Cropping bioenergy and biomaterials in marginal land: The added value of the biorefinery concept

A biorefinery is an integrated pattern of farming and conversion activities capable to provide bioenergy and biomaterials as alternative to fossil-based refineries, increasing jobs and income in rural areas. Considering the need to avoid competition with food production in arable land, non-food cropping on marginal land is being explored worldwide focusing on lignocellulosic crops (“second-generation” substrates). The viability of bioenergy and biochemicals from non-food crops in marginal land of Southern Italy was explored, using Brassica carinata as a test crop. An LCA-consistent, integrated evaluation method, named SUMMA (Sustainability multi-scale multi-method Approach) was applied for joint assessment of material, embodied energy, environmental support (emergy) and economic flows and performance. Two hypotheses were tested: (a) cropping for bioenergy (biodiesel+heat); (b) bioenergy and biomaterials within a biorefinery framework. In addition to biodiesel production from seeds, the first hypothesis assumes the conversion of residues (cake meal and straw) into heat for local industrial use, while the second one is based on a lignocellulose-to-chemicals biorefinery. Cropping for bioenergy provides a small net energy yield with no economic return. Instead, converting lignocellulosic residues to high added value biochemicals definitely improves the process performance from both energetic and economic points of view.