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Why is electric heat so expensive?

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On average in 2019, it took an average of …

10,551 BTU or 3.1 kW of coal or 7,732 BTU or 2.3 kW of natural gas to produce 1 kilowatt of electricity, which is equal to 3,412 BTU.

With fossil generation, it takes quite a bit more kWh of the fossil fuel burned to turn into usable electricity. It took roughly 4.65 kWh worth of coal to make the 1.5 kWh of electricity, as it fossil fuels have significant losses due to the inefficiency in converting coal or oil into electricity.

How much does your 120 volt plug-in electric heater in your house use when it’s on? It doesn’t really matter whether it’s a $12 Walmart heater fan, or a $300 radiant heater in a fancy wood cabinet. All are same energy efficiency – when you apply resistance to electricity, 100% becomes heat, including the heat produced by the fan coils or indicator lights.

All 120-volt heaters are 1.5 kW or 5,118 BTU, because 120-volt wall outlets can only supply 12.5 amp constantly. In theory, you could make a space heater smaller then 1,500 watts but nobody does because electric coils are cheap to manufacture, and when you are warm, the thermostat just shuts off.

So every hour a heater heater is operating, it’s 1.5 kWh.

Oddly Fascinating

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I find it oddly fascinating that in the split phase electricity system used in the United States, the only power that flows on the neutral wire back to the center tap of the pole transformer is the difference in amperage between the phases.
So if you have …
20 amp draw on the Phase A
30 amp draw on Phase B
You’ll have 10 amp flowing on the neutral, which is also referenced to the ground
If you disconnect the neutral from the center tap of the transformer, the 20 amp load will work okay but the 30 amp circuit will see its voltage cut by 1/3rd.

America’s Three Power Grids

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America has three electrical grids that are not synchronized to each other, and can not move alternating current electricity between one and another.
 
Generally speaking, a power plant in Oklahoma can't send electricity to most of Texas or Colorado.
 
Each grid was built separately and are incompatible with each other, although a limited amount of electricity can be moved between the interconnections using AC to DC to AC conversion. But such conversion is complicated and expensive, and isn't as simple as stringing lines between the grids.

 

America\'s Three Power Grids

120/240V Single Phase 3 Wire Explanation And Demonstration

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The split phase system in America is a bit confusing but actually it's kind of ingenious in the sense that no wire has more than a 120 volt potential to ground. But it turns out there is more than meets the eye - the nuetral line actually carries any current not equal between the two phases back to the transformer - and if it's disconnected only the lowest amperage of the two phases will work. Fascinating stuff.