[G-CPTN]

I believe it is possible to harvest timber from plantations before it is mature enough to be used for construction and then replant and repeat the process.
Of course, you need to include the energy expounded to reduce the trees to chips and the fuel used to transport it from the forest to the boiler facility where it is consumed (and the fuel used by the vehicle to return to base).
Where the chips are a by-product of normal forest management the equations are probably beneficial, but when wood-chips have to be 'grown' specifically for use as biomass then costs will rise.

(My one-time employer was buying cotton waste to include in brake linings. The specification for this was carefully written to ensure repeatability, though this reflected the original product.
In due time the supplier raised the price to levels that seemed unreasonable for what had been a waste product. The reason turned out to be that the supplier had discontinued the original process and, in order not to lose the business, had resorted to 'manufacturing' the waste from scratch according to the specification.)
I suspect the same will happen to supplies of 'biomass' as greater use is adopted of this material.
People with log-burning stoves are finding the cost of logs escalating as demand for these is rising.

In Denmark in the 1980s, many 'district heating' systems were established, supplying hot water from a 'power station' that was fuelled with straw from agricultural 'waste'. I don't know what they used when the straw ran out . . .