Potential biogas production from agricultural by-products in Sicily: a case study of citrus pulp and olive pomace

Abstract

Renewable energy sources represent a suitable alternative to conventional fossil fuels, due to the possible advantages in terms of environmental impact reduction. Anaerobic digestion of biomasses could be considered an environmental friendly way to treat and revalorise large amounts of by-products from farming industries because it ensures both pollution control and energy recovery. Therefore, the objective of this study was to define a methodology for evaluating the potential biogas production available from citrus pulp and olive pomace, which are suitable agricultural by-products for biogas production. In the first phase of the study, the spatial distribution of both olive and citrus-producing areas was analysed in Sicily, a geographical area of the Mediterranean basin highly representative of these types of cultivation. Then, a GIS-based model, which had been previously defined and utilised to evaluate the amount of citrus pulp and olive pomace production, was applied to this case study. Based on the results obtained for the different provinces of Sicily, the province of Catania was chosen as the study area of this work since it showed the highest production of both citrus pulp and olive pomace. Therefore, a further analysis regarded the quantification of olive pomace and citrus pulp at municipal level. The results of this analysis showed that the total amount of available citrus pulp and olive pomace corresponded theoretically to about 11,102,469 Nm3/year biogas. Finally, the methodology adopted in this study made it possible to identify suitable areas for the development of new biogas plants by considering both the spatial distribution of the olive and citrus growing areas and the locations of the existing processing industries.

A GIS‐based spatial index of feedstock‐mixture availability for anaerobic co‐digestion of Mediterranean by‐products and agricultural residues

“…In previous work, where only two by‐products, i.e. olive pomace and citrus pulp, were considered as biomasses for biogas production, the geographical areas of five municipalities within the province of Catania (i.e., Acireale, Calatabiano, Caltagirone, Mascali, and Scordia) resulted in the most suitable location for planning the sustainable development of new biogas plants with regard to the minimization of transportation costs for feedstock supply and logistics, which is relevant for the reduction of economic, social and environmental impacts of biogas plants.…”

“…Approximately 3.9 million metric tons of biomass residues are produced annually by Sicilian agriculture, and include wastes from food processing (i.e., citrus pulp, olive pomace, and whey), livestock wastes (mainly from cattle), crop residues, some energy crops, and agricultural processing residues (waste fruit and vegetables) . Among these, wastes from food processing and livestock production account for more than 60% of the total biomass produced (Valenti et al ., unpublished) . Food wastes and animal manures are very good feedstocks for anaerobic digestion to produce biogas and liquid/solid fertilizers (Valenti et al, unpublished) …”

“…Previous research studies have demonstrated that the province of Catania was the Sicilian province with the highest potential production of citrus pulp and olive pomace. Moreover, it was found that the six most abundant biomasses available in Catania were citrus pulp, olive pomace, whey, poultry litter, cattle manure, and corn silage.…”

“…In this regard, a first GIS modeling approach was used to develop spatial indices suitable to assess citrus pulp and olive pomace availability in Sicily, which is the largest agricultural area in Italy with more than 6 million tons per year of agricultural commodities . The most productive areas of these two types of by‐products were also analysed and a second GIS modeling approach was combined with techno‐economic assessment and economic sensitivity analyses to facilitate the development of a biogas industry in Sicily . Four geographical areas were located for new biogas plants by minimizing transportation costs during the feedstock supply and logistics phase .…”

Post-Occupancy Evaluation of Buildings for Sustainable Agri-Food Production—A Method Applied to an Olive Oil Mill

“…Only a careful and correct design of these buildings enables to pursue sustainable food products [1,2].…”