An Evaluation of the Energy Potential of Agri-Food Waste: Green Residues from Tomato (Solanum lycopersicum L.) and Shea Nutshells (Vitellaria paradoxa)

Addressing the agricultural challenges of agri-food waste accumulation, this study assessed the energy potential of green residues from tomato (Solanum lycopersicum L. cv. Kmicic) plants in different fertilizer configurations and Shea nutshell (Vitellaria paradoxa) waste. Two key parameters were compared: (I) Calorific Value (CV), representing thermal treatment, and (II) Biogas and Biomethane production potential, representing biochemical treatment. Potential was estimated using the Baserga method and the fermentable organic matter (FOM) method. Additionally, the effect of tomato fertilization on the elemental composition and energy potential of its waste was analyzed. Shea waste showed better properties for both thermal and biochemical utilization, with a CV of 16.29 MJ/kg. The Baserga and FOM methods of estimation showed that the highest Biogas yields from Shea waste were 504.18 and 671.39 LN/kg DM, respectively. Among fertilized tomato residues, volcanic tuff fertilizer additive resulted in an optimal C/N ratio (28.41) and a high Biogas production potential of 457.13 LN/kg DM (Baserga) and 542.85 LN/kg DM (FOM). These findings demonstrate the feasibility of employing tomato waste and Shea waste as promising feedstock for energy production.