I've once tried suspending my PowerBook and it ran out of power on the battery. Bummer.
But you can actually hibernate your Mac, just like any PC based laptop. Just follow the instructions in the link above, it worked for me and my February 2005 vintage PowerBook, even with secure virtual memory enabled. Just make sure to read and follow the instructions carefully, including the parts about recovering from mistakes.
Author M. G. Liebach
LastMod 2016-05-01 (9fc4632)