SA's big battery does its job

The Hornsdale Power Reserve, alias the Big battery, in South Australia

When Elon Musk's big battery in South Australia was announced, right-wing anti-renewable commentators and politicians has a field day, mocking the battery and comparing it to other Ozzie icons like the big banana and the big pineapple.  It will only power SA for 3 minutes, they crowed gleefully.  Bring back coal, they cried.  Only coal is reliable, they chanted.  Useless leftist rubbish, they implied.

The big battery was never meant to provide all the load shifting needed in a grid which is 2/3rd powered by renewables.  What is was targeted to do was to fill a gap temporarily while gas backup plants were fired up.  It was intended to provide FCAS (frequency control and auxiliary services).  What happens when a big generator "trips" (goes off line) or a power line is blown down is that it causes a "jerk" in the voltage and frequency in the grid.  If frequency or voltage remains too low for too long, other generators disconnect themselves from the grid for safety reasons, creating a cascading failure leading to large scale blackouts.

The big battery passed its first big test with flying colours:

State Energy Minister Tom Koutsantonis says the investment in the battery has already proved its worth, exceeding expectations in its first test.

Last week, when the coal-fired Loy Yang power plant in Victoria tripped and went offline, the Tesla battery delivered 100 megawatts into the national electricity grid in 140 milliseconds.

"That's a record," Koutsantonis told 5AA radio.

"The national operators were shocked at how quickly and efficiently the battery was able to deliver this type of energy into the market."

By comparison, South Australia's Torrens Island power station would take half an hour to an hour to energise and synchronise into the market, according to Koutsantonis.

[Read more here]

Now note that the power stations which tripped (Loy Yang) were coal power stations, supposedly much more reliable than wind.  This was the fourth major outage of a coal generating unit in a couple of weeks.  So much for coal's "reliability".  And the Torrens Island power station is a gas peaker plant.  Which also failed in the last "system black" in South Australia.

The rabid-right commentators and pollies have been conspicuously silent about the big battery's record-breaking success.

What would it cost to provide large-scale time-shifting storage in South Australia, so that the State would be protected against extremely high wholesale electricity prices?

Demand in the afternoon and evening (2.30 to 8.30) peaks at anywhere between 1500 and 2000 MW, except on extremely hot days with the wind off the desert centre of Australia when demand can peak at 2500 to 3000 MW.  So ten percent of a more normal afternoon demand profile would be 200 MW, for about 6 hours or 1200 MWh.  The big battery cost US$50 million for 129 MWh of storage.  So 1200 MWh of storage would cost US$470 million.  And it would probably pay for itself from the arbitrage between low or negative wholesale prices at night, when the wind blows but demand is low, and the afternoon peak when wholesale prices can be extremely high.  Of course, you might want to wait a little--battery costs will halve over the net 5 years.  Plus the new CSP plant will be coming on line in 2020 or '21.  That will provide 150 MW for 10 hours into the night.  And there  is likely also to be a salt-water pumped-hydro facility at Cultana in SA which will provide 225 MW for 8 hours.

Moral of the story: the battery is already showing its value, even as coal power stations keep on tripping.  Expanding it (or building other banks at key grid nodes) to provide 200 MW 6 hours into the night would cost just $470 million, now, and much less in years to come.  And with diversified storage coming from CSP as well as  pumped hydro will mean South Australia will easily be able to reach 100% renewables.

Here's RenewEconomy's piece which provides a bit more info.