The largest battery in Australia (which was until recently the largest in the world), the Hornsdale Power Reserve in South Australia, has been successful at preventing black outs from unexpected power disruptions. Since it was commissioned in late 2017, wholesale spot power prices have not again approached $10,000/ MWh – although in January this year they did exceed $5000/MWh.

The battery system reacts quickly to network disruptions and can send power back into the grid when it is needed most – and when prices are momentarily 10 or 20 times higher than the average wholesale price. It can charge in the middle of the day when excess solar generation causes the wholesale price to fall to zero or lower. It is this fluctuating market pricing that causes extra generation to start up and shut down – usually in the form of gas-fired power plants.

There are only a handful of batteries around the world that are of the scale of Hornsdale, and they play an important role in power security and affordability in the networks where they are located, particularly where variable renewable penetration is high (South Australia is 60% renewables).

As Australia’s electricity network transitions towards renewables over upcoming decades, storage will be increasingly relied upon to deliver power during longer periods when demand exceeds supply. An overcast, still day followed by a still night will mean short and medium term storage will not be able to recharge on a network largely powered by wind and solar generation, if there isn’t enough excess generation from the wind blowing somewhere else coming in. Storage will need to keep supplying power overnight – or even for days without recharging. This isn’t a situation that occurs now while Australia’s electricity is still mostly generated by coal-fired power stations.

Battery technology, while advancing quickly, will continue to play a key role in filling short term supply shortages. Storage of the scale of pumped hydro will fill longer term shortages as generation is increasingly dominated by variable wind and solar.