Harnessing Livestock and Vineyard Residues for Sustainable Energy Production in Portugal

This study investigates the potential of utilizing livestock waste and vineyard residues for sustainable energy production in Portugal. Through the physical and chemical characterization of swine waste, grape seeds and skins, cork powder, sawdust, and biochar, 53 distinct samples, including 11 individual biomasses and their derived mixtures, were analyzed to identify optimal combinations for biofuel pellet production. The best-performing mixture, composed of 50% swine waste, 25% grape seeds and skins, and 25% cork powder, achieved a Lower Heating Value (LHV) of 18.34 MJ/kg and low ash content, qualifying it as a class B pellet. This mixture offers significant energy potential while minimizing environmental impacts. The research also presents three energy valorization scenarios, with the most balanced scenario meeting up to 6% of Portugal’s electricity demand and providing energy savings equivalent to 485,463 tons of oil equivalent (toe) annually. A case study on a “Case Study Farm” in the Douro region, managing 2000 pigs and producing 500 tons of wine grapes annually, demonstrated that implementing the optimal biomass mixture could generate 3854 MWh of heat and 1156 MWh of electricity per year. This could result in annual revenues of EUR 189,258 from pellet sales, covering the initial investment of EUR 283,938 within 6.36 years, with a total surplus of EUR 689,666 over 20 years. These findings highlight the economic viability and environmental benefits of converting agricultural waste into renewable energy, contributing to Portugal’s carbon neutrality and reducing energy dependence.