Cooks like the convenience and speed of a microwave oven, but they may wonder how its energy use compares with gas or electric stoves for a task such as heating water for a cup of tea. The answer depends on several variables, including the price of electricity versus gas, and the relative efficiency of the appliances involved.
Typically, though, a microwave is slightly more efficient at heating water than the flame on a gas stove, and should use a little less energy. The reason: the microwave’s heat waves are focused on the liquid or food inside, not on heating the air or container around it.
Given this logic, it is hard to believe that an electric stove-top would be any better, but an analysis by Home Energy magazine found otherwise. It says that an electric burner uses about 25 percent less electricity than a microwave to boil a cup of water.
That said, the difference in energy saved by using one method over another is negligible: choosing the most efficient process might save a heavy tea drinker a dollar or so a year. “You’d save more energy over the year by replacing one light bulb with a CFL (compact fluorescent light bulb),” says consumer advocate Michael Bluejay.
Although a microwave may not save much energy or money over a stove burner when heating water, it can be much more energy efficient than a traditional oven. According to the federal government’s ENERGY STAR program, cooking or re-heating small portions of food in the microwave can save as much as 80 percent of the energy used in the oven.
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