hey Kevin as bad of a reputation as cottonwood has for fuel it can be used.
Just takes very special handling.
Absolutely must take the tree down in full winter dormancy, leaf-off, sap-down. Get it split up an as dry as can asap (hard winter freeze-drying works); then absolutely must keep it out of the snow and rain, under cover.
If allowed to get re-wet then it is wait until the next year after the summer dring season.
Taken down in full sap up and may take you two years to get it air dried. Here - PNW wetside it will rot first before that two years.
Just takes a lot of it.
Leaves a lots of ash.
And burnt too wet - smells like cat-piss to me. Wifie complains mightily.
go for it
J-I-C Steve Unruh