Energy Return on Investment (EROI) of the Linseed Cultivation for Biodiesel Production

The aim of this study was to assess the sustainability in terms of energy used compared to that obtained in the cultivation of linseed for oil production (Linum usitatissimum var. Sideral), by using the index EROI (Energy Return On Invested). For this purpose, an experimental field of linseed was realised in the south-eastern Sicilian area (Syracuse province). The field has been cultivated in autumn-winter cycle and no irrigation was carried out. For the entire crop cycle, some agricultural operations have been carried out: tillage (shredding, harrowing and hoeing), sowing, fertilizing, weeding and rolling after sowing and finally harvesting. All cultural practices have been preceded by a selection and adjustment of the machines most suitable. At the end of the cultivation cycle an analysis concerning the energy embodied in machinery and tools utilized, in seed, chemical fertilizer and herbicide was performed. Moreover, the energy embodied in combustible and lubricant oil was computed. In addition, the energy consumption relating to machines and reagents required for the processes of extraction and transesterification of the vegetable oil into biodiesel have been also considered. The total energy consumed for the cultivation of one hectare of linseed from sowing to the production of biodiesel (Input) amounted to 15,217.39 MJ/ha. On the other hand, the estimated energy obtainable from diesel fuel production (Output) amounted to 21,740.03 MJ/ha. The ratio Output/Input gets the index EROI which in this case is equal to 1.43. The result of this index confirms that the cultivation of linseed for the production of biofuels is convenient in terms of energy return on investment.