Meet the biggest heat pumps in the world

BBC News

The giant heat pumps designed to warm whole districts

Across Europe huge heat pumps are being installed that can heat tens of thousands of homes.

abstract

• 16 December 2025, 00:06 GMT

The pipe that will supply the heat pump, drawing water from the River Rhine in Germany, is so big that you could walk through it, fully upright, I'm told.

"We plan to take 10,000 litres per second," says Felix Hack, project manager at MVV Environment, an energy company, as he describes the 2m diameter pipes that will suck up river water in Mannheim, and then return it once heat from the water has been harvested.

In October, parent firm MVV Energie announced its plan to build what could be the most powerful heat pump modules ever. Two units, each with a capacity of 82.5 megawatts.

Brilliant. But wonder what chilling Rhine water will do to riparian and deep water ecosystems. Many flora/fauna are temperature sensitive. They being Germans, I have some hope they worked this out, maybe the volume of water used and chilled isn't enough to make a significant difference.

ETA: it looks like the fraction is tiny. Rhine flow rate gets up to over a million liters/sec along the Upper Rhine where Mannheim sits. And near three million at the Nordsee. (BTW, do not trust Google AI on river flow rates - go directly to technical sources)

Edited December 16Dec 16 by TheVat

7 minutes ago, TheVat said:

Brilliant. But wonder what chilling Rhine water will do to riparian and deep water ecosystems. Many flora/fauna are temperature sensitive. They being Germans, I have some hope they worked this out, maybe the volume of water used and chilled isn't enough to make a significant difference.

ETA: it looks like the fraction is tiny. Rhine flow rate gets up to over a million liters/sec along the Upper Rhine where Mannheim sits. And near three million at the Nordsee. (BTW, do not trust Google AI on river flow rates - go directly to technical sources)

The article I read claims it will only chill the river by 0.1C. (Which in view of global warming would if anything fractionally hold temperatures closer to previous values, but only to a pretty negligible extent.

They are growing pinot noir now quite successfully along the Rhine, I understand (spätburgunder). I've got a couple of bottles in the cellar but have not yet tried them.

I think a point to consider is

What happens when everyone along the Rhine wans to do this ?

I have a doctor friend who lives along the Rhine and already has a private deep bore water source heatpump.

42 minutes ago, studiot said:

I think a point to consider is

What happens when everyone along the Rhine wans to do this ?

I have a doctor friend who lives along the Rhine and already has a private deep bore water source heatpump.

Good point. And, thinking a bit harder about this, climate change is expected not just to warm the climate on average but also create greater extremes. And of course it will be during extreme cold that the demand for heat will be greatest - and thus the cooling effect on the river as well. So one would probably need to limit heat extraction projects based on the cooling effect at extremely low temperatures in winter.

5 hours ago, studiot said:

Meet the biggest heat pumps in the world

BBC News

The giant heat pumps designed to warm whole districts

Across Europe huge heat pumps are being installed that can heat tens of thousands of homes.

abstract

• 16 December 2025, 00:06 GMT

The pipe that will supply the heat pump, drawing water from the River Rhine in Germany, is so big that you could walk through it, fully upright, I'm told.

"We plan to take 10,000 litres per second," says Felix Hack, project manager at MVV Environment, an energy company, as he describes the 2m diameter pipes that will suck up river water in Mannheim, and then return it once heat from the water has been harvested.

In October, parent firm MVV Energie announced its plan to build what could be the most powerful heat pump modules ever. Two units, each with a capacity of 82.5 megawatts.

Have they recycled Thomas the Tank Engine? (he looks a bit grey around the jowls)

15 hours ago, exchemist said:

Good point. And, thinking a bit harder about this, climate change is expected not just to warm the climate on average but also create greater extremes. And of course it will be during extreme cold that the demand for heat will be greatest - and thus the cooling effect on the river as well. So one would probably need to limit heat extraction projects based on the cooling effect at extremely low temperatures in winter.

In northern Europe, once you get below about 10 metres soil depth, the annual variation in temperature is barely significant. Moreover, the thermal inertia is so high relative to vertical heat flux, that most groundwater analyses I've worked with over the years show around a six-month lag between surface and sub-surface temperatures. ie the higher borehole temperature peak (such as it is) tends to occur in the winter months. Which is somewhat counterintuitive. But useful perhaps.

1 hour ago, sethoflagos said:

In northern Europe, once you get below about 10 metres soil depth, the annual variation in temperature is barely significant. Moreover, the thermal inertia is so high relative to vertical heat flux, that most groundwater analyses I've worked with over the years show around a six-month lag between surface and sub-surface temperatures. ie the higher borehole temperature peak (such as it is) tends to occur in the winter months. Which is somewhat counterintuitive. But useful perhaps.

How would this relate to the temperature fluctuations of a large river?

22 hours ago, studiot said:

What happens when everyone along the Rhine wans to do this ?

That sounds like one of those "good problems."

6 hours ago, exchemist said:

How would this relate to the temperature fluctuations of a large river?

Unclear. The lower Rhine is not deep.

My comment was more applicable to the latter part of your quote concerning @studiot 's friend's borehole source. Apologies if this caused confusion.

1 hour ago, sethoflagos said:

Unclear. The lower Rhine is not deep.

My comment was more applicable to the latter part of your quote concerning @studiot 's friend's borehole source. Apologies if this caused confusion.

OK I see. I had overlooked the borehole aspect.