News & Discussion: Electricity Infrastructure

[Waewick]

Isn't pumped hydro meant to be a great to smooth electricity price and supply ?

[rubberman]

Isn't pumped hydro meant to be a great to smooth electricity price and supply ?

It is. But you have to have a suitable location for the storage. Then there’s the capital cost of the storage, pipes and pumps/turbines. Then there's the time taken to spool those turbines up and synchronise. Maybe ten minutes. That's a lot faster than coal or gas, certainly. However, batteries can react in milli-seconds.

[SBD]

Isn't pumped hydro meant to be a great to smooth electricity price and supply ?

It is. But you have to have a suitable location for the storage. Then there’s the capital cost of the storage, pipes and pumps/turbines. Then there's the time taken to spool those turbines up and synchronise. Maybe ten minutes. That's a lot faster than coal or gas, certainly. However, batteries can react in milli-seconds.

The AFR article linked at the bottom of page 19 said that Snowy Hydro had 60MW of fast-start hydro kicked in within a few seconds of the problem. Presumably pumped hydro could also have fats-start generation. The articles don't explain the physics of how that differs from the other hydro that took a few minutes to ramp up.

[rubberman]

Isn't pumped hydro meant to be a great to smooth electricity price and supply ?

It is. But you have to have a suitable location for the storage. Then there’s the capital cost of the storage, pipes and pumps/turbines. Then there's the time taken to spool those turbines up and synchronise. Maybe ten minutes. That's a lot faster than coal or gas, certainly. However, batteries can react in milli-seconds.

The AFR article linked at the bottom of page 19 said that Snowy Hydro had 60MW of fast-start hydro kicked in within a few seconds of the problem. Presumably pumped hydro could also have fats-start generation. The articles don't explain the physics of how that differs from the other hydro that took a few minutes to ramp up.

They do it by having "spinning reserve". That is, they run the turbines up to speed with no load, and when they need to despatch power, they throw a switch and open the supply valves a bit more. Of course, all the while they are spinning with no load, they are losing water. They also use load banks as part of the process, but that's a bit of a complication of little import.

[PeFe]

Apparently AGL are having a few difficulties with their virtual power plant trial.
From In Daily

Slow going for AGL's Adelaide 'virtual power plant'

Its launch gained national notoriety after then Premier Jay Weatherill confronted Josh Frydenberg on live television, but AGL’s “virtual power plant” has since faded into the background with Adelaide customers facing long delays after paying deposits to be connected to the experimental system.



The project, which supposedly went “live” in March 2017 with that now infamous press conference, is designed to connect 1000 home solar and battery systems using smart software to create a 5MW “virtual power plant” that could be used to supply energy and services to the grid if needed.

Many South Australians jumped at the subsidised costs of the batteries under the project, expressing interest or paying a deposit, but an unknown number – potentially hundreds – are still waiting to be connected after 18 months of delays.

GL revealed today that some customers would not be connected until next year – about two years after the project began.

AGL suspended the roll-out last year to reconsider the technology it was using, restarting in March this year and pitching for more people to sign up. From March, customers were offered either an LG Chem Resu battery paired with a SolarEdge inverter for $2990 or a Tesla Powerwall 2 for $5490.

Full article : https://indaily.com.au/news/2018/09/26/ ... wer-plant/

[Waewick]

AGL, whilst have always done well by me, seem to be a bit like a casino offering free buffet.

[PeFe]

More on the Tesla big battery, and the use of batteries in general.

https://reneweconomy.com.au/tesla-big-b ... nce-38273/

[claybro]

Bear with me here, because even after reading this article, and others relating to large battery storage, I am still to find an accurate answer on how long a large battery array can supply power. Yes I understand their value to smooth out load, or to step in and sell power when prices spike, but how long can the output last? I also get how individual homes can be powered by solar and battery storage alone but the article mentions SA going 73 percent renewable by 2021?. Now if every state has the same goal, and there is a long cloudy period with minimal wind, as is often the case over SE Australia in Winter how will the batteries recharge, and how long will the storage last, once it is no longer possible to draw power from the coal plants?

[PeFe]

This is how I believe the big Tesla battery works ( if anyone knows better please correct me)

100mww/129mwh Tesla Battery....

Maximum output at one time........100mw
Total storeage capcity of battery.......129mwh (usually written as mega watt hours)

So the battery can export 100mw of power for 77 minutes.....(129 divided by 100....then times 60)

If you only export 50mw, then the duration of export doubles.....ie 154 minutes.

The avearge daily electricity use in South Australia (midday figures) is around 1500-1600 mw (this is the amount of electricity being used at one time)
So the batery can only replace 100mw of this for 77 minutes.
Peak summer electricty use in SA is around 3000mw at one time.

Claybro wrote

Now if every state has the same goal, and there is a long cloudy period with minimal wind, as is often the case over SE Australia in Winter how will the batteries recharge, and how long will the storage last, once it is no longer possible to draw power from the coal plants?

I dont see energy shortages occurring in winter with renewables......if its "calm" (ie no wind) in South Australia, then that means its usually sunny, so solar farms/rooftop solar will in general make up for that. And the wind will also come back soon enough (and if its not windy in SA then it is probably windy in the eastern states)

The big issue for renewables in this country is summer heatwaves.......
(and for fossil fuels as well, large power plants such as gas and coal plants are forced to run thir generators at full capacity for hours on end, greatly increasing the chances of turbines failing)
.....when the sun goes down and there is no wind on a run of hot nights (with millions of people turning on their airconditioners) that is when the blackouts are likely to occur. Any bit of added power from storage is greatly appreciated on those nights...batteries, pumped hydro, virtual power plants (thousands of home batteries joined together to output spare electricity)

I believe also future batteries will be positioned next to renewable generators, if its not a wind farm then its a solar farm, and when the day comes there are no coal plants left in this country then gas will probably be still around, but should the cost of storeage keep falling (batteries or pumped hydro) then that will signal the end of fossil fuels.

Latest costs for wholesale power generation
Wind/solar $50-60 mega watt hour (this what Victoria will pay for new solar/wind farms after their latest reverse auction)
Coal $72 mwh (projected cost for new black coal plant)
Pumped hydro $80mwh
Renewables+storeage $78 mwh (this is what the SA govermnent is paying for the Aurora at Port Augusta).......so not long to go, if that storage price keeps falling.

[Spurdo]

This is probably a silly question, but if the grid goes 100% renewable what happens if there is prolonged bad conditions (e.g wind drought) and the storage runs out?

[Norman]

There should be gas backup, and solar fills the gaps as well during wind droughts.

[SBD]

The Dalrymple battery is rated at 30MW/8MWh. Lower Yorke Peninsula customer load seems to top out at about 5MW (in winter, anyway, they don't have summer data on the website yet). That means the battery would keep the lights on on Yorke Peninsula for over an hour with no wind and no connection to the rest of the grid. The local wind farm can generate up to 90MW, so vastly exceeds the local demand.

In an event like the one a few years ago when the entire state tripped out, either of the two batteries would likely be able to provide the necessary bootstrap power to allow generators and interconnectors to reconnect faster than happened without them.

[SBD]

This is probably a silly question, but if the grid goes 100% renewable what happens if there is prolonged bad conditions (e.g wind drought) and the storage runs out?

I expect the gas-fired peaking generators will remain available for a very long time. They would only be decommissioned once it becomes far too expensive to keep them available but never called on. SA currently has over 1900MW of Open Cycle gas turbines and reciprocating engines. If they never operate, the largest cost of owning them is probably vandalism.

My reading of the tea leaves is that the SA-NSW interconnector is required - to keep the lights on in NSW. SA looks to be fine thank you as far as generation capacity, bot sometimes it is expensive. Often the gas turbines here are used to generate power for export through the Victorian interconnectors (but Vic often exports more to NSW than it imports from SA and Tas).

[Nort]

Yeah what we are heading towards seems to be solar and wind connected to storage with gas generators available as a backup.

[PD2/20]

An article has appeared on the ABC website this morning about the Tesla Hornsdale battery http://www.abc.net.au/news/2018-10-02/t ... r/10326420. It usefully highlights its role in providing FCAS (Frequency Control Ancillary Services) rather than replacement of normal generating capacity.