## 3 Results and Discussion
### Potential for Energy Exploitation  
One advantage of many solid biofuels is their ease of use. Firewood, for example, is a widely-used fuel in rural areas of Mexico [11] that is extracted from forests and used, almost immediately, to satisfy the needs of both residential and industrial sectors. Something similar occurs with densified materials derived from wood waste or residues such as sawdust. These compacted materials are generally used for immediate combustion [16]. We foresee a similar scenario regarding _Sargassum_ spp. The calorific \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & **Hemicellulose (\%)** & **Cellulose (\%)** & **Lignin (\%)** & **Additional Extractives (\%)** \\ \hline _Sargassum_ spp. & 7.7–8.7 & 9.2–13.1 & 8.7–10.5 & 67.7–74.4 \\ \hline Standard deviation & 0.6 & 2.1 & 1.0 & 2.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of the principle polymeric components of _Sargassum_ spp. Figure 7: FTIR characterization of _Sargassum_ spp. value of these algae measured 13.5-13.8 MJ/kg, a figure that, in the worst case scenario, would provide approximately 203.74 MJ/m\({}^{3}\) of dry material, considering a low level of exploitation of 11.1% of the total weight of the algae collected; this estimation assumes that the other 88.9% are not exploitable due to moisture loss and the content of sand and other algae with lower energy content (though this may be overestimated because the sand content is low). This estimate may change in the months of greatest influx, when all that is extracted is mainly _Sargassum_ spp., and the scenario of energy use would be greater [40]. Based on this first approximation of the extraction and processing of _Sargassum_ spp. with simple mechanical grinding (agate mortar), the potential for generating exploitable energy seems promising. As a first example, considering only the _Sargassum_ spp. removed from a few municipalities along the coast of the Mexican Caribbean in the month of August 2015 (reported by the Secretary of Environment of Quintana Roo see [PERSON] et al. [19]), the amount of exploitable energy indicated by the calorific value calculated herein could provide 3.9 terajoules (TJ; Figure 8a), as shown in Figure 8. In terms of energy content, this is equivalent to approximately 205.26 tons of primary use _Pinus_ spp. wood (per unit equivalent mass) [64], or 81.25 tons of the liquid gas distributed in Mexico [11]. This is a significant volume of exploitable energy. It is important to note that [PERSON] et al. (2018) [65] observed a huge belt of _Sargassum_ spp. in the area of the Atlantic Ocean between West Africa and the Gulf of Mexico that contained \(>\)20 million tons of biomass in the month of June 2018. Even in the most unfavorable scenario, the potential exploitable bioenergy contained in that volume of _Sargassum_ spp. that arrive on the Mexican Caribbean coast in 2018 would be \(>\)30 petajoules (PJ), an astounding figure that represents a little over 15% of total energy consumption in Mexico generated by burning firewood in that same year (249.08 PJ) [11]. Flows of _Sargassum_ spp. onto the coasts of the Mexican Caribbean coast have been frequent. Reports indicate that in September 2015 the volume averaged 2360 m\({}^{3}\)/km [19]. Figures were lower for 2016 and 2017, but increased again in 2018. In May of that year, the average influx was 8793 m\({}^{3}\)/km [66]. The scenarios of 2015 and 2018 represent an energetic potential in the form of solid biofuel of 480.82 GJ/km and 1791 GJ/km, respectively. A comparison of the exploitable energy derived from _Sargassum_ spp. to other solid biofuels and liquid gas in the state of Quintana Roo presents the interesting results [67] as shown in Figure 8b. Although this material cannot compete with liquid gas in terms of calorific value, it is comparable to such fuels as firewood and pellets made of densified materials [16], and its behavior is similar.