Thread: Future of the Australian Electricity Market

Originally Posted by russ57

If so, it's not capped now.
Price currently 460 (vic), and heading north. It's been quite high all day. I wonder if some generator is having difficulty. Again.

Russ

The truth of the matter is that the market is volatile to put it euphemistically. Have a look at this snapshot from today. QLD and NSW are not the only states to have issues and of course there is no coal fired generation resident in SA: Just courtesy of the interconnectors from NSW, without which they would be cactus.

Market Dispatch 8 July 0843Hrs.PNG

Regards
Paul

Did I mention the market is volatile?

Spot price 8 July 1315hrs.PNG

-VE $ in SA. Demand in QLD is low, which probably explains the price. Doesn't seem warm where I am!

Regards
Paul

Swiss "water battery" with 20 million kWh of capacity is finally functional | TechSpot

Originally Posted by woodPixel

Swiss "water battery" with 20 million kWh of capacity is finally functional | TechSpot

Well at face value that looks good, 20GWh over 20 hours, so it's producing at a rate of 1GW per hour. You need big mountains for that kind of thing to operate in abundance, and we don't have enough of them – they've all been eroded down. Switzerland has the advantage of a small population (consumption) in a small sized country which is damn near all mountains, although the cold makes up for some of that.

Paul what is the output per hour of your plant (assuming it's the latest, most efficient solid fossil fuel tech)?

Originally Posted by FenceFurniture

Well at face value that looks good, 20GWh over 20 hours, so it's producing at a rate of 1GW per hour. You need big mountains for that kind of thing to operate in abundance, and we don't have enough of them – they've all been eroded down. ...

Interesting analogy, FF; I did some googling:

• Height of Mt Kosciusczko - 2,228 metres,
• Height of Lac du Vieux Emosson - 2,205 m,
• Height of Lac d'Emosson - 1,930 m
• Generating fall between the two lakes - 215 metres.

I was surprised by the 215 m generating head, but it probably makes sense when you remember that they have to pump the water back up top.

Originally Posted by GraemeCook

I was surprised by the 215 m generating head, but it probably makes sense when you remember that they have to pump the water back up top.

I guess it depends on how an increased fall affects efficiency – if it's the same or similar then it doesn't really matter, just whatever fits into the topography. Terminal velocity would probably come into it too.

Mt Victoria (~15km west of here) has a very steep drop away to the west, down Victoria pass (and if you don't follow the road it's even steeper). The drop is about 220m. We could use one of those here!

Originally Posted by FenceFurniture

Paul what is the output per hour of your plant (assuming it's the latest, most efficient solid fossil fuel tech)?

FF

Nominally the two units are rated at 425MW each, but ever since comissioning they have been run at 435MW each whenever possible. I say whenever possible because there are many factors that may reduce this output. For example I think I have already mentioned that on hot days ours turbine backpressure will limited our generation: Closely associated with this is our condensate temperature through the Polishers (the polishers maintain the demin water at a high level of purity) as they have a maximum we cant't exceed. Another limitation is through the Baghouse, which captures the fly ash and minimises visible emissions into the environment: This tends to occur when the coal is particularly poor quality with higher levels of ash. Any of these factors could result in decreased generation.

Also, in round figures, 5% of the generation is consumed on site by our auxliaries including pumps and fans etc.. So "over the fence" on a good day with everything running sweetly we can generate 827MW. We are a relatively small station compared to the NSW stations.

On the hydro aspect, the head pressure and flow rates are the critical factors. This article explains some of this and the beginning is quite general while it develops technical theorey later on.

Hydropower Head and Flow - Renewables First

It doesn't take into consideration pumped hydro and, as Graeme mentioned, this may be significant and I am sure there is an optimum head pressure for these installations. Many of the largest hydro stations are "once through" such as The Three Gorges and Itaipu. They rely on huge, consistent flows.

This is not really available in Australia. Pumped hydro requires two dams, which increases the construction cost considerably.

Regards
Paul

Originally Posted by Bushmiller

So "over the fence" on a good day with everything running sweetly we can generate 827MW.

So is that 827MW per hour? If so then the Swiss jobbie can put out about 21% more than your station, which I guess is pretty good for pumped hydro. I have no idea what our current and future pumped hydro put out.

Originally Posted by FenceFurniture

So is that 827MW per hour? If so then the Swiss jobbie can put out about 21% more than your station, which I guess is pretty good for pumped hydro. I have no idea what our current and future pumped hydro put out.

But remember, pumped hydro is intended as a battery, not to run all the time, but to supply electricity when the sun ain't shining and the the wind ain't blowing. Methinks it ultimately comes down to the costs and reliability of the sources of power for the pumps.

Originally Posted by FenceFurniture

So is that 827MW per hour? If so then the Swiss jobbie can put out about 21% more than your station, which I guess is pretty good for pumped hydro. I have no idea what our current and future pumped hydro put out.

Yes , that is close. In the article they actually say the six turbines are capable of 900MW at a time which I make closer to 10% more than us. It is unlikely they are able to completely drain the dam so there would be some constraints compared to the theoretical maximum. It also assumes the dam is full and the holding dam downstream of the turbine/pumping station is exactly matched to the storage dam. I noted too that it has taken 14 years and almost A$3 billion to build. Our station cost A$1.4 billion back in 2003 when commisioned.

I was mentally comparing it to the Snowy 2.0 scheme, which also involves a lot of tunneling, and is already behind schedule.

Originally Posted by GraemeCook

But remember, pumped hydro is intended as a battery, not to run all the time, but to supply electricity when the sun ain't shining and the the wind ain't blowing. Methinks it ultimately comes down to the costs and reliability of the sources of power for the pumps.

Absolutely. It relies heavily on other sources of power to pump back up the hills when the cost is cheap.

Hydro can also be activated very quickly and is a good source of stablising power.

Regards
Paul

Originally Posted by GraemeCook

But remember, pumped hydro is intended as a battery, not to run all the time, but to supply electricity when the sun ain't shining and the the wind ain't blowing.

Yes of course, but my point was that it can produce electricity on demand at a slightly higher rate than the Millmerran station for up towards 20 hours, which is pretty impressive, even though Millmerran is smaller than other ff stations.

Originally Posted by Bushmiller

Absolutely. It relies heavily on other sources of power to pump back up the hills when the cost is cheap.

Hydro can also be activated very quickly and is a good source of stablising power.

Regards
Paul

Wonder on the crude mechanical efficiency of the system? How much more energy is needed to pump the water up hill than is generated by letting in flow down hill?

Always amuses me when you see on other websites, repeated suggestions that pumped hydro utilises free wind or solar electricity. Presumes no capital or maintenance costs!

Originally Posted by GraemeCook

Wonder on the crude mechanical efficiency of the system? How much more energy is needed to pump the water up hill than is generated by letting in flow down hill?

Always amuses me when you see on other websites, repeated suggestions that pumped hydro utilises free wind or solar electricity. Presumes no capital or maintenance costs!

Graeme

While I am not decrying pumped hydro in any way, there is another issue that we have not addressed. The turbines in a pumped hydro station double as pumps and are used to send the water back to the top dam. They can't, of course, do both at the same time and as pumps I don't know how efficient they are compared to a dedicated pump, but like any compromise machinery they are probably not as good as they could be. Neither do I know how quickly they can change from generating mode to pump mode or vice versa.

With six turbines available at the Swiss plant, some could be generating while others are pumping, although the scenario most of us visualise is pumping through the day utilising cheaper power and generating at night when solar is non existent and wind may have subsided. However, once renewables become dominant there will be, say, sixteen hours of darkness to generate, but only eight hours during the day to pump back up the hill. While those figures of generation/ pumping could vary (summer to winter) and could certainly be challenged, it is clear that the full potential may not be available at all times. I would also say this is true of most forms of generation as I pointed out in post #773 at my own station. Potential generation and actual generation may not always be the same and when this occurs at times of crisis we end up with a crisis unless there is a sufficient amout of reserve power.

As you say, not very much comes for absolutely free! There are always costs or breakdowns.

Regards
Paul