EVALUATION OF BIOMASS AVAILABILITY FOR BIOGAS PRODUCTION AT REGIONAL LEVEL BIOMASAS PIEEJAMĪBAS IZVĒRTĒJUMS BIOGĀZES RAŽOŠANAI REĂIONĀLĀ LĪMENĪ I.Dzene, F.Bodescu Keywords: biomass, biogas feedstock, biogas potential, GIS modelling, organic waste, regional level Introduction Considering the actual state of global needs for all forms of energy, assessing the potential of organic wastes that could be processed to obtain biogas, is one of the main tasks for a region’s successful socio-economical development. The availability and assessment of natural resources, renewable or non-renewable, is a complex issue and the assessment of biomass for energy production is no exception. A plethora of studies have been carried out in order to evaluate the biomass potential for energy use [1,2,3,4]. The use of currently available data in integrated deterministic modelling approach allows the assessment of total biomass availability. Results obtained depend on the different aims of the studies and are affected by the different assumptions made. This study is not an exception: it has a series of assumptions, and a series of limitations. The conceptual approach of combining the benefits of relational database and Geographical Information Systems (GIS) modelling was tested in two eastern European countries – in Latvia and Romania. This methodology was applied for biomass potential studies in the framework of the European Commission Intelligent Energy Europe program project “BiG>East”, assessing the theoretical biomass potential in six Southern and Eastern European countries. The existing methodology could be further developed in order to evaluate the technical feasibility of selected biomass; however, this is the task of future research and is not considered in this evaluation study. Methods used Based on the literature [5,6,7,8], feedback from farmers (their existing local practices) and the current use of by-products, local models were developed to evaluate the use of agricultural and waste products and to calculate the feedstock availability for biogas production in each region. To evaluate the biomass potential, different sources of information were used, e.g., EUROSTAT data were used to assess land use, agricultural production yields, population and tourism potential, as well as national statistics were used for the evaluation of agricultural wastes (from primary and secondary production), sewage sludge and food-processing wastes. Finally, biomass availability was calculated at the regional level, indicating the regions with low, medium and high potential. The overall approach of assessing biomass resources was first to estimate the quantity of material generated from municipal waste and agricultural practices in each of the research areas. In the next step, the quantity of material that could be recovered from these practices, taking into account the technical and environmental constraints associated with other site factors, was evaluated. Data sources for land management included monitoring and reporting information from national and European regional statistical institutions. The amounts of annually generated agricultural residues were calculated based on the annual average area of hectares harvested, yield values per hectare, and estimated residue generation factors [9,10]. In order to calculate the amount of biomass resulting from animal