Yes, the reported COPs are quite good. Much better than the few figures measured in the UK and slightly better than a large number of older figures measured in Switzerland.
He is always careful to refer to 'best of class' when justifying recommendations. One of my worries is whether that is achievable or whether real results will be subject to the British building disease. But this does seem to support his case that only recent evidence is relevant for numerical estimates.
Unfortunately, despite putting himself forward as a energy expert McKay doesn't seem to be very familiar with combined heat and power. Here are some empirical figures from Germany and Denmark respectively:
(1) The above ground source heat pump study (source: Fraunhofer)
To produce 1 kWh of heat, 0.8 kWh of fuel must be burned at the power station (on the basis of the UK electricity generating system, which has an overall efficiency of 0.36 and includes a mixture of gas- and coal-fired plants)
If I understand correctly I think that means an effective 'efficiency' of 125%, which is still better than for example a gas boiler? I too take issue with his use of good gas-powered generators rather than grid average as the basis of his comparison but I think once you adjust for that factor his estimates are compatible and they are still larger than 1 !
Incidentally, where did you find the value for the grid efficiency. I've been looking for it for several days without success
(2) Today's CHP system in Copenhagen (source: Danish Board of District Heating)
To produce 1 kWh of heat, 0.12-0.13 kWh of fuel must be burned at the power station (it's modified to reject heat at 70 or 80 degC instead of sending cooling water to the sea or river at 25 or 30 degC; the electricity output sacrificed is taken into account in working out the fuel burned per unit of heat).
So once we go beyond gas boilers, for buildings in towns CHP would appear to be more energy-efficient than heat pumps. It's able to use other heat sources after gas is no longer available, such as solar and geothermal.
I know even less about CHP than I do about heat pumps so I must demonstrate my ignorance. Surely it is necessary to burn at least 1 kWh of fuel to produce 1 kWh of heat, unless a heat pump is involved? So I don't understand the figure you quote - can you try to explain further, please? Or with a reference, perhaps I can work it out myself.
His argument is that electricity is more valuable and that in cases like this it is more efficient to use primary plant optimised purely for electricity generation and then feed [some of] the electricity to a heat pump to generate whatever fraction of heat is required.
He also argues that such an arrangement is more flexible in the proportions of energy delivered to the end user either thermally or as electricity, which can be useful as the seasons change.
But I still don't feel I understand the issues well enough to form my own opinion on what part of what he says is right.
Also, too many ground source coils in towns could cool the ground too much.
Yes, he's quite clear that GSHPs cannot be the only solution in urban areas for this reason. His discussion of ground storage is quite interesting.
I e-mailed McKay on this subject but didn't receive a reply.
I have had replies to my simple questions so I hope it's just the festive season and pressure of work and that you too receive a reply. Or perhaps your questions were more educated and require more thought and time to formulate a reply?