up 10.9% in a day on 3x average daily volume?, page-27

Key thing is that the hydro power is displatchable. As you say, the economics is all about arbitrage - sell it when prices are high, buy when prices are low. With the increase in both rooftop and large-scale solar, there will be plenty of occasions when power prices are low or negative during the day when the weather is fine (and of course it is in Sunny Queensland).

Having said that, Kidston Hydro is now a JV with Energy Australia, and Energy Australia is responsible for all power offtake and maximising the returns from selling power. The key thing is that the hydro power is displatchable. I would guess that the two main areas that EA would concentrate on is power to firm contracts for renewable power from wind and solar, as well as for use in the evening peak when power prices are highest.