Help is at hand though courtesy of [petey53], who made his own ground source heat pump for his Toronto house ... and the cold side is a long length of pipe buried in the garden.

Here, the installation area for the TEG application corresponds to the length of the pipe ... to the heat pump. The academics said the TEG showed sufficient applicability as a power source ...

Ground-source heat pump systems are one of the most efficient ways to do climate control, but digging the wells can be ...

Ground-source heat pumps are more efficient than air-source models. But they are typically more expensive and less commonly used, as they require either a deep bore hole or a horizontal system dug ...