Apparatus for biomass torrefaction which includes a serpentine elongated housing, the housing having three generally U-shaped axial portions having first and second axial extremities and an intermediate section, the first and second axial extremities are disposed in normal use at a higher elevation than the first and second axial extremities, the intermediate section being configured for holding a liquid. Other forms of the invention include the method for biomass torrefaction which includes providing a quantity of biomass, providing a liquid heat transfer fluid, providing at least a first housing for holding the heat transfer liquid, elevating the temperature of the liquid heat transfer liquid, heat treating the biomass by passing it through the heat transfer liquid in the first housing at a temperature and duration sufficient to accomplish torrefaction of the wood. In some forms of the method, the process further includes the step of pelletizing the biomass prior to performing the treating step.