Heatpump with PCM buffertank.
WP stands for Warming Pump. Heated water is pumped into a big isolated tank filled with water and PCM.
PCM stands for Phase Change Material. Ice Is also a good PCM but too cold to warm your house.
Melting 1 kg ice of 0 degrees C into water of 80 degrees needs the same amount of energy to heat that kilo water up form 0 to ca 80 degrees C.
Now we take something like candlewax. It melts at about 55 degrees and can store much more energy than ice..
