Watt Does It Use? The Evolution of Microwave Power Consumption

Learn about the evolution of microwave power consumption. Source: Sidekix Media

Ah, leftover night. Hard to imagine it without that handy microwave! How was this technology discovered? In this piece, we share the evolution of microwave power consumption.

As a device that heats food quickly, the microwave oven offers convenience, ease, and access in ways many people take for granted. As a relatively young kitchen appliance, the microwave oven came to fruition by accident – a fortunate innovation born out of melted chocolate. But how was this technology discovered? How has its power consumption evolved?

From Radars To Chocolate

In 1945, an engineer named Percy LeBaron Spencer, self-taught and working at Raytheon Corporation, was working on magnetrons—vacuum tubes that use magnetic and electron fields to produce short-wave radiation in radar equipment. Spencer’s experiments with magnetrons, a product Raytheon produced en masse as a defense contractor for the U.S. military, made them easier to produce and more efficient. While he earned a Distinguished Public Service Award from the Navy for the achievement, he’s best known for what his activities did to a candy bar in his pocket. 

While the technology behind microwaves has remained the same, the evolution of microwave power consumption over the years has been significant.
A Magnetron and Its Casing. Source: Wikimedia Commons

While working with magnetrons, Spencer noticed the chocolate bar in his pocket had melted. The only potential cause, from Spencer’s assessment, was the radiation coming from the magnetrons. After grabbing a few nearby popcorn kernels, Spencer placed them near the tube – watching as they popped into light, fluffy fare. Spencer’s amazement compelled him to grab a colleague and, together, they stood by as it shook, ultimately exploding in the colleague’s face. 

Spencer began to experiment with the small waves of radiation—microwaves—sending them into metal boxes to see what happened to various kinds of food. Spencer found that microwaves heated food much more quickly than a conventional oven, albeit at different rates for different substances. By the next year, Spencer patented the technology. And in 1947, Raytheon introduced the first microwave oven to consumers. 

A demo model along the way in the evolution of microwave power consumption.
A Microwave Demo Model From 1956. Source: Wikimedia Commons

Microwaves Enter The Marketplace 

The original microwave oven went to a restaurant in Boston, Massachusetts. There it stood more than 5 and a half feet tall. It weighed 750 pounds, cost $5,000, and used three kilowatts of power. Roughly the equivalent to what it would take to power an entire home in the United States for two and a half hours today! Clearly there has been significant evolution in microwave power consumption since then. Cooling the magnetrons required a continuous flow of water, prompting the installation of an elaborate plumbing system at the restaurant. 

At first, the microwave oven was not a success. Its size, expense, and lack of reliability prompted Raytheon—and its competitors—to revamp the design. It was also an energy hog. The evolution of microwave power consumption had a long way to go.

During the early 1950s, microwaves cost between $2,000 and $3,000. That cost only come down to about $1,300 when Tappan debuted its first home model by 1955. Still cost prohibitive to average consumers, it wasn’t until the next decade that Raytheon produced a countertop version of a microwave oven. Raytheon, who had introduced the “Radarange” in 1947, introduced a 100-volt version of their product to the marketplace in 1965. Produced by their subsidiary Amana, the microwave oven was streamlined for domestic use and cost about $500. By the early 1970s, microwave ovens were growing in popularity and prices continued to fall. 

An old school microwave from Radarange.
A Radarange from 1971. Source: Wikimedia Commons

As Prices Fall And Efficiency Rises, Microwaves Take Over Kitchens

The decades that followed included several important steps in the evolution of microwave power consumption. Litton Industries, Inc. introduced two microwave ovens in 1972, both under $400. By 1975, microwave ovens were outselling gas ranges. In 1986, 25% of households in the US possessed the appliances. And according to the Bureau of Labor Statistics, over 90% of US households owned a microwave oven by 1997.

The prevalence of microwave ovens can be seen in developed countries around the world. Canada and France have all seen exponential growth in microwave oven ownership during the late 20th and early 21st centuries. In less-developed locations, there have been comparable increases, although rates of ownership remain far lower. 

Kitchen Appliances: How Do Microwaves Stack Up?

As microwaves became more popular and affordable, they increasingly came equipped with features that allowed for power level and temperature adjustments. Users could not only cook meals, but they could defrost stored foods or reheat leftovers. Similarly, microwave ovens heat food by inputting energy into the food itself. So there’s no loss in energy akin to what would be seen with gas or steam heat. 

The evolution of microwave power consumption has been significant. A modern microwave oven uses between 500 and 1300 watts while heating, depending on its size. Toaster ovens use a comparable amount of wattage, but both provide far more efficiency than a conventional oven. According to ENERGY STAR, using a microwave instead of an oven can reduce energy consumption by 30 to 80 percent. Microwaves also outperform toaster ovens in overall energy efficiency, in large part because the latter produces excess heat lost in the cooking process.

However, as with many household appliances, most people leave their microwave ovens plugged in all of the time. This means that they draw constant energy as they stand at the ready. Because many microwaves include digital clocks, standby mode can actually consume more power than heating and defrosting food! Microwaves consume roughly 35 kilowatts annually while in standby mode. Still less (although not by much) than the 39 kilowatts used by combination ovens. 

Microwave ovens receive praise for the benefits they provide – speed, ease of use, and even nutritional benefits. That said, many still have concerns about their safety. So while no ENERGY STAR microwave label exists, there are many regulations in place to regulate performance and safety of the appliance. 

Know Your Numbers

To find out more about how much energy your specific microwave uses, use the WattDoesItUse power consumption guide. And if this post has inspired your inner history buff, check out our ongoing series featuring the evolution of your household appliances as well as their power consumption:

For more fun facts and specific energy saving strategies straight to your inbox on the first of every month, subscribe to the blog here.

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