Houses will never be heated by electricity in the north. Its currently -30 degrees celsius in the Calgary where I live. Its going to be -35 tomorrow. People would literally die if you got your wish.
This resource suggests that the frost line in Calgary is about nine feet underground: http://www.urecon.com/applications/municipal_ambient_below.h... . That's the depth at which the ground temperature is above freezing for the whole year. That means that a heat pump can exchange heat via pipes buried nine feet under your property. Technologically, it's extremely feasible. Whether or not it makes sense for you will depend on economic factors, of course.
Also, people often don't realize that the temperatures that matter thermodynamically are degrees Kelvin, not Celsius. 30 below 0 is 243K; 20 above (room temperature) is 293K. The coefficient of performance for a Carnot heat pump at those temperatures is 293 / (293 - 243) ~= 5.86; that means that one joule of work will transfer 5.86 joules of heat. This isn't great, but it's less of a difference than people would expect given our subjective experience of how cold -30C is. The coefficient of performance for a heat pump trying to heat 0C ambient temperatures up to room temperature (or alternatively, an air conditioner cooling 40C temperatures to room temperature) is 293 / (293 / 273) = 14.65, so your heat pump in Calgary will be maybe 2.5x less efficient than one in NYC. Drill below the frost line, like you suggest, and you'll get similar efficiencies regardless of where you are.
No it is not feasible. You are not digging up ground under then tens of thousands of houses that already exist in the city in any economically feasibly way.
I'm in Minnesota. True air source heat pumps aren't great at such temps, but ground source heat pumps it doesn't matter at all. Lot higher install cost though.
Don't be silly. Heat pumps with water that go down drilled holes (the term for it here in Sweden is mountain heat) would work just fine and probably be cheaper too
Heat pumps are used all over the Nordics and work just fine. Air one can get quite expensive to run during the coldest days but ground heat pumps literally do not care how cold it is outside (the ground temperature will stay the same anyway)
For Helsinki they are moving to heat pumps for the district heating as they want to close the 2 remaining coal plants in the next couple years.
I agree that heat is more challenging in climates like yours. But it's not impossible. Extreme insulation and smart energy management goes a long way (check out passive houses), and if thermal is really needed natural gas is not our only option. Do trees grow near you? Grind them up and burn them, they're carbon neutral. Better yet, geothermal heat pumps which I'm hopeful will become more cost effective in the near future.
Tens of thousands of houses already exist in the city that are nearly all heated with natural gas. There is not a single economically feasible way to change those houses
You just moved the goal posts from "impossible" to "not economically feasible" - those aren't the same thing. I agree, economically, it's very difficult. We need governments to help with the cost, because it will be enormous. The cost of not doing it is even higher.
Also, the % of people who live in climates like yours is relatively small, so everyone who doesn't live in those places should not be using this as an excuse for inaction.
It's -17C now, a couple weeks back it was -29C... I have 100% (geothermal) heat pump heating and it's 24.5C inside at all times. The buildings/houses require a good thermal insulation but heating, itself, is not an issue.
Ground source heat pumps exist, but cost a minimum of $10,000 to install. That is only if you have a large enough plot of land and the right soil type. It can easily be $20,000.
