The February 2018 electricity update of the Australia Institute’s Climate & Energy program, an independent public policy think tank based in Canberra, has released the latest electricity update of its National Energy Emissions Audit with a review of the performance of the South Australian ‘big battery’. The Audit was written by the respected energy analyst Hugh Saddler.
According to the review, “the Hornsdale Power Reserve “big battery” was used daily to charge overnight, when wind generation is often abundant and cheap, and discharge in the late afternoon, when total demand and spot market prices usually reach peak levels, demonstrating the very valuable role that energy storage can play in the operation of an electricity supply system with high levels of renewable generation.”
The graph shown above “shows consistent pattern of charging up overnight, when prices are very low (well below $100 per MWh on all three days) and discharging in the late afternoon, when prices are very high ($8,000 per MWh between 4.00 and 4.30 pm local time on 7 February, which is 3.30 to 4.00 pm.”
The report noted “a couple of important points to bear in mind when interpreting the graph:
- Energy flows are capped at 30 MW because only 30 MW of the total battery capacity of 100 MW is committed to energy arbitrage. The remaining 70 MW are held in reserve to provide frequency control services, contributing to the security of the grid.
- Since the battery can charge and discharge in a matter of seconds, and frequently does so, the relatively coarse- grained data in Figure 11 under-estimates flows of energy in and out of the battery, though it does accurately represent the maximum power (30 MW).
“The experience of operating Hornsdale Power Reserve already demonstrates that multiple smaller energy storage facilities, which will certainly include both batteries and small pumped hydro projects, located close to wind and solar generators, are almost certainly better suited to matching variable supply with varying demand than a single monster project located a thousand kilometres or more away, via multiple transmission lines which often reach saturation capacity when demand for electricity reaches peaks.”