At California port, some ships plug in to power up

(AP)—In less than a year, many of the diesel-powered cargo ships docking at California ports won't just tie up—they'll also plug in.

The Port of Long Beach, the second-busiest in the U.S., on Monday showed off electrical plug-ins at its wharves that comply with new state guidelines coming in January 2014.

Those guidelines require ports at six major California ports from San Diego to Oakland to eventually require shippers to shut off their diesel and use electricity to run on-board systems for 80 percent of all their port visits—or face stiff fines. The Port of Long Beach will overall spend $200 million outfitting its terminals with power.

Shippers must pay for retrofitting their vessels and must pay for the power—expenses that can cost millions.