Batteries.

Then I suspect that the graphic is based on some very weird numbers.

The numbers are from BloombergNEF. Why do you think they’re weird? Batteries are incredibly cheap now.

The battery storage requirement for wind / solar to address within day flex & a dunkelflaute period is v.large. Especially given the time period shown when ‘heat’ is expected to be well on the way to electrification. Without seeing the numbers / assumptions it is difficult to compare.