Currently, Mexico is facing an energy transition, therefore updated policy regulations pertaining to the sustainable use of biomass are needed. In particular, policy that favors the sustainable use of biomass to produce energy and bioproducts to privilege climate change mitigation is needed. This review describes the use of maguey (Agave spp.) and nopal (Opuntia spp.; also known as “cactus”) for biofuel production, especially in marginal areas. Emphasis is given on documented case studies discussing features of production and cultivation for both maguey and nopal, in addition to their potential for fuel production. Environmental and social sustainability issues in terms of waste value and new opportunities as bioenergy feedstocks and byproducts are also discussed. Although the paper does not deeply describe aspects of biomass transformation, such as bioprocess configurations, it gives characteristics of production in addition to cultivation. Agave and Opuntia species may represent a suitable feedstock for biofuels, bioproducts, bioenergy and biorefineries, especially in dry lands (semi-arid and dry sub-humid), deforested areas, agroforestry systems and agricultural semi-terraces known as metepantle in Mexico.

Cedrela odorata (Meliaceae) is a native timber tree to Tropical America, known for its high-quality wood, unfortunately, plantations of this species are severely attacked by Hypsipyla grandella. The attraction or repellency of this pest is related to secondary metabolites such as phenols and limonoids (triterpenes); therefore, it is important to study these compounds to understand the phytochemical phenomena behind this problem.  With this aim, the concentration of total phenols and limonoides was evaluated in C. odorata leaves from a plantation established in Tezonapa Veracruz, Mexico. For this, a total of 66 tree leaves samples, from seven sites, were analyzed. Phenols and limonoids concentration showed significant differences not only among different provenances, but also among individual trees of the same site (Tukey, p≤0.05). Phenols concentration was variable and in the range from 49 to 223mg EAG/g e for total phenols, from 7 to 158mg EC/g e for flavonoids and from 4 to 104mg EC/g e for proanthocyanidins. Limonoids concentration was also variable, ranging between 227 and 748mg EL/g e. A major compound was found by High-Performance Liquid Chromatography with Ultraviolet Diode Array Detection (HPLC-UV-DAD), which corresponded to a flavonol kaempferol glycoside derivative; additionally, a flavanol catechin was also detected at low concentrations. GC–MS allowed the identification of the sesquiterpenoids β-elemene, E-caryophyllene, aromadendrene, α-humulene, γ-cadinene, D-germacrene, bicyclogermacrene, and the poly terpenoids D-α-tocopherol and β-sitosterol. Our results suggest that the evaluation of phenols may play an important role as a selection parameter for improvement and conservation programs, if they are complemented with conventional breeding practices.

The objective of this study was to evaluate the biomass production, chemical composition, proximate analysis, calorific value and theoretical yield of bioethanol of Taiwan grass under 6 cutting frequencies. The highest production of biomass (33 t DM/ha), cellulose content (41.3%), calorific value (17.5 MJ/kg DM) and potential bioethanol yield (7,936 L/ha) were recorded at a cutting frequency of 180 days. The highest moisture content of the dehydrated samples and ash and crude protein concentrations were observed at a harvest frequency of 30 days with 9.2, 12.1 and 10.5%, respectively. The highest concentrations of extractives were obtained at harvest frequencies of 60 and 120 days (13.9 and 13.7%, respectively), while lignin concentrations were greatest at harvest frequencies of 150 and 180 days (21.1 and 20.9%, respectively). The highest concentration of fixed carbon was observed at a harvest frequency of 90 days (18.5%), while the lowest concentration of volatile matter occurred at a harvest frequency of 30 days. The data indicate that Taiwan grass has significant potential for use to produce bioethanol but assessment of the carbon footprint, life cycle analysis, energy yield (energy produced:energy consumed) of the entire production process is needed to ensure there are positive effects on climate change and greenhouse gas emissions before this process is adopted.

El objetivo de este estudio realizado en 2017 fue caracterizar el pasto mombaza (Megathyrsus maximus) para evaluar su potencial como materia prima para la producción de biocombustible líquido (bioetanol). La producción anual de biomasa, el poder calorífico, la composición química y el rendimiento teórico de bioetanol fueron determinadas en cuatro frecuencias de corte (30, 60, 90 y 120 d después del rebrote). Los datos se analizaron con el procedimiento GLM (SAS) y las medias de los tratamientos se compararon con la prueba de Tukey (p 0.05). La mayor producción de biomasa, poder calorífico, producción de energía, producción de bioetanol, FDN, LDA y hemicelulosa se obtuvieron en la frecuencia de corte de 120 d con 11 Mg ha-1 año-1; 16.1 MJ kg-1; 178.4 GJ ha-1 año-1; 238.2 L Mg-1 MS y 68.6, 6.5, 23.3%, respectivamente. No obstante, el mayor contenido de celulosa y FDA se encontraron en la frecuencia de corte de 90 d, con 41.2 y 47.4%, respectivamente. Los valores más altos de humedad, PC y cenizas se encontraron en la frecuencia de corte de 30 d con valores de 8.2, 10.4 y 12.1%, respectivamente, mientras que el contenido de EE fue mayor en la frecuencia de corte de 60 d (1.6%). De acuerdo con los resultados obtenidos en este estudio el pasto mombaza (Megathyrsus maximus) puede ser considerado como una materia prima atractiva para la producción de bioetanol en climas tropicales.