Geo-thermal is a little misleading because the systems you are talking about use very high temperatures found in volcanic parts of the world, which is obviously

Geo-thermal is a little misleading because the systems you are talking about use very high temperatures found in volcanic parts of the world, which is obviously pretty easy. A ground source heat pump only requires 10 degrees or more of heat difference, easily found 30 metres below ground in most moderate temperature countries - it then uses the same technology as air-conditioning. Loads of them are already installed in the UK.