There are district cooling systems as well, there don't seem to be any scale problems in the engineering. It's more attractive if you have a body of cool water

There are district cooling systems as well, there don't seem to be any scale problems in the engineering. It's more attractive if you have a body of cool water nearby for the heat pumps. But the users need to have different heat exchangers than just radiators, if you just put cold water into radiators they'll start sweating precipitation and you'll get mold etc damage.