I have about quart of soup left over. Is it more efficient to reheat it on my gas range or in my microwave?
—Paul, in Kalamazoo, Michigan
A microwave is a lot more efficient way to reheat than a stovetop, partly because a stovetop wastes a fair amount of heat. According to the EPA, the microwave uses 80 percent less energy when heating up relatively small amounts. Although the microwave needs a lot of electricity, it’s a relatively short burst of power. As the immortal Yogi Berra might put it, “A watched pot never boils, but it boils quicker in a microwave.”
Of course you can make regular gas or electric cooking somewhat more efficient by matching the size of the burner to the size of the pot, and, well, duh, keeping a lid on unless the recipe forbids. The EPA, for example, warns that using a six-inch pot on a eight-inch burner can waste a goodly portion of a burner’s heat.