Indeed it is. The US Environmental Protection Agency (EPA) called geothermal heat pumps, as the technology is also known, one of the most energy-efficient, clean and cost-effective solutions available - which isn't a bad endorsement.
It's an increasingly mature technology too, with a million installations in the US. Any specialist engineer should be able to install one, and they last for years with next to no maintenance.
seems to me like a waste of free clean energy not to
you can also use them to cool buildings in summer
..tho no govt grant if you do that
the Centre for Efficient and Renewable Energy at Southbank Uni has it..
"The eight-storey building, designed by Grimshaw Architects, is in Keyworth Street and will have the latest ground source heating and cooling technology eliminating the need for heaters and chillers. Required drilling reached 28 metres.