There is a section in the "Sustainable Energy - without the hot air" about this: https://www.withouthotair.com/c21/page_152.shtml https://www.withouthotair.com/

There is a section in the "Sustainable Energy - without the hot air" about this: https://www.withouthotair.com/c21/page_152.shtml https://www.withouthotair.com/c21/page_152.shtml The constraint for large scale city heat pumps in the winter would be that you don't freeze up the ground. The suggested solution is A/C via heat pump in the summer. But if you have just too much excess heat anyway then that's actually good news.