Despite their central importance to our daily lives and the energy system, electric motors receive relatively limited direct attention from policy makers. Even simple questions of how many motors exist in the economy and how much energy they consume seem to be missing from our discourse. Compare this treatment with the prominent lightbulb efficiency standards from the Energy Independence and Security Act of 2007 or the fuel economy standards for automobiles.
This neglect can create subtle headwinds to motor innovation or to investments in motor maintenance and efficiency—measures that potentially save money and make our electric grid easier to operate. While electrical generation sources—such as steam power plants, wind turbines, and solar panels—are counted carefully and monitored with sub-second precision, knowledge of how many electricity motors are deployed or how much energy they consume is limited to periodic surveys and estimates. The result of this inattention is we are left with an imprecise and anecdotal rule of thumb: Electric motors use around 50 percent of all electricity produced.
At present, most electric motors draw energy directly from the electricity grid. The North American grids are maintained at 60 hertz, meaning the alternating current that flows through transmission and distribution wires oscillates 60 times per second. Larger motor systems and the rotational inertia that accompany them play an important role in helping slow declines in frequency when the grid is under strain. As electric vehicles (EVs) become more common, the share of electricity used by motors will also increase, but since this new load is operated behind a battery, grid stability won’t be impacted in the same way as if new industrial motors were added directly to the grid.
The total amount of electrical energy that ends up in EVs is still very small in the United States, despite the recent uptake of electric or hybridized drivetrains in the past five years. A typical EV might travel 3 miles per kWh of electricity, the latest available figures from 2020 show that at-home EV charging used 3.2 TWh—roughly a third of what was used for America’s hot tubs (9.5 TWh). However, automakers have indicated that in the coming decades combustion engines will no longer be available for light-duty vehicles, meaning that electric motors will become a more substantial part of overall transportation-related energy consumption.