The coffee chain added Duracell Powermats to some stores in Boston last fall, and has expanded the test to Silicon Valley, reports Venessa Wong at Bloomberg Businessweek.
There will be about a dozen of the mats, which are supposed to be more energy-efficient than outlets, in select stores, Wong writes.
The test is expected to expand to stores across the country in the future.
But that doesn't mean Starbucks wants customers to stay for too long.
The chain began covering some electrical outlets at locations in 2011 to discourage laptop users from plugging in and camping out.
Other coffee shops across the country are also trying to keep squatters at bay with anti-laptop policies.