In northern states almost all residential energy use is heating. The amount of electricity used is minimal, therefore even modest amounts of electricity generation can meet need. Wyoming is the only northern state that has natural gas in notable amounts, all other states import a lot of their energy (especially heating) needs.

If most states stopped importing energy they would have to go back to wood and coal-fired stoves. That would be a huge quality of life reduction in terms of convenience and home air quality.