Where I live electricity has been getting cheaper faster than natural gas, so at some point it makes more sense to do a heat pump.
Plus if natural gas is cheap it can also be used to generate electricity without having to run and maintain natural gas lines to every house as well as electrical lines.
Therefore the choice is between a gas furnace at 90%, or gas to electricity to a heat pump at 150%, if we care about the efficiency of gas usage between the two options.
But when comparing price per kWh of delivered gas vs electricity, ignore the 50% gas-to-electricity efficiency, because that's irrelevant. It's just the 90% vs 300%.
Therefore a gas furnace is cheaper if the delivered price per kWh of gas happens to be no more than 30% that of electricity in your area. Of course the rate for gas will more likely be in therms than kWh, but that's a simple conversion (1 therm = 29.3 kWh).
I suppose that's the case in Texas?
> if natural gas is cheap it can also be used to generate electricity without having to run and maintain natural gas lines to every house
It's recently become so high, I wonder if it's more economical to run hybrid cars on gas instead of charging them.