I was thinking about doing something similar on a smaller scale to dump the heat concentrated by an air conditioning system. I was thinking that it might be useful for heating in the winter.

I’m quite sure I’ve read about people doing this in Scandinavia. Pumping warm water into an insulated tank in the ground for use in winter.

Can’t member where I read about it :(

Also Okotoks Alberta[0]; Drake Landing Solar Community

[0] https://www.dlsc.ca/

What is used to convert it back to electricity and how efficient are such systems?