!00% renewables = 100% unaffordables

100% renewables, plus 100% battery 'firming', is an unaffordable pipe dream.

Batteries are the weakest link in the 100% renewables supply chain. Their capacity to store dispatchable power is puny, weather-dependent, unreliable, inefficient and extremely expensive.

Consider small changes in seasonal weather only. Assume 100% reliance on batteries for 'firming', smoothing dispatchable power supply across seasons. Batteries store power for half the year, and dispatch it all in the other half. The required battery supply is enormously costly.

Suppose solar power smooths seasonality in the NEM. Assume battery costs fall to just 10% of SA's Hornsdale 'big battery' costs. The back-up batteries for reliability would still cost A$1.2 to A$2.3 trillion dollars. On average, that's about the current A$ value for Australia's entire GDP.

That finding is based on the published performance and cost of SA's Hornsdale 'big battery'. It uses a very simple numerical calculation assuming minor seasonal variations in average solar intermittency. Reality is worse. It must cover larger seasonal variations in solar intermittency.

For solar, see 'Reliable' renewables: What cost battery storage and structural inflation?. For wind, see 'Reliable' wind power: What cost battery storage?

Suppose wind power smooths seasonality in the NEM. Again, assume battery costs fall to 10% of SA's Hornsdale costs. The reliability-required back-up batteries would still cost A$0.6 to A$1.2 trillion dollars. On average, that's about half the current A$ value for Australia's entire GDP.

Why are wind power's seasonal smoothing battery costs less ruinously expensive than for solar power? On average, wind is less intermittent than solar power. It's still a long, long way from 24/7 reliable base-load power across the seasons.

Reliance on solar and wind, plus batteries,for seasonal smoothing alone, is unaffordable.

Back-up batteries for 100% reliance on solar and wind, for seasonality smoothing alone, would eat up the equivalent of 50% to 100% of the value of Australia's entire production.

This is just for the cost of batteries to smooth small seasonal renewables intermittency variations.

Reality is more costly. The conclusions above ignore other renewables costs.