Electric heating: Engineering methods

Resistance, induction, arc or microwave: which one wins where

What this tab covers The engineering methods that can do this conversion, compared on efficiency, scale, economics, limitations and reliability.

Four ways of making heat from electricity, plus the heat pump as the main alternative for low-temperature heat.

Comparison

Method	Efficiency	Scale	Economics	Limitations	Reliability
Resistive heaters, kettles and geysers²	100% electricity to heat at the element; tank standing losses reduce delivered heat	1-3 kW kettles to tens of kW instantaneous heaters and MW-scale industrial boilers	Cheapest to buy; high running cost compared with heat pumps	Large peak loads on the grid	Simple; elements scale up in hard water
Induction heating and hobs¹	About 85% for hobs	Domestic hobs to industrial melting and hardening furnaces	Hobs cost more than resistance types but save energy	Needs magnetic (iron-based) cookware	Electronics are the usual failure point
Electric arc furnaces³⁵¹¹	400-500 kWh/t; a peer-reviewed model uses 450 kWh/t as typical	Tens to hundreds of tonnes per heat; about 560 million tonnes of steel in 2025 (calculated)	Electricity about USD 39/t (calculated); much lower capital than blast furnaces	Needs scrap or DRI; scrap quality limits steel grades	Electrode and refractory wear
Microwave ovens⁶¹⁰	50% or less, electricity to food	Domestic countertop and built-in units; industrial systems at 915 MHz	Small energy use (about 71 kWh a year cooking)	Uneven heating; poor for browning	Magnetron output declines with age
Heat pump (comparison)²	More than double resistance water heaters	Domestic to district heating	Higher purchase price, lower running cost	Hard to reach very high temperatures	Compressor and refrigerant circuit

For temperatures below about 100 degrees C, resistance heating is simple but uses two or more times the electricity of a heat pump. Induction and microwaves win by putting heat directly into the target. For melting steel, the arc furnace is the only mature all-electric route, already making about 30% of world steel.

How each method works

Resistive heaters, kettles and geysers

Current through a sheathed resistance element heats water or air directly; storage geysers keep a tank hot, instantaneous units heat on demand.

Induction heating and hobs

An inverter feeds a copper coil with high-frequency current; the changing field induces eddy currents in the pan or metal workpiece.

Electric arc furnaces

Graphite electrodes strike arcs into a charge of scrap or directly reduced iron, melting it; oxygen and carbon injection add chemical heat.

Microwave ovens

A magnetron produces 2,450 MHz waves that bounce around a metal cavity and are absorbed by water in food.

Heat pump (comparison)

Uses electricity to move heat from outside air or ground into water or rooms, rather than making it.

Sources

ENERGY STAR Emerging Technology Award 2021: Residential Induction Cooking Tops US EPA / DOE ENERGY STAR, 2021
DOE finalizes efficiency standards for water heaters to save Americans over USD 7 billion on household utility bills annually (press release, 30 April 2024) US Department of Energy, 2024
World Steel in Figures 2026 World Steel Association, 2026
Article modelling electric arc furnace electrical energy consumption (University of Ljubljana authors), DOI 10.1007/s40831-021-00390-y Journal of Sustainable Metallurgy (Springer), 2021
Energy issues in microwave food processing: a review of developments and the enabling potentials of solid-state power delivery (Atuonwu and Tassou, Critical Reviews in Food Science and Nutrition; author manuscript) Brunel University London repository, 2019
Joint comments to DOE on microwave oven test procedures (ASAP, ACEEE, Consumer Federation of America and others, citing DOE's 2013 proposed rule) Consumer Federation of America, 2018
Theoretical Minimum Energies to Produce Steel for Selected Conditions (Fruehan, Fortini, Paxton and Brindle, Carnegie Mellon University) US Department of Energy, Office of Industrial Technologies, 2000