@peterdutoit Google tells me France requires about 445 terawatt hours of electricity per year. Divided through (365 × 24) that results in about 50 gigawatts used, on average, at any point during the day and year.

So 11 GW from car parks would cover almost a quarter of France's power consumption.

Of course these are all averages and power consumption varies wildly between day and night, summer and winter, etc.

But huge if true.

Do those numbers sound about right or did I miscalculate somewhere?