## 4 Conclusions  
This study explored the potential of utilizing wine pomace and distillation stillage, by-products of the wine industry, as sustainable sources for pellets production. The findings indicate that both materials exhibit promising characteristics for energy recovery, each with distinct advantages and challenges. The drying behavior of wine pomace and distillation stillage showed effective profiles, reaching stable states with minimal moisture content. Wine pomace exhibited a slightly higher mass loss than distillation stillage, which showed a lower moisture content (5.454%), and ash content (3.762%) compared to wine pomace, making it a preferable candidate for pellets due to the reduced residue after combustion. However, wine pomace had higher volatile matter content (62.695%), suggesting a more intense initial energy release during combustion. Distillation stillage has higher carbon (54.928%) and hydrogen content (6.725%) than wine pomace, correlating with a higher heating value and energy output. This was confirmed by the calorimetric analysis. However, distillation stillage also had higher sulfur content (0.153%), potentially leading to more SOx emissions. The results underscore the viability of wine pomace and distillation stillage as alternative bioenergy sources, contributing to waste valorization and sustainability in the wine industry. Future research should focus on optimizing pretreatment processes to address the high ash content in both biomasses, improving the overall yield and consistency of bioenergy production. Investigating methods to reduce sulfur content in mixed biomass pellets can enhance their environmental compatibility and reduce potential equipment corrosion and environmental pollution. Conducting pilot-scale studies to validate laboratory findings and assess the economic feasibility of large-scale implementation of bioenergy production from these wine by-products is crucial. Furthermore, exploring additional value-added applications of grape pomace and distillation stillage in pharmaceutical, cosmetic, and agricultural sectors can promote a circular economy and reduce reliance on fossil fuels. Writing--Original Draft: M.O., R.T. and B.M.M.T. ; Investigation: M.O. and B.M.M.T. ; Formal analysis: M.O. and B.M.M.T. ; Writing--Review & Editing: M.O. and A.D.S.B. ; Conceptualization: A.D.S.B. ; Methodology: A.D.S.B. ; Data Curation: A.D.S.B. ; Validation: A.D.S.B. ; Resources: A.D.S.B. ; Supervision: A.D.S.B. All authors have read and agreed to the published version of the manuscript. This research received no external funding. This study explored the potential of utilizing wine pomace and distillation stillage, by-products of the wine industry, as sustainable sources for pellets production. The findings indicate that both materials exhibit promising characteristics for energy recovery, each with distinct advantages and challenges. The drying behavior of wine pomace and distillation stillage showed effective profiles, reaching stable states with minimal moisture content. Wine pomace exhibited a slightly higher mass loss than distillation stillage, which showed a lower moisture content (5.454%), and ash content (3.762%) compared to wine pomace, making it a preferable candidate for pellets due to the reduced residue after combustion. However, wine pomace had higher volatile matter content (62.695%), suggesting a more intense initial energy release during combustion. Distillation stillage has higher carbon (54.928%) and hydrogen content (6.725%) than wine pomace, correlating with a higher heating value and energy output. This was confirmed by the calorimetric analysis. However, distillation stillage also had higher sulfur content (0.153%), potentially leading to more SOx emissions. The results underscore the viability of wine pomace and distillation stillage as alternative bioenergy sources, contributing to waste valorization and sustainability in the wine industry.