One thing is constant, and that is, that things are always changing.
Something that is effective today may not be tomorrow.

For years the fuel of choice in a rural setting was propane. It was
70-90 cents/gal. Now it is 2.10/gal and btu for btu yielded you can
heat with low-tech electric resistance heat for less money.

1 Million BTU Electricity = $24.90 (TN)

1 Million BTU Propane (80% Furnace)=$28.46