Mapping optimal locations of forest biomass for solar-powered biorefinery plants in the Mediterranean region

This study assesses forest aboveground biomass (AGB), solar irradiation, and road connectivity to determine the optimal number and distribution of solar-powered biorefinery (SPB) plants in three Mediterranean countries. AGB availability was evaluated by applying spatial restrictions (forest cover, elevation, slope, and soil type) and combined them into a multi-criteria analysis (MCA). Subsequently, two of these factors, canopy cover and slope, along with three additional ones, effective AGB, vegetation productivity, and road proximity, were weighted to determine a suitability score, normalised from [0-1] and aggregated to 1 km resolution. Suitability maps were integrated into a decision support system to cluster suitable areas and identify optimal host cities. High suitability pixels (values > 0.5) were assigned to nearby (250,000 inhabitants). A final index, weighted inversely by distance, was then calculated to assign a total suitability score to each city. A balance between selecting too few cities, which limits AGB availability due to transportation costs, and selecting too many cities, which adds no marginal AGB relative to the estimated costs of building a SPB plant, was found applying a simulated annealing method to a cost-function. A spatial database was developed for Spain, Italy and Greece that includes: (i) raster suitability maps in a geographic coordinate system at ∼1 ha pixel resolution, (ii) raster suitability maps in a cartographic coordinate system at 1 km resolution, and (iii) a vector dataset of high suitability points with the five attributes used in the MCA.