Pumped Storage: what is the scale needed?

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#2530044 28-Jul-2020 13:01

wellygary:

MikeAqua:

The fundamental problem ins NZ seems to be that the population is increasingly concentrated in the upper half of the North island, while a lot of clean generation is in the South Island.

More clean generation is required in the North Island.

I have no idea where.

Basically Geothermal (central NI+ northland ) and Wind (on the Coastlines)- there was talk of a multi MW scale PV plant at the refinery, but I think that idea might have died with COVID

What has killed any uncommitted generation plant is not COVID, it's Tiwai Point -> Manapouri

Since it appears that a very large chunk of hydro generation that had been devoted to Tiwai Point is about to become available for 'general grid use', nobody can predict what electricity prices are going to look like over the next five to ten years, so nobody can work out whether their proposed generation plant might make a profit or be a financial millstone.
Since there is a significant chance that a proposed generation investment might turn into a money hole instead of a money tree, nobody is going to go ahead with any construction that isn't already irrevocably committed.

Decision makers will be able to make the call on building new generation plant only once they know: that Tiwai Point is actually closing for certain; and whether and when TransPower is going to do grid upgrades to being Manapouri power north; and what government policy is going to be towards carbon pricing (and hence thermal generation and coal-fired boilers).
Most of these decisions depend on the election outcome to some degree or another.

I wouldn't expect any decisions on new generation plant until early 2021

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elpenguino

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#2530057 28-Jul-2020 13:19

MikeAqua:

wellygary:

Basically Geothermal (central NI+ northland )

Some of our geo plants have quite high GHG emissions.

https://nzgeothermal.org.nz/geothermal-energy/emissions/

It's above zero, but it's very low compared to ,say coal and gas, about 1/15th of a coal plant.

Re the concrete potential energy idea, that might stack up in certain places but where you have space and water availability I doubt anything approaches the simplicity, ease of maintenance and safety of pumped hydro.

And don't forget making concrete has a high carbon footprint in the first place.

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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#2530071 28-Jul-2020 13:31

elpenguino:

Re the concrete potential energy idea, that might stack up in certain places but where you have space and water availability

I have questions about a giant tower of concrete blocks in an earthquake prone country.

Very nice pun BTW.

Mike

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#2530220 28-Jul-2020 16:02

Lake Onslow pumped hydro is basically the special sauce that makes a 100% renewable electricity supply viable (along with a lot more conventional renewable generation).

Assuming we build enough renewable power plants to cover a little more than our typical annual usage (say to a 1:15 dry year event), having around 5000GWh of energy stored in the hills of the south island will give us the confidence we need to decommission the last of our of our fossil fuel power plants.

The question is if it is worth spending $4b on this is worth it. It's a lot of money for a scheme that will ultimately sit waiting to save our bacon in a 1:15 or higher return period dry year event.

Would be extremely cheap by comparison to say keep the Huntly on standby (with a massive pile of coal nearby), along with some of the other plants I listed in post 2529393 to cover us for such a situation. Given they would only run lightly every 15 years, and wouldn't be run hard untill a 1:100 event comes up, the emissions would be relatively low. My guess is that it would be cheaper to abate emissions on other sectors.

The next question is timing.

Because the Lake Onslow project is so massive, it will take roughly a decade to complete. (5 years to build, 2 years to fill. + a few years at the front end for consenting, political decision making, getting funding etc). As such we need to anticipate how valuable the plant will be in a decade, rather than now. If we think it will be really valuable we need to start now.

On the other hand there is a massive list of largely renewable power plants that are in the consenting process or are consented.

https://en.wikipedia.org/wiki/List_of_power_stations_in_New_Zealand#Proposed_power_stations

With $4b expenditure we could build these now, Many could be completed in a few years, and from that point have an immediate impact on NZ's emissions by crowding out coal & gas generation.

The key issue with the above is that they are uneconomic based on the current NZ electricity market basically doesn't work if the goal is to get close to 100% renewable energy.

Regarding the question about spilling. If the question is about how much is split because NZ doesn't need the power, the answer is not much, power prices in NZ rarely approach zero, and it is cheap to start a hydro turbine, so most will generate rather than spill whenever possible. (other than playing games in the electricity market that is - rare and agents the rules)

But there are heaps of other reasons that water gets split, in all of the below .

Transmission constraints (either capacity limits or outages) mean the electricity can't be moved out of the area - this will be manapori in a big way in a years time (until the transpower upgrades are done)
More water than the plant can be use. In wet years / times, inflows are often a lot more than what the power station can use. - once any storage is full you have to spill the rest. May not be cost effective to build more turbines for conditions that only exist a few days or weeks a year.
Outages & Maintenance of Plant / Dam. Dam might need flushing to avoid silting. Turbines may have maintenance outages.
Flood management. - Spillways and rivers downstream have limited capacity & earth dams can fail catastrophically if over topped. In addition some schemes have emergency spillways that have high costs to re-instate if tripped (i.e. will damage bridges, & wash out large area's). Owners of such schemes will preemptively spill if they can see a weather system approach that has the potential to damage infrastructure.

In summary, we will need to build more renewable generation capacity as we don't have surplus of it at the moment.

It is possible some of our south island schemes can be run a bit more aggressively with the fallback of 5000GWh of storage in Lake Onslow. Currently we do run them down too low to keep a buffer of storage in case of adverse events.

MikeAqua:

The fundamental problem ins NZ seems to be that the population is increasingly concentrated in the upper half of the North island, while a lot of clean generation is in the South Island.

More clean generation is required in the North Island.

I have no idea where.

This is not a problem.

Electricity is routinely generated long distances from where is it consumed.

If it is cheaper to do it that way (after accounting for transmission costs & losses), it makes total sense.

There are little opportunity for cost effective grid scale renewable generation in big urban centers, so some distance of transmission will be required by basically.

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#2530230 28-Jul-2020 16:22

Scott3:

Electricity is routinely generated long distances from where is it consumed.

If it is cheaper to do it that way (after accounting for transmission costs & losses), it makes total sense.

There are little opportunity for cost effective grid scale renewable generation in big urban centers, so some distance of transmission will be required by basically.

BC quite happily exports power to California, over 1000km away, NZ's issue is the HVDC capacity (+ lower SI) is not enough now that the situation with Tiwai has changed...

But to have built everything to a capacity to instantly cope with closing Tiwai would have seen $100s of million of assets sitting idle for years..

Once the smelter closes, the network will adjust and investment will flow to increasing transmission capacity...

Scott3

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#2530234 28-Jul-2020 16:26

PolicyGuy:

What has killed any uncommitted generation plant is not COVID, it's Tiwai Point -> Manapouri

Since it appears that a very large chunk of hydro generation that had been devoted to Tiwai Point is about to become available for 'general grid use', nobody can predict what electricity prices are going to look like over the next five to ten years, so nobody can work out whether their proposed generation plant might make a profit or be a financial millstone.
Since there is a significant chance that a proposed generation investment might turn into a money hole instead of a money tree, nobody is going to go ahead with any construction that isn't already irrevocably committed.

Decision makers will be able to make the call on building new generation plant only once they know: that Tiwai Point is actually closing for certain; and whether and when TransPower is going to do grid upgrades to being Manapouri power north; and what government policy is going to be towards carbon pricing (and hence thermal generation and coal-fired boilers).
Most of these decisions depend on the election outcome to some degree or another.

I wouldn't expect any decisions on new generation plant until early 2021

Yip.

Once the transmission upgrades are complete, a substantial amount of low marginal cost power from manapouri will hit the wholesale market, squeezing out higher cost producers and dropping the wholesale price for everybody.

If the goal is 100% renewable we need to either complexity rework or get rid of the current wholesale power market.

It doesn't incentive's the kind of overbuilding that is needed for this goal, and once you start having periods with nothing but renewable dispatched (essentially telling windmills not to run despite good wind, or hydro plants to spill rather than run), the wholesale price will fall to near zero, meaning no generators can cover the fixed costs of their operations.

It has also long been argued that the market fails to adequately compensate generators for holding reserves. This is one of the reason's only two of the of the original four units remain at Huntley. Arguably this plant is one of the best to have on standby for extreme events (easy to stockpile a lot of coal, ability to run on gas if needed, little transmission constraints between it and Auckland).

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#2530254 28-Jul-2020 16:43

wellygary:

BC quite happily exports power to California, over 1000km away, NZ's issue is the HVDC capacity (+ lower SI) is not enough now that the situation with Tiwai has changed...

But to have built everything to a capacity to instantly cope with closing Tiwai would have seen $100s of million of assets sitting idle for years..

Once the smelter closes, the network will adjust and investment will flow to increasing transmission capacity...

Today's peak on the HDVC link was around 500MW north. That link can handle 1200MW, Manapouri's (consent limited) capacity is 800MW.

So, yes there is a limitation in the HDVC link, but getting the power to the bottom of the link is the much more pressing issue. There are also options to upgrade the HDVC link if needed.

One issue that will crop up with more reliance the HDVC link is the need to maintain n-1 redundancy. 1200MW+ is a lot of capacity (or shedable load) to keep on standby in the north island in case the link trips.

I was working at a power company one summer (lower electricity demand & spot price time typically). HDVC link was shutdown due to the need for firefighters to fight a (unrelated) fire close to or under the overland portion of the link. The system was able to cope without blacking out any suburbs, but the wholesale market went haywire. Our office building was taken off the grid (fall over to backup generator) such was the wholesale price.

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#2530331 28-Jul-2020 18:59

Scott3:
Today's peak on the HDVC link was around 500MW north. That link can handle 1200MW, Manapouri's (consent limited) capacity is 800MW.

So, yes there is a limitation in the HDVC link, but getting the power to the bottom of the link is the much more pressing issue. There are also options to upgrade the HDVC link if needed.

The grid north from Haywards is the limiting factor, not the link itself.

Tracer

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#2530387 28-Jul-2020 21:38

Those in the know make the same criticisms many here have: https://www.rnz.co.nz/news/national/422165/industry-figures-say-lake-onslow-hydro-project-not-worth-it. Of course the engineers etc. aren't considering the political opportunities like photo ops and oodles of press releases that come with a project like this, only the financial, environment and technical aspects.

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#2530426 29-Jul-2020 06:13

A far cheaper alternative to Lake Onslow is to keep the aluminium smelter, but have an electricity supply agreement where pot lines are shut down during dry years.

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#2530446 29-Jul-2020 07:51

Tracer:

Of course the engineers etc. aren't considering the political opportunities like photo ops and oodles of press releases that come with a project like this, only the financial, environment and technical aspects.

And that's because the Engineer's scope is limited to the technical aspects of designing and building these systems - fulfilling the functional objectives of a project - within the limitations of physics, practicality, safety and cost.

The funding, goals, philosophy, and regulation behind the creation of this infrastructure is the government's job, particularly if the capital required is large, the public benefit long term and obvious, and the immediate financial returns not enough for them to guide the wealth and capacity of private business to do the job (and yes - they can also claim the photo ops..).

Running the country, and spending money on our behalf to provide for our future well-being and happiness, requires anticipating our future needs and building ahead of demand.
To assess the real future benefits of a large investment now, the economic and business case has to include such vague concepts as sustainability, accepting input from various people and organisations, and being constrained by legislation.

Because they're unable to see into the future they have to take educated guesses.

NZ has committed to some lofty goals.. the “Zero Carbon Amendment Bill” requires NZ to reduce greenhouse gas emissions by 30 per cent below 2005 levels by 2030. The National Party voted for it, while promising to amend it when they got in, something that looks less likely this round. So it stands as-is.

The Climate Change Commission reports give an idea of how a low-carbon future might look.

Their aim of 100% renewable energy by 2035 is one reason they recommended pumped hydro.

Another CCC 2035 goal is having 50% of New Zealand’s vehicle fleet electric, and deploying up to 1,100 MW of battery storage, which is interesting in itself - More electric vehicles should increase electricity demand overall, but by charging overnight, they might eventually perform a similar function to pumped hydro at a lower cost.

I can only imagine they've realised these goals are so ambitious as to be unachievable (without large subsidies) and that pumped-storage is the more realistic option.

If as @Scott3 pointed out, it takes a decade to construct this, there's only 5 years left to hit 100% renewables
It solves two problems that will become more apparent in that coming decade. The 'dry year' problem, and the need to buffer the fluctuations of wind power.

Wind power accounts for close to 700 MW of installed capacity in NZ - over 5% of our supply. But an amazing 2,500 MW worth of new wind farms have received resource consent. Climate change isn't likely to halt the roaring 40's, but modelling shows an increasing number of abnormally dry years making traditional hydro less a reliable baseline.

Holding coal fired Huntly in reserve – while acceptable from an engineering point of view, doesn't sit well with their goal of completely eliminating fossil fuels from the electricity system.

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#2530452 29-Jul-2020 08:16

JessieB:

A far cheaper alternative to Lake Onslow is to keep the aluminium smelter, but have an electricity supply agreement where pot lines are shut down during dry years.

Erm - who would be responsible for (as in own/run) this massive loss-making excercise?

It would make the A$4.5 Billion Victoria's spent subsidising Alcoa's Portland aluminum smelter look like pocket change.

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#2530581 29-Jul-2020 10:22

Sidestep:

- More electric vehicles should increase electricity demand overall, but by charging overnight, they might eventually perform a similar function to pumped hydro at a lower cost.

I've always been a dubious about that V2G function. I don't plug my car in overnight to discharge it: it needs to be charged in the morning when I am ready to go to work. And during the day it's sitting on the side of the road or in any case it's not plugged in (and if it was, I'd also want it to be charged when it was time to go home again).

I guess it's less important if you've got a battery 2.5x the size of the one in my Leaf, but even so I'd be annoyed if I got up to go on a long drive in the morning and found it had only 100km range remaining because it was balancing the grid overnight.

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#2530604 29-Jul-2020 10:29

you could plug it in at 6pm when you get home, use power from the car till night rates kick in then change to charging the battery in the car. use the cheap power from the car battery, instead of expensive peak power pricing.

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#2530620 29-Jul-2020 10:43

Jase2985:

you could plug it in at 6pm when you get home, use power from the car till night rates kick in then change to charging the battery in the car. use the cheap power from the car battery, instead of expensive peak power pricing.

That would then require me to install a dedicated EVSE for 7kW+ AC charging, which is another expense that not everyone will feel like paying. I'm sure it would pay for itself eventually, but clearly "it will pay for itself eventually" isn't that strong a driver to change behaviour, or everyone would already be driving EVs.

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