Table 2 reveals that the energy yield
at the most severe torrefaction conditions is 74.1%, this implies,
in turn, that at least 74% of energy in the microalga residue is
retained from torrefaction The contour map of energy yield shown
in Fig. 4 suggests that the slopes of the contours before the torrefaction
duration of 30 min is shaper than those after 30 min.