The future of energy generation and storage

[Value Collector]

Pumped hydro recirculates water and is therefore not dependent on rainfall to fill the dam.

.

Thats my point, its no different to building a regular hydro dam, except you have to pump the water.

(Batteries) They don't last forever and eventually need to be replaced. In the absence of disasters like earthquakes, pumped hydro will last decades -> centuries

So a hydro system requires no maintenance, for decades or centuries???

Sure you have to replace battery cells eventually, their life will get better and better as the chemistry improves, the moving parts in pumps and turbines will need to be replaced also.

Not to mention all the environmental considerations of building dams.


But the concept of pumped hydro has been around for decades, if its the silver bullet, why isn't it already filling the gap, the answer is its not easy to just build pumped hydro everywhere.

 

[SirRumpole]

But the concept of pumped hydro has been around for decades, if its the silver bullet, why isn't it already filling the gap, the answer is its not easy to just build pumped hydro everywhere.

Governments don't want to spend money and companies don't want to invest in big infrastructure.

That could be about to change as we seem to have reached a tipping point.

What about the environmental factors of disposing of used batteries ?

 

[sptrawler]

T


But the concept of pumped hydro has been around for decades, if its the silver bullet, why isn't it already filling the gap, the answer is its not easy to just build pumped hydro everywhere.

Value Collector
The reason it sin't already filling the gap is, we didn't need it we had cheap power, until recently.

What about the environmental factors of disposing of used batteries ?

That's not the only issue, at present the amount of carbon footprint, digging up the resources and manufacturing batteries has to be taken into the equation. The EV is less polluting than an internal combustion engine vehicle, but they are still polluting.

 

[Smurf1976]

A few comments relating to various recent posts.

Generation versus storage: If it puts power into the grid then from a technical perspective it's a source of generation. Likewise anything that takes power out of the grid is a load. Beyond that it's all semantics really.

There is no practical means of storing AC power at present and due to the very nature of it quite likely there never will be. Instead, what we do have the ability to do is to take AC power from the grid, convert it into something else which can be stored, and then use that something else at a later time to produce AC power when we need it. But we can't store AC power as such.

So a battery or pumped hydro system is using stored energy to generate AC power "on the spot" in the same way as a coal-fired plant is using the stored energy in coal to generate AC power "on the spot". Same with nuclear, gas and so on. They all involve taking one form of energy and converting it, often via multiple steps, into AC power.

Coal or nuclear : Chemical energy in the coal > heat > steam > mechanical power > electrical power.

Hydro: Kinetic energy from the falling water > mechanical power > electrical power.

A power station of whatever type is simply a building(s) housing machinery that takes one form of energy (kinetic, chemical etc) and converts it into electrical power. That's it really, everything else is just supporting infrastructure from canals to workshops to cooling towers.

So what's the point of storage then?

In short it enables AC power to be taken from the grid, converted into something else which can be stored, stores that something else, then runs back the other way to convert that stored energy back into AC power.

Batteries: AC power > DC power > chemical reaction > stored chemical energy. Then to get it back to AC power it's: stored chemical energy > chemical reaction > DC power > AC power.

Pumped hydro: AC power > mechanical power > stored as kinetic energy (water pumped up hill). Then to get it back: Kinetic energy (water run down hill) > mechanical power > AC power.

The underlying reason to have storage is not to store AC power as such, we can't do that at least at present, but to enable the use of an energy source which is intermittently available as the "fuel" to run the generators. Typically that energy source is surplus coal or nuclear power (when demand is low) or intermittent sources such as wind or solar when production exceeds present demand (strong wind in the middle of the night, full sun at noon on a mild day, etc).

The inverter (drawing on the batteries) or hydro turbines are still generators though when they put power back into the grid, at no point do they store AC power as such. All that differs is how we get the energy ("fuel") to run them. Making it using AC power taken from the grid overnight etc versus mining coal or gas.

So do we need storage?

If we want to use more intermittent sources of generation (solar, wind etc) then yes we do. There will be times when we need more power than the wind etc can produce at that point in time and other times when we have more wind energy than we can use. Using that surplus AC power from wind etc when it's available, storing it as kinetic or chemical energy, and then using that stored energy to run a generator is a workaround to the problem that wind and solar are intermittent.

If we don't want to use more intermittent sources then the only reason to build storage is if doing so is cheaper than building more generating capacity to directly use coal, gas etc. Historically the 3 pumped storage schemes we have now in Australia were built for that reason - taking surplus energy from coal-fired power stations overnight and storing it was cheaper than either building more coal-fired power stations to meet peak demand or alternatively using oil-fired generation (gas wasn't really an option back then).

Lifespan: Hydro, either pumped or natural flow (reservoir filled by a river, the conventional approach to hydro and which does produce energy as such since no pumping is required) is inherently durable since it involves few moving parts, does not involve corrosion as part of its operation (as batteries do) and nothing operates at high temperatures. Keep the machines well maintained, paint the inside of the pipelines every few decades, keep a watch on the dam to make sure it hasn't deteriorated and that's pretty much it. All that stuff lasts a very, very long time if properly maintained.

Looking at the Tasmanian experience, Hydro Tas has 53 large dams, about 150 smaller structures (weirs etc), 30 power stations with 61 generating units and the system was progressively commissioned since 1914.

Thus far only 2 large dams have required any major work:

Rowallan was given a major upgrade due to concerns that it didn't meet modern standards and could become a risk in the event of a truly major flood. So the top of the dam was literally dismantled, the spillway rebuilt, and the dam put back together again. It now meets modern standards for safety.

Catagunya, the largest dam of its type in the world when built and still internationally significant today, had the steel cables (which are under incredibly high stress constantly) replaced only because Hydro couldn't prove beyond all doubt that they hadn't deteriorated. They may well have been fine but it couldn't be proven that they weren't deteriorating so they were replaced "just in case". Better to be safe than sorry.

The original Miena 1 & 2 dams were replaced by No. 3 dam but that was to increase storage capacity and not due to any problem with the old dams. Just wanted a higher one, something that wasn't done originally since there was no need (or $) at that time.

The others are all monitored but doing fine so far.

For the power stations, they all get very regular maintenance but haven't required replacement as such.

The original Waddamana A & B stations plus Shannon were replaced by Poatina not due to being worn out, they weren't worn out, but because development of Poatina at a different location more than doubled power production from the same water source. It wasn't done that way originally since (1) no need for that much power, Poatina alone generates far more than anyone could have used when Waddamana was commissioned back in 1916 and (2) the technology to build power stations underground with incredibly high water pressure just didn't exist back then. Also there would have been insufficient $ to build it back then even if it had been possible.

Duck Reach was replaced by Trevallyn for the same reason. 40 times the output using the same water. Not done originally because back in 1895 there just wasn't a need for much power.

So none of them have worn out and all the others are still running just fine. Tarraleah (1938) and Lake Margaret (1914) are both old and still going strong today.

For the other bits, well the wooden pipeline at Lake Margaret had to be replaced due to wearing out (but hey, it was built of wood so lasted pretty well actually) and every now and then there's a bit of work done on canals, weirs etc to keep them in good order but it's nothing major, just maintenance really.

So overall the experience has been that a few things will go wrong but overall the system is incredibly robust provided that proper maintenance is done. Yes, Hydro most certainly does check literally everything at regular intervals and if a pipeline needs painting inside then it gets painted. Etc.

The experience with the Snowy scheme and at older hydro plants in Victoria is much the same. A few bits and pieces need to be fixed every now and then, plus regular maintenance, but as whole they're very robust.

So far as I'm aware the only major hydro failure, beyond minor breakdowns etc which happen to all mechanical things, in Australia thus far has been Dartmouth power station (Vic) which failed catastrophically in 1990 when two steel beams entered the turbine, stopping it immediately, and the force of that moved the whole structure about 2 metres. Major damage resulted which took about 3 years to repair.

So apart from that one incident the track record of hydro in Australia is pretty good.

So what about batteries then?

There's a lot less experience with large scale batteries but the crux if of it is that they have a limited lifespan by virtue of how a battery works. 10 years is what most will say but you might get 20 if you're lucky and it's not used too heavily. There's not a lot that can be done to extend that - it's not like you can go inside a battery and patch things up.

What about the environment?

Any form of storage has the advantage of enabling greater use of renewable energy sources such as wind and solar. That's the good part.

Hydro: There's no denying that building a hydro scheme alters the local environment but the actual impacts are extremely site specific. One thing though, the effects are there for all to see - go and have a look at any hydro scheme and you can see the impact for yourself whereas it's much harder to determine the full impact of something like a gas-fired power station once you consider production of the gas as well as the use of it.

Battery: Mining and processing of metals are the big ones environmentally and it's hard to assess every impact given the lengthy supply chain involved. All that can really be said is that it's the opposite of hydro in that it's not really site specific at all, pretty much the same impact no matter where you put it.

Which is better really comes down to the specific site (hydro) and what your environmental priorities are. Some will argue that toxic materials are the biggest problem, others will say it's habitat destruction or river flows which matter most. So it's hard to really compare one to the other without referring to a specific site for hydro and having previously decided what the environmental priorities are.

 

[sptrawler]

As usual a terrific post smurph, one thing that I feel could be added, pumped storage and hydro gives inertia which you have mentioned in earlier posts.
From my limited exposure to large scale battery/inverter UPS, they wouldn't be able to black start a grid of any magnitude, where as a hydro/turbine could.
I'm not against batteries, far from it, I just think at present it is difficult to sift the advertising bling from facts.
They have a place and they are getting better and better, but IMO they have a long way to go, Tesla stuffing 6,000,000 cells in containers doesn't do it for me.
Could someone tell me how many megawatts the Tesla installation was, and how big an installation the S.A Government is talking about?

 

[SirRumpole]

You have done it again Smurf, thanks.

 

[sptrawler]

Smurph, Bass link inverter is what 500MW, could it be used to black start Victoria, or does it need a supply to synchronise to?

 

[Smurf1976]

Smurph, Bass link inverter is what 500MW, could it be used to black start Victoria, or does it need a supply to synchronise to?

The output limits are 594 MW into Vic only (for short periods - few hours) and 478 MW in either direction continuously.

I'm actually not certain if it could be used for a black start or not, that certainly hasn't ever been done, but I think the answer is no.

Certainly here in Tas if we ever had to do a black start (let's hope not but it's not impossible it could happen) then at the main generation level it would be done with hydro. At the house (power station) set level there's an assortment of small hydro units and diesels for that specific purpose.

In layman's terms - start the small hydro unit, use power from that to start the main generators and then liven up the grid. Diesel engine as a second way of doing it just in case the small hydro unit happened to break at the worst possible time. Also batteries at some power stations. That all gets tested in various exercises, and it does go as far as disconnecting a power station from the grid and black starting that station, but thankfully it hasn't been necessary to do it for the grid as such for a very long time (many decades).

 

[sptrawler]

In W.A we've had a couple of black starts, we used a small gas turbine, but I've never seen a battery inverter system that can synch a dead system.
The only ones I've seen have been U.P.S systems, three phase, with lead acid batteries. Reasonable size though, they were backup on a communications base.

 

[macca]

Thanks Smurf, good info, well written so that us laymen can understand it.

It would seem to me that pumped hydro is a reliable proven method and batteries are the latest whiz bang idea. I would be prepared to bet that the SA government will jump at the batteries

PS: After avidly reading all of Smurfs stuff, we laymen of ASF probably know more about electrical storage and networks in OZ than 95% of the population, including the pollies

 

[Tisme]

In W.A we've had a couple of black starts, we used a small gas turbine, but I've never seen a battery inverter system that can synch a dead system.
The only ones I've seen have been U.P.S systems, three phase, with lead acid batteries. Reasonable size though, they were backup on a communications base.

Once upon a time commercial high rise would have backup generators, some synched many not. Should be mandatory in all high rise, including apartments with grid load shed start via the state energy regulator.

My preference was always gas turbine in the 80's

 

[basilio]

Thanks Smurf, good info, well written so that us laymen can understand it.

It would seem to me that pumped hydro is a reliable proven method and batteries are the latest whiz bang idea. I would be prepared to bet that the SA government will jump at the batteries

PS: After avidly reading all of Smurfs stuff, we laymen of ASF probably know more about electrical storage and networks in OZ than 95% of the population, including the pollies

Yep. But closer to 99.5% of people. Great analysis Smurf. Much appreciated

 

[Smurf1976]

Thanks for the positive comments everyone.

There's a bit of confusion and an assortment of conflicting stories about the detail but the shutdown of Hazelwood is now imminent. Depending on who you listen to the shutdown begins either tomorrow (Friday) or alternatively on Monday, or possibly sometime in between.

Either way it's imminent and now the panic seems to be getting underway with claims and counter claims politically and a few calls for government intervention to stop the shutdown.

There has already been a major effect on prices, with hedge contracts for coming months being close to triple historic prices. Suffice to say that impact makes the carbon tax look rather trivial in comparison.

Hydro Tas was the fist to visibly act with a revaluation of water in storage and Snowy Hydro has since done much the same. Obviously both businesses would have slightly differing views but they both see prices going up. They have no real choice other than to change their own pricing by the way, if they didn't then they'd be drastically undercutting everyone else and the result of that is that AEMO would dispatch them flat out and empty the lakes pretty quickly (especially Snowy). They need to price in a manner that results in physical dispatch matching what's sustainable, limited by water inflows, so that's what they've done.

Snowy has recently become keener on pumping (pumped storage) at Tumut 3, the largest Snowy Hydro station (and the largest hydro plant owned by anyone in Australia). This power station is both a conventional hydro scheme, it generates net energy through water diversion, but also has the ability to pump and that's getting some more use than it has done in recent years.

Hydro Tas has simply looked at the market and is finding that running gas-fired generation is actually profitable at times so that's what it's doing. With the water in major storages having a high value going forward and gas prices moderate at the moment it makes sense to use some gas. So the Tamar Valley CCGT has been running base load since January and recently the modest size (58 MW) OCGT next to it has has been getting some use in preference to the hydro stations. Also no secret in the industry that Hydro has been buying pretty much everything it can get from rivals on the spot market in order to supply its own contracted loads. No point using your own water when it's rapidly gaining value and someone else is still selling cheaply.

A number of generating companies, and that includes publicly listed ones such as AGL and Origin, others such as Energy Australia and government owned ones such as Hydro Tas have all been doing a lot of maintenance lately. If you've got to take plant offline for a while then you may as well do it before Hazelwood closes and sends prices through the roof.

Who's actually going to pick up volume once Hazelwood does shut remains to be seen but most likely the answer is "just about everyone". AGL and Origin will probably gain some volume via their coal and gas plants. Snowy and Hydro Tas will likely generate more from gas and will operate their hydro systems differently. Energy Australia don't have so many options but they've got some as have others.

What Engie, owners of Hazelwood, will do is anyone's guess at this stage given they don't seem overly keen on actually generating power at Pelican Point and they already run Loy Yang B pretty much flat out.

None of the others can add more peak power into Vic without investing in something new however. All they'll be doing is running what they've already got harder in the absence of Hazelwood. Keeps the lights on when demand is moderate but doesn't fix the problem during the peaks.

So we're now pretty much on the eve of all this starting to unfold. If not tomorrow then it's next week. Could get interesting and the biggest issue in the short term is going to be financial rather than physical. Don't be surprised if retailers who don't have their own generation start going broke and if a few factories announce closure in the very near future.

As of now, output from Hazelwood (note that all units are nominally 200 MW although for several years post-privatisation were routinely run at 220 MW constantly. The SECV never went beyond the designed 200 MW so far as I'm aware and typically ran a bit below that.)

Unit 1 = 165 MW
Unit 2 = 180 MW
Unit 3 = 170 MW
Unit 4 = 161 MW
Unit 5 = 174 MW
Unit 6 = 176 MW
Unit 7 = 182 MW
Unit 8 = 128 MW

So all running but not going brilliantly which is no surprise. 5 of them have "fix it or shut it" orders from workplace safety regulators because the boilers are stuffed (in layman's terms the pipes have thinned out too much due to corrosion and are in danger of bursting - and we're talking high pressure steam suddenly being released here if they do fail, hence the interest of workplace safety inspectors).

Pipes? There's a whole lot of pipe here not just a few bits. Think in terms of "boiler is actually built out of pipes" not "there's a pipe coming out of the boiler". However many pipes you're imagining rest assured there's a lot more. A hundred times more than you're likely thinking. Hence whilst patch ups aren't uncommon actually replacing them all is a major exercise (cost if they did it would be over $100 million certainly).

Another problem they have is with the coal mills. Put simply raw coal from the mine goes into the mill and comes out as a fine dust (like talcum powder except that it's coal) and it's that dust which is burnt in the boilers. Now, there's 8 mills per boiler, 8 boilers in the station = 64 mills and I'm reliably told that the whole lot are in bad shape.

You might be getting the impression that the owners have let the place run down......

 

[SirRumpole]

Meanwhile the politicians run around like headless chooks.

I would like to be in the backup generator business right now...

 

[noco]

Meanwhile the politicians run around like headless chooks.

I would like to be in the backup generator business right now...

Yes, particularly in South Australia and Victoria.....Well, Jay Weatherill has told big business in SA to install their own generators because he cannot guarantee supply .......More diesel generators means more air pollution which they and the Greenies are trying to prevent...It does not really make sense....They are defeating their own purpose with renewable energy which is dearer and unreliable

 

[sptrawler]

Smurph, it will be interesting if, as happened at North Power Station in S.A, they start blowing it up.

That would really put a cracker up the pollies bums, I bet they are already thinking of nationalising Hazelwood.

 

[SirRumpole]

The following article was written by a political reporter but contains technical aspects of frequency control that Smurf may like to comment on.

http://www.abc.net.au/news/2017-03-...s-power-system-weakened-by-wind-solar/8381356

 

[sptrawler]

Turnbull's statement, may come back to haunt him.

http://www.theage.com.au/federal-po...y-to-keep-hazelwood-open-20170323-gv5d5y.html

An extract below:
In an opinion piece for News Corp, Mr Abbott said taxpayers should subsidise Hazelwood to keep it alive until Mr Turnbull's proposed $2 billion expansion of the Snowy Hydro scheme comes online sometime next decade.

"If we want secure and affordable power supplies, we can't lose the ones we currently have even if they involve burning coal," Mr Abbott wrote.
The push has been rejected by the federal and Victorian governments. Mr Turnbull said Hazelwood's closure was a commercial decision taken by its majority owner, French giant Engie, and there was more than enough generation capacity to cover its loss.

 

[Smurf1976]

The following article was written by a political reporter but contains technical aspects of frequency control that Smurf may like to comment on.

Translating it to layman's terms:

An AC power system (eg the grid) runs at a specified frequency which in Australia is 50 Hz. So that's 50 complete cycles of the AC sine wave each second.

A key concept is that anything sychronised to the grid will be at the same frequency. So the frequency at Loy Yang power station (Vic) will the same as someone could measure in their home in Brisbane since it's all one big interconnected AC system.

Now, the frequency needs to be controlled pretty tightly. A 1% variation is pushing the limits of what's acceptable. If it's 2% then that's an incident and warrants a proper engineering investigation and report. If we're talking about 5% or more away from where it should be then at that point a total system collapse is a very definite possibility since neither power stations nor connected loads will be happy at that level.

So it's like saying that you're driving a car at 50 km/h. Slow below 49.5 km/h and that's a problem. Below 49 and you'll find yourself being thoroughly investigated as to what went wrong. Below 47.5 and there's a risk that you've just wrecked the car and at the very least it's now coming to a complete standstill, getting it going again will take hours or days.

So it's all pretty unforgiving and there's not much room for error.

If generator output exceeds load then frequency will rise across the entire system. The opposite will occur if generator output is less than load. This all happens pretty quickly - seconds or at the most minutes depending on the severity of the mismatch.

All of which brings about two key requirements for generation:

1. It must match the combined load of all consumers in real time. Therein lies the problem with wind and solar with their uncontrolled and constantly varying outputs versus the directly controllable output from coal, gas or hydro.

2. The more inertia you've got, the better.

Inertia? In simple terms it's just physical mass. You've got a great big steam, gas or hydro turbine with a lot of metal in it. That physical attribute means there's energy stored simply by virtue of it turning and it takes quite a bit of effort to slow it down. Lots of big rotating machines thus naturally tend to stabilise system frequency.

As a concept that's very similar to a fully loaded freight train. It slows down only gradually even if someone were to completely cut power (from whatever source eg diesel) to the engines. The train will travel quite some distance before it completely stops. Even applying the brakes it still takes a while because all that energy, inertia, has to go somewhere (dissipated as heat in this case).

In contrast a solar panel and most wind farms contribute absolutely zero inertia to the grid. Zero. Even though wind does involve big rotating machines, they're not synchronised to the grid directly - and it's hard to do that with wind because if they were synchronous machines then they'd always be turning at the same speed.

There are some partial workarounds to create "synthetic" intertia at wind farms using fancy electronics. That helps but (1) no amount of electronics is at present a full substitute for the sheer physical mass of a great big rotating steam, gas or hydro turbine and alternator and (2) most wind farms don't have that at all since it costs more $ to install, means more things to maintain, and produces no extra revenue.

So a grid being powered predominantly by solar or wind becomes electrically weak. It can still be delivering the exact same quantity of power as if it were supplied from coal, gas or hydro but without those big rotating machines there just isn't the inertia to stabilise frequency. It becomes like a motorbike rather than a freight train - speed increases or decreases very easily.

If there's low intertia then the room for error in matching generation to load decreases accordingly and generation now needs to respond far more quickly to changes in load. Problem is, the very same circumstances which create that low inertia, high use of wind and solar, are the same generation sources which aren't much good at varying their output in response to changes in load.

This creates a situation where the remaining synchronous generators, that's coal, gas, hydro and any oil-fired plant that happens to be running, are now in a situation of generating (say) 30% of the power but having to provide 100% of the response to changing load and they've got to respond to changing output from wind and solar as well. If load goes up at the same time as wind and solar output falls, or vice versa, then that's a pretty tough challenge for the few synchronous machines to cope with.

Overall it's a bit like any situation where only a small % of the team are really playing the game and everyone else is along for the ride. Works only as long as it doesn't get too difficult but it's pretty easy to end up in a situation where those seriously playing are "swamped' and just can't cope, after which the whole thing collapses.

As analogy, suppose that you were given the task (with full backing of the law etc so all legit) of stabilising the ASX20. Your job is to keep the index precisely flat overall, with daily variations no greater than 0.5%. You can buy or sell any stock in the index you like, you've got as much cash as you'll need and you can order any company to issue new shares at any time of your choosing so as to dilute their value. Sounds pretty easy doesn't it? Just buy or sell all 20 stocks as needed to keep the price flat. So easy you could do it sitting on the beach just using a smart phone.

Now suppose I change the rules of that game and that you must still keep the ASX20 flat but the only stock you can trade is BHP. Nothing else. You can buy as many BHP shares as you like but you can't increase their price to anything above the historic all time high and you can't decrease it below 20% of its all time high. And you can't do anything at all about the other 19 stocks in the index.

That's going to work just fine so long as the other 19 stocks only move by fractions of a % but you're completely screwed if there's a decent move. Doubling the price of BHP, whilst the other 19 all fall 20%, isn't going to keep the index stable. It might work this week or even this year but pretty clearly it's going to fail at some point given that you have no control over most of what you're trying to stabilise.

That latter scenario is comparable to the dilemma faced by synchronous generators in a system with heavy use of wind and solar. They can keep frequency stable only as long as nothing major happens. The moment we get a surge in load combined with the wind rapidly diminishing they're pretty much stuffed and the whole system falls in a heap.

Under normal circumstances only the SA and Tasmanian grids are ever electrically "weak".

SA - because at times wind can supply more than 100% of the system load.

Tas - because under certain circumstances there's a single very large generation source (Basslink supply from Vic) which generally occurs at the same time (middle of the night when power is cheap in Vic so Hydro Tas is a keen buyer) as overall system load is low and just 4 factories are using 70% of all power consumed in the state.

In Tas the workaround is an elaborate and unique (custom designed and built) system which dumps specific industrial loads in the event of a non-synchronous generation (Basslink) failure before the rest of the grid even "sees" that anything happened. That effectively contains any sudden failure to only affecting specific industrial loads with neither the hydro system nor other consumers "seeing" any impact at all.

In Tas there's also a similar scheme to make the GGCT (gas) plant seem smaller than it is in the event that it suddenly fails. So if the CCGT fails then the hydro system takes about 69% of the "shock" and the rest is dissipated via a specific industrial load. That was done to eliminate risk to the rest of the system if the worst does happen.

It wouldn't be impossible to have the hydro system absorb those shocks, failure of either Basslink or the CCGT, by the way and technically it can certainly do that. Trouble is that doing so means running a lot of machines at low output for extended periods when 99.9% of the time there's no need (knowable only in hindsight). That costs money through loss of efficiency and unnecessary wear on machines so the workarounds were done for economic reasons with the benefits being shared between Hydro and those industries forming part of the scheme.

The underlying issue with Tas is simply that Basslink is the only link to other states. Any failure, even just a random trip for no real reason (and that's an inherent risk with DC interconnectors especially those not running parallel to an AC link), thus results in the Tas system becoming completely independent of the other states. That's not a problem in itself, we just did 5 days running separately due to a planned outage of Basslink, but it creates technical difficulties if such a failure occurs suddenly without warning when Basslink is operating at a high level of transfer. Hence the workarounds to keep the system stable if that occurs (and there have been far more incidents than those reported publicly although most are simply a trip - best analogy would be having to restart a computer after it locked up but after restarting it then works perfectly and there's nothing actually wrong with it as such).

In SA the present "workaround" involves large scale blackouts. They don't have any elaborate control systems, just the normal UFLS (Under Frequency Load Shedding) that every grid has but nothing else. Beyond that, all they can do is "export" the problem to Victoria via drawing heavily through the interconnector but that has limits and with the system collapse last year those limits were exceeded to the point that the interconnector shut down to protect itself from damage due to being heavily overloaded. There was another very close "near miss" incident more recently when the explosion happened at Torrens Island - the interconnector was certainly overloaded for a brief period and came pretty close to the "throw my hands in the air and give up" point.

End result is that if something goes wrong when the grid is in an electrically weak position in SA then the lights go out in a big way if the problem is too large to be stabilised via Victoria or whatever synchronous (gas or diesel in SA's case) generation happens to be running at the time.

Qld, NSW, ACT, Vic don't presently have these issues since:

1. At no time is wind, solar or other non-synchronous and controllable generation dominant. The majority of supply being from dispatchable synchronous generation - coal, gas, hydro and on occasion minor amounts from oil. They don't presently have the issue with very high levels of wind and solar, as a % of the total, as occurs in SA.

2. Generally no issues with loss of interconnection. Vic and NSW are strongly interconnected at AC via the Snowy scheme and that applies even if all Snowy power stations are idle at the time (as they commonly are overnight). Qld - NSW are connected by two AC and one DC circuit which are pretty reliable in practice. ACT is simply part of the NSW system, any distinction between the two being purely administrative rather than technical.

3. No individual loads or generation sources account for a large portion of the total as occurs in Tas.

WA (south west) system is completely separate to anything else and also reasonably robust. There is wind and solar but it's not dominant to the extent that it is in SA. That said, as a smaller system not connected to anywhere else it does have some vulnerabilities, a problem can't be shared with another state but must be dealt with locally, and that has caused some issues in the past but overall it's fairly robust.

NT has multiple small systems, each completely independent of each other and not electrically connected. Darwin and surrounds is the most significant and does have the vulnerability of high reliance on Channel Island power station and the gas supply to that but its overall track record isn't bad. No real issues with non-synchronous or non-controllable generation.

 

[Value Collector]

Some thoughts on impacts of dams.