This is already widely done in Nordic countries and well understood. I went to a geothermal plant about 25km outside Reykjavik. It also supplies much of the com

This is already widely done in Nordic countries and well understood. I went to a geothermal plant about 25km outside Reykjavik. It also supplies much of the communal hot water for the city. Between the plant and the city, in the depths of winter, it loses 1deg C.