It's kind of funny IMO, in the old days, the most efficient heat source would be burning something directly in your home, where typically 80% of the heat is utilized, and one of the most CO2 friendly heat sources is firewood or pellets because it's renewable energy.

But with the heat pump that typically has a 4:1 yield in heat, meaning that 1kWh of power yields 4 kWh of heat.
A power-plant running on pellets, will transform 45% of the heat to electricity.
But using a heat pump, even 45% electricity with a 4x yield for making heat is 180% utilization!!
So 180% against traditionally about 80% from firing the pellets directly at home, means that the heat-pump is twice as environmentally friendly as one of the most efficient ways to heat houses used to be, even when accounting for a 10% loss of electricity in transportation from plant to household.

The funny part being, that burning and making electricity from the heat far away, then transport the electricity to the homes, and transform the electricity to heat again, is more efficient than burning stuff directly in the home!

Heat pumps have really come a long way. I'm planning on installing an air-to-water heat pump for hot water on demand as well as powering in floor heating. I'm going to pair it with an air-to-air heat pump to provide instant temperature increases if desired and cooling during the summer