> There actually is, however, some value in having different units for methane vs electricity, since you have to run methane through a suboptimal furnace to harness its energy. Granted, modern gas-powered furnaces are usually more than 90% efficient, but there's still some loss.
Well, heat pumps transfer more than 1 kWh of heat transfer for every kWh of electricity. You have to account for the performance factor anyway, whether you're using natural gas or electricity.
The point is that, once you've divided by COP or AFUE, you get price per effective kWh, which you can then compare directly. As opposed to getting a price per therm, which you must apply a conversion factor to.
With cogen, you get both electricity and heating out of the unit. If it's all in kilowatt-hours, then you simply add them up and compare to the kWh of the incoming natural gas to get efficiency. But how does a therm of electricity translate to volts and amps?
As for the kilowatt-hour, I think the reason we don't use megajoules is that metric time never took hold. If we had metric hours, minutes, and seconds, then the kilowatt-hour would be as awkward as the hectare-centimeter.
Well, heat pumps transfer more than 1 kWh of heat transfer for every kWh of electricity. You have to account for the performance factor anyway, whether you're using natural gas or electricity.
The point is that, once you've divided by COP or AFUE, you get price per effective kWh, which you can then compare directly. As opposed to getting a price per therm, which you must apply a conversion factor to.
With cogen, you get both electricity and heating out of the unit. If it's all in kilowatt-hours, then you simply add them up and compare to the kWh of the incoming natural gas to get efficiency. But how does a therm of electricity translate to volts and amps?
As for the kilowatt-hour, I think the reason we don't use megajoules is that metric time never took hold. If we had metric hours, minutes, and seconds, then the kilowatt-hour would be as awkward as the hectare-centimeter.