You need hydrogen to produce synthetic methane, and plants to produce it. The larges source of H2 globally is from you guessed it, natural gas. To get if from e

You need hydrogen to produce synthetic methane, and plants to produce it. The larges source of H2 globally is from you guessed it, natural gas. To get if from electrolysis, you need an electrolysis plant near your synthetic methane plant and both need to be near water because it's difficult and dangerous to store H2. All of that would take more than months. You could probably replace a large number of boilers in 3 months. Not enough to solve the problem, but enough to make a dent. Electric boilers, while less efficient than heat pumps, only cost around $700 each and are basically a 1 for 1 replacement for a gas boiler.