The U.S. Department of Transportation on Tuesday said it will add 500 charging stations at its buildings nationwide over the next decade to serve employees who drive electric-powered vehicles to work.

In making the announcement, the DOT becomes the first Federal agency to sign on to the Department of Energy's Workplace Charging Challenge, an inititiave that 240 other U.S. employers have signed onto and agreed to provide places for employees to plug in while they are at work.

Four Minnesota companies that are part of the challenge have or are providing charging stations for employees: Xcel Energy, 3M, Great River Energy in Maple Grove and General Electric in Eden Prairie.

Another firm, Connexus Energy in Ramsey, Minn., provides EV Chargers for its employees and was one of the first in the state to install a DC fast charger on campus, said spokeswoman Samantha Neral. It is not part of the Workplace Charging Challenge.

For now, most drivers of electric vehicles charge up at home, "but accessing chargers at work can help owners double their vehicles' all-electric daily commuting range," the Department of Energy's website says.

The DOT's entrance into the charging challenge comes as sales of plug-in electrified vehicles (PEVs) have surpassed the 1 million sales worldwide,. according to Hybrid.com. It also supports President Obama's "Ev Everywhere Grand Challenge," which will enable the United States to produce plug-in electric vehicles that are affordable for the average American family by 2022.