alt Hacker NewsA heatpump needs power to operate, but will generate at least 3x more heat than the electricity to power it.
The article describes how there will be a water battery.
So it can be thought of as a part of a bigger countrywide or europe-wide plan and grid?
Sure, but if you build a nuclear reactor suitably close to your city (!) it produces hot water directly in addition to electricity. It's just a much bigger pain to ship hot water over long distances than electricity.