In this work a power characterization of adult stages of the species Eucalyptus globulus and Eucalyptus nitens has been made. The study has been made in six different plantations in Cantabria (North coast of Spain), located at a latitude 43º28'N, and a longitude 3º48'W. The region has approximately 30,000 Ha dedicated to the growth of Eucalyptus. After the collection of samples they were weighed, analyzed and burned, resulting a mean net calorific value of 17,384 kJ/kg and 17,927 kJ/kg for the E. globulus and E. nitens, respectively. Finally, the economic and environmental consequences that the crop of these species would suppose for the region of Cantabria were analyzed.