A spinning disk dissipates about 6W on average, for 100 000 disks that's 600kw. With an average of 0.12 USD paid for a kwh times 24 hours, their energy bill is

A spinning disk dissipates about 6W on average, for 100 000 disks that's 600kw. With an average of 0.12 USD paid for a kwh times 24 hours, their energy bill is less than 2000 USD a day. Their HDD cost based on the "81.76 — The number of hard drives that were installed each day in 2017." and we know they mostly now do 8TB at roughly 0.02 USD per GB according to https://www.backblaze.com/blog/hard-drive-cost-per-gigabyte/ https://www.backblaze.com/blog/hard-drive-cost-per-gigabyte/ which is 13000 USD a day. That means even if we had SSDs at zero watts, they would need to be (13+2/13) ~ 15% more expensive than HDDs in order to break even but if you look at https://pcpartpicker.com/trends/price/internal-hard-drive/ https://pcpartpicker.com/trends/price/internal-hard-drive/ you will see it's still about 8 times as expensive. Obviously there's some savings due to floor space but the savings are going to be really low there. And this is just the economics side.