If you price it on throughput and not storage size, because Snowy 2 is very constrained on when it can charge and discharge then the realistic 8Twh per year you can get out of Snowy2 loses to batteries by a factor of 3 based on your costs.

But that's assuming the batteries can charge and discharge in full every day.

The truth is probably somewhere in the middle where Snowy can act as seasonal storage with a big capacity that isn't used every day.

I think it would then also lose on price if compared with a portfolio of batteries alongside solar and wind to directly supply electricity and continually recharge the batteries over seasonal scales but that is a more complex comparison.

In general I think even good hydro schemes (and Snowy 2 is not a good one) rely on non-electrical factors to be worthwhile now batteries have plummeted in price, e.g. managing seasonal water flows for agriculture, and the electricity can be seen as an additional benefit.

sigh This reminds me of all of the tedious arguments by people reminding us that solar panels don't work at night, implying that they are therefore useless.

Or the ones that remind you that batteries are useless for seasonal storage.

Or that the wind doesnt always blow.

Yes, individually all of them have crippling flaws and all of them work best when combined with technology that has complementary crippling flaws.

Snowy 2 won't be used instead of batteries it'll be used alongside batteries.

Right now nothing comes close to beating its price / gwh no matter how much the cost overruns or how many people dump on it for being 7x cheaper per gwh than batteries instead of 10x.

More countries should be building one as well as building out grid level batteries. They complement each other.