Search

This paper introduces a methodological framework for assessing the sustainability of solid biofuels in Mexico. The designed framework comprises 13 normalized indicators and two diagnostic studies, covering the economic, social, environmental, and institutional sustainability dimensions, and their intersections. Indicators are normalized using the concept of load capacity of a system, similarly to the planetary boundaries. Thus, the graphical representation of results facilitates their multidimensional analysis. The framework was applied to three case studies: traditional fuelwood in rural households, charcoal for restaurant grilling, and electricity cogeneration from sugarcane bagasse. This was part of an iterative process of testing and refining the framework and simultaneously demonstrating its application in the Mexican bioenergy context. This led to the conclusion that the resulting framework (a) provides a useful, quantitative, and comprehensive overview of both broad and specific sustainability aspects of the assessed system; (b) requires a balance of accessible but also scattered or sensitive data, similarly to most existing frameworks; (c) is highly flexible and applicable to both modern and traditional solid biofuels; and (d) is simple to communicate and interpret for a wide audience. Key directions for improvement of the framework are also discussed. [ABSTRACT FROM AUTHOR]

Biomass represents 10% of the total energy use and 55% of all renewable energy in Mexico. It is a key energy source to help Mexico achieve a low-carbon development path to comply with the strict climate mitigation targets needed to avoid catastrophic consequences. However, a major limitation in the construction of reliable future mitigation scenarios is the lack of information regarding in-country greenhouse emission factors associated to both traditional and modern bioenergy devices. This paper aims to close this gap, providing detailed estimates of energy and emission factors from bioenergy devices in the Mexican residential and industrial sectors. In particular, four energy tasks, comprising 67% of current bioenergy use in the country, were selected (charcoal production, biomass drying, space heating, and cooking) with a total of nine bioenergy devices: traditional earth mound charcoal kiln, flash dryer, heater, five types of cookstoves, and an open fire. The thermal efficiency ranged from 10 ± 1 to 26 ± 5% for the cooking devices, 95 ± 1 to 96 ± 1% for the space heater, 34 ± 8% for the charcoal kiln, and 10 ± 2% for the biomass dryer. The modified combustion efficiency was calculated to be 88 ± 1% for the earth mound charcoal kiln, 96–98% for the cookstove, and 93–98% for the space heater. The products of incomplete combustion ranged from 21 ± 6 to 48 ± 12 g for the cooking devices and 58 ± 18 to 340 ± 107 g for the space heaters. CO2 emission factors ranged from 102 ± 2 to 119 ± 2 g/MJ for the local biomass stoves. Relative to other pollutants, the CO emissions per energy unit were the highest, ranging from 1193 ± 184 mg/MJ for the space heater to 18,121 ± 1232 mg/MJ for the earth mound charcoal kiln. The total global warming potential was estimated to be 35 ± 2 gCO2e/MJ for the ONIL stove (modified) and 158 ± 4 gCO2e/MJ for the earth mound charcoal kiln. The estimates presented in this study represent an important contribution to Mexico's inventories in terms of energy performance and emissions parameters of four energy tasks in the industrial and residential sectors. This information will be a baseline to estimate carbon footprint, life cycle assessments, GHG emissions scenarios, and mitigation strategies for local and regional Mexican conditions. [ABSTRACT FROM AUTHOR]

In Mexico, the possibility to exploit orange peels or sugarcane straw to generate heat has not been fully explored, even though they are major agronomic wastes generated in Mexico. Therefore, this paper aims to assess the heat generation's environmental and economic performance from these feedstocks in a fruit-processing facility located in Veracruz, Mexico. The environmental performance was assessed through the life-cycle assessment methodology, while the economic performance was estimated through the total levelized cost of energy (TLCE) considering two scenarios: (1) a base scenario where orange peels are burnt to produce process steam, and (2) a second scenario where sugarcane straw is co-fired with it. Both scenarios assume to partially displace heavy-fuel–oil (HFO) for steam generation. Results indicate that the impacts of the use of residual biomass-based heat on the potential global warming, ozone layer depletion, marine aquatic ecotoxicity, and cumulative energy demand are 34–63% lower than when using HFO and decrease the TLCE by 18–21%. However, there is also an increase in other environmental impact categories such as human toxicity, photochemical oxidation, or eutrophication. The use of orange from organic farms improves the environmental results in some of these categories. The drying and combustion of the biomass, as well as the waste treatment, are the major contributors to the environmental impacts. On the other hand, capital and fuel costs are the major contributors to TLCE. Overall, the use of orange peels and sugarcane straw to generate heat is attractive from the environmental and economic point of views. [ABSTRACT FROM AUTHOR]

Detailed studies about energy content and chemical characterization of biomass alternatives are necessary to determine their main features as solid fuels. The aim of this study was to analyze and compare the properties of five types of residual biomass pellets produced throughout Mexico: sawmill pine waste (SPW), spent ground coffee (SGC), pecan nutshell (PN), oil palm waste (OPW), and mango waste (MW). Conventional characterization analyses revealed significant differences in HHV (21.44–17.37 MJ/kg), elemental composition showed a lower carbon content in SPW and MW (around 46%), OPW (close to 47%), and higher carbon content in PN and SGC (around 51%). The concentration of the main structural polymers showed notable significant differences (p < 0.05) too: 49–17% for cellulose, for hemicellulose 21–5% and for lignin 26–4%. High-throughput instrumental techniques were also used: FTIR provided additional information on chemical composition in pellets on which lignocellulosic biomass was not predominant, presence of pectins and starch in MW, and high content of fatty acids in SGC and OPW; TGA showed different thermal stability of pellets in the combustion process, where OPW and SPW presented the lowest and highest thermal stability, respectively, while XPS showed different types of bonds between C and O in the surface of materials with a relevant presence of bonds associated to lignin covering PN and SPW. Based on results of this investigation, a possible rank for the energy use of these five biomasses is suggested: PN, SPW, SGC, OPW, and MW, but future deep research is necessary that incorporate other relevant attributes, mechanical properties, emission profiles, corrosion, and slagging effects. [ABSTRACT FROM AUTHOR]