Today, hydrogen is one of the best options for generating electrical energy, for both industrial and residential use. The greatest volume of hydrogen produced today derives from processes that utilize petroleum. Although hydrogen has numerous benefits, continuing to produce it by these means is undesirable. This document presents a review of the literature on biohydrogen production based on an analysis of over 15 types of terrestrial and marine biomasses. The fundamental components of different production systems are described, with a focus on the thermochemical processes of pyrolysis and gasification, which have been identified as two of the most effective, practical ways to produce hydrogen from biomass. It also discusses catalysts, solid residues, and residual water that are used in the thermochemical production of biohydrogen. The article ends with an analysis of hydrogen and its benefits as an energy option with great potential in the short term to participate in the transition from fossil fuels.

Today, energy use is an important and urgent issue for economic development worldwide. It is expected that raw material in the form of biomass and lignocellulosic residues will become increasingly significant sources of sustainable energy in the future because they contain components such as cellulose, hemicellulose, lignin, and extractables with high energy-producing potential. It is then essential to determine the behavior of these materials during thermal degradation processes, such as pyrolysis (total or partial absence of air/oxygen). Pyrolyzed biomass and its residual fractions can be processed to produce important chemical products, such as hydrogen gas (H₂). Thermogravimetric (TGA) analysis and its derivative, DTG, are analytical techniques used to determine weight loss as a function of temperature or time and associate changes with certain degradation and mass conversion processes in order to evaluate kinetic properties. Applying kinetic methods (mathematical models) to degradation processes permits obtaining several useful parameters for predicting the behavior of biomass during pyrolysis. Current differential (Friedman) and integral (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink, Popescu) models vary in their range of heating speeds (β) and degree of advance (α), but some (e.g., Kissinger’s) do not consider the behavior of α. This article analyzes the results of numerous kinetic studies using pyrolysis and based on thermogravimetric processes involving over 20 distinct biomasses. The main goal of those studies was to generate products with high added value, such as bio-char, methane, hydrogen, and biodiesel. This broad review identifies models and determines the potential of lignocellulosic materials for generating bioenergy cleanly and sustainably.

This study shows the energy potential of pine wood waste for the production of solid biofuels, and was carried out in an indigenous community in the state of Michoacán. One of the main economic activities of this community is the production of handcrafted furniture, which generates a large amount of wood waste. The most relevant results obtained in this research show that the community generates approximately 2268 kg of sawdust and 5418 kg of shavings per week, and the estimated energy potential per year for both sawdust is 1.94 PJ and for shaving is 4.65 PJ. Based on the particle size observed, the wood residue can be used to generate pellets or briquettes. Other average results in sawdust and (shavings) are the following: initial moisture content 15.3% (16.8%), apparent density 169.23 kg/m³ (49.25 kg/m³), ash 0.43% (0.42%), volatile material 84.9% (83.60%), fixed carbon 14.65% (15.96%), hemicelluloses 12.89% (10.68%), cellulose 52.68% (52.82%), lignin 26.73% (25.98%), extractives 7.69% (10.51%), calorific value 17.6 MJ/kg (17.9 MJ/kg). The major chemical elements in the ash were Al, K. Fe, Ca, P, Na, and Mg. Finally, the results obtained indicate that this biomass can be used to generate pellets or briquettes in this indigenous community.

Diverse methodologies exist to determine the chemical composition, proximate analysis, and calorific value of biomass. Researchers select and apply a specific methodology according to the lignocellulosic material they study and the budgetary resources available. In this project, we determined the primary chemical constitution and proximate analysis of Prosopis laevigata (Humb. & Bonpl.) Jonhst wood using a traditional chemical method and a novel procedure based on the deconvolution of the DTG signal produced by TGA. The highest calorific value was verified using a calorimetric pump based on mathematical models. We also conducted elemental analysis and a microanalysis of ash, and applied Fourier transform infrared spectroscopic analysis (FT-IR). The means of the results obtained by the chemical method and TGA-DTG, respectively, were: hemicelluloses 7.36%–(8.72%), cellulose 48.28%–(46.08%), lignin 30.57%–(32.44%), extractables 13.53%–(12.72%), moisture 2.03%–(4.96%), ash 1.77%–(1.90%), volatile matter 75.16%–(74.14%), and fixed carbon 23.05%–(18.93%). The procedure with the calorimetric pump generated a calorific value above 20.16 MJ/kg. The range generated by the various models was 18.23–21.07 MJ/kg. The results of the elemental analysis were: carbon 46.4%, hydrogen 6.79%, oxygen 46.43%, nitrogen 0.3%, and sulfur 0.5%. The microanalysis of ash identified 18 elements. The most abundant ones were potassium ˃ calcium ˃ sodium. Based on the infrared spectrum (FT-IR) of Prosopis laevigata wood, we detected the following functional groups: OH, C-H, C=O, CH_2, CH₃, C-O-C, C-OH, and C4-OH. Our conclusion is that the TGA-DTG method made it possible to obtain results in less time with no need for the numerous reagents that chemical procedures require. The calorific value of P. laevigata wood is higher than the standards. Finally, according to our results, proximate analysis provides the best model for calculating calorific value.

The COVID-19 pandemic has generated multiple impacts. In particular, in the educational sector, the virtual class modality generated changes in the patterns of energy consumption at the institutional level; the identification of this consumption will allow us to reflect on new energy saving and efficient use strategies. In this research, we present a case study of the effects of the COVID-19 pandemic on electricity consumption in 13 state universities in Michoacán, Mexico. Electric energy consumption has been evaluated before and during the presence of the COVID-19 between 2019 and 2020. The comparative analysis estimated the reduction in energy consumption and its economic and environmental impact. The results show a considerable decrease in electricity consumption, generating an average saving of 76.24 MWh/month, which translates into an annual emission reduction from 2019 to 2020 of approximately 497 TnCO_2e, and in economic terms of $8,882.25 USD each month. In general, it was identified that consumption patterns in the use of machinery and computer equipment for administrative activities were drastically reduced. If education continues in virtual or hybrid modes, energy consumption schemes will continue to decline and institutions could move towards resilient, affordable, and sustainable models of energy production and consumption.

The generation of biomass residues in different productive activities of rural communities in Mexico represents an area of opportunity for the generation of bioenergy for various purposes. Solid biofuels (SBF), for example, are an alternative for the exploitation of these residues. The present study shows a comprehensive proposal for the analysis of residues of Pinus spp. generated by the artisanal sector of a rural community in Mexico. The proposal is based on four stages: a) characterization of the physico-chemical and functional properties of the residues, by Scanning Electron Microscopy (SEM), Infrared (FTIR) and Raman Spectroscopy, Thermogravimetry (TGA-DTG), determining the calorific coefficient and polymeric compounds present by fiber analysis; (b) spatial, temporal and dimensional analysis of the waste generated in the town studied; (c) assessment of the energy potential available in space and time; (d) definition of guidelines for the management of solid biofuels for the community through collection, processing and final disposal centers. The results of the assessment of timber residue from 50 artisan workshops that represent 25% of the total in the community show that the identified heating value of the dry residue ranges from 17.6 MJ/kg to 18.1 MJ/kg, attributed to the presence of polymeric compounds such as cellulose, hemicellulose and lignin, the latter in the order of 28%, which contributes to a high energy potential, and whose compounds were identified by TGA-DTG analysis, FTIR, SEM and fiber analysis. The energy potential was estimated at approximately 7 TJ/year for the analyzed workshops. In which case, the economic savings obtained from unburned firewood would amount to about $20,000 USD/year. As regards the reduction in firewood consumption due to the use of residues for energy purposes, about 350 Tn/year would be mitigated, which would reduce the community’s emissions by more than 76 TnCO₂/year. A strategic management proposal was also established, aimed at providing spaces for the collection, processing and final disposal of solid biofuels from wood residues, which in sum represent an energy alternative that is sustainable in environmental, economic and social terms, for the same community.