Some metals must be melted by either one or the other type of furnace. That normal question is which type you must use to melt titanium, or something else.
Efficiency depends on where you start counting energy to heat conversion.
If you have an electric furnace, do you start counting at the point where feel is burned to turn the generator that makes the electricity you feed to the furnace, or do you only consider the meter reading of kWh delivered to the furnace itself.
Overall efficiency will typically be highest where the number of energy conversions are minimized, therefore direct oxy fuel to furnace melt temperature will have the most overall efficiency.
Fuel - to electricity - to heat is not going to be as efficient as is a direct fuel burn -to heat process.
Operational efficiency is normally higher for the system with the simplist components. A burner does not have any complex components as does an electric resistance heater. Pipe, Control valve and burner vs transformers, current Controllers and resistance elements.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
Also i wonders which method is faster in time to melt non ferrous metals like aluminium chromium cobalt copper nickel molybdenum gold platinum titanium tantalum silver zinc in 1000 cm3 quantity for an example?
