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.

This study presents a prospective study for the potential exploitation of pelagic Sargassum spp. as a solid biofuel energy source. It was carried out in three stages. First we conducted a morphological, physical-chemical, and structural characterization using scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and X-ray diffraction (DRX), respectively. Second we evaluated the material’s functional properties as a solid biofuel based on its calorific value and the quantification of polymeric components like hemicellulose, cellulose, and lignin, as well as thermogravimetric and differential analysis to study the kinetics of its pyrolysis and determine parameters like activation energy (E_a), reaction order (n), and the pre-exponential factor (Z). Third we analyzed the energetic potential considering the estimated volume of pelagic Sargassum spp. that was removed from beaches along the Mexican Caribbean coast in recent years. Results of the kinetic study indicate that Sargassum spp. has an enormous potential for use as a complement to other bioenergy sources. Other results show the high potential for exploiting these algae as an energy source due to the huge volumes that have inundated Caribbean, West African, and northern Brazil shorelines in recent years. As a solid biofuel, Sargassum spp. has a potential energy the order of 0.203 gigajoules (GJ)/m³. In the energy matrix of the residential sector in Mexico, its potential use as an energy source is comparable to the national consumption of firewood. The volume of beachcast Sargassum spp. that was removed from ~8 km of coastline around Puerto Morelos, Mexico in 2018–2019, could have generated over 40 terajoules/year of solid biofuel.

Background: The need for energy sources with low greenhouse gas emissions and sustainable production encourages the search for alternative biomass sources. However, the use of biomass fuels faces the problem of storage, transport and lower energy densities. Low-density values can negatively affect energy density, leading to an increase in transportation and storage costs. Use of pellets as alternative biomass source is a way to reduce the volume of biomass by densification, which improves their energy quality. They are produced by diverse biomass resources and mainly from wood materials. In all cases, it is important to evaluate the fuel characteristics, to determine their suitability on the heating system and handling properties. Methods: The present study determines and compares data from proximate analysis, calorific values, physical and mechanical properties of wood pellets produced from the common tropical species Acacia wrightii, Ebenopsis ebano and Havardia pallens. Data were obtained from pellets produced from each species chips collected from an experimental plantation and analyzed through ANOVA and Kruskal–Wallis test at 0.05 significance level. Results: The results of diameter, length and length/diameter ratio didn’t show statistical differences (p > 0.05) among species. Acacia wrightii showed the highest density (1.2 g/cm³). Values on weight retained and compression test showed statistical differences (p = 0.05) among species. Havardia pallens was more resistant to compression strength than A. wrightii and Ebenopsis ebano. Statistical differences (p < 0.01) were also observed for the volatile matter and calorific value. E. ebano has the lowest volatile matter (72%), highest calorific value (19.6 MJ/kg) as well as the fixed carbon (21%). Discussion: The pellets of the species studied have a high energy density, which makes them suitable for both commercial and industrial heating applications.A pellet with low compression resistance tends to disintegrate easily, due to moisture adsorption. The percentages obtained for the resistance index were higher than 97.5%, showing that the pellets studied are high-quality biofuels. Proximate analysis values also indicate good combustion parameters. Pellets of Acacia wrightii and Ebenopsis ebano are the more favorable raw material sources for energy purposes because of their high density, calorific value, low ash content and they also met majority of the international quality parameters.

Physicochemical Characterization of Water Hyacinth (Eichhornia crassipes (Mart.) Solms)