Vineyard Pruning Extracts as Natural Antioxidants for Biodiesel Stability: Experimental Tests and Preliminary Life Cycle Assessment

Evaluationof the sustainability of using vineyard pruningwaste extracts as natural additives for biodiesel production is discussed,along with comparative impacts with butylated hydroxytoluene. The control of the oxidative stability of biodiesel andblendsof biodiesel with diesel is one of the major concerns of the biofuelindustry. The oxidative degradation of biodiesel can be acceleratedby several factors, and this is most critical in the so-called secondgeneration biodiesel, which is produced from low-cost raw materialswith lower environmental impacts. The addition of antioxidants isimperative to ensure the oxidative stability of biodiesel, and theseare considered products of high commercial value. The antioxidantscurrently available on the market are from synthetic origin, so theexistence/availability of alternative antioxidants of natural origin(less dependent on fossil sources) at a competitive price presentsitself as a strong business opportunity. This work describes and characterizesa sustainable alternative to synthetic antioxidants used in the biodieselmarket developed from extracts of vineyard pruning waste (VPW), whichare naturally rich in phenolic compounds with antioxidant properties.A hydrothermal extraction process was applied as a more efficientand sustainable technology than the conventional one with the potentialof the extracts as antioxidant additives in biodiesel evaluated inRancitech equipment. The VPW extract showed comparable antioxidantactivity as the commercial antioxidant butylated hydroxytoluene (BHT)typically used in biodiesel. The stability of the biodiesel is dependentfrom the amount of the extract added. Further, for the first time,the assessment of the environmental impacts of using natural extractsto control the oxidative stability of biodiesel in the productionprocess is also discussed as a key factor of the process environmentalsustainability.