Residual Agroforestry Biomass–Thermochemical Properties

Abstract

Research Highlights: Biomass from Mediterranean agroforestry vegetation may be a potential source of renewable energy. However, due to the high heterogeneity of this type of resource, the study of its characteristics becomes necessary for its efficient use. Objectives: The aim of this study was to evaluate the thermal and chemical properties of 14 different kinds of agroforestry biomass groups: shrubs, forest, and agricultural wastes. Materials and Methods: The higher heating value (HHV), the elemental analysis (C, H, O, N, S), ashes, mineral elements (Na, K, Ca, Mg, and P), trace elements (Mn, Fe, Zn, Ni, Cu, Cr, and Cd) and halogen elements (F and Cl) were quantified and compared with CEN/TS 147775 and CENS/TS 14961 standards, looking forward to future use for energy purposes, namely through combustion processes, as an alternative to fossil fuels. Results: The shrubs present the highest values of higher heating value (20.5 MJ kg−1), followed by the forest wastes (19.2 MJ kg−1) and the lowest in the agricultural wastes (18.5 MJ kg−1). Concerning the elemental analysis, the difference between groups C, H, and O are very small and not statistically significant, while for N, S and ashes values are higher in agricultural than shrubs and forestry wastes. The same tendency was found for the mineral nutrients. For the trace elements, the lowest content of Mn, Fe, and Zn is found in agricultural, Ni, and Cr content in the shrubs and Cu in the forest wastes. The halogen elements are present in greater amount in shrubs than agricultural and forest wastes. Conclusions: Although the high values of the halogen elements which may raise sintering problems and corrosive effect on metal parts in furnace and boiler, in general the shrubs biomass are those with better characteristics for energy uses, namely through combustion processes.

Waste Recovery through Thermochemical Conversion Technologies: A Case Study with Several Portuguese Agroforestry By-Products

“…The results obtained in the elementary analysis differed slightly and insignificantly from other studies [111][112][113][114][115]. These differences are related to the fact that the elementary analysis could have been determined using different methodologies from the one used in the present work.…”

Torrefied Biomass as an Alternative in Coal-Fueled Power Plants: A Case Study on Grindability of Agroforestry Waste Forms

“…The results obtained in the elementary analysis differed slightly from other studies; however, these differences were not significant [79][80][81][82][83]. It is understood that these results are related to the fact that the elementary analyses in other works could have been determined by using different methodologies from that used in the present work.…”

Maritime Pine, Its Biological and Silvicultural Traits for the Basis of Natural Resources: An Overview

“…Regarding the elementary chemistry contents, several studies have shown that the woody biomass of the P. pinaster, not only contain high heating value (HHV), between 20.15 and 21.60 Mj/kg, but also low undesirable elements contents, such as N, S, K, Na, Ca, Mn, Ni, Cr, Cu, F, Cl, and ashes [171][172][173][174][175][176][177]. Thus, the P. pinaster wood is one of the most suitable types of biomass for energy purposes, namely through combustion processes, given the high HHV and the low risk of sintering and corrosive effect of chloride salts and HCl on metal parts in furnace and boiler, that occurs when the halogen elements (F and Cl) are high [178][179][180][181][182][183][184][185][186].…”