Energy Blog: Cooking With Gas … and Electricity

There is a lot to be said for seasonal foods. In our household, we eat a lot more fresh fruit in the summer and more baked meals in the winter. Obviously, availability plays a factor—the local farmer’s market is a veritable cornucopia right now, with each stand spilling over with just-picked delicacies.
 
But there is more to it than that. In hot weather, no one in my household wants to run the over at a high temperature for an hour or more to bake a loaf of bread or roast a chicken. The heat from that long cooking added to the elevated summertime temperature would be unbearable. To avoid the paradox of adding Btus of heat in the kitchen while trying to expel them from other parts of our household, we wind up ordering in, dining out, or microwaving leftovers a lot more in July and August than we do in December and February.
 
Every five years, the U.S. Energy Information Administration conducts a wide-ranging survey of household energy use called the Residential Energy Consumption Survey (RECS). Results from the 2020 survey are slowly being released, with the final report scheduled to be released next year.  One recently published slice of data looked at food preparation. Some of the results were surprising.

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For instance, in spite of the growing number of single-person households and the stereotype of singles eating cold pizza for days on end, some 79 percent of households cooked at least one hot meal a day on average, with just under 20 percent cooking three times a day. There was some stark regional variation, according to the EIA press statement: 
 
“Households in the Pacific Census Division and the New England Census Division were generally more likely to cook hot meals at home daily,” the press release stated. “For example, in Washington (in the Pacific Census Division), 88 percent of households prepared at least one hot meal each day, and in Maine (New England Census Division), the share was 86 percent. Households in the South, such as Alabama (69 percent) and Louisiana (68 percent), were less likely to cook hot meals daily.”

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Another regional variation was found in the energy source for ovens and range tops. In spite of the large natural gas resources found in Texas and the Appalachia region, the four states with the highest percentage of gas-fueled stoves were California (with 70 percent), New Jersey, New York, and Illinois. At the other extreme, states that had fewer than 20 percent of households using gas stoves include North Dakota, South Dakota, Maine, Vermont, New Hampshire, and the entire southeast aside from Georgia.
 
That energy use adds up. According to one analysis from the Michigan utility DTE, a roast or slow-simmer chili would consume about 3 kWh of electricity in an electric over or stovetop. A slow cooker, which applies less heat over a longer period of time, would consume only 0.8 kWh. The 2020 RECS data doesn’t break out slow cooker use by region, but in 2015, 38 percent of households in the northern Mountain region (think Montana and Idaho) and 36 percent of households in the South Atlantic states used one once a week.
 
One kitchen appliance that is nearly universal is the microwave oven. Around 97 percent of U.S. households have at least one—and there are more households that have two or more than households that have none. The penetration of microwaves into American kitchens is an overall energy saver. As this recent analysis from CNET concluded, “A microwave uses significantly less energy than either a gas or electric oven. To use your microwave for one hour every day would cost you about half the total energy of a natural gas oven and 60% less than an electric oven.”
 
What’s more, because most of the energy goes into heating the food rather than the air, microwaves could help keep kitchens cooler than doing similar cooking with a stove or over. I haven’t mastered the art of microwave cookery—I’m more of a stovetop and broiler guy myself—but maybe I should try to get the hang of it before next summer.

Jeffrey Winters is editor in chief of Mechanical Engineering magazine.