Since launching the program, the Energy Department has been approached by dozens of companies and expects the number involved in the challenge will grow, Davis said.
Verizon, which joined the challenge, sees workplace charging as an additional step the company can take toward energy efficiency, said John Columbus, a spokesman. The company already uses alternative-fuel vehicles, including electric-powered vans, in its service fleet, he said. The company plans to evaluate which facilities have the greatest number of workers driving electric vehicles and install charging stations where they would get the most use.
Its goal is to double the number of charging stations at its facilities by 2015. Verizon did not disclose how many charging stations it has now, but currently it has none in Maryland.
"This is about enhancing what we're doing for employees who are making eco-friendly choices," Columbus said.
GM has 239 charging stations for its workers at company facilities, mainly in Michigan and California, but also the eight in White Marsh, said Britta Gross, director of advanced vehicle commercialization policy for the automaker. It has hundreds more at Chevy dealerships and for testing purposes at plants, she said.
"Our goal is to keep pace with the purchase of the vehicles by our employees," Gross said.
Gross said strong sales of GM's electric vehicles have shown consumers like the cars. "The sales are starting to look really powerful, so now the question is what more can we do to ready the marketplace to commercialize the electric vehicle. Workplace infrastructure is really important. That is where we're at right now."
GM installed its charging stations at the White Marsh plant about 18 months ago. So far, the spaces are getting limited use. But demand is expected to increase among employees, and GM plans to add four more charging stations to the parking lot of a newly completed plant on site where workers have begun to phase in production of electric motors for the Chevy Spark EV. GM plans to introduce the all-electric car in several weeks.
Tiger, the plant manager, has been driving a Chevy Volt for several weeks and has begun using the charging station. He said he's used about a gallon of gas a week in the hybrid electric.
"It takes 10 seconds to plug it in and unplug it," Tiger said of his Volt. "It's easy and convenient to do. You can't mess it up."