# Use of Invasive Acacia Biomass to Produce Biochar and Solid Biofuels
## 4 Conclusions  
The yields obtained in the processes are around 50%, except in the case of the branch/leaf material of _A. melanogaster_, with a yield of 25%. An optimal balance is achieved, considering this parameter as biochar quality and the net energy cost of production.  
According to the obtained results, using low pyrolysis temperatures and short times in a simple oven with double chamber, moderately high values are achieved compared to the references and the original biomass material in all samples. Wood material of _A. melanogaster_ and _A. dealbata_ obtained the highest fixed carbon value, with 66%, very similar to the fixed carbon value of _A. melanogaster_ leaf/branch. No significant difference was detected between the values obtained for the two species in wood material, although a significant difference was obtained for the leaf/branch material, which reached a higher value. In any case, the results show that it is possible to obtain biochar with fixed carbon above 50%, which can be used for various applications, such as soil recovery or amendments, reducing the carbon emissions and ecological footprint, allowing for the manufacturing of all types of added-value products, such as activated biochar.  
Ash values were coherent and predictable in view of the initial moisture content and fixed carbon obtained. In relation to pH, the values obtained for biochar samples enable the use of this type of substrate to improve acidic soils that are very typical in Northwestern Spain.  
Pellets biofuels showed high density, close to 1400 kg m\({}^{-3}\). It can be concluded that, with acacia waste, it would be possible to obtain the best pellets potentially manufactured in theory and with better physical and energetic densities than the products usually sold at the conventional market. This study highlights the effectiveness of this approach in the sustainable management of protected areas, contributing to the management of invasive species, addressing environmental issues, and promoting the circularity of residual biomass. Ultimately, this study underscores the innovation and promising utility of _Acacia_ biomass-derived biochar in enhancing the sustainability and management of protected spaces.  
Conceptualization: O.G.-P. and L.O.T.; methodology: O.G.-P. and L.O.T.; validation: O.G.-P. and L.O.T.; formal analysis: O.G.-P. and L.O.T.; investigation: O.G.-P. and L.O.T.; writing--original draft preparation: O.G.-P.; writing--review and editing: O.G.-P. and L.O.T. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was partially supported through a FEADER 2023/011B for aid for the implementation of projects of the operational groups of the European Innovation Partnership (AEI) (MR331B)-ECOCHAR of Xunta de Galicia, in the Strategic Plan for the Common Agricultural Policy (PEPAC) 2023-2027 (DOG no 141, of 26 July 2023) and the PID2022-138374 OA-I00 Grant, funded by MICIU/AEI/10.13039/501100011033/and ERDF, EU.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors on request.  
**Conflicts of Interest:** The authors declare no conflicts of interest.