The future of energy generation and storage

[Smurf1976]

One thing to note is that, contrary to the assertions of some via the mainstream media, the interest in batteries and renewables doesn't mean gas has suddenly become obsolete.

Here's some official Australian government gas consumption data for 2017-18 (latest that seems to be online) for the south-eastern states where supply is of concern in the coming years:

Victoria:
Electricity generation = 51.0 PJ (3830 GWh or 8.1% of electricity generated in Victoria)
All other gas use = 240.3 PJ

NSW (includes ACT):
Electricity generation = 26.2 PJ (3046 GWh or 4.2% of electricity generated in NSW)
All other gas use = 106.6 PJ

SA:
Electricity generation = 71.4 PJ (7753 GWh or 52% of electricity generated in SA)
All other gas use = 55.4 PJ

Tasmania
Electricity generation = 8.6 PJ (980 GWh or 8.3% of electricity generated in Tasmania)
All other gas use = 4.8 PJ

Total south-eastern Australia:
Electricity generation = 157.2 PJ
All other gas use = 407.1 PJ

So overall 72% of gas consumption in south-eastern Australia is used for purposes not relating to electricity supply. Unless consumers undertake a mass shift away from the use of gas, that demand for gas remains no matter what happens so far as power generation is concerned.

For the other 28%, realistically some decline is likely but it's not going to zero anytime soon.

First because those figures include electricity generated from gas by industry, mining and so on for their own use on site. If they're not connected to the grid anyway then it's irrelevant to them what happens with grid supply.

Second because it includes co-generation facilities which are connected to the grid but where some facility, eg a factory or hospital, needs the by-product heat from the power station. That means it will run, because they need that heat, no matter what the overall electricity supply situation is. Failing that, they'd switch to their backup boilers and be burning gas in those instead so either way they're using gas unless they go as far as switching to some other fuel.

Putting that into perspective, off-grid and co-generation gas-fired electricity is roughly 30% of total gas-fired electricity in Victoria and NSW and closer to 10% in SA and Tas.

Third because in general the energy companies are building batteries and pumped storage due to plant which is closing due to reaching end of life and, with some exceptions, that plant is mostly coal not gas. At this stage nobody's proposing a complete abolition of gas-fired generation.

So it's fair to say that ~80% of the market for natural gas in south-eastern Australia is not impacted by what goes on with renewables, storage etc at least in the short term since it's either not for power generation at all or it's off grid or co-generation.

Of the remaining ~20%, some reduction is possible but not to zero anytime soon. We won't see zero use of gas-fired power in the medium term.

So there's still an ongoing need for natural gas at least in the medium term and that means there's still a market for gas producers, pipeline companies and so on to operate in noting that a substantial volume of existing production is exiting the market in the next few years due to field depletion. Ignoring the politics and focusing on the financial, if listed companies such as Santos (ASX: STO) and others go ahead with their proposals then they'll find a buyer for the gas.

 

[qldfrog]

Actual voltage at the house level and consequences for solar power feed back
Found article interesting
https://www.abc.net.au/news/2020-08...over-voltage-limits-unsw-study-finds/12534332

 

[sptrawler]

Actual voltage at the house level and consequences for solar power feed back
Found article interesting
https://www.abc.net.au/news/2020-08...over-voltage-limits-unsw-study-finds/12534332

That is what I was talking about, when suggesting eventually they may have to upgrade distribution transformers, to automatic tap changing ones.
Currently most are changed manually at the transformer, so they are generally set in an average position to give 240v over most scenarios, but as more and more solar goes in the voltage difference between after dark and mid day makes the range too great.

 

[basilio]

That is what I was talking about, when suggesting eventually they may have to upgrade distribution transformers, to automatic tap changing ones.
Currently most are changed manually at the transformer, so they are generally set in an average position to give 240v over most scenarios, but as more and more solar goes in the voltage difference between after dark and mid day makes the range too great.

Did you have an opportunity to check out the story SP ?

The main points I believe were
1) It is a real technical challenge to balance voltages across the network systems
2) Historically the networks were always running too high. This was before solar panels came on teh scene
3) The industry never really tried to address the problem because it would cost big bucks .
4) The addition of solar panels has taken network voltage beyond the trip points and in many cases have resulted in solar panels being disconnected from the network.

So yes it does need to be fixed
https://www.abc.net.au/news/2020-08...over-voltage-limits-unsw-study-finds/12534332

 

[sptrawler]

Did you have an opportunity to check out the story SP ?

The main points I believe were
1) It is a real technical challenge to balance voltages across the network systems
2) Historically the networks were always running too high. This was before solar panels came on teh scene
3) The industry never really tried to address the problem because it would cost big bucks .
4) The addition of solar panels has taken network voltage beyond the trip points and in many cases have resulted in solar panels being disconnected from the network.

So yes it does need to be fixed
https://www.abc.net.au/news/2020-08...over-voltage-limits-unsw-study-finds/12534332

Which is exactly what I said in my comments, the difference is what I suggested was a probable fix, why are you asking me if I read the story?
Maybe if you understood the topic, it would make more sense to you.

 

[basilio]

Which is exactly what I said in my comments, the difference is what I suggested was a probable fix, why are you asking me if I read the story?

No offence meant SP.
One of the key points in the story was noting that currently there is much more overvoltage in the system than undervoltage. You suggested that the current system is set at 240 average but from the article that doesn't seem to be the case.

Even though the nominal voltage on the grid is 230 volts, the researchers found 95 per cent of readings were higher than that level.

When voltage levels are near or even above 253 volts, there's already no room for households wanting to feed even the smallest amount of solar energy back into the grid.

The fact that just upgrading the transformers to ensure less over voltage is straightforward is great.

 

[sptrawler]

No offence meant SP.
One of the key points in the story was noting that currently there is much more overvoltage in the system than undervoltage. You suggested that the current system is set at 240 average but from the article that doesn't seem to be the case.

Even though the nominal voltage on the grid is 230 volts, the researchers found 95 per cent of readings were higher than that level.

When voltage levels are near or even above 253 volts, there's already no room for households wanting to feed even the smallest amount of solar energy back into the grid.

The fact that just upgrading the transformers to ensure less over voltage is straightforward is great.

The voltage from the generator is usually around 16,000v, that then is stepped up to 132,000v, 220,000v, 330,000v or some other very high voltage, that is to reduce the current required on the transmission lines.
It is then stepped down to a usable voltage at its destination point, that voltage could be 22,000v, 16,000v, 6,600v,3,300v, then when it gets to the domestic reticulation level it is further dropped to, 440v, 240v.
So obviously control at the generator is mathematically impossible, so the transformers in the network have the function of controlling the voltage in their sector of the circuit.
So the final distribution transformers, through out the suburbs, are all designed from a era when the current went one way and the load was reasonably stable therefore the transformer output could be set and would only need changing if a lot more houses were put on the line.
Now we have the situation where everyone in the streets connected to the transformer, are putting load on the transformer overnight and the voltage drops, but during the day they are all pushing voltage back into the transformer with their solar panels which raises its voltage.
It is a bit like trying to keep the level in a tank constant with a tap filling it, and people drawing from it overnight but all putting hoses in during the day and the tank just keeps overflowing during the day, and running empty overnight.
How do you set the filling tap so it keeps the tank level constant? By having a tap that adjusts automatically, that is what I was talking about with auto tap changing distribution transformers.
It is obviously a lot more complex than just that, things like VARS, operating limitations etc have to be considered
Hope that helps with your understanding.
If you want to read up a bit on VARS, here is a bit of an overview, the more you understand the more you grasp the issue.
https://www.kele.com/content/blog/what-are-power-system-vars

 

[basilio]

Thanks for the detailed explanation of electricity distribution SP.
Understood and appreciated.

Obviously a more automated system of voltage regulation makes sense in an era when households are both taking power and putting power back into the grid.

Some years ago I trained and worked as an Energy Auditor for small/medium business. Part of that process was setting up units on the meters to record energy use over a 1-2 week period. Those downlaods also incorporated read outs of voltage and even in those times there was some quite big overvoltage figures coming up at night in some cases. We had to have a talk to energy suppliers about that.

The concern voiced in the article was that, overall, power companies are currently running systems at higher voltages than is good for the customers or their appliances. The extra load from solar panels means this issue now requires real attention rather than fobbing it off.

 

[sptrawler]

The concern voiced in the article was that, overall, power companies are currently running systems at higher voltages than is good for the customers or their appliances. The extra load from solar panels means this issue now requires real attention rather than fobbing it off.

A lot of what gets printed needs to be taken with a grain of salt, whether it is the power companies deliberately running voltages high, or the system causing the issue is the first thing that requires working out.
In W.A the Collie to Kalgoorlie line gains 16kv due to the capacitance on the line, when it is lightly loaded, but having said that the power companies may be running the voltage high as a method of controlling the solar output someone who knows more than me has alluded to that.
But one thing is for sure, the media will print whichever suits their circulation.

 

[basilio]

But one thing is for sure, the media will print whichever suits their circulation.

Perhaps.
But in this case they were simply reporting on the research done by UNSW. That was the news.

 

[sptrawler]

Perhaps.
But in this case they were simply reporting on the research done by UNSW. That was the news.

To me the article read like a reporters interpretation of research done by UNSW, but hey what would I know.
Maybe you could show me where they 'quoted' the UNSW, rather than the reporter just giving their and others interpretation?
The only interesting part of the story from a personal technical view was:
"We need more information. This is the challenge — knowing what is going on in the grid," Andrew Dillon, chief executive of ENA, said.

But Mr Dillon promised the networks were looking for cost-effective solutions to high voltages that would not drive up power bills.

"There are simple measures we can take to start to remedy this and they are all underway pretty much everywhere," he said.
To me the rest was just 'fluff'.

But that to the layman probably is the least interesting component, and probably why the story is all about some guys personal problem, that is the why the whole debate becomes emotional rather than technical.
As I've said over and over, there are huge issues and they are being overcome, but no one has a magic wand, it takes time, labour, technical input and money.
The other problem is because we are in transition, the problems are dynamic not static and have to be solved in an ongoing manner.

 

[qldfrog]

To me the article read like a reporters interpretation of research done by UNSW, but hey what would I know.
Maybe you could show me where they 'quoted' the UNSW, rather than the reporter just giving their and others interpretation?
The only interesting part of the story from a personal technical view was:
"We need more information. This is the challenge — knowing what is going on in the grid," Andrew Dillon, chief executive of ENA, said.

But Mr Dillon promised the networks were looking for cost-effective solutions to high voltages that would not drive up power bills.

"There are simple measures we can take to start to remedy this and they are all underway pretty much everywhere," he said.
To me the rest was just 'fluff'.

But that to the layman probably is the least interesting component, and probably why the story is all about some guys personal problem, that is the why the whole debate becomes emotional rather than technical.
As I've said over and over, there are huge issues and they are being overcome, but no one has a magic wand, it takes time, labour, technical input and money.
The other problem is because we are in transition, the problems are dynamic not static and have to be solved in an ongoing manner.

also, the supposedly engineer suspects that the voltage is above 250V?
I have a multi-meter: it takes 2 sec to check the actual figure and i would not trust an engineer with no multi-meter ;-)

 

[sptrawler]

also, the supposedly engineer suspects that the voltage is above 250V?
I have a multi-meter: it takes 2 sec to check the actual figure and i would not trust an engineer with no multi-meter ;-)

When I installed the first solar system on my place 10 years ago, it was always tripping on over voltage and I did see over 250v, but I haven't seen those voltages for a long time.
As the person in the article said, there are things they can do to remedy the problem and steps are being taken everywhere.

 

[Smurf1976]

No offence meant SP.
One of the key points in the story was noting that currently there is much more overvoltage in the system than undervoltage. You suggested that the current system is set at 240 average but from the article that doesn't seem to be the case.

There's a simple explanation for it all.

Historically, pre-solar days, under normal circumstances in the context of supply to homes and small business voltage would only ever go down, not up, between the transformer and the consumer. Voltage rise can happen in the context of industry and long distances but not normally for small loads in the suburbs.

As such, if you've got a nominal voltage range of 216V - 253V then, since it was only going to go down never up, it made perfectly rational sense to intentionally aim at the upper end of that range. Aim for 250 and not much chance anyone's going be below 216.

Same with anything. If you're buying clothes for children and they're half way between sizes, well the kids are going to get larger not smaller so it's an easy choice to go a bit too large rather than a bit too small with the shoes, trousers or whatever. Give it a few weeks and it'll be just right.

The trouble is that with so much solar, it is indeed now the case that voltage can go up within the distribution network to exceed that at the transformer. All of a sudden the old approach not only doesn't work but it fails rather spectacularly to be aiming at the upper end and then it rises further. That's akin t saying that the kids do indeed get smaller at times, all past thinking has been turned on its head completely.

Just turning it down permanently isn't a solution however. At 6pm in Winter with everyone cooking dinner, running heaters etc and with no sun then the problem of voltage drop is as real as it always was. Send out, say, 230 at the transformer and someone's going to be complaining that it's 202 in their house. Can't get around physics there, that was always the reason for jacking the voltage up toward the upper end of the range, it gets around the problem that it will drop under load in the network.

There's really 3 solutions to this:

1. Put the electricity to use within the network at the time it's being produced. The old logic of heating water in the middle of the night, or using gas to do it, is very rapidly becoming obsolete.

SA now routinely sees minimum demand in the early afternoon, not overnight, with WA, Vic and parts of the NT rapidly heading to the same situation indeed at a local level some parts of those states already are. Other states will get there in due course and already are in some localised areas within them.

So shifting non-time critical electrical loads to the middle of the day makes massive sense, and increasingly so does shifting from the direct use of fuel to electricity where the end product (eg hot water) can be stored.

2. Do clever things in the network. That is, change transformer taps in relation to actual measured voltages or at least based on a reasonable proxy (eg weather and time of day will get it pretty close). That requires some investment but not dramatically.

3. Accept that ultimately there are limits to how much rooftop solar makes sense. The rationale behind it is that the land cost is zero and the electrical network is already there. That idea works to a point but fails if we have to spend $$$ upgrading the network, in which case the alternative option of building large solar farms is an alternative means to the same end result without adding stress to the distribution network.

Here's a 53,000 kW solar farm which if fully operational will in practice produce comparable output to around 10,000 household systems given that the latter will have issues with sub-optimal orientation, shading and so on which a large solar farm doesn't. Further, it does so more consistently through the day thus reducing the need for storage capacity:

https://www.google.com.au/maps/@-31.9877709,141.3908337,2659m/data=!3m1!1e3?hl=en

Now zoom that map out. Please don't anyone try and tell me that land's a problem - not in Australia it isn't. Even Victoria and Tasmania have far more land than they're going to need for solar farms.

Here's another one, 108 MW, again it's the proverbial drop in the ocean in terms of land use. https://www.google.com/maps/@-35.27469,139.4859376,2560m/data=!3m1!1e3?hl=en

So we won't sensibly put solar on literally every house, it's just not sensible to go beyond the point where the cost of doing it becomes uneconomic compared to the large scale alternative. That in itself means that distribution network upgrades only need go to a certain point beyond which further expenditure makes no sense.

 

[SirRumpole]

TransGrid (transmission operator in NSW) has announced a preference for developing a 150 - 200 MW / 1,550 MWh compressed air energy storage facility at Broken Hill. If built this will be by far the world's largest such facility.

Do you have any more detail on this ?

I was wondering what the storage "container" would be, eg do they pump the air into an underground cave , metal cylinders or what ?

It's a very interesting proposal anyway.

 

[Smurf1976]

Do you have any more detail on this ?

I was wondering what the storage "container" would be, eg do they pump the air into an underground cave , metal cylinders or what ?

It's a very interesting proposal anyway.

I'm no expert on the detail but in short the idea is an underground cavern, eg an old mine or an intentionally dug out area in hard rock, and with associated water sitting on top (tanks etc above ground) to keep the pressure up.

Beyond that, it's just using very conventional equipment from the oil and gas industry to be dealing with high pressure gas underground. Only real difference being this is just air not flammable gas, but it's using the same equipment so that aspect of it is considered well proven.

The above ground plant, if you didn't know what it was you'd think it was oil/gas related based on the drawings etc I've seen. Lots of pipes, tanks etc and all looks like something normally associated with the oil or gas industry.

I'm no expert on the detail it though but that's the basic concept.

Claimed efficiency is 60%+ round trip. So not as good as a decent pumped hydro or battery system but it's still reasonable. In theory at least it should all be pretty durable too, versus batteries which have a very finite life.

I should point out that there is a bit if skepticism about it but time will tell. TransGrid, the NSW transmission operator, have presumably done some decent research in deciding to go with it.

See here: https://www.ecogeneration.com.au/pressure-builds-as-compressed-air-storage-projects-attract-funds/

 

[sptrawler]

Must admit I'm a bit on the skeptical side, but it would be great if it proves successful for large scale storage/generation, plenty of disused mine shaft around.
This statement from the article supports what we have been saying for a while.

“Long duration storage is effectively a hedge product where you are taking low-cost energy, storing it and moving it to when the market needs it,” says Allen, mindful of negative pricing and curtailment events that have plagued large-scale solar plants this year.

“To be able to store that cost-effectively for longer durations than batteries you need technologies like pumped hydro … and we’re effectively an alternative to pumped hydro that can be effectively sited,” he says. “We can go to where the grid or generation needs it as opposed to where the topology dictates it should go.”

The Australian Energy Market Operator’s Integrated System Plan foretells dramatic augmentation to transmission, but it still calls out for about 17GW of energy storage with an average duration of 4-5 hours, Allen reminds EcoGeneration. “It will be challenging to do that at a competitive level of cost from a battery.”

 

[basilio]

I'm no expert on the detail but in short the idea is an underground cavern, eg an old mine or an intentionally dug out area in hard rock, and with associated water sitting on top (tanks etc above ground) to keep the pressure up.

Beyond that, it's just using very conventional equipment from the oil and gas industry to be dealing with high pressure gas underground. Only real difference being this is just air not flammable gas, but it's using the same equipment so that aspect of it is considered well proven.

The above ground plant, if you didn't know what it was you'd think it was oil/gas related based on the drawings etc I've seen. Lots of pipes, tanks etc and all looks like something normally associated with the oil or gas industry.

I'm no expert on the detail it though but that's the basic concept.

Claimed efficiency is 60%+ round trip. So not as good as a decent pumped hydro or battery system but it's still reasonable. In theory at least it should all be pretty durable too, versus batteries which have a very finite life.

I should point out that there is a bit if skepticism about it but time will tell. TransGrid, the NSW transmission operator, have presumably done some decent research in deciding to go with it.

See here: https://www.ecogeneration.com.au/pressure-builds-as-compressed-air-storage-projects-attract-funds/

Impressive story.
Hope it works well.
Good find.

 

[Smurf1976]

So there's still an ongoing need for natural gas at least in the medium term and that means there's still a market for gas producers, pipeline companies and so on to operate in

I've posted the details in this thread since it's proposed by that company:

https://www.aussiestockforums.com/threads/ctp-central-petroleum.2905/page-26

In short, the idea is a gas pipeline from the southern end of the existing NT pipeline connecting from there to Moomba in SA with a capacity of 124 TJ / day.

Since Moomba already connects through to NSW and SA, that effectively does provide an increased daily supply into the south-eastern market. Not a massive one, 45 PJ a year, but significant.

 

[sptrawler]

Meanwhile a large (relative to grid) solar farm starts up in W.A's mid West, very near a large wind farm.
Interesting comments by the installation builder.
https://reneweconomy.com.au/west-au...farm-sails-to-full-generation-capacity-40707/
From the article:
The 100MW Merredin solar farm – by far the biggest in the state of Western Australia to date – has reached its full generation capacity in a timeline that would be the envy of solar developers and owners in the eastern states.

The project’s developers, Risen Energy, said on Wednesday that it had worked closely with network service provider Western Power and the Australian Energy Market Operator through the staged live commissioning process, and Merredin was now exporting 100% capacity output, compatible with the grid’s requirements.

“It has been a pleasure to work with Western Power and their smooth coordination with AEMO has enabled us to reach this milestone of achieving a fully operational solar facility which will supply green power,” said Risen Australia general manager Eric Lee.