I don't know about the electric company here, but local tree trimmers often have loads of ground wood chips they are willing to deliver for free. Look in the yellow pages and start calling. Otherwise, as WillsC says, they have to pay to dump them. at the landfill.
I do prefer the mulch from the dump however. Neither has viable weed seeds, but the mulch from the dump is finer and decomposes faster. That suits my needs better.