Renewable energy in Sicily: sizing of a plant for Biogas production and energetic assessment of Biodiesel production from oilseed crops

The topics of the PhD thesis have the objective of assessing three different aspects of the renewable energy sector: i) sizing of plants for the production of biogas through anaerobic digestion of agricultural waste and by-products of agro-industries; ii) evaluation of the mechanization and energetic aspects of the cultural practices and the harvesting of oil crops; iii) assessment of the sustainability of biodiesel production from Linum usitatissimum L. and Camelina sativa, with particular attention to the pressing of the seeds and the trans-esterification of vegetable oils. As regards the first topic the aim of the work was to develop a procedure for verifying the availability of biomass for biogas production in a territory of Ragusa province (south-east Sicily) and to calculate the power of a co-generator engine for a biogas plant taking in consideration the quantity and the biogas yields of this biomass. In order to assess the quantity of biogas and electricity production per year two hypothesis have been evaluated. The first examines the available biomass for only some months of the year and the second examines the available biomass all the year round. With regard to the second and third topic, the purpose of the research activities was primarily concerned with the following aspects: to calculate the quantitative parameters of mechanization such as work capacities, unitary time, fuel consumptions of farming practices to calculate the qualitative parameters of the work done during the seeding and harvesting such as the product obtained in respect of the product expected; to assess the cultivation sustainability of unconventional oil crops as Linum usitatissimum L. and Camelina sativa, in south-eastern Sicily for biodiesel production in terms of energy used compared to that obtained, by means of EROI index; to analyse the mechanical pressing of seeds in terms of a) vegetable oil yields and chemical characteristics; b) machine work capacity; c) energy consumptions; d) characterization of the operating parameters of the screw press plant; to evaluation the trans-esterification process in terms of a) yield into biodiesel by varying the temperature of the process; b) yield into biodiesel by varying the amount of methanol and potash; c) physical-chemical characteristics of FAME according to EN 14214