Building a pumped hydro scheme at Lake Onslow in central Otago to tackle the dry year problem where hydro-electricity lakes run low, would take seven to nine years to build, and come with an estimated price tag of $15.7 billion, the Government says.
The Government says it will progress to the next stage of the NZ Battery Project, which is looking into the viability of pumped hydro as well as an alternative, multi-technology approach to build "a resilient, affordable, secure and decarbonised energy system," Minister of Energy and Resources Megan Woods says.
Woods says the Government will continue looking at alternatives including a combination of comparator technologies and scoping a possible smaller pumped hydro scheme in the central North Island, subject to agreement with iwi. Newsroom reports the North Island site is at Upper Moawhango, near the Waiouru Military Camp.
Woods says biomass, flexible geothermal energy, and hydrogen have been identified as the possible alternatives to pumped hydro, because they have the most potential collectively to store enough energy to help solve the dry year problem.
“Until we address the dry year problem, we will continue to rely on burning expensive and polluting fossil fuels to produce our electricity. That’s bad for the climate and our power bills,” says Woods.
“Pumped hydro is an ingenious way of storing energy in a big reservoir, which is released into a lower reservoir when more power is needed, like a giant battery. A dry year solution would be a huge step towards our mission to move towards more renewable energy generation and power more of New Zealand in New Zealand."
There's much more about the proposed Lake Onslow pumped hydro storage project in this episode of our Of Interest podcast featuring Earl Bardsley, who first proposed the idea in 2005. Previously it has been estimated the project would cost at least $4 billion.
"Phase 1 investigations show a pumped hydro scheme at Lake Onslow would take approximately seven to nine years to build, with an estimated building cost of $15.7 billion. In comparison, initial estimates for the capital element of the portfolio option are about $13.5 billion, but with significantly higher ongoing operating costs," Woods says.
“We always knew that any dry year battery storage solution will require significant investment, that’s why it’s important we thoroughly test these scenarios and get it right."
“Now some more detailed work has been done we have a much clearer picture of the projected costs which have differ significantly from the 2006 high level costings. The next phase will be to dig even further before we look at spending such a huge amount of money, but one thing we do know is that doing nothing to plan for climate change is not an option," Woods says.
She says there's still a long way to go with a lot more work required to understand the full environmental, cultural, social and commercial impacts, as well as the engineering requirements.
"A detailed business case is expected to be developed by the end of 2024, followed by a final investment decision, which is expected to take a further two years.
The NZ Battery Project was established in late 2020 to find innovative solutions to the dry year problem, when hydro-electricity lakes run low, leading to the burning of more fossil fuels to cover the electricity shortfall, and often higher power bills, the Government says.
120 Comments
By offering no GST on home solar installations that connect to the grid, and offering loans at OCR - 2% for these, you eliminate SOME of the need for this mad idea, and you do not need to upgrade the grid.
I suggest that this would cost a few billion only and be a wise investment as it also improves resillience in a disaster....
would also take pressure off dams during a dry winter/summer as you could also offer same deal for EV purchase for same.
Absolutely agree, although even low interest loans would be an option too. Install price of solar is pretty high atm, I bought panels from china and an inverter from a local electrical supplier, saved about 8-10k by installing myself.
Might still need pumped hydro though if all transportation energy is switched over to electric, albeit with potential decreased total transport energy through efficiencies, mode changes etc
What will really kick things off is cheap flexible/rollable solar panels which hopefully aren't far away as we have rollable TVs at a consumer level.
A solar sunshade I can pull out in the same way the classic Kiwi sunshade on a deck used to work would go some way to alleviating the lack of suitable roofing for many houses. From there a traditional inverter and battery set-up would be perfectly fine. Then at night I can simply retract it and let roll up, safe from the weather and unroll it again the following day. You could presumably motorise it to as some pergola products do as well.
It won't get you the same return as fixed panels but it would be a great option for those in town houses without the roof space or pitch to mark that kind of set-up work.
It can by installing batteries but adds a lot to the expense of the installation. In my opinion home solar is not financially viable in any reasonably sized town or city where distribution is close by or already available. I would be happy to have some solar panels connected directly to my hw cylinder but that option is not available yet and would require a hot water cylinder with a 2nd temperature device and an additional the elemen and components to run off dc direct. Would require legislation to force cylinder manufacturers to put in a 2nd temperature sensing device.
If I recall correctly a grant with given to a Uni scientist in the last 3 or 4 years to investigate the use for solar PV direct to the end appliances. First of all given to the wrong discipline. Should have gone to the electrical engineering department, not a scientist.
Our hot water cylinder runs off solar PV panels (10) almost exclusively. There is wetback heating in the winter, and it gets 1 hour of grid boost a night (for free - thanks Electric Kiwi). 95% of hte time we have enough hot water.
The product we use is the Solar i-Boost. It works well. On a sunny day we get about 7kWh of heating before the tank is hot and the rest gets exported to the grid. I'd like to get batteries to store the excess, but we only get about 90 kWh excess generation, so it's not economic.
Panels from here:
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SHANGHAI PVSYS NEW ENERGY CO.,LTD
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10kW Invertor from J A Russell
https://www.solar.jarussell.co.nz/product-page/goodwe-inverter-solar-6k…
Yeah seems to be going well so far. They send all the brackets and hardware you need for mounting the panel.
None of this solves the dry year problem that Onslow is designed to fix. Too much intermittent generation with our current setup means more coal and gas to fill in the gaps, and the risk of too much power generation with nowhere to go (spilling water at the dams because all the solar panels are pumping?)
Onslow is not about power generation - it will be a net consumer. It is about smoothing our generation in the short (buffering solar and wind) and long term (dry year storage).
Not a scalable solution. The grid would be overwhelmed on sunny days and have rolling blackouts in the evenings and mornings, unless we also build lots of power plants to sit idle in the day and run in the dark.
Or...we could build Onslow to buffer a whole load of individual generation.
I'm really struggling to understand how more solar helps smooth out our generation. My mind is picturing our typical daily demand curve (especially in winter) with peaks in the morning (~9 a.m. this morning) and evening (~6 p.m. yesterday), and comparing that to a typical solar generation curve with a huge spike in the middle of the day.
Hey lads its me, your local Bitcoin proponent :)
You might actually like to know that Bitcoin Fixs This, and is doing so in the United States. Texas with its independent grid ERCOT and massive amounts of isolated wind generation really love it.
https://bitcoinmagazine.com/technical/forget-bears-bitcoin-duck-curve
Variable demand is a tool the energy grid has never had before and will be key with the increase in unreliable energy sources the greenies love.
Simple mfd. 1. If lots of houses (potentially most) like mine have minimal demand on the grid, including at night then the existing system copes.
2. In the 'dry years' the extra generation helps supply lots of the consumption. And, helps keep our existing storage from being run down.
Most of the experts, including EECA would disagree with you. Mfd is right. EECA years ago wrote off solar as an effective technology for NZ. Unlike Australia, our peak consumption occurs when there is no sun. Dry years doesn't mean there's not a lot of cloud cover, it just means there's not a lot of rain when there needs to be.
So in other words, years before we saw really affordable home storage options for solar, they wrote off solar. Gotcha. Given that some automotive manufacturers are only now just getting around to the fact that EVs are a reality, do you think they might have made that call a little too early and been a little too hasty?
Different mindset needed.a good example is the Canterbury catchments which in summer use around 2% of load for irrigation.Genesis new solar farm,which will feed mostly into Ashburton providing half the summer load.if it is wet and cloudy the irrigators are not used,they also do not irrigate during peak loads (for $$$ reasons) The electricity abated will come from southern generation even in low storage years as minimum river flows need to be maintained,and during average levels it will significantly add to storage.
https://twitter.com/Poission51/status/1611875700562354176/photo/1
Onslow helps to solve two problems, the dry year issue and the problem of renewables being intermittent (soaking up energy during the day and/or when the wind is blowing and sun is shining). You are suggesting building more intermittent generation. And outside of peak use times (early morning, 5-8pm).
Its lower level than this. We need to keep a sustained flow and solar panels only work during the day. Pumping water up and down from Onslow into lake Roxburgh means we get water pumped back into the lower Clutha dams for use again. It also means if we do subsidise solar panels, while the sun is shining we move water up into lake, cos everyones solar panels can be used fully. Then when the peak comes around and solar is low, we start releasing water. Its an elegant solution to a hard problem.
And how would you store the electricity generated by so much solar? (If you're suggesting we use lakes at night and solar during the day then I'm sorry the numbers don't stack up. The lakes would still go dry.)
Lots and lots of batteries would do it. But once all those batteries are factored in the cost / benefit equation of solar goes backwards real fast.
I'm all for Onslow, but I fear that without an organisation like the Ministry of Works to manage the contracts and oversee the scheme that we'll get the usual cost overruns. Before anyone screams cost overruns and 'Uncle MOW' let's put some context around that first. 23 hydro schemes build between 1945 - 85. All but 5 designed and constructed by the MOW. For the most part, on time and within budget. The cost overruns were usually in the North Island and to do with the complex volcanic geology. "A nightmare" as one engineer told me.
Big is beautiful in the wonderful world of hydro-electricity. It's much more efficient in the long-term, both in cost and the environment, to go big than have lots of little schemes. Hydro is expensive to build, but costs almost nothing to run because the fuel (water) is free. Maintenance costs are virtually zero.
Here is a good place to start. Zero population growth. Until government takes declining energy and resource availability seriously they are frankly just full of it! Personally I don't want to be lumped with an "Onslow", just because govt is so oblivious to reality. In ten years they will be looking for another Onslow, or nuke site, just so we can fit more humans in. Insanity!
https://www.interest.co.nz/public-policy/120338/almost-18000-foreign-wo…
It may cost $15b to build, but what will it actually cost over and above to generate a return on that through power bills at a consumer level? The Government might be able to afford it with the backing of 5m taxpayers, but presumably there will be a cost recovery (and return premium) added to power bills for the next few decades to cover the cost.
So.... can households afford to pay for this on and ongoing basis, in addition to actually paying to build it in the first place as taxpayers?
Does the cost include upgrades to transmission lines? That bit was left out of the Snowy River 2 debacle. Also located the wrong end of country with low rainfall and the highest evaporation.
"Snowy Hydro now expects completion in 10 years, not four, by 2026. Some experts consider even this extended timeframe to be optimistic. Construction of the tunnels is running at least six months behind the latest schedule and the transmission connection is unlikely to be built by 2026 anyway. The all-up cost has increased at least five-fold, to $10 billion-plus
...Snowy Hydro avoids mentioning the transmission connections to Sydney – $4 billion-plus for HumeLink and the Sydney ring – and to Victoria. To make matters worse, Snowy Hydro refuses to contribute to these transmission works, leaving it to electricity consumers to pick up the tab."
https://www.smh.com.au/national/five-years-on-snowy-2-0-emerges-as-a-10…
...
$15b /2m households = $7500 per household.
Thats a good chunk of the cost of solar and battery for our house. Would make me wonder how feasible it will be to go solar and battery and disconnect from the grid. 15years of network charges (once they abolish the low user tariffs) would probably cover the rest of the solar install.
That wouldn't be a linear spread too. Spending that money in the North on household-level resilience would drastically reduce the need to for a hugely complex engineering megaproject in the South. You might only need to spend a fraction of that to make the whole thing not worth doing.
Last time I did the maths, to emulate Onslow's storage capacity would require approx. 100 Tesla power walls per household in NZ, at a cost of approximately 1 trillion dollars. This does not include any discount for charge lost by the batteries when you want to keep them charged for a period of years.
This proposed scheme is an absolute beast.
Except thats not what I am discussing, i'm talking purely from a self interest point of view.
Also, did you factor in how much all those houses having solar and being self sufficient (and possibly even exporting to the grid) for large periods of time would mean that we don't need to generate as much power from the southern hydro scheme. Thereby hugely reducing the need for Onslow?
I fear it will be a huge white elephant as by the time it is finished and functional how much wind and solar will have been added?
Not sure your original comparison works if you're only looking at self-interest. You won't be able to 'opt out' of the National decision and pocket the $7.5k to spend on solar. It would make sense to compare the two from a 'what if all households do this instead', in which case you will find the same capabilities are extremely expensive.
On a fundamental level, household batteries are much more expensive than Onslow, even if the cost overruns several times the original budget. Household generation is more expensive than grid-scale plants. It might make financial sense to install a solar panel on your roof, but it would be an expensive way for the country to do things.
Yes in terms of cost, but is there an 80/20 situation here where concentrating a bunch more self-generation without the huge transmission costs will give you a huge chunk of the benefits of Lake Onslow without the absolutely stonking 100% capital cost and ongoing run-rate required to generate the return to make it worth-while?
While the Onslow storage might have some staggering long-term absolute numbers, it would take something like a volcanic-fallout to take large chunks of rooftop/garden/solar farm PV out of the equation to the extent that households are totally reliant on something like the grid. So you might not be able to give each household 100 Tesla Powerwalls but I'd say many or most might need two, tops, plus the additional ongoing generation solar would give them would be fine (unless Mr Burns blocks out the sun again).
And once you have spend a bit of money on those households in the North and vastly improved your grid resilience, you might find there isn't a lot of appetite for a stonking megaproject in the South, with all the risk to transmission lines that getting it from down there to up here might entail.
Depends how the govt pays for Onslow, if it via general taxation then no, but if they levy fees on future electricity bills then it does.
You seem to be ignoring that Onslow isn't additional generation. If we want to convert coal fired process heat (eg many of Fonterra sites) from coal to electricity we'll need a lot of new generation, and Cars from fossil fuel to EVs is yet more Electrical load.. Onslow is not new generation. Adding solar on houses is. Adding wind farms is.
As the generation mix moves away from hydro the dry year problem reduces, it becomes the cloudy week problem, and the windless week problem, and the diversification means the chances of having both at the same time reduces.
More like what comes out of the beasts rear end. Even at 20k per household you could put solar on 785000 dwellings for 15.7 billion.
Thermal generation is mainly Huntly to supply north of Taupo. If solar took the load during the day (even without battery storage) then
North Island hydro capacity could be saved for night demand.
You’d need to pair those systems with batteries which would significantly reduce your bang for buck. Also, what is the useful life on those systems? Onslow will be a 100+ year asset I imagine, the life of a solar panel/battery is what? 15-20 years? So you’d need to plan to replace them 5 times.
Power grids are extremely expensive to build, we just forgot that in the past people spent the money to build infrastructure.
We have also just gotten far worse at building such infrastructure for an affordable price.
We are about to have a mountain of unemployed people, the appropriate move is to kick off very large stimulus programmes performing this sort of work.
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"Pumped Hydro" is a way to store energy, HOWEVER it's always going to take more energy to produce than it outputs - this is primary school science in most developed countries.
Just another project doomed to fail.
What a bunch of bundies - they've brought into the "pumped hydro" grift hook-line-and-sinker.
You'd have to be ignorant or 'on the take' to think this is a good idea. After their time in government it's rumoured MPs involved with 'pumped hydro' plan to develop a petrol-motion-machine.
I don’t know what point you think you are making. Any storage system loses power. Pumped hydro is incredibly efficient compared to all other options. Price that amount of storage out in lithium ion batteries, hydrogen (talk about bad efficiency) or concrete block lifters and you will see what I mean.
Fossil fuels are about as efficient as hydrogen but with considerably worse side effects, i.e. climate change. Which is what we are trying to solve.
It IS hydro generation, so dunno what you are talking about. The systems are about 80% efficient, which isn't bad at all.
Using energy to produce less stored energy and outlying billions in the process (plus ongoing costs) - what could possibly go wrong for the consumer?
I can tell you now this is 100% a boondoggle and likely will be scaled bank if it ever goes ahead.
Spend the money on oil and gas exploration/extraction I say.
The existing hydro lakes do not have enough capacity to see us through a dry year. Onslow would have significantly more storage capacity than all current hydro lakes combined.
We could certainly increase the storage capacity of our existing lakes, at a dramatic cost to their attractiveness - Are we happy for Tekapo or Taupo townships and lookout points to be separated from their lakes by hundreds of metres of dusty ground? Are we prepared to move the surrounding houses and infrastructure to allow a higher range?
There will be no additional transmission costs. There already is a high voltage direct current link from the southern lakes to the North Island that minimises loss. Onslow will only generate when the Southern lakes are low and not generating. Because it is nearby to the southern lakes it can use the same transmission lines.
If we had a competing pumped hydro scheme in the North Island, with similar characteristics, we would be all over it. But you can only play the cards you are dealt.
There are smaller possible schemes as mentioned in the article, which would need to be supplemented by other areas of flexible demand e.g. the Hydrogen plant Meridian and Contact want to build (also in the South Island, as that is where the electricity supply is). The Gentailers are definitely pushing the portfolio approach, as it will be better for them than Onslow effectively capping power prices.
If thats done on a daily basis then it will never get filled up.
Unless a whole heap of additional generation is installed over and above the status quo. So the cost benefit study will have to include this additional generation which might go half way to making Onslow not necessary in the first place!
Onslow is a dog.
A lot of people just do not understand how these systems work.
Solar/wind is now the cheapest power there is. In the USA they are building mountains of it, not because the government said so but because it’s cheap. Look up the numbers for Texas they are massive.
Now, the sun doesn’t shine all the time and the wind doesn’t blow all the time. So you need to partner wind and solar power with storage and you factor that into the cost. Pumped hydro is often the cheapest storage there is - geography allowing.
That’s why we need Onslow, it will unlock a massive increase in solar and wind. And when you compare that to buying coal and paying for carbon credits it’s a damn good deal.
Large scale pumped hydro like Onslow and NZ solar are natural complements. Because NZ solar produces more energy in summer when electricity demand is less. Pumped hydro could store this surplus summer energy for use in winter.
Wind and solar already are more cost competitive than coal. South Australia is rapidly becoming renewable just from wind and solar.
https://www.climatechangenews.com/2022/09/16/south-australia-set-to-bec…
Are you saying they would pump water up 600m or so, then not use the head of water to generate more electricity when it comes back down? Onslow would just shift the hydro generation to generators sitting above lake Roxburgh when other lakes can't pump cos their water level is too low. Then the spilled water gets used also through the rest of the Clutha dams as well.
The whole scheme is simple a slightly less efficient extra hydro plant that can run when others can't. Still hydro power doing the work though.
No, you just haven't read the thread. I am responding to someone who thinks we should burn hydrocarbons or use hydro generators because they are more efficient. Who didn't seem to realise the system will use one of the efficient systems they describe.
I understand its storage, but it has hydro generators at the bottom. If it had, for instance some form of power that creates hydrogen at the bottom, it wouldn't be as efficient because that hydrogen conversion and back again would create too many losses.
Don't know? The hydrogen economy looks like it will wind the clock back to the time the ozone layer was rapidly depleting. As long as we can keep fuel cell powered SUVs on the UV steralized road, should be all good though. pg39
https://assets.publishing.service.gov.uk/government/uploads/system/uplo…
How often do we actually have an excess of electricity to use on pumped hydro, and how much.?Figures please, not vague assertions.
Separately, what Co2 emissions would be involved in building this and how long is the payback time in CO2 terms
Thirdly would the $30 billion +interest be better spent on other power generation development or energy efficiency??
Thats very easy to visualise, theres complete and live data publically available.
https://www.transpower.co.nz/system-operator/live-system-and-market-dat…
And scroll down to the graph that shows installed capacity and current utilisation. As you can see our installed Hydro already dwarfs any other contributor to the grid, especially anything else renewable. So we already have a large and effective hydro 'battery' to be held in reserve and used as required, except we reply on it doing the heavy lifting every day already. Onslow is a white elephant.
Apparently our lakes are not very deep so they aren’t great at storage compared to other countries. The advantage onslow gives is massive storage.
In terms of the surplus to fill onslow, obviously some comes from wet years, but also increased solar and wind. Once you build onslow it can store the energy from these sources and even out the supply, even potentially storing it for months - something that would never be cost effective using a lithium ion battery.
And its better than this as well. Because it represents stored power, if we found we weren't utilizing it enough (i.e. the water was sitting around for dry year storage), we could take say 20% of it and use it for some sort of high powered generation, then let it build up again. It would then be a resilience store as well as a potential to feed into another industry.
For instance, imagine there is a large market for hydrogen. We could create a hydrogen production plant at the bottom, that gets turned on when we have a long period of excellent power making weather, to soak up extra energy and or decrease our balance of trade deficit or power our own trucks/planes/boats.
No country in the world has ever been upset because they have had an excess supply of energy.
Interesting questions, which I cannot fully answer as I'm just an interested observer and not an expert.
1. I suspect this is fairly rare at the moment. Our intermittent generation can only be built up to a certain level as we only have so much buffering in the system to smooth out the peaks and troughs. Building Onslow would mean we could build much more and generate frequent surpluses to store.
2. No idea, I suspect the next stage of the project might look at this. The alternative is ongoing burning of coal, which is pretty nasty stuff in terms of emissions, vs the one-off costs of Onslow.
3. See 1. It's not an either-or. The Gentailers are already investing heavily in generation (just read their NZX announcements), so no need for the Government to look at this really. Energy efficiency - yes, I am very surprised the Government has focused on things like electric car subsidies rather than, say, insulation and e-bikes. However, neither of these deals with our dry year problem.
There is a difference between a generation problem and a supply problem. You need baseload generation to support renewables - what are getting built. Onslow does that. It will timeshift the supply to guarantee it’s available when it’s needed. We will still need massive amounts of new renewables but Onslow enables that.
From a power producers point of view. Say I’m considering building solar/wind power. But how much will I get paid? Well onslow helps because it will buy power from those producers raising their prices and release that power when prices are very expensive. So renewable power produces have less risk and power users (industry) have less risk and everyone is happy. Or we can continue with the current horror show where lots of business have to shut down when there is a power shortage and prices go through the roof.
It would be good to know the price or cost of that 'dry year' horror show compared to the $15bn build cost. I think to calculate the dry year cost would be something like the kWh rate difference between a normal and dry year plus the costs of whatever blackouts and voluntary industrial shutdowns occur. I think it would be in the $billions. So doing nothing is not a cost free option.
P.S Onslow seems like a better deal to me than spending $360bn on nuclear subs like the Aussies are doing
1) If i'm interpreting the charts on page 44 of https://cdn.auckland.ac.nz/assets/business/about/our-research/research-… right, its averaged about 1350Gwh/year over the period charted.
2020 we generated a total of 42,858 Gwh. So average is we spill about 3.1% of additional electricity generation. (If anyone has better numbers please link them)
2) Concrete is carbon intensive, and there would be a lot of it used.
3) Good question.
For the same costs, I would rather have 4 nuclear reactors built on Chatham Island by CNNC https://en.cnnc.com.cn/
+1 for pumped hydro. The excess oligopoly returns of the corporate energy companies need to go.
we should have never privatised the energy market. GDP is linearly correlated to energy use.
A system optimal design run by a zero profit SOE for NZ Inc is a much better solution than corporate oligopolies screwing excess profits out of New Zealanders.
All we’ve done is pushed up the price of electricity in NZ and made NZ inc less competitive in the process.
THIS. We have got a dysfunctional "market" that encourages crazy behaviour by the Gentailers: https://www.rnz.co.nz/news/business/420160/meridian-spilled-water-to-hi…
Which is why National is against the idea, it would stop their mates in the industry from excess profiteering.
If we want to have a decent economy, we NEED cheaper electricity, no ifs or buts. A 1000 pound gorilla is exactly what is needed. Cost should come out of central taxes, probably climate change funding as well (fuel taxes/carbon credits etc). Pretty sure this is already a couple of billion per year in funding. If build time is 10 years, then it works out.
Lets be clear - existing gentailers will f#$king hate it. That's a GOOD thing, they know profits will shrink as they profit hugely during dry years.
Personally, both public and private energy generators have issues. One thing for sure, energy is a valuable resource and should be priced to avoid unnecessary waste. If you are hoping for free energy from the magic energy tree, that's not going to happen! The price tag on this project should be a clue!
I see the best options for NZ as more geothermal which could be held as reserve - cheaper to build and better location for transmission
Matched with a greater lake range for the likes of Taupo where the generation output of the water flowing down the waikato is huge. Possibly also increase storage in the central north island diversion lakes - this could be effectively a battery without the need to pump as it comes from rainfall (solar evaporation is the pump and cheapest available)
and more solar for housing but especially for industry where it can be cost effective and works without the need for battery storage - generate during the day and use during the day
It will require the likes of transpower to be a pricing customer though to buy and hold hydro or geothermal capacity - but still cheaper than Onslow just not as flashy for the politicians or design boffins pushing the barrow
This only makes sense when and if we have surplus renewable generation. this doesn't happen very often in New Zealand as our renewables operate as a base supply with non renewables making up the 20% shortfall. (note EV marginal extra demand can only be supplied by fossil fuel at the moment until we achieve close to 100% renewable generation)If we had lots more wind and solar renewable (but volatile) generation then pumped storage will be great at storing any surplus that cannot be stored by managing the storage in our conventional hydro system. I am pleased to see that they are looking at a pumped storage proposal on the central plateau as this closer to the center of demand and will enable the DC link to operate more fully.
Note also that A significantly smaller but cheaper pumped storage set up could be easily set up between lakes Wanaka and Hawea
With reference to the wet year/dry year. This happens when the direction of the annual prevailing winds across the southern alps change. So in a wet year the rains predominantly fall on the east side of the alps and vice versa. Another way to deal with the dry years would be to bore tunnels at favorable locations in the alps and divert the excess water from the west in a dry year into the hydro system storage lakes. E.g. The Landsbourgh river on the west coast could spill excess flow into Lake Hawea. I am sure that there are other options.
Some very relevant and well research background data here as posted by an earlier Interest contributor. (you have to be patient)
https://www.youtube.com/watch?app=desktop&v=HkaV2BB1T58&feature=youtu.be
Ten fatal flaws with the Lake Onslow concept
https://www.energywatch.org.nz/issues/EW85_7-2022.pdf
and a summary from a previous edition:
Summary
• The scale of the original Lake Onslow scheme is 10 times larger than is needed to address the so-called “dry-year” problem.
• The scope of the project has changed: -
o Level reduced from 800 m to 760 m.
o Tunnel increased from 15 km to 24 km
o Soil removal from 27 km2 added
• The Teviot Valley dam would be 1.5 km long making it the second [longest] hydro dam in the world after the Three Gorges dam in China.
• The increased water losses due to seepage and evaporation would require permanent pumping to maintain the Lake Onslow level.
• The round-trip efficiency would be <60%
• The cost of electricity to fill Lake Onslow would exceed the revenue from electricity sales in a low-hydro year. So, there is no economic rationale to proceed.
• Filling Lake Onslow would create an electricity shortage in New Zealand of greater magnitude than the “dry-year” problem.
• The NZ Battery Project should abandon the Lake Onslow concept forthwith without the need to proceed with re-estimating the capital cost of the ~$4 billion project.
I have always wondered why they haven't put hydro at "The neck" between Lake Hawea and Wanaka... about 50m of head, but decent enough flow to be tenable it seems?
Surely you can see the issues with pumping water up from Landsborough River (around 280m in height) across a fault line, along about a 50km tunnel, to a lake that sits at 340m? Still pumped hydro, and through a National park as well?
Regarding having surplus renewable energy, seems like a chicken and egg scenario. Until we have a way to store surplus renewable energy, extra investments don't really stack up? Who is going to put in a massive wind farm if it can only be used half the time? Wouldn't a massive storage mechanism to "suck up" any extra generation mean the generators can get a greater ROI for any new generation? That wind farm that was only going to be used half the time can now be used anytime, because Onslow will suck up the difference.
They should get a quote directly from Elon Musk and a personal guarantee it will cost that price. I think he would do it. Part of the scheme could be a Tesla substation etc and I'm sure his project managers would do a better job than our public servants or the "big four" rip off agencies often called in to consult.
Just build it, get on with it. We know we are going to need to drastically increase our energy storage because we are going to have so many electric vehicles and other things increasing electricity demand. Onslow will last how many decades or centuries? It will pay for itself many times over...
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