If instead of spending $16B on this; we could buy back a significant portion of the power companies they sold and make them work as a single system with the lakes as primarily a storage resource.

Then put in these more intermittent sources over the next few years with the existing lakes as the giant buffer.

[–] Dave@lemmy.nz 1 points 5 days ago (1 children)

What's the difference from today? With pumped hydro at least you have somewhere to send excess power generation.

One important thing here is about the ramp up time. I wasn't able to find anything that explains about how long it takes for a hydro power station to start producing when it's off (and equally, to stop when it's on). It feels like it should be quick, open a gate and the water falls and spins the turbine, surely this can happen within seconds or minutes?

If that's the case, then loading up on solar should effectively balance out the water usage, so you could generate heaps of power on sunny days and use no hydro, then bring hydro online to help cover the night.

At the moment I believe hydro is used a lot for covering the base load, but if it can be turned on and off quickly there's no reason that needs to be the case. But if it takes hours to turn on or off a hydro station, then the argument for pumped hydro is stronger since you can pump while it's running (using excess solar generation).

[–] absGeekNZ@lemmy.nz 3 points 5 days ago (1 children)

You are mostly correct, hydro is used as base load rather than storage.

The use of hydro is dictated my market forces rather than efficiency.

Hydro ramp rates are fairly fast 15-30 minutes, usually faster because you are not going from stopped to 100%

Batteries should be used to buffer short term fluctuations, these can ramp up in seconds and hold for a while to let the hydro catch up.

[–] Dave@lemmy.nz 1 points 5 days ago (1 children)

Batteries should be used to buffer short term fluctuations, these can ramp up in seconds and hold for a while to let the hydro catch up.

Battery storage at grid scale is pretty new, and I don't think NZ has any yet (just a planned one up north). A big downside too batteries is they will need replacing a lot, I hope we have appropriate recycling facilities to handle it.

One of the main benefits of hydro is the longevity. If you go big then you can build something that will still be going 100 years from now, making a very low cost per watt over it's lifetime. The scheme in the OP seems like it's building a whole new dam, they must think that adding the pumping to is is worthwhile otherwise they would just build the dam without the pumping component.

The use of hydro is dictated my market forces rather than efficiency.

I'm curious what you meant by that, that we use hydro because it's cheap?

[–] absGeekNZ@lemmy.nz 3 points 5 days ago (1 children)

No, they use hydro because they get money now rather than using something else and save the lake level for traditionally dry periods.

Also, over the last decade nonrenewable has been installed at great cost, this is not due to the best choice for everybody, but because the power companies get significant return.

It is really hard to justify anything against solar right now, but we are installing a very small amount.

[–] Dave@lemmy.nz 1 points 5 days ago (1 children)

Our power scheme does seem to incentivise scarcity as then the generating companies get paid more for generating the same amount of power. I see what you mean now about a government owned and coordinated hydro scheme, where hydro is used when it's the best option instead of when it pays the most.

It is really hard to justify anything against solar right now, but we are installing a very small amount.

Are we? Every time I turn around a new solar farm seems to pop up.

[–] absGeekNZ@lemmy.nz 3 points 5 days ago (1 children)

In a well run system we would install 10 times as much, while retiring the dirty, expensive and maintenance heavy old plants.

Honestly, the $16B being used for this scheme, spent on solar and and battery would deliver a much greater benefit to NZ, but would 'crash' the price of power to historical lows, thus meaning that the investment would be self defeating.

The flow on benefits from such low power process would more than pay for the investment

[–] Dave@lemmy.nz 4 points 5 days ago (1 children)

Haha I keep forgetting that most importantant point. I think building a giant hydrodam would pay for itself over time and provide a lot of much needed power, but I keep forgetting about the opportunity cost! The "what else could we spend $16B on" part of the puzzle!

[–] absGeekNZ@lemmy.nz 3 points 4 days ago (1 children)

Yea, to me it is an efficiency problem.

There was an analysis done for the LPG terminal @ $2.7B over 15years. With the LPG we would get just over 1TWh of energy; but the same money, spent on solar would get 1TWh every year.

Extrapolate that out and you would be hitting 5TWh every year with solar. NZ uses around 120GWh/day. Adding 5TWh/yr (would add 13.7GWh/day) or more than 10% of our total generating capacity.

The other thing to remember; is that this is not a generation asset; it a demand shifting system. Very useful, but it doesn't bring new capacity online, where as the same money spent on solar would bring significant new capacity online.

[–] Dave@lemmy.nz 1 points 4 days ago (1 children)

The other thing to remember; is that this is not a generation asset; it a demand shifting system. Very useful, but it doesn’t bring new capacity online, where as the same money spent on solar would bring significant new capacity online.

I may have misunderstood, but isn't this $16B project to build a brand new dam and brand new hydro generation capacity? It sounds like this hydro would add 8TWh of annual generation capacity:

If run for approximately six months, the huge project would produce around 4 terawatt hours of power – more than all of the country’s current hydro schemes put together.

The pumping part is the demand shift, but the project appears to add significant generation capacity even without the pumping part.

[–] absGeekNZ@lemmy.nz 1 points 4 days ago (1 children)

Generation would occur through underground turbines then, at off-peak times, water would be pumped from Te Mata-Au/Clutha River, via a lower reservoir, back up to refill the depleted lake.

The project would generate up to 1000 megawatts of electricity. If run for approximately six months, the huge project would produce around 4 terawatt hours of power – more than all of the country’s current hydro schemes put together.

The way I read this is that the bulk of the power will be from the pumped part of the scheme; not new generation. Some will come from the 'natural' filling of the lake. But the story doesn't say what % that would be; I have to assume that it is minor, otherwise it would have been highlighted as a major part of the justification for the project.

Also their math is shit; 4TWh = 1000MW running for 4000 hrs; which is just under 6 months (4320hrs); so how much time are they pumping for...only 320hrs out of 6 months....or ~8% of the time.

This whole project is based on unicorn fart justifications. This project will not run continuously; it will be used to buy power low and sell high. At best it will stabilise the pricing to reduce the big swings.

You know what works well in a dry year....solar.

[–] Dave@lemmy.nz 2 points 4 days ago (1 children)

I just assumed that the article focuses on the pumped part because it's new and exciting. They also discuss that this opens up opportunities for wind and solar, any thoughts on that? It kind of implies the wind and solar projects couldn't happen without it.

“Being down in Central Otago, this project will unlock a great deal of wind and solar development in Southland. There’s a lot of projects in Southland that need support for the intermittency of wind and solar.”

If the project goes ahead, it will provide firming for “several thousand megawatts of wind”, making investment in renewables more viable for generators, he says. Onslow investors “could well be part of that”.

[–] absGeekNZ@lemmy.nz 2 points 4 days ago

Yes....

The idea of the 'infinite' grid; is that all points are 'equivalent' in the system. Local generation is no more advantageous than remote generation.

This is of course not how reality works. But it isn't too far off, when you consider how efficient the HT system is at transferring energy.

Local generation mainly provides resilience for when there is a natural disaster. This is obviously extremely important; but it is not a justification in and of itself. Also what does 'provide firming' actually mean when we consider the context.

If there is several thousand megawatts of wind planned and economically viable; local storage shouldn't effect that. A MW of power produced in Southland may be consumed locally; or it may be consumed in Auckland; electrically from the point of view of the grid; these are the same place. Power will flow to where it is easiest; we direct the flow using various methods, but it is physical laws that drive the flow.

If we add 1GW of solar in Northland; it will be better than 1GW in Southland, simply because the Northland system will be smaller to get the same output.

If Southland has great wind resource; that is great and it should be developed; the whole country will benefit.