Pumped storage to deal with Auckland's water problems?

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neb

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#2519705 8-Jul-2020 21:51

pdh:
A 3 or 4,000 litre tank is pretty tiny - would do a couple for a fortnight.

Depends how you use it, if it's to ride out water restrictions then it should be fine, i.e. allow you to continue doing things like watering the garden and washing the car when it's curtailed with mains water. This also makes thing much easier since you just drop rainwater into the tank and don't have to worry about water quality, backflow preventers, and other stuff.

PhantomNVD

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#2519740 9-Jul-2020 00:12

pdh:
A 3 or 4,000 litre tank is pretty tiny - would do a couple for a fortnight.

The two of us use 7,500 litres a month of Auckland town water.
We mellow the yellow, but we shower daily.
We're now living in a unit, with no bath, garden or car-washing.

For a 7 month dry spell, we'd need 52,500 litres of water.
That'd be two of the biggest tanks you can deliver over the road.

We're currently building a house outside Auckland's supply area.
For us plus a tenant (ie: 3 people), I'll have 56,000 litres of tank.
That's all I want to cram on an 800 sqm section.

In a traditional year, that should run the house & flat, water a garden and keep the cars clean.
In a very dry year, we'll survive, but the garden would live or die on trucked-in top-up.

In a normal year, my new roof could fill the tanks 6 times over.
It'll collect 3,250 litres for every 10mm of rain that falls.

So do some back-of-the-envelope work if you want to drought-proof.
A 3,000 litre tank might only water a small garden ;-)

Pfft! We have 320L of fresh water on our bus/Motorhome conversion and it last us (family of 4 showering daily) 7 days easily, prime factor is the 10L/min pump and the 5L/m califont, so showers are 2 mins each (and 10-20L) but this just proves if there was a drought on And people REALLY wanted to conserve water they just need to change their habits!

pdh

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#2519743 9-Jul-2020 01:19

> just change their habits.

I knew there'd be one in the crowd ;-)

We've also lived in a caravan for two 6 month spells - 170 litres lasted us 7-10 days in the desert.

Then there was the kayaking trip to the Whitsundays - with only 70 litres of water for 10 days.

So I know we can live well on a damp rag...
It's your choice to stretch your water to 7 days - but not to 14.
Carry water a kilometre in a jar on your head - you'd conserve even more.
With a bigger tank, it's an agreeable luxury to use more.

My post was simply a heads-up for those without tank experience - to consider their personal usage and capacity.
People can be as water-poor or profligate as they like.
It's not rocket science, but running some simple numbers can't hurt.

pdh

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#2519745 9-Jul-2020 02:05

Just going back to the OP's question...
This looks to me a splendid opportunity for a very affordable Green solution.

Let's build a solar-powered intermittent pumping & filtration station to keep the existing Auckland reservoirs full.

(a) Auckland has lots of Reservoir capacity - but for much of the year it's half (or less) full.

(b) Auckland has a continuous source of near-infinite water. On the driest day ever, the Waikato River could supply 20 Aucklands. There are times of the year when the Waikato has enough water for 250 Aucklands. And it floods.

(c) We get lots of sunlight every week for solar - but we can't always use it when it's available. Many human energy requirements are immediate. That means that sometimes there is nowhere for the Solar to be used. Big Tesla battery banks are expensive - the one in Australia was 100 million - for 100 million Wh. It would run Auckland for about 40 minutes; but that's not what it's intended for - as a peak leveller, it's great. It's just an expensive way to store solar energy.

So, let's take surplus solar and pump pre-filtered Waikato water up into the reservoirs. That's a very cheap battery. It uses water - when it's available, which is currently always. It can be driven entirely by (peak) solar - which we say we want more of. And it uses the vast storage which we already have.

As a bonus, we could fund it all by reducing the reservoir rain-catchment areas.

What's not to like ?

Scott3

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#2519854 9-Jul-2020 10:07

pdh:

Just going back to the OP's question...
This looks to me a splendid opportunity for a very affordable Green solution.

Let's build a solar-powered intermittent pumping & filtration station to keep the existing Auckland reservoirs full.

(a) Auckland has lots of Reservoir capacity - but for much of the year it's half (or less) full.

(b) Auckland has a continuous source of near-infinite water. On the driest day ever, the Waikato River could supply 20 Aucklands. There are times of the year when the Waikato has enough water for 250 Aucklands. And it floods.

(c) We get lots of sunlight every week for solar - but we can't always use it when it's available. Many human energy requirements are immediate. That means that sometimes there is nowhere for the Solar to be used. Big Tesla battery banks are expensive - the one in Australia was 100 million - for 100 million Wh. It would run Auckland for about 40 minutes; but that's not what it's intended for - as a peak leveller, it's great. It's just an expensive way to store solar energy.

So, let's take surplus solar and pump pre-filtered Waikato water up into the reservoirs. That's a very cheap battery. It uses water - when it's available, which is currently always. It can be driven entirely by (peak) solar - which we say we want more of. And it uses the vast storage which we already have.

As a bonus, we could fund it all by reducing the reservoir rain-catchment areas.

What's not to like ?

What's not to like? - Obscenely high capital costs.

Note that watercare is capital constrained and has a large number of wastewater projects that also urgently need funding for environmental reasons.

The system you are proposing would require:

- A pre-treatment plant which cleans up the waikato river to a standard that is not damaging to the ecology of watercares other dams, and is clean enough for their other treatment plants (Waikato treatment plant is special for treating dirty waikato river water).

- A dedicated pre-treated water set of pipelines to feed to various dam's at least 34km away. Waitakere's are 50km away as the crow flies, but much more if you want to go around the harbor. Long distance pipelines are very expensive.

- A network of pumping stations to push the water across long distances, and up from the roughly 16m elevation of the waikato river to the 160m+ of the reservoirs.

- A subsequent capacity upgrade of the treatment stations drawing from said reservoirs.

- An epic amount of solar panels to provide the energy for the above.

This infrastructure would need to be oversize by double or triple as it is going to be only run when solar energy is available, rather than 24/7.

System would likely be one of the more expensive ways (double treatment, massive treatment costs) to get water to Auckland, and as such likely would only be run as a last resort.

Consent to take water from the Waikato would need to allow for variable flow, resulting in higher peak flow rate.

Frankly watercare's current expansion plan is way more sensiable. It is to basically:

-Duplicate the current Waikato water treatment plant in stages (along with duplicating the treated water pipeline to feed the Auckland). Sized to run 24/7

- Various water main & pump station upgrades to allow treated water to be moved around the Auckland regions.

- Install treated water reservoirs to cater for local demand growth in pukekohe.

- Upgrade of ageing Huna treatment plant for greater reliability.

The above allows water from the Waikato (assuming a consent is granted) to be drawn, treated and injected into the watercare metro piping system, where it can be moved around as required.

The availability of more treated water from the Waikato reduces the need to take water from the raw water reservoirs in the hills, allowing them slowly to re-fill with rain. This avoids the cost of pumping water up hundreds of meters of elevation, and potential issue with ecology of those waterways. Also the project in itself adds capacity to the system, meaning capacity upgrades are not needed elsewhere.

In times with plentiful water, production from the Waikato would be dialed back, and cheaper to treat (and largely gravity fed) water from the ranges would be used more.

Scott3

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#2519882 9-Jul-2020 10:38

neb:

Depends how you use it, if it's to ride out water restrictions then it should be fine, i.e. allow you to continue doing things like watering the garden and washing the car when it's curtailed with mains water. This also makes thing much easier since you just drop rainwater into the tank and don't have to worry about water quality, backflow preventers, and other stuff.

Note that Auckland's water restrictions apply to all residential properties connected to the metropolitan network, so a little rain water harvesting system does not get around the outdoor hose ban.

Most such system's have transparent automatic fall over, so without going and checking the status of the system, you don't know if you are getting rain water or towns water through the outside taps anyway.

Also, the most dire water issue's are likely to happen in drought time anyway, when a little rain water harvesting system is likely to be already empty.

pdh

341 posts

Ultimate Geek

#2520499 10-Jul-2020 01:35

I'm not saying that my hand-waving concept for Peak-Solar-powered reservoir-replenishment from the Waikato is smart - or even viable, but I don't think your criticisms, er, hold much water.

> What's not to like? - Obscenely high capital costs.

> Note that Watercare is capital constrained and has a large number of wastewater
> projects that also urgently need funding for environmental reasons.

Well yes, obviously, capital is constrained for almost everything - even Military Budgets and Elon have to qualify.
But if Auckland's water monopoly isn't a bankable business - nothing is.
Funding an acceptable-quality water infrastructure isn't a financial problem - it's a political one.

I know that Auckland water supply and sewage treatment has been poor for at least the last 40 years - I've lived through the many water crises and swum at the polluted beaches. I've listened to politicians claim that the systems are world-class and that all the incidents are unexpected and one-off. Yeah, right...

"Obscenely high capital costs" - no I don't think so.

A few years ago, the Waikato Pump Station project built a 2 cumec river intake, an advanced treatment plant and a 37 km long pipeline for 100 million $NZ. That stabilised 33% of Auckland's peak consumption. Was that obscenely expensive ? You don't seem to think so - you admire the current plan to duplicate it.

Looking at what you say I'd need:

(a) a pre-treatment plant: Yes, but we need that for any use of the Waikato. Indeed, lack of this capacity is what has delayed us using more available & consented water for this 2020 crisis. Or are you saying that water must be cleaned more to go into the reservoirs than to my tap. I hope not. So - cost is not unique to pumping to a reservoir.

(b) Dedicated pipelines: Similar to the recent (and the planned 2nd) 37 km Waikato to Mangere ? So - affordable.

(c) Pumping up hill: Conservation of energy - pump it up, you recoup it on the way down (yes, minus pumping losses). That's what the cheap solar is for. My whole idea is based on our available reservoirs and available energy. Solar energy is hard & costly to store - pumped water is one way. Yes it's intermittent, but most of the world buys into that not mattering. As renewable energy sources proliferate, surplus energy will be looking for storage.

(d) Capacity Upgrade of treatment stations: Hey - that's cheating. You've already got the capacity to handle the reservoir water - we've only got trouble because it hasn't rained enough. Or that's what we've been told.

(e) Epic amount of solar panels: And every politician in the country would break an arm signing off on it !

(f) Needs to be 2x or 3x bigger: No it doesn't - it's only to top up natural rainfall. Absent 100 year events, we are told that Auckland's reservoir system copes just fine. Some of us may believe that.

You appear happy with Watercare's planned way forward - duplicating the current Waikato system. Which takes us up to 66% of Auckland's requirement. Yes, that'll work fine - for all the reasons you suggest.

If I was more cynical, I might even think that 2020's water scare will help push the politicians though a Business Case in 6 months instead of the usual 6-10 years. Never waste a crisis !

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