Assuming 2/3 of residential heat demand transitions to heat pumps, and assuming an optimistic COP of 3 in the worst weather (highest flow temperatures, lowest air temperatures ... perhaps more like 2.5), then the power required to heat this fraction of houses is 2/3 / 3 = 2/9 of the mean gas demand. [0] linked report figure 1 shows a (smoothed by eyeball) demand of around 140GW "local gas demand" during the Beast from the East. This implies heat pumps would take over 31GW to power, which is more like 60% of the current UK electricity supply.
[0] https://ukerc.ac.uk/publications/local-gas-demand-vs-electri...
It absolutely ripped though gas just to keep a couple of rooms warm enough to live in, and it was still two jumpers and thermal trousers indoors. God only knows how the pensioner who lived there before managed.
9,000kWh for electricity vs 16,000kWh for gas
That’s with charging an EV too.
Electric cars are similarly 3-4x more efficient than petrol cars on a kWh of fuel basis.
So while we should expect increased electricity demand as transport and heating are electrified, the increase in electricity usage will be far less than the decrease in kWh of fuel.
