The increasing importance of biomass energy in Wallonia has led the author of the article and the ensuing research to estimate, as a first stage, at the regional and municipal levels, the gross natural energy potential of three sources of biomass that have an impact on the non-built space and the regional planning: energy crops (or cultivated biomass), livestock manure and wood energy. Analysis of these potentials makes it possible both to describe the particularities of their spatial distribution on the Walloon territory and to distinguish the factors that influence that distribution. As a second stage, the author offers several original scenarii – these also resulting from the study in question – of biomass energy development in the agricultural space, on the basis of factors identified in the first part. The results are compared with the European objectives and with those of the PMDE3. This article’s ambition is to propose lines of thinking and orientation of the Walloon regional planning in view of the envisaged development of biomass energy (particularly energy crops and livestock manure) by taking account of the current characteristics of its non-built space.