Comprehensive characterization and predictive modeling of Spanish biomass for efficient solid biofuel utilization

Biomass is a promising renewable energy source in Spain, but its heterogeneous composition affects combustion behavior and operational suitability. This study investigates the main properties, and slagging and fouling behavior of 18 representative Spanish biomass samples, focusing on identify significant patterns and differences between woody, fruit and herbaceous groups. Standard tests were conducted for elemental, proximate, and energy analysis, and slagging and fouling indices were calculated to assess operational suitability. Statistical methods were used to identify significant differences in chemical properties and higher heating values (HHV) among the biomass groups. Results showed carbon content between 39.41 % and 55.54 %, hydrogen between 4.64 % and 12.38 %, and sulfur below 0.15 %, minimizing corrosion risks. Ash content varied widely (0.29–22.61 %), with chestnut pellets exhibiting the lowest values and wheat straw the highest. Pistachio shell achieved the highest higher heating value (HHV, 25.13 MJ/kg), while wheat straw had the lowest (14.96 MJ/kg). There was significant variability in major and minor elements, with some samples showing elevated levels of toxic metals like chromium and lead. Non-parametric tests, including both our experimental dataset and 88 additional biomass characterizations from literature, identified significant differences across different biomass groups, with woody biomasses showing more favorable combustion properties. A robust predictive model for HHV estimation was developed using both experimental and literature data, achieving a strong correlation with measured values.