In this paper are reported changes in heat values (HV) with the season
s of the year for the different species which make up most of the unde
rgrowth in Galicia (Spain). Knowledge of these values is essential whe
n evaluating the possibility of exploiting the energy content of the b
ushes in energy-recovery plants.The calorific values of combustion at
25 degrees C were measured by static-bomb calorimetry for forest resid
ues originated in activities related to afforestation, firebreaks, for
est clearing etc. From combustion experiments, the mean calorific valu
e was found to be close to 19000 kJ kg(-1), similar to the calorific v
alues of municipal solid waste (MSW). For this reason, these forest re
sidues can be used as an additional fuel to be added to MSW in energy
recovery plants and this will also minimize the risk of forest fires.