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The future of energy generation and storage

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Some recent goings on in the National Electricity Market:

Sunday 2nd December saw negative prices in SA and Victoria, that is the spot price was below zero, between 9:30 am and 3:30 pm. The drivers were high levels of wind power generation, widespread sunshine and mild temperatures in Adelaide and Melbourne which resulted in low consumption.

Transmission capacity to both NSW and Tas was running at the limit, flow being from Vic to those two states, such that there was no ability to shift any more. Wind and solar were supplying about 63% of demand in Vic and SA at the time, with thermal (coal, gas) plant still online for reasons of system strength* and due to the technical and economic difficulties of a short term shutdown of plant that needed to operate at high outputs once the sun went down.

*System strength - in layman's terms that could be considered as inertia. Like a freight train moving at 100 km/h has a lot of intertia whereas a feather moving at the same speed doesn't. That inertia and other things like the ability to adjust output to match demand are critical to controlling the system and in the ability to "ride through" unexpected incidents (faults) without the risk of a system black (that is, the whole system ending up dead). In simple terms when something goes wrong that "freight train" might slow down slightly whereas the feather comes to a complete halt. Hence with present infrastructure going to zero conventional generation (coal, gas, hydro, oil) isn't an option even briefly.

At present there is very limited storage capacity of any type within Vic / SA. There's the Hornsdale Power Reserve (aka the Tesla "big battery") in SA and that was being charged through much of this time and there's also some smaller battery systems but they're by no means enough.

Power that went to NSW and Tas displaced other generation rather than being "stored" as such. That said, since in Tas the generation displaced was hydro, and that water is held in the dams, that's a sort-of means of storing it in practice.

Meanwhile demand in NSW and Qld looked more like a typical weekday than a weekend, being driven by hot weather. This was to the point that some high cost oil-fired plant in Qld had a run for a few hours.

The obvious point there is that more transmission capacity between (Vic + SA) and (NSW + Qld), treating that as two regions not four, would have been beneficial. The details don't really matter so long as it means either more flow from Vic to NSW, or from SA to NSW, or from SA to Qld.

To that end there's a proposal being progressed to link SA and NSW early next decade. The trouble however is that with about 2000 MW of new wind and large scale solar, plus however much small (rooftop) solar, about to be built in Vic and SA that new link is already insufficient with only about 40% of that capacity. Plus it must be said that there's a limit to how much NSW itself could absorb, since NSW also has solar and wind generation.

All of which brings us to storage of this intermittently available surplus electricity especially since:

On current forecasts consumption in SA on Thurday 6th of December, with a forecast maximum of 39 degrees in Adelaide, will be almost exactly equal to available generating capacity within the state. So there's nothing to spare except supply available from Victoria. But:

On the same day demand in Victoria is currently forecast to reach 7605 MW, versus supply within the state at 7206 MW. The lights will stay on so long as nothing disrupts supply from Tas and NSW but there's not a huge amount of room to move.

The following day, Friday 7th, the situation is forecast as about a 650 MW gap between supply versus demand in Vic. Demand should be down in SA however due to cooler temperatures so flow SA to Vic is likely in addition to supply available from Tas and NSW.

If this sounds like a lot of juggling and all getting a tad precarious then that's not far from the truth. There are a couple of significant generating units out of service in Vic at present, Loy Yang A unit 4 and Yallourn unit 3, the latter having had a recent fatal incident.

There is also some less significant (smaller) plant that isn't running and probably won't be for quite a while. The details of that aren't public knowledge so far as I'm aware so I won't elaborate beyond saying it's in the Vic + SA combined region. It's old stuff yes.

Whilst forced load shedding or blackouts aren't expected at the present time, it's still a bit tight and we're only looking at 36 degrees in Melbourne and 39 in Adelaide which aren't extreme.

So any form of storage would be useful amidst all of this given there's a surplus shortly followed by a fairly tight supply situation. :2twocents
 
Humid said:
I currently run my pool and bore after 9pm at 14 cents/kw during the day it’s 28 cents.
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If you're in NSW, ACT, Qld or NT it's not a problem yet.

Other states it's a case of price structures failing to adapt to a changed situation quickly enough.
 
So the pumping of water is done with the use of coal fired electricity generation in off peak hours? Wiki. says the plants are net consumers of electricity because of the energy used to pump water up hill.
 
Wysiwyg said:
So the pumping of water is done with the use of coal fired electricity generation in off peak hours? Wiki. says the plants are net consumers of electricity because of the energy used to pump water up hill.
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Probably initially that may be the case, as it is much more efficient, to leave steam generators on line than to take them off and put them back on again. The process takes a few hours and burns fuel just to attain pressure and temperature conditions, to enable it to be put online again.
So if the plant is required for morning and evening peak, it makes sense to leave it on in the middle of the day to pump the hydro storage, then take the unit off overnight and use the pumped storage.
When there is enough renewables, to supply the load and run the pumped storage, then we won't need the steam plant.
I don't think I will be around to see it happen.
 
Yes it makes sense to have a solar and wind energy farm running the pumps so the storage, pumps/generators should be built together for a more efficient solution.
 
Wysiwyg said:
So the pumping of water is done with the use of coal fired electricity generation in off peak hours?
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Any source of surplus generation be it coal or otherwise.

The basic problem here is that if you get a mild sunny day with plenty of wind then you've got very strong generation from solar and wind plus low demand due to no use of heating or cooling and especially so when this occurs on a weekend. Now what, exactly, do we do with the power? It's use it, store it or lose it.

At present that's an issue in SA and soon to be one in Victoria. Qld and NSW don't have enough wind and solar for that to be a problem yet but it will be in due course.

Then at other times there's high demand and little or no solar or wind generation. It varies a bit from day to day and seasonally but demand peaks around 6pm when solar generation isn't working overly well and it may or may not be windy. Keeping the lights on requires that some form of dispatchable (not weather dependent) generation exists of sufficient capacity be it coal, gas, oil or hydro.

Building pumped storage thus addresses both problems and is an alternative to building new coal, gas or oil (diesel, fuel oil, kero) generation.

In the short term yes it will in practice mostly store energy produced from coal or gas but anything hydro has an extremely long life compared to anything else mechanical or electrical and for most of its lifespan is likely to be storing energy produced from solar or wind. That said, even where it does store energy from coal it will be improving the efficiency of coal or gas-fired generation by stabilising load.

Gas turbines in particular are terribly inefficient at partial load, they're best run either flat out or not at all. Meanwhile coal plant incurs substantial energy losses to start and stop so there's a benefit in maintaining a more constant load.

When I say hydro has a very long lifespan, well the best way to put that is to say that if you go to Queenstown Tasmania you will find the Lake Margaret power station not far out of town.

Lake Margaret's machines were running during World War 1 and they are still running today and apart from the pipeline replacement 2006 - 2009 they've rarely stopped in all that time. That's the original machinery sitting in exactly the same place it has always sat and doing what it has always done.

There aren't many things built by humans which are more permanent than that and there would be very few mechanical or electrical things which were around for both World Wars and are still in full use serving their original purpose today. :2twocents
 
An old photo of a now closed power station that I'm posting since I believe it may have some personal relevance to another member of ASF (though they've probably seen an aerial shot of it sometime anyway.....).

Note the absence of coal conveyors - this was prior to the fuel conversion.

The photo isn't mine but was placed in the public domain by the plant's owner many years ago. Has been scanned from paper.

KPS 2.JPG
 
It is startling to see the march of solar and wind energy through the the Australian energy system. The trick now is to create intermittent storage capacity and clearly some form of pumped hydro is easiest cab off the ranks.

I do think however that there should be a very close look at the reliability of the current coal and gas fired generators. I think Smurf has made many observations about the outages in these systems and perhaps the commercial temptation to allow such events to happen if it results in a juicy price spike.

The forecast for increasing summer heatwaves doesn't sit well with the current system.
 
What about the amount of electricity that could be generated if all current dams and reservoirs that supply town water were put to use. There is non reusable water flowing constantly somewhere that could be generating electricity.
 
Wysiwyg said:
What about the amount of electricity that could be generated if all current dams and reservoirs that supply town water were put to use.
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There are some examples where it is done but certainly more opportunities.

There's quite a few smaller ones in NSW (other than the Snowy scheme) operated by Meridian Energy (ASX: MEX) whilst in Victoria there's some larger ones such as Eildon (100 MW) and Dartmouth (165 MW) in addition to dams built primarily for power generation operated by AGL (ASX: AGL). Also some smaller examples in other states too.
 
Interesting to read that the Dartmouth Dam cold water killed off many fish stocks in the natural river systems. Also the turbine inside the dam wall being jammed by some steel doing serious damage.
A breach of the wall would have obliterated only a couple of small towns
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Wysiwyg said:
Interesting to read that the Dartmouth Dam cold water killed off many fish stocks in the natural river systems. Also the turbine inside the dam wall being jammed by some steel doing serious damage.
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The dam itself was built for water storage for irrigation, power is just a by-product, so water release and consequent effects are really a function of that purpose (irrigation (agriculture)) rather than the power per se. If that makes sense.....

The incident was certainly among the most dramatic occurrences at any power station in Australia that's for sure. It didn't simply wreck the machine but rather, it moved the whole structure.

It's not just the impact of the beams jamming the turbine but that doing so slammed all the vanes shut and stopped the water flow. Water hammer is a rather drastic thing when it happens on that scale.

Anything involving lots of energy has the potential to go horribly wrong. The risk is never zero although in this case it happened to a relatively cautious operator.

Here's a video of a load rejection test at Liapootah power station (Tas). It's a "real" test, that is an actual removal of load from the unit and then see that everything works as it should. It's a lot of water but the volume involved at Dartmouth was about 3.5 times the quantity. Stop that in an instant and the result isn't good.

 

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