Heating from gas is quite peaky (morning and evening heating cycles), whereas heat pumps are best when run low-and-steady.
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.
Sorry, alignment issue! Probably transport is less troublesome as it has a decent element of demand side response to it (batteries sufficiently large for a couple of days without charging).
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...