[wavegeek]

> lots of proven ways

None of which work beyond a few hours. The sheer number of batteries and the amount of pumped hydro needed is phenomenal. As one data point, Elon Musk's much heralded $100m battery in South Australia stores a few seconds of Australia's total energy use. A few tenths of a second for the US.

When it is cloudy and there is no wind for a week, renewables are a complete failure.

> is dropping in price

Batteries have been dropping in price for 140 years. But the best batteries have only been getting better at about 7% per year. Specific technologies have improved faster than this early on in their lives (e.g. LiIon) but during most of this improvement they were far from the best.