urgent frequency regulation though.

Maybe recent energy price increases has changed future reckoning though

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