Forests can be exploited for obtaining biomass, which belongs to a bioenergy group with great energy potential that could replace fossil fuels. This article presents a novel procedure to quantify, map and define biomass, which takes into account both environmental and economic issues. With regard to the environment, only the annual growth of tree species is considered, and not the previous stocks. The growth is determined by logarithmic equations through an original procedure supported by a biomass estimator, which represents the amount of biomass generated annually for energy use, and by means of Excel tables, the exploitable biomass values are obtained. Previously, and by using GIS, areas with slopes exceeding 20% are discarded, thus avoiding soil erosion and damage, and in any case that biomass is not extracted for economic reasons. The same procedure is followed, discarding those areas located more than 4 km from forest roads and runways, as transport costs are increased. Finally, those layers with low energy potential are eliminated as well. Therefore, annually selected quantities of biomass can be obtained safely and abundantly by using detailed distribution maps of the resources, and through planning and performing efficient forestry extraction works
