I do not know what the production cost of torrefied biomass fuel pellets is. It has to include the land use cost, which would include the value of use for crops other than biomass. It has to include seed stock, fertilizer, cost of applying fertilizer, perhaps spraying and irrigation, cost of harvesting, cost of transporting to the plant, chopping, drying, torrefaction, and densifying into pellets. Some of the energy inputs into this process will not be carbon neutral.
I can find no references that state the pellet fuel BTUs per acre of biomass production that goes into making the pellet fuel. I have found references that state that the cost of the torrefied fuel pellets is unknowable because it depends on too many variables to state an all-inclusive cost. My understanding is that there are no full scale production plants making torrefied biomass pellets, but rather, only small scale, laboratory experimental plants.
I believe the biomass carbon neutral fuels will be mandated by regulations, and therefore cost is not a critical factor as it is with normal free-market product development. So, at this time, the main focus of torrefied fuel is to perfect it so it can be used in power generation plants. Cost control will come later as producers compete with each other. But for the time being, carbon neutral fuels do not have to price compete with fossil fuels because they are not substitutable with each other.