Conventional electric stoves use resistive heating elements, much like a space heater, in order to heat the cooking surface. This heat is then transferred, through conduction, to the cookware and, in turn, to the food. An induction stove instead utilizes electromagnetic induction to directly heat the cookware.
Induction stoves work by passing high frequency alternating electric current through coils mounted under the surface of the cooktop. This generates an oscillating magnetic field. The resultant magnetic field induces an eddy current in the conductive cookware, causing resistive heating directly in the cookware. In ferromagnetic materials, magnetic hysteresis provides additional heating. This means that heat energy is added to the cookware directly rather than transferred by conduction.
This mode of operation has a few key benefits. Perhaps most significantly, a much greater efficiency is possible. According to the US Department of Energy, induction cooking results in up to 90% of the energy input being transferred to the food, compared with 74% for conventional electric and 40% for gas. Due to the higher efficiency, less waste heat is released. This is especially beneficial during summer because the kitchen will remain cooler. Additionally, since the cookware is being heated directly, the surface of the stove does not get hot during operation. Some warming of the cooktop is inevitable due to its contact with the hot cookware, but it quickly cools when the pan is removed from the surface. This is a significant safety boon, especially in the presence of pets or children. Finally, since induction cooking directly heats the cookware, it heats quickly and can be throttled up and down rapidly, much like gas.
It is important to note that commercially available induction stoves must be used with ferromagnetic cookware. While the primary physical principle involved in induction heating can be applied to any conductor, the material properties of aluminum, copper and other non-ferromagnetic materials prevent them from being practical for induction-based cooking. To determine if a particular cooking vessel is suitable for use with induction cooking, simply see if a magnet sticks to it. If the magnet sticks, it will work.
In terms of installation, an induction range is very similar to a conventional electric unit. Both typically require a 240 Volt circuit. If one is switching from gas, this circuit will likely have to be installed prior to an induction stove. This is an additional cost that should be accounted for before making a purchase.
The Solar Initiative is now offering a subsidy towards the purchase of induction stoves on Block Island. Specifically, the Solar Initiative will contribute 50% of the purchase price, up to a maximum subsidy of $1500.
For more information, please contact Wade Ortel at wade@thesolarinitiative.com