Particle size is a physical property that sometimes limits the quality of briquettes, so it is recommended to use different sizes in mixtures for their manufacture. The objective of this research was to evaluate the effect of different particle sizes of sawdust in mixtures on some physical, mechanical, and energetic properties of briquettes made from Pinus durangensis sawdust, as well as set the ranges within the appropriate values found to obtain desired values. Three particle sizes were established (large, medium, and small), and 10 mixtures were prepared using different percentages of each particle classification. The particle density, volumetric swelling, compressive strength, impact resistance index (IRI), and gross calorific value of the briquettes were evaluated. For the determination of optimal mixtures, the surface response methodology was used under a three-factor simplex-lattice model. The particle density values were in the range 0.92 to 1.02 g cm⁻³ and the volumetric swelling was 0.96 to 3.9%. The highest resistance to compression was 37.01 N mm⁻¹, and the IRI was found in the range of 53 to 107%. The gross calorific values were from 19.35 to 21.63 MJ kg⁻¹. The selection of different particle sizes for the mixtures increases the quality of the briquettes.

An alternative to mitigate the consumption of fossil fuels is the use of biomass as an energy source. In this sense, the rural sector in Latin America has great potential due to its multiple biomass sources. For this reason, this study aims to analyze potential technologies related to the production of energy from biomass and its application in the Latin American rural sector. To achieve this, four key processes are analyzed. First is biomass conditioning through solar dryers. Next are the thermochemical processes that allow for their transformation into biofuels, for which the pyrolysis and the hydrothermal methods were selected due to the flexibility of the products obtained. Subsequently, cogeneration is studied to produce electrical and thermal energy from biomass or its derivatives. Finally, to close the CO₂ cycle, a balance of CO₂ fixation in a forest plantation is presented as an example of carbon accumulated in biomass. The literature systematic review allowed us to determine that the technologies mentioned in this work have different degrees of implementation in the Latin American rural sector. However, they have great potential to be applied on a large scale in the region, making it possible to adapt energy production to climate change and improve the life quality of its inhabitants.

Lack of knowledge regarding the fuel quality of diverse tree species prevents their use. Furthermore, the potential use of wood with the bark of different tree species for pellet production is still relatively unexplored in the scientific literature. In Mexico, the sawdust of Quercus genus (oak) is underutilized, despite it being an important forest resource, due to some anatomical and technological characteristics. The sawdust of Quercus with bark is also considered to have a low economic value. The objective of this study was to analyze the energy characteristics of barked and debarked Quercus sideroxyla, Q. rugosa, Q. laeta, and Q. conzattii in order to evaluate their potential for pellet production. Granulometric distribution, bulk density, proximal analysis, and calorific value tests were carried out. The sawdust of the four tree species studied was in accordance with the limits established by the standard EN 14961-2. Sawdust with a particle size of 0.425 mm had the highest percentage of retained mass (30.33%) (p < 0.05) in the granulometry test. There were no statistical differences in granulometry (p > 0.05) between barked and debarked sawdust for all Quercus species. Barked sawdust presented higher bulk density (p < 0.05) than debarked sawdust (246 and 224 kg/m³, respectively). The moisture content did not show statistical differences (p > 0.05) between barked and debarked sawdust. The volatile material was higher (p < 0.05) in debarked sawdust (88.7%) than in barked sawdust (85.0%). The ash content was below 0.5%. The fixed carbon was higher (p < 0.05) in barked sawdust (14.6%). The calorific value was higher (p < 0.05) in barked sawdust and for the Q. rugosa species (19.5 MJ/kg). The results suggest that the oak species analyzed, both barked and debarked, showed good potential for pellet production. Future studies should quantify fuel quality for a variety of diameter distributions, and analyze pellet mechanical properties and ash slagging risk.

The phenomena of capillarity, dipole–dipole attractions, and hydrogen bonding make the application of mass transfer models to predict the drying rate by air convection in wood chips imprecise. So, the modification of these models by tailoring their equations is required. This study aims to adapt theoretical mass transfer models to improve the prediction of drying time for Pinus spp. chips subjected to a known hot air stream with known velocity, temperature, and relative humidity. An experimental device was constructed to control the variables, where the air stream passes vertically through a cylinder filled with wood chips. The tested air velocities ranged between 7 and 10 m/s, with relative humidity between 10 and 30% and temperatures between 40 and 70 °C with 3 and 6 cm chip columns. It was demonstrated that the drying rate of chips in a convective process with air is not constant but rather decreases over time, and that the critical moisture content is above 42%. Factors such as the height of the chips pile influence the predictive equations for the drying rate. The average relative drying rate ranged between 0.063 and 0.040 g of water s⁻¹ kg of dry chip⁻¹ in both heights; meanwhile, the average absolute drying rate was between 0.0031 and 0.0032 g of water s⁻¹. Modifications of the models have been developed that adjust theoretical values with experimental values, resulting in an r² value of 0.80.