Consideration of boiler vs heat pump

It’s easy to think that a heat pump is a more green solution than a replacement boiler. After all if you are on a green tariff for electricity and you have a heat pump, surely there are no carbon emissions.

However thinking in more detail about the overall picture, it seems that electricity generated in the UK always includes burning fossil fuels (mostly gas).

If I were to switch from a gas boiler to a heat pump, that would be adding an additional load to the grid that previously wasn’t there, and I can only assume that in the short term that can only come from burning more gas.

I appreciate that one day, once all the electricity being produced is green the picture changes, but for now, I think that even if I’m on a green tariff and get green electricity, the consequence of me increasing demand means that some other consumer not on a green tariff has to get a larger proportion of non-green electricity.

A key question to which I don’t know the answer is how long will it be before there are at least some times when the whole energy supply in the UK is from green sources.

So, if extra gas has to be burnt to produce the electricity for a heat pump then I believe that the efficiency of this process is 30 to 40%. Clearly the heat pump multiplies the input energy, but even if it achieves a factor of 3, that still means that roughly the same amount of gas has been burnt on my behalf to produce that electricity as if I had burnt the gas at home.

Given that heat pumps are more expensive and a less established technology, I think I’d be reluctant to make the switch at the moment.