Heat pumps are a low carbon way to heat your home and they run on electricity. Electricity in the UK grid is being generated by more and more renewable sources so the carbon emissions of heat pumps already look good, and are getting lower and lower.
Heat pumps do not create heat, they move heat from one place to another. That is why you can use 1kW of electricity to drive the pump which will then typically provide 3kW of heat to warm your home. Heat pumps can take that heat from the air, the ground, or from water. These are called air-source, ground-source, and water-source heat pumps.