In this work, the waste from 10 forest species of Cantabria have been characterized from the point of view of energy. The studied species were the waste of. Eucalyptus globulus, Eucalyptus nitens, the hybrid E globulus x E nitens, Eucalyptus viminalis, Eucalyptus smithii, Eucalyptus regnans, Eucalyptus gunni, Fagus sylvatica, Quercus robur and Pinus radiata. The leaves were the tree part with the greatest NCV (net calorific value) in all the species. The best results were obtained for the leaves of E smithii (24.5 MJ/kg), F. sylvatica (22.8 MJ/kg) and E. nitens (22.5 MJ/kg), at minimum moisture. Values around 65,000 MJ per hectare and year were obtained for the Eucalyptus spp., and 47,000 MJ per hectare and year for the P. radiata. The economic-environmental analysis revealed that the use of the forest waste for energy production would mean an approximate annual income of 8 ME and would fix the annual CO2 emitted by the Cantabrian industries at 78%. (C) 2007 Elsevier Ltd. All rights reserved.