The OLinWASTE project is a €4 million EU initiative involving ten partners from six European countries. Its goal is to develop a smart zero-emission biorefinery for converting olive mill waste into high-value products including plant bioimmunostimulants, biopesticides, biofertilisers, bio-based plastics, and bioenergy. The University of Surrey is leading the development of a system digital twin (SDT) to enhance sustainability and efficiency in the biorefineries.