Electric heating
Heating with electricity: resistance heaters, induction, electric arc furnaces and microwaves.
Conversion and use · Conversion devices · No. 105
- Conversion and use
A kettle turns all its electricity into heat, yet a heat pump water heater does the same job on less than half.
Chart: Illustration: Electric heating
Where it comes from
Chart: Map of where it comes from
Electricity becomes heat in four ways: pushed through a resistance, induced as swirling currents in metal, struck as an arc, or beamed into food as 2,450 MHz microwaves.
Three things to know
- No resistance heater can beat 100% efficiency, but a heat pump water heater moves outside heat and uses less than half the electricity.
- Modern arc furnaces need 400 to 500 kWh per tonne of steel, not far above the roughly 370 kWh needed just to melt scrap.
- A home microwave gets 50% or less of its electricity into the food, though cooking uses only about 71 kWh a year.
The journey
- 1 Grid powerAlternating current at 50 or 60 Hz
- 2 Power shapingTransformer, inverter or magnetron conditions the current
- 3 Heat madeResistance, eddy currents, arcs or microwaves
- 4 Into targetWater, pans, food or a scrap charge
- 5 End useGeysers, hobs, ovens and steel melt shops