Pumped Storage: what is the scale needed?

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#2529487 27-Jul-2020 14:20

elpenguino:

nickb800:

Presumably the role for pumped storage in dry years is to carry surplus electricity from night time into the day, rather than save (say) a months worth of water.

That might be true if there was a large thermal generation component to electricity supply but with 90% hydro that can be brought online quite quickly it's easier to generate less at night time.

I was more thinking in the vein of Manapouri - it's historically been set up to run at a steady level 24/7 - mating this with pumped hydro 'just down the road' would mean that it can continue to operate as it does now once Tiwai closes. I understand it doesn't have much of a storage range, but I'm not sure how flexible it is, or how much flexibility could be achieved with modification (to suit a post-Tiwai market).

wellygary

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#2529496 27-Jul-2020 14:31

nickb800:

I was more thinking in the vein of Manapouri - it's historically been set up to run at a steady level 24/7 - mating this with pumped hydro 'just down the road' would mean that it can continue to operate as it does now once Tiwai closes. I understand it doesn't have much of a storage range, but I'm not sure how flexible it is, or how much flexibility could be achieved with modification (to suit a post-Tiwai market).

Te Anau and Manapouri have collectively about 400gwh of storage, with an annual production of ~5000gwh, that equates an average daily output of ~14ghw, so its about one month of storage...

Mating it with an Onslow pumped scheme would very good for load balancing,

elpenguino

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#2529563 27-Jul-2020 15:04

nickb800:

elpenguino:

That might be true if there was a large thermal generation component to electricity supply but with 90% hydro that can be brought online quite quickly it's easier to generate less at night time.

I was more thinking in the vein of Manapouri - it's historically been set up to run at a steady level 24/7 - mating this with pumped hydro 'just down the road' would mean that it can continue to operate as it does now once Tiwai closes. I understand it doesn't have much of a storage range, but I'm not sure how flexible it is, or how much flexibility could be achieved with modification (to suit a post-Tiwai market).

https://www.meridianenergy.co.nz/who-we-are/our-power-stations/lake-levels

Manapouri has a usable range of 1.8 metres, if I read that right.

There's always a base load of demand for those lakes that cannot be overfilled.

Interesting to see on this page that the lakes are currently 52% full - it obviously hasn't been raining as much as I thought/perceived.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

neb

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#2529572 27-Jul-2020 15:14

jonb:
I've visited the station in Dinorwig, North Wales. That's an impressive setup, and helps boost the peak capacity for Liverpool, Manchester areas.

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

Interesting useless fact I just read about it, one of its roles is to deal with TV pickup, which is when a popular TV program ends and everyone rushes to the toilet causing pumping stations to run more than normal, putting a higher-than-normal load on the grid. They actually run advance planning for major broadcast events to calculate how many thousand MW they'll have to have available when the broadcast ends.

Geektastic

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#2529578 27-Jul-2020 15:25

neb:
jonb:

I've visited the station in Dinorwig, North Wales. That's an impressive setup, and helps boost the peak capacity for Liverpool, Manchester areas.

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

Interesting useless fact I just read about it, one of its roles is to deal with TV pickup, which is when a popular TV program ends and everyone rushes to the toilet causing pumping stations to run more than normal, putting a higher-than-normal load on the grid. They actually run advance planning for major broadcast events to calculate how many thousand MW they'll have to have available when the broadcast ends.

The common joke version of this was always people putting the kettle on in the ad break during Coronation Street!

frankv

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#2529579 27-Jul-2020 15:27

Wonder if pumped storage might be appropriate on the Waikato river? There are a series of lakes & dams, with the lake below a dam being not too far vertically below the bottom of the dam. Presumably you could pump the water back up. It would have the benefit of only affecting the existing hydro lakes. And maybe it would be more useful in the North Island than the South?

elpenguino

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#2529586 27-Jul-2020 15:34

frankv:

Wonder if pumped storage might be appropriate on the Waikato river? There are a series of lakes & dams, with the lake below a dam being not too far vertically below the bottom of the dam. Presumably you could pump the water back up. It would have the benefit of only affecting the existing hydro lakes. And maybe it would be more useful in the North Island than the South?

Have a look at the links I posted. NI storage is about 10% of that in the SI.

Bang for buck says SI.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

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wellygary

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#2529641 27-Jul-2020 15:51

frankv:

Wonder if pumped storage might be appropriate on the Waikato river? There are a series of lakes & dams, with the lake below a dam being not too far vertically below the bottom of the dam. Presumably you could pump the water back up. It would have the benefit of only affecting the existing hydro lakes. And maybe it would be more useful in the North Island than the South?

There is negligible storage capacity in the Waikato system, ( other than Taupo, and even that has only 1.4 metres of range)

Its basically a "run of river" system..

https://www.waikatoregion.govt.nz/assets/PageFiles/36999/20150316Hydrology.pdf

neb

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#2529644 27-Jul-2020 15:54

frankv:
Wonder if pumped storage might be appropriate on the Waikato river?

We already did this one.

Tracer

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#2529745 27-Jul-2020 17:51

SaltyNZ:

Pumped storage isn't designed to run the country for a month. It is designed to take advantage of excess generation in a demand dip (usually at night) to pump up, and drain down to provide a boost during a demand peak. It is a battery, but with a running time measured in hours rather than minutes as with a lithium-ion grid store.

If that was the goal there would be no point building it in the South Island where it'd be constrained by HVDC (presumably Tiwai is gone and grid upgrades done by the time this dam is built), and increase reserve requirements in the North Island.

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#2529761 27-Jul-2020 18:41

How many blocks of concrete would be needed for this to replace pumped storage?

https://energyvault.com/

https://qz.com/1686109/softbank-bets-on-energy-vault-to-store-energy-in-concrete-blocks/

The idea seems so simple I wonder why no one is using it yet.

neb

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#2529762 27-Jul-2020 18:53

logo:
The idea seems so simple I wonder why no one is using it yet.

There's been a bunch of kinetic storage ideas, instead of going up you can also go down, e.g. with disused mine shafts. Alongside other ideas like molten salt and compressed air they combine the low energy density of pumped hydro with the low capacity of LiIon and flow batteries.

So that's why you've never heard of them being used. If you want quantity, do pumped hydro. If you want quality, do LiIon or flow batteries.

As an side, there's also the lifetime of the storage. LiIon: 1,000 cycles. Pumped hydro: 1,000 years.

Scott3

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#2529810 27-Jul-2020 20:30

wellygary:

frankv:

Wonder if pumped storage might be appropriate on the Waikato river? There are a series of lakes & dams, with the lake below a dam being not too far vertically below the bottom of the dam. Presumably you could pump the water back up. It would have the benefit of only affecting the existing hydro lakes. And maybe it would be more useful in the North Island than the South?

There is negligible storage capacity in the Waikato system, ( other than Taupo, and even that has only 1.4 metres of range)

Its basically a "run of river" system..

https://www.waikatoregion.govt.nz/assets/PageFiles/36999/20150316Hydrology.pdf

Taupo nominal full storage is 572GWh. Combined generation capacity of the 8 downstream power plants is 1052MW. As such taupo has just over 500 hours of storage (if we ran it flat out with no inflows).

Not quite run of the river, but enough to contribute to daily / weakly demand spikes, and have a small contribution to managing seasonal demand.

The storage talked about for Lake Onslow is an order of magnitude bigger.

In short, the Waikato would be non-viable for pumped storage. The main reason why is because it has a decent rainfall catchment for it's storage capacity. Why bother with pumping water, when you simply just wait to let the lake refill for free on it's own. Plus Taupo is a natural lake so pumping water from another central north island lake (many are dirty) would have ecological impacts.

Lake Onslow is viable for the following reason's:

Relatively close (24km to Lake Roxbrough) to source water for pumping (and discharge)
Massive elevation difference between Lake Onslow & Lake Roxbrough (around 530m elevation). More elevation difference means more energy per liter, hence allowing smaller tunnel, penstock, tailrace diameters (decreasing civil works cost), and meaning reducing the physical size requirement for the upper lake for a given storage requirement.
Lake Onslow is an artificial reserviour anyway, to has leser ecology to protect than a natural lake.
(Potential) storage capacity massive compared to amount of rainfall in catchment, meaning waiting for it to refill with rain after each dry year event isn't feasable, so it is worthwhile to pump water.
Presence of Roxbrough Dam (320MW) downstream of the discharge point of the pumped hydro means more bang for buck from any stored water (In a dry year, the water will get used in the pumped storage scheme, then used again in the Roxbrough dam).
South Island location is fine for the goal of mitigating dry year risk. The term "Dry year" in the NZ electricity market refers to low inflows in major south island catchments. As such there is heaps of transmission capacity to send the power north in a dry year. (currently the HDVC link will spend substantial time sending power south in a dry year).

Scott3

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#2529819 27-Jul-2020 20:39

logo:

How many blocks of concrete would be needed for this to replace pumped storage?

https://energyvault.com/

https://qz.com/1686109/softbank-bets-on-energy-vault-to-store-energy-in-concrete-blocks/

The idea seems so simple I wonder why no one is using it yet.

"The SoftBank investment will help it first build a full-scale prototype—one each in Italy and India—and then build multiple towers—each with a capacity of 35 MWh—for actual customers soon after"

5,000GWh = 5,000,000MWh

5,000,000/35 = 143,000

That probiably answers the reason of why it is unsuitable for the application of providing dry year cover for New Zealand.

[edit] - to answer the question as to why it is not being used elsewhere in the world, it ultimately comes down to that fossil fuels (and the associated emissions) are fairly cheap, so it is more cost effective to build gas & oil fired peaked plants.

NZ doesn't really have this issue as we have a lot of hydro to soak up daily, weakly, and a portion of seasonal spikes.

In countries that have a lot of combined cycle (fossil fuel) thermal, it is likely cost effective to build a smaller combined cycle plant + an open cycle peaker plant, and a larger combined cycle plant plus a storage plant. Peaker's while less efficient tend to be cheap to build.

Also consider that no storage is 100% efficient. Tesla power walls have around a 90% round trip efficiency, pumped hydro is around 70% (the lake onslow one might be less given the 24km distance between lakes). This efficiency loss will eat up a good chunk of the extra efficiency gains from a a combined cycle plant compaired to an open cycle - again might as well pair a CC plant with a peaker.

This leaves basically one remaining use case - Where there is a lot of combined cycle plants with minimal fuel costs such as nuclear and geothermal, and/or a massive amount solar /tidal / wind energy, leading to dramatic mismatches between demand and supply on a daily basis.

Any "built" energy storage means will be more about covering peaks of several hours, and no more than a couple of days. Even using reclined materials, those 35 tonne blocks of concrete can't be cheap. Nice thing about pumped hydro is your storage medium (water) is essentially free. In essence a you have to build is a dam to keep the water in place, some pipe, some turbines etc. But it is highly reliant on finding an appropriate site where the elevation difference is provided naturally, and the civil costs are reasonable (i.e. only need to build a short dam as hills on other sides function as a natural dam).

neb

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#2529822 27-Jul-2020 20:44

Scott3: Lake Onslow

That name has been forever ruined by this guy.

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