Water-source heat pumps...

[AE-NMidlands]

I don’t think I mentioned thermal conductivity? Surface area of the collector will have a bearing on the cost - slinky loops, for instance, meaning more collector pipe to be buried. The cost of burying the slinky is substantial compared to one tank of water for the energy collection.

Boreholes don’t need much space but the deep shaft is likely to cost an order of magnitude more than burying a slinky type of collector.

You didn't, but I thought that

"As usual, a hyped-up story to interest the uninformed public.

I expect the only difference between a ground source system and this is the cost of burying the loop (or drilling the borehole!)

completely missed the point that this takes heat from surface water, and as such isn't handicapped by heat movement through subsoil. Not many people have hot earth near the surface, and the cost of drilling deeper is significant as you say. I note that you don't comment on the risk of GSHPs over-cooling the ground...

You may not have noted that my comments were addressed to ground source heat energy compared to this supposed “new invention” rather than the intricacies of each. I addressed the quality of the report, which was heavily distorted.

Boreholes most certainly will not materially change the temperature of the surface soil.

If you wish to quote my posts, please keep the comments appropriate to it, not deviate at a tangent to the content.
RAB

Correct and obvious, but I was pointing out that they say in https://www.sea-warm.co.uk/product/

Ground source heat pumps using boreholes take heat out of the ground faster than it is replenished, leading to a gradual decline in the ground temperatures and a reduction in heat pump efficiency

which (if true) is something not widely commented on, and might change the choice if a property owner has both ground and water flow available.
It will be interesting to see how the EA handle applications for licenses, as this isn't so different to a small water wheel by a stream