Heat is awfully hard to transfer in the first place, especially when it's not even that hot. It's handy if you can put your data center underneath a swimming pool, for example. But I'm not aware of any large-scale heat recovery projects from data centers. Data centers generally spend extra energy to remove the heat...

But honestly who cares if your power comes from renewables in the first place -- solar and wind? It doesn't seem right to even frame it as "wasting" heat in the first place, anymore than the sun's heat was being "wasted" warming up the ocean in the first place.