I had a friend who went to Mississippi and Louisiana for two years to help with the clean-up from Hurricane Katrina as a truck driver. He told me at the dumping sites the wood debris was taken to be used for two main purposes;
(1) to be chipped into mulch
(2) to used for making charcoal.
I never really thought it as feasible, but the wood is free.
I guess that is why some brands have nails and pieces of plywood in them all the time.
Humphrey's DownEast Beast W/BBQ Guru