"World's largest heat pump" is a 🇫🇮 lämpöpumppu (the only Finnish word I know, don't ask)And in the competition for largest heat pumps, it is a bit like the Olympics: with many subcategories (heat source), there are many winners

25 MW heat pump now in operation in Stuttgart

https://www.enbw.com/presse/grosswaermepumpe-liefert-fernwaerme-fuer-10-000-haushalte.html

Kiel using sea water in the Kieler Fjord:

https://www.stadtwerke-kiel.de/privatkunden/nachhaltigkeit-soziales/waermewende-kiel/dekarbonisierung-der-kieler-fernwaerme

"Wrompa" is Poland's largest heat pump: once operational, it will be able to transfer 12.5 MW of heat from wastewater to the district heating system (which is currently 100% coal-based)

https://www.gov.pl/web/climate/wrompa---heat-pump-in-wroclaw

60 MW heat pump for Flensburg’s district heating, using sea water as heat source

https://www.stadtwerke-flensburg.de/foerdepost/presse/grosswaermepunpe-johanson-controls
https://www.ndr.de/nachrichten/schleswig-holstein/Stadtwerke-Flensburg-bestellen-riesige-Meerwasser-Waermepumpe,waermepumpe204.html

Scheduled for operation this year: 60 MW heat pump for Hamburg district heating, using sewage as a heat source

https://www.hamburgwasser.de/umwelt/energiegewinnung/abwasserwaerme

From: @klimareporter
https://mstdn.social/@klimareporter/113837219477713300

Mannheim , which has had a 20 MW heat pump using the Rhine as a heat source for two years, is planning to add two more: one 100 MW unit and another with a capacity of 150 MW. The latter is on a par with the Rhine heat pump under construction in Cologne, but Mannheim leads on total capacity.

https://www.swr.de/swraktuell/baden-wuerttemberg/mannheim/zwei-grosse-flusswaermepumpen-in-mannheim-von-mvv-geplant-100.html