Energy in the bark alright.
Woodgasifier the biggest problem it introduses in much more mineral-ash.
How big of problem?
Depends on the actual mineral ash content of the bark.
That minerals melting/self-sticky (non-technical word for it) temperatures.
Just how excesive of reduction zone hot you are operating at.
The amount of passed trough steam you are allowing.
See? Couple of, three, more factors too. Grate type and activity of that grate. Grate level superficial velocity. Ash minerals interactions.
If the bark is no more than, say, 15-20% of the fuel wood bulk you put in you will probably not have a problem.
100%, all bark burning is 100% problems to operate past…
tree-farmer Steve unruh