camelot-forum.co.uk

The authors make a strong and plausible case for their claims below so well worth a read for anyone wishing to know more!

Most studies of European 100% renewable energy overlook pumped-hydro energy storage (PHES), for the following, incorrect, reasons: there are few PHES sites; more dams on rivers are required; large areas of land are flooded; large amounts of water are required; there is a heavy environmental cost; and the capital cost of PHES is high. All these perceptions are wrong.

Fortunately, Europe has unlimited, low-cost, off-the-shelf, low-environmental-impact, long-duration, off-river pumped hydro energy storage (PHES), that requires tiny amounts of land and water and does not require new dams on rivers.

https://www.pv-magazine.com/2025/03/14/ ... in-europe/

And can often help diminish/ eradicate downstream flooding of historical flood plains - which always seem to be the first place they build houses ?

PHES has many benefits for water management but it required joined up thinking that the politicians no longer seem able / willing to mandate

Moxi

Adokforme wrote: ↑Mon Mar 17, 2025 11:17 am The authors make a strong and plausible case for their claims below so well worth a read for anyone wishing to know more!

Most studies of European 100% renewable energy overlook pumped-hydro energy storage (PHES), for the following, incorrect, reasons: there are few PHES sites; more dams on rivers are required; large areas of land are flooded; large amounts of water are required; there is a heavy environmental cost; and the capital cost of PHES is high. All these perceptions are wrong.

Fortunately, Europe has unlimited, low-cost, off-the-shelf, low-environmental-impact, long-duration, off-river pumped hydro energy storage (PHES), that requires tiny amounts of land and water and does not require new dams on rivers.

https://www.pv-magazine.com/2025/03/14/ ... in-europe/

In the picture that lower reservoir looks to have flooded quite an extensive valley, I would expect there to be significant objections... and lots of the alps and S Europe generally are limestone riddled with caves: not really ideal for putting a big reservoir on!
I think it is a wildly over-optimistic assessment.

I'm finding it extremely interesting, but can't work out if it is viable or not.

But to start off, am I reading it correctly, that this isn't looking at river valleys, but instead just locations that can be flooded with a relatively small dam? Or to be precise, locations where two areas can be flooded, with a height differential between them?

Next question, I totally get the point that interconnection can help, but looks like North Western Europe struggles with storage capacity. Now we may be OK, as Scotland looks good, and I assume we'd be able to use the transmission capacity built out for RE (especially Scottish wind) to move the power from storage when RE is weak. But .... the poorer served areas do look to include UK, France and Germany, and I mention that because they have large populations, representing a huge share of European demand, whilst being close enough for a dunkelflaute event to impact them all at the same time.

But counter argument, S. Eastern France looks good, and the next big populations of Spain and Italy are a little further away (for weather) and better served for potential locations, so maybe OK?

Teeny criticism about the storage capacity needed, the article states:

Europe has over 6000 premium PHES sites with a combined storage of about 1100 terawatt hours, which is about 40 times more storage than required for a fully electrified and decarbonized Europe.

I make that ~27TWh. But, UK Gov discussion papers, suggest we (the UK) will need 20-50TWh. I think that reflects a net zero grid circa 2030, growing in demand by perhaps 150% by 2050 as we electrify everything. So UK alone may exceed the figure stated.

Counter argument again, the article does mention interconnectors, and via sharing, total storage doesn't need to scale up to the sum of all individual nations, but still, it seems a tad low to me, but at this stage, that's just pedantry.

So .... is it theoretically possible, economically viable? Anyone know? PHS is certainly more efficient at maybe 75-85%, than the other LDES options like CAES, LAES, H2, flow batts etc, which are in the 50-70% range (I think).


Edit - Here's the older article with a little more info Energy storage is a solved problem

The easiest way to see why nonsense is to imagine in small scale to compare with alternatives.

Approximation: An acre.foot of water and a 16' drop is about 10 KWh. Not trying to be exact, losses pumping up and coming down generating, but in the right ball park. On an ideal site (quite steep grade between ponds say 100' pipe big enough for say 3 cfs at low loss <<about 4 hr time)

Could you imagine THAT being cost competitive with 12 KWh of battery storage? Not just cost in terms of money but environmental cost. We aren't talking about needing high power density or portability of battery so even very old tech NiFe batteries could be used (Edison battery). Those don't require exotic materials.

PS -- I'd not judge cost by the current price of Edison (about $1000/KWh). The only reason so costly is few makers as little demand for these. Only those applications not requiring light weight/small space/portability but demanding ruggedness, very long life, and ability to survive abuse in an unattended situation need Edison cells.

If I recall correctly this study was started a few years back and had some media coverage back then too - I think the methodology was looking simply at geography with respect to areas of land where there is sufficient height differential into which something could then be built - ie it wasn't looking at areas with existing water courses/lakes/rivers - but where you could build two caverns at different heights and connect them with pipes.

Therefore that something would need to include putting the water there in the first place. They argue in the discussion that this is relatively trivial as pumped hydro is close to a closed loop system. So if money was no object, then yes, you could say "unlimited" potential for pumped hydro storage is available in Europe's diverse geography.