Traditional electric stoves use resistance heating elements, much like space heaters, to heat the cooking surface. Then, the heat is transferred to the cookware by conduction, and then to the food. In contrast, induction stoves use electromagnetic induction to directly heat cooking utensils. The working principle of the induction stove is to pass high-frequency alternating current through a coil installed under the surface of the stove. This generates an oscillating magnetic field. The resulting magnetic field induces eddy currents in the conductive cookware, which directly causes resistance heating in the cookware. In ferromagnetic materials, hysteresis provides additional heat. This means that heat energy is added directly to the cookware instead of being transferred by conduction.

This mode of operation has several key benefits. Perhaps most importantly, higher efficiency is possible. According to data from the US Department of Energy, induction cooking causes up to 90% of the energy input to be transferred to food, compared with 74% for traditional electricity and 40% for gas. Due to higher efficiency, less waste heat is released. This is especially beneficial in summer, as the kitchen will stay cool. In addition, since the cookware is directly heated, the surface of the stove does not become hot during operation. Some heating of the cooktop is inevitable due to contact with hot cookware, but when the pot is removed from the surface, it will cool down quickly. This is a major safety benefit, especially if there are pets or children. Finally, since the induction cooker directly heats the cooking utensils, it heats up quickly and can quickly throttle up and down, much like gas.

It should be noted that commercially available induction cookers must be used with ferromagnetic cookware. Although the main physical principles involved in induction heating can be applied to any conductor, the material properties of aluminum, copper and other non-ferromagnetic materials make it unsuitable for induction-based cooking. To determine whether a particular cooking vessel is suitable for induction cooking, just look for magnets stuck to it. If the magnet sticks, it will work.

In terms of installation, the sensing range is very similar to traditional electrical devices. Both usually require a 240 volt circuit. If you switch from gas, you may have to install this circuit before the induction furnace. This is an additional cost that should be considered before purchasing.

The Solar Energy Initiative now provides subsidies for the purchase of induction stoves on Block Island. Specifically, the solar program will provide 50% of the purchase price, with a maximum subsidy of US$1,500.

For more information, please contact Wade Ortel at wade@thesolarinitiative.com