At current battery prices of $132/kwh and oil at $88/barrel, 300 TWh of batteries per decade is actually 40% more expensive than 90 million barrels of oil per day.

Damn, we are that close. We are using expensive, high-density batteries meant for electronics and transportation for stationary storage. CATL is already claiming $40-$50/kwh for sodium ion batteries that begin production next year. In five years there will be even more grid-targeting battery solutions on the market at low price points.

From a practical business perspective, the falling prices of batteries may not be ideal from an investor's perspective. If I buy $100M of batteries and the price drops 50% in five years, I just "lost" 50 million dollars. You'd have to be at a point where the proceeds to storage exceed the depreciation of the product in order to pencil out, I think. So a lot of storage that could be built probably won't be built until the technology war shakes out.

>CATL is already claiming $40-$50/kwh for sodium ion batteries that begin production next year.

Tried to look this up, but didn't find anything. Where's that?

To be fair they stated it in the most roundabout way (40%-50% cheaper than LFP batteries) and with no time horizon. I think I got that from reports on their recent shareholder meeting but I will have to look it up better.