Just to counter your edit: >But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge ene

Just to counter your edit: >But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge energy consumption. Gas is simply burning fuel. Yes, we should save gas for rainy days. But I hate to say that it is more efficient and cheap. There is no comparison. You are very mistaken, the energy required to compress refrigerant is less than the energy captured and delivered if COP > 1, which is the point of a heat pump. At COP 1 it is basically heat of compression and equal to a resistive heater at COP greater than 2 the heat pump captured more heat from the environment than used to compress the refrigerant. I am not sure if you are arguing in good faith, if so here are some of the simplest resources I can find to explain how a heat pump can exceed a furnace in efficiency even when taking power plant and transmission losses into account, with easy to understand graphics: https://greenbusinesswatch.co.uk/cop-vs-spf https://greenbusinesswatch.co.uk/cop-vs-spf https://energyeducation.ca/encyclopedia/Coefficient_of_performance https://energyeducation.ca/encyclopedia/Coefficient_of_perfo... http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.h... This should really be taught and drilled in lower education, the difference between heat and temperature and relationship to power, how heat engines work, etc. This stuff basically makes modern society possible and we will never progress in decoupling our power sources from use of the power which is what electrification allows which allows us to transition away from throwing carbon up in the air for energy.