Improving Cooking and Energy Performance with Induction Cooking
By John Sustar, E Source Research Analyst -- Foodservice Equipment & Supplies, 7/1/2007
Induction cooking, popular in Europe for many years, continues to gain ground in U.S. commercial kitchens thanks to several energy-related benefits. In contrast to conventional cooking methods, induction cooking generates heat within the cooking pan, leading to less wasted energy and a cooler kitchen. Induction cooking also practically eliminates safety issues associated with open-gas flames or a hot electric surface. In addition, induction cooking heats food more quickly than gas, provides very stable cooking temperatures, and the cooking surfaces tend to be easier to clean than those for conventional stoves.Unlike with conventional electric and gas cooktops, induction cooking features an instantaneous and direct transfer of energy. Induction cooking uses electricity to generate electromagnetic energy to heat cookware made of magnetic material. When turned on, a coil that sits beneath a ceramic and glass cooktop produces a high-frequency alternating current and magnetic field that flows through the cookware. Molecules in the cookware become excited, causing the cookware to become hot and cook the food. The magnetic field does not affect the cooktop’s ceramic surface, which means only the heat of the pan will warm the glass, ensuring that the unit stays much cooler to the touch than conventional ones. Induction only operates when the pan actually sits on the surface, unlike electric or gas stoves, in which the heating elements maintain a constant temperature on the surface as long as the dial remains in the “on” position.
Most induction cooking units will work with any pan that contains some magnetic material. For example, magnetic stainless-steel or cast-iron pans work, but copper, aluminum and heat-resistant glass do not. Manufacturers do warn that a pan must be in good shape and sit completely flat on the cooking surface in order to work properly. Some induction cooktops even have a feature that automatically turns them off or alarms the user if a non-magnetic object or a small magnetic cooking utensil is accidentally left on the cooktop.
In terms of energy transfer, gas cooking tends to be only 55 percent efficient and conventional electric about 70 percent efficient. Induction cooking, in contrast, transfers 85 percent to 90 percent of the energy directly into the pan. And because induction cooktops do not generate ambient heat, users can save significantly on cooling bills and have more comfortable kitchens. According to the American Council for an Energy Efficient Economy, operators using an induction cooktop instead of a conventional one can reduce annual energy consumption by10 percent to 20 percent.
Even more than gas stoves, induction cooking allows for very quick and accurate temperature changes. Neil Annis, sous-chef at the four-star Lespinasse restaurant in New York City, which installed a portable four-burner induction range in 1994, says that induction cooking is a professional chef’s tool because you can maintain very precise and even temperatures. And it is so safe you can almost put your hand on the stove without getting hurt. Though the Lespinasse still uses conventional cooktops, Annis adds that he sees worldwide trends in restaurants having cooler kitchens, so he could imagine a bigger role for induction cooking in the future. His only concern is that though the induction cooktop is durable, it may not be as durable as conventional cooktops.
Cost represents another reason induction cooktops have not taken off more. Induction burners can cost a great deal more than conventional stoves — three to four times more expensive, according to some estimates. Stand-alone models ranging from 2 kW to 5 kW cost between $1,500 and $3,000, and an induction oven can cost up to $40,000. But less-expensive induction cooktops are available, including portable, single-burner units that cost between $250 and $350. The lower cost reflects the use of less expensive components and reduced power, in the range of 1.3 kW to 1.5 kW. Smaller units work well at an on-site cooking station outside the kitchen. Another hurdle to acceptance in the U.S. market is the fact that many chefs learn to cook with gas burners, which leaves them unfamiliar with and untrusting of an electric cooktop in which they don’t see the flame.
It will probably be a few more years before the technology becomes widely available and accepted as energy-efficient cooking equipment.
