Torrefaction is what happens to coffee beans when they are roasted.
It is not charcoal production, we are not talking about Biochar.
The purpose of torrefaction is that it converts fibrous hydrophilic bulky perishable wood into; energy dense, easily handled, easily ground, safely storable, non perishable hydrophobic biocoal.
The energy density increases are very important and are the reason why torrefaction should be done at wood waste source. With a 6 to 9 fold (or more) increase in energy density from raw waste to finished product.
There are two other important reasons why torrefaction is the only sensible process for making wood biomass feasible;
- The torrefaction process produces enough energy as heat and fuel gasses to run the process.
- Torrefied wood is much safer to store and handle than raw wood pellets. Raw wood pellets have an inherent Spontaneous Combustion risk and also pose an increased asphyxiation hazard.
It is all well researched, documented and in the public domain