**1. Introduction**

In the past few years, a significant increase in the demand for agricultural species for biofuels production that compete with the food and feed sectors have been reported, such as, starch-rich crops (corn, wheat, barley, oats as well as tubers and roots such as sweet potatoes, yams, cassava and potatoes), sugar-rich crops (sorghum, sugar beet and sugar cane) and oil-rich crops (sunflower, soybean, coconut, palm, sesame and olive), increasing the pressure on suitable soils for agriculture [1]. To avoid the risk of conflicts on land use due to competition for food and feed, it is necessary to limit and even prohibit the use of land presenting high carbon stock for the implementation of non-food crops or directed to the production of energy. The greater relevance is to utilize uncultivated land (or wasteland) and degraded soils that are not implemented in conventional agriculture [2].

Portuguese Decree-Law n. 152-C/2017 (created from European Directive 2015/1513), highlights the need to reduce the use of conventional biofuels obtained from food raw materials and from species grown on agricultural land or land with a high organic load. Another principle is to encourage the promotion, production and use of advanced biofuels for energy production obtained from waste, wood-pulp materials (forest biomass including their waste), non-food cellulosic material such as waste derived from agricultural food species (straw, stover, husks and shells) or grassy species (miscanthus, ryegrass, arundinaria gigantean, panicum), waste from human and animal food sector and, finally, algae [3]. These types of feedstocks can be used in thermochemical conversion technologies such as gasification, combustion, pyrolysis and hydrothermal liquefaction and in biochemical conversion technologies such as fermentation for the production of bioethanol, biogas, biohydrogen or biodiesel.

Portugal is a country characterized by 39% of forests, 26.3% of agriculture-based land, 12.4% of bush and 8% of agroforestry systems, with the remainder corresponding to pastures (6.5%), artificial territories (5.1%) and other (2.7%) (data obtained from the Portuguese Carta de Ocupação do Solo or Land Use Mapping (COS 2015) for the continental territory, developed by the Direção-Geral do Território, DGT) [4]. Considering those values, it can be said that Portugal is a biomass producer because most of its territory (more than 85%) is covered by vegetation, utilized in several economic sectors, including the production of biofuels and others forms of energy such as electricity and heat [4]. In Portugal, the installed power derived from biomass in July 2015, with and without cogeneration, was 474 MW, including those obtained from the use of agricultural waste, forest waste, and pulp and paper industry waste [5]. According to Ferreira and colaborators (2017) [6], the total biomass resources potential estimated for the country in 2017 was of 42,489.7 GW h/year, and Portugal intends to have 60% of its generated electricity coming from renewable resources by 2020, in order to satisfy 31% of its final energy consumption by the same year. However, the current biomass status is not enough to reach this target. Energy crops and microalgae are considered a good option to cover the existing deficit. However, in Portuguese territory the production of dedicated crops for energy is negligible and more studies and investment in R&D are needed, and the same applies for microalgae production for energy.

In order to identify suitable areas for the implementation of energy crops and microalgae, it is necessary to take advantage of geographic information science through the ArcGIS software of the Geographic Information System (GIS), developed by ESRI (Environmental Systems Research Institute). It is characterized by a multiplicity of functions such as the capture, collection, measurement, storage, organization, modeling, editing, analysis, treatment, mapping, sharing and publication of data with relevant information of potential zones for the planting of energy crops and microalgae production according to certain parameters, such as the type of area, soil, water needs and edaphoclimatic conditions. For these reasons, geo-referencing is fundamental and must be integrated in studies that promote the development of biomass for energy, so that productivities can be accurately estimated to help model the potential of bioenergy production.

The main objective of the Portuguese Project "CONVERTE-Biomass Potential for Energy" was to support the transition to a low-carbon economy, identifying the existing and still to be explored biomass typologies in mainland Portugal, namely urban waste, industrial waste (such as agro-food waste including sludge from wastewater treatment plants) and energy crops and microalgae. Therefore, the aim of this work is to present the design and construction of georeferenced databases (mapping) in mainland Portugal to evaluate areas/soils for the implementation of energy crops, areas/soils/waters for microalgae production and areas of cultivated agricultural/silvicultural species (including their residues) with energy potential. To our knowledge, no such studies have merged these three types of biomass in the same work. Moreover, in the construction of those maps, the focus will be on the cultivation of energy crops and microalgae production with low indirect land-use change-risk, taking into account also its sustainable use (environmental, social and economical).
