Is a heat pump efficient in a climate like N. Minnesota where temps can be below 0 for extended periods?
GSJ

Your question is not easy to answer. Your area still has many days of 25 to 70 degree weather where a heat pump will really shine. You need to have a complete energy audit done on your home to find out the REAL FACTS since all else is opinion and a guessing game.

In a word, no. A heat pump works by extracting heat from the outside air and transferring it to your house. When it is below zero, there isn't much heat to be had.

I'd say once you go below about 40, the heat pump will need to be supplemented with electric heat (they do that automatically). Heating in this manner is expensive (unless you have really cheap electricity).

Hope this helps,
WallyH

Edit: I see hvac1000 just beat me to the punch with a more accurate answer. He is the true expert.