# Can differences in temperatures over long distances be used to create energy?

Today there is a temperature difference of 50 degrees Celcius between the northern and southern part of Norway. In Finnmark it's so cold that boiling water will turn into ice and snow if thrown into the air. In Vestfold where I live it's almost spring these days.

This makes me wonder if there's a way to generate power from this temperature difference over such long distances. It's maybe 1700 km to drive by car, so I guess a device must cater for roughly the same distance.

Is there a workable way to do this, economics aside? If there is, what then if we bring the economy into the picture?

• This is how the atmosphere feeds hydropower and wind energy.
– user137289
Commented Jan 27, 2020 at 15:03
• Pedantic point: You can't create energy; but I assume you mean usefully harness the energy.
– JMac
Commented Jan 27, 2020 at 15:05
• What were the actual temperatures in the northern and southern parts of Norway? Commented Jan 27, 2020 at 15:09
• Kautokeino -37 Celcius. Tafjord +10 Celcius. I am in Larvik, Vestfold, and it's +6 now at 16:20, but I know it was higher earlier today. Commented Jan 27, 2020 at 15:21
• nrk.no/finnmark/… Commented Jan 27, 2020 at 15:21

Is there a workable way to do this, economics aside? If there is, what then if we bring the economy into the picture?

Well, if one were able to operate a heat engine using the temperature difference involved, then the maximum theoretical efficiency of such an engine would be the Carnot efficiency, or

$$ζ=1-\frac{T_L}{T_H}$$

or about 17% between the temperatures 10$$^0$$C and -37$$^0$$C. So, weigh this against the costs of linking a heat engine to two temperature reservoirs located 1700 m apart and draw your own conclusions.

Hope this helps.

The manner in which this is usually done is to just allow the temperature difference to affect atmospheric pressure, which then sets winds in motion. We then use windmills to harvest the kinetic energy of the moving wind.

You don't need just a temperature difference. You also need a medium which can absorb and transport a significant amount of heat. As I recall, there is a power plant in Hawaii which takes heat from warm surface ocean water and sinks it into cold deep water. (Their biggest problem is dealing with water intakes being fouled by ocean organisms.) You might look for a region where a warm current from the south is within a reasonable distance of a cold current from the north. Or perhaps, warm ocean water with a large very cold radiator.