Combined cycle gas power plants are about 60% efficient. Coal power plants are around 40%, but even the dirtiest parts of Florida aren't all coal (https://app.e

Combined cycle gas power plants are about 60% efficient. Coal power plants are around 40%, but even the dirtiest parts of Florida aren't all coal (https://app.electricitymaps.com/map https://app.electricitymaps.com/map) But of course this is short-sighted, because the grid is greener in most places, and will get even greener over the lifetime of the heat pump, while the gas furnace won't get any better.