Abstract The constant growth in global urban waste generation has led to an increasing need to address its management sustainably. Despite the proven effectiveness of converting this waste into energy in various countries, its implementation in Colombia is still in its early stages. In this study, a bibliometric analysis and systematic review of the literature was conducted to assess urban solid waste valorization technologies and their potential integration into biorefineries in the Colombian context. Among the identified technologies, incineration, gasification, pyrolysis, anaerobic digestion, and landfill gas recovery stand out. Anaerobic Digestion emerges as an attractive option due to its versatility. However, there is a recognized imperative to dynamically choose technologies, considering the diversity of contexts and specific conditions in Colombia. Additionally, gasification and pyrolysis appear as viable options, each with its own advantages and challenges, reflecting the complexity and variability in waste management. Concerning landfill gas recovery, its significance as an essential installation in controlled landfills is emphasized, dismissing its consideration as an independent alternative. While the literature suggests that incineration is perceived as less favorable in social, economic, and environmental terms, it is crucial to recognize the dynamics and specificity of each situation. The choice of technologies must be adaptive and guided by a contextual approach that considers the heterogeneity in waste composition, available infrastructure, and other factors that vary significantly from one scenario to another. This dynamic and adaptive approach is essential to address the complexity of urban waste management and find sustainable solutions in the Colombian context.

Resumen El crecimiento constante en la generación de residuos urbanos a nivel global ha generado una creciente necesidad de abordar su gestión de manera sostenible. A pesar de que la conversión de estos residuos en energía ha demostrado ser efectiva en varios países, su implementación en Colombia aún se encuentra en una etapa incipiente. En este estudio, se llevó a cabo un análisis bibliométrico y una revisión sistemática exhaustiva de la literatura con el propósito de evaluar las tecnologías de valorización de los residuos sólidos urbanos, así como su potencial integración en biorrefinerías en el contexto colombiano. Entre las tecnologías más relevantes identificadas se encuentran la incineración, la gasificación, la pirólisis, la digestión anaeróbica y la recuperación de gas de vertedero. La Digestión Anaerobia destaca como una opción atractiva debido a su versatilidad. No obstante, se reconoce la necesidad imperante de adoptar una elección dinámica de tecnologías, considerando la diversidad de contextos y condiciones específicas en Colombia. Además, la gasificación y la pirólisis emergen como opciones viables, cada una con sus propias ventajas y desafíos, reflejando la complejidad y variabilidad en la gestión de residuos. En relación con la recuperación de gas de vertedero, se subraya su importancia como instalación esencial en vertederos controlados, desestimando la consideración de una alternativa independiente. Si bien la literatura sugiere que la incineración se percibe como menos favorable en términos sociales, económicos y ambientales, es crucial reconocer la dinámica y especificidad de cada situación. La elección de tecnologías debe ser adaptativa y orientada por un enfoque contextual que considere la heterogeneidad en la composición de residuos, infraestructura disponible y otros factores que varían significativamente de un escenario a otro. Este enfoque dinámico y adaptativo es esencial para abordar la complejidad de la gestión de residuos urbanos y encontrar soluciones sostenibles en el contexto colombiano.

Abstract The main objective was the development of an optimized municipal waste gasification reactor geometry utilizing plasma. Here, numerical simulation utilizing the COMSOL Multiphysics software was used to achieve an optimized bidimensional geometry. Initial conditions for the reactor were defined using the researchers’ experience. Then, 16 different combinations of four geometric parameters were set, where the gas chamber’s superior, and inferior radius, it’s length and lastly the fusing chamber volume were varied. Of these, two combinations that optimized the mixing of gases and heat exchange with the exterior were found. It was confirmed that these designs allowed for the proper melting and gasification of the theoretical waste. Further, the smelted material also possessed a viscosity lower than 10 Pa s needed to flow out of the reactor.

Resumen El objetivo principal de esta investigación fue el desarrollo de una geometría optimizada para un reactor de gasificación de residuos municipales con plasma. Se realizó una simulación numérica de la geometría bidimensional de un reactor de gasificación por plasma con el fin de conseguir un rendimiento optimizado con el uso del software COMSOL Multiphysics. Se definieron condiciones iniciales del reactor y se crearon 16 distintas combinaciones geométricas que varían cuatro aspectos geométricos del reactor: los radios inferior y superior de la cámara de gases, la longitud central de la cámara y el volumen de la cámara de fundición. De estas, fueron halladas dos combinaciones que optimizan los aspectos de mezclado de gases y transferencia de calor hacia el ambiente. Se confirmó que los diseños planteados alcanzan las temperaturas necesarias para la fundición y gasificación de los desechos. Además, el material fundido teórico alcanza la viscosidad necesaria menor a 10 Pa s para poder fluir fuera del reactor.

Abstract: The primary objective of this research study is to characterize the gasification of oil-palm frond and trunk obtained as residual biomass from oil-palm crops by using air as a gasifying agent. Screening type experimentation is applied by using a downflow free-fall reactor. At 800°C and 0.24 equivalence relation (ER), the results for oil-palm frond show a yield of 1.85 Nm3 gas/kg dry biomass and a heating value of 4.08 MJ/Nm3. For oil-palm trunk, the yield is 1.30 Nm3 gas/kg dry biomass and the heating value is 4.56 MJ/Nm3. The gas obtained has the potential to generate 1.05 kW-h/kg dry biomass for oil-palm frond and 0.90 kW-h/kg of dry biomass for oil-palm trunk. In conclusion, energetic utilization of residual biomass (fronds and trunks) should be explored in Colombia to optimize oil-palm economic and environmental production processes in a circular economy scheme.

Resumen: El principal objetivo de esta investigación es caracterizar la gasificación de hojas y tallos obtenidos como biomasa residual en el cultivo de palma de aceite utilizando aire como agente gasificante. Se desarrolla una experimentación tipo barrido y se utiliza un reactor de caída libre de flujo descendente. A 800°C y relación de equivalencia (ER) de 0.24, los resultados muestran para las hojas un rendimiento de 1.85 Nm3 gas/kg biomasa seca y un poder calorífico inferior de 4.08 MJ/Nm3. Para el tallo se obtiene 1.30 Nm3 gas/kg biomasa seca y poder calorífico inferior de 4.56 MJ/Nm3 . El gas obtenido tiene un potencial de generación de energía eléctrica de 1.05 kW-h/kg de biomasa seca para hojas y 0.90 kW-h/kg de biomasa seca para tallo. En conclusión, el aprovechamiento energético de las biomasas residuales (hojas y tallo) debería ser explorado en Colombia para optimizar económica y ambientalmente los procesos de producción de aceite de palma en un esquema de economía circular.

ABSTRACT Regional development in the state of Pará (Brazil) continues to be limited by lack of access to energy. This is a problem that is widespread in several rural communities and agricultural regions. Therefore, this study aimed to analyze the potential use of palm oil and cocoa processing waste biomass, which are abundant in the state and whose energy capacities can be used to generate electricity in biomass gasification plants. To do so, a literature review on elementary and calorific value analysis of palm oil (empty fruit bunches, fibers, kernel shell and cake, trunks, and others) and cocoa (pod husks) were conducted. The findings have shown that both waste biomass materials have satisfactory energetic characteristics for use in gasification plants. Thus, palm oil and cocoa processing waste biomasses are alternative energy sources for producers of these fruits in upstate Pará, enabling the development of the region. Brazil (Brazil regions Therefore plants so empty bunches fibers cake trunks others pod husks conducted Thus region

ABSTRACT Huge increases in the volume of waste produced by society have created an urgent need for new and improved municipal solid waste (MSW) processes. In many countries, traditional methods to manage MSW, such as landfills, have been abandoned in favor of more effective and environmentally efficient technologies. These include gasification (decomposition at high temperatures), recycling, and composting (of organic matter). The purpose of this research was to assess certain financial, social, and environmental indicators, especially the IRR and cost-benefit ratio of changing the technologies used in MSW processing. The research focuses on assessing these changes in the CONRESOL area — a consortium that covers almost all the municipalities in the metropolitan region of Curitiba, Brazil. To this end, scenarios were proposed that apply various technological combinations and two collection fees. Of the three proposed scenarios, the one with the best socioeconomic and environmental results (Internal Rate of Return, Net Present Value, Discounted Payback, and Benefit/Cost ratio) combines gasification, recycling, and composting. This scenario generated the least GHG emissions and the highest number of jobs. (MSW processes countries landfills decomposition temperatures, temperatures , temperatures) recycling matter. matter . matter) financial social indicators costbenefit cost benefit processing Curitiba Brazil end fees Internal Return Value Payback BenefitCost Benefit Cost jobs

RESUMO O enorme aumento no volume de resíduos produzidos pela sociedade criou uma necessidade urgente de processos novos e melhores para tratamento dos resíduos sólidos urbanos (RSU). Em muitos países, os métodos tradicionais de gerenciamento de RSU, como aterros sanitários, foram abandonados em favor de tecnologias mais eficazes e ambientalmente eficientes. Eles incluem gaseificação (decomposição em altas temperaturas), reciclagem e compostagem (de matéria orgânica). O objetivo desta pesquisa foi avaliar alguns indicadores financeiros, sociais e ambientais, especialmente a taxa interna de retorno, a emissão de gases de efeito estufa, a geração de empregos e a relação custo-benefício da mudança de tecnologia utilizada no processamento dos RSU. A pesquisa se concentra em avaliar essas mudanças na área do Consórcio Intermunicipal para Gestão dos Resíduos Sólidos Urbanos (CONRESOL) — um consórcio que abrange quase todos os municípios da região metropolitana de Curitiba, Brasil). Para tanto, foram propostos cenários que aplicam diversas combinações tecnológicas e duas taxas de cobrança. Dos três cenários propostos, aquele com os melhores resultados socioeconômicos e ambientais (Taxa Interna de Retorno, Valor Presente Líquido, Payback Descontado e Relação Benefício/Custo) combina gaseificação, reciclagem e compostagem. Esse cenário gera as menores emissões de gases de efeito estufa (GEE) e o maior número de empregos. RSU . (RSU) países sanitários eficientes decomposição temperaturas, temperaturas , temperaturas) orgânica. orgânica orgânica) financeiros retorno custobenefício custo benefício CONRESOL (CONRESOL Curitiba Brasil. Brasil Brasil) tanto cobrança Taxa Retorno Líquido Benefício/Custo BenefícioCusto Benefício Custo GEE (GEE (RSU

ABSTRACT Sieving analysis, close analysis, real and apparent density of pine sawdust were studied as part of the application studies of this plant biomass, in pyrolysis and gasification processes. Sieving analysis was applied to determine the average diameter of particles according to different definitions; Gaudin-Andreiev and Rozin-Rammler models were adjusted to obtain the mathematical model of size distribution. The real and apparent density of the biomass was determined and the next analysis was carried out by the international standard GOST 2851-45. As a result, it was obtained that the Sauter diameter was 0.37mm. The model with the best fit for the size distribution data was the Rozin-Rammler model. The real and bulk density and porosity were 468.05kg/m3, 177.11kg/m3 and 0.75 respectively. The next analysis showed that the content of moisture, volatile matter, fixed carbon and ash were 7.65%, 83.54%, 16%, 10% and 0.37%, respectively, porosity 0,75. The properties of pine sawdust show its potential as a raw material for the generation of fuels or energy carriers, applying pyrolysis and gasification processes.

RESUMEN El análisis de tamizado, análisis próximo, densidad real y aparente de aserrín de pino fueron estudiados como parte de los estudios de aplicación de esta biomasa vegetal, en procesos de pirolisis y gasificación. El análisis de tamizado fue aplicado para determinar el diámetro promedio de partículas según diferentes definiciones; se ajustaron los modelos de Gaudin-Andreiev y de Rozin-Rammler para obtener el modelo matemático de distribución de tamaño. Se determinó la densidad real y aparente de la biomasa y se realizó el análisis próximo por la norma internacional GOST 2851-45. Como resultado se obtuvo que el diámetro de Sauter fue 0,37mm. El modelo con mejor ajuste para los datos de distribución de tamaño fue el de Rozin-Rammler. La densidad real, aparente y la porosidad resultaron 468,05kg/m3, 177,11kg/m3 y 0,75 respectivamente. El análisis próximo mostró que el contenido de humedad, de materia volátil, carbono fijo y de ceniza fue de 7,65 %, 83,54 %, 16%,10 % y 0,37 % respectivamente. Las propiedades del aserrín de pino muestran su potencialidad como materia prima para generación de combustibles o portadores energéticos, aplicando procesos de pirolisis y gasificación.

ABSTRACT Cuba has forestry industry residues gasification plant for at the "Gran Piedra Baconao Integral Forestry Company" in Santiago de Cuba, which includes a gasifier, internal combustion engine, and a wood dryer, that uses residual energy from the engine. In this work, an experimental theoretical evaluation of the cogeneration indices of the installation is carried out. The evaluation was carried out from mass and energy balances in the equipment that make up the installation from an experimental database resulting from 1194 hours of work of the, electrical energy generating for the sawmill and the national electrical network. The evaluation showed an electrical energy production efficiency of 11,07 %, a total cogeneration electrical efficiency of 41,94 %, and a net electrical energy production efficiency of 20,30 %. Other cogeneration indicators determined were net heat index of 4,93 kW/KW and renewable energy produced-fossil energy consumed ratio of 4,18.

RESUMEN Cuba cuenta con una planta de gasificación de residuos de la industria forestal en la “Empresa Forestal Integral Gran Piedra Baconao” de Santiago de Cuba que incluye un gasificador, motor de combustión interna y un secador de madera que utiliza la energía residual del motor. El objetivo del presente trabajo consiste en realizar una evaluación teórica experimental de los índices de cogeneración de la instalación. La evaluación se realizó a partir de balances de masa y energía en los equipos que conforman la instalación a partir de una base de datos experimental resultante de 1194 h de trabajo de la instalación, generando energía eléctrica para el aserrío y la red eléctrica nacional. La evaluación mostró una eficiencia de producción de energía eléctrica del 11,07 %, una eficiencia eléctrica de cogeneración total del 41,94 % y una eficiencia neta de producción de energía eléctrica del 20,30 %. Otros indicadores de cogeneración determinados fueron: índice de calor neto de 4,93 kW/kW y relación energía renovable producida-energía fósil consumida de 4,18.

ABSTRACT Gasification is one of the thermo conversion processes with the greatest application prospects for the transformation of biomass into a fuel with greater added value and field of application. Within the technologies currently in use, downdraft gasifiers are the most widely used for small capacity installations. During the thermodynamic evaluation of these gasifiers, one of the energy losses to take into account is the heat losses to the environment and given the variety of heat transfer processes that occur within the reactor, the calculation method are complex. In the present work, a simplified model is developed to evaluate these heat losses to the environment. The model allows from the project stage to evaluate the losses based on the dimensions of the reactor, the thermal properties of the construction materials and the working temperature of the bed with an error of less than 1% with respect to the non-simplified method.

RESUMEN La gasificación es uno de los procesos de termo conversión con mayores perspectivas de aplicación para la transformación de la biomasa en un combustible de mayor valor agregado y campo de aplicación. Dentro de las tecnologías que actualmente se utilizan, los gasificadores de flujo descendente son los más difundidos para instalaciones de pequeña capacidad. Durante la evaluación termodinámica de estos gasificadores, una de las pérdidas de energía a tener en cuenta son las pérdidas de calor al medio ambiente y dada variedad de los procesos de transferencia de calor que ocurren dentro del reactor, los métodos de cálculos resultan complejos. En el presente trabajo se desarrolla un modelo simplificado para evaluar estas pérdidas de calor al medio ambiente. El modelo permite desde la etapa de proyecto evaluar las pérdidas en función de las dimensiones del reactor, las propiedades térmicas de los materiales de construcción y la temperatura de trabajo del lecho con un error menor del 1% con respecto al método no simplificado.

ABSTRACT Colombian municipal solid waste (MSW) production trends indicate that sanitary emergencies could occur in the largest cities of the country by 2030 because of the end of their landfills' useful life. In this work, the energy recovery from different MSW through the updraft plasma gasification process to produce syngas as a substitute gaseous fuel was assessed from an economic viewpoint. The study was carried out using the results of an implemented model under a thermochemical approach using Aspen Plus. The economic assessment was conducted using the levelized cost of syngas production (LCOS), which was regarded as an economic indicator that considers tax incentives in the context of the Colombian renewable energy regulations (Law 715 of 2014). The combination between operational conditions (air flow and plasma temperature) allowed finding the maximum efficiency by means of a sensitivity analysis. The maximum efficiency ranged from 79,22 to 83,46%, highlighting the flexibility of the plasma gasification process to treat MSW. The lowest levelized syngas production cost reached with tax incentives varied from 13,19 to 22,95 ¢US$/kWh. Therefore, a waste disposal charge was proposed to make these projects feasible, which must range between 11,25 and 23,56 ¢US$/kWh (123-259 US$/t).

RESUMEN Las tendencias de la producción de residuos sólidos urbanos (RSU) en Colombia indican que podrían producirse emergencias sanitarias en las ciudades más grandes del país para 2030 debido a la finalización de la vida útil de sus rellenos sanitarios. En este trabajo se evaluó, desde un punto de vista económico, la recuperación de energía de los diferentes RSU mediante el proceso de gasificación por plasma en contracorriente para producir un gas de síntesis como combustible gaseoso sustituto. El estudio se llevó a cabo utilizando los resultados de un modelo implementado bajo un enfoque termoquímico en Aspen Plus. La evaluación económica se realizó mediante el costo nivelado de la producción de gas natural sintético (LCOS), que se consideró como un indicador económico que considera los incentivos fiscales en el contexto de la legislación colombiana sobre energía renovable (Ley de 1715 de 2014). La combinación entre las condiciones operativas (flujo de aire y temperatura de plasma) permitió encontrar la máxima eficiencia mediante un análisis de sensibilidad. La eficiencia máxima varió entre 79,22 y 83,46 %, destacando la flexibilidad del proceso de gasificación de plasma para el tratamiento de los RSU. El menor costo nivelado de la producción de gas natural sintético alcanzado con los incentivos fiscales varió de 13,19 a 22,95 ¢US$/kWh. Por lo tanto, se propuso un cobro por disposición de residuos para hacer factibles estos proyectos, que debe oscilar entre 11,25 y 23,56 ¢US$/kWh (123-259 US$/t).

RESUMO O Brasil é um país de cultura agrícola, e há mais de cem anos é o maior produtor de café. Assim, o trabalho propõe alternativas para o aproveitamento dos resíduos agrícolas da produção de café, analisando-os do ponto de vista ambiental e econômico. Uma lavoura de café foi selecionada no município de Santa Rosa da Serra (Minas Gerais, Brasil), e três cenários foram estabelecidos. Cenário 1: a casca é descartada ao ar livre; cenário 2: uso energético da casca para gaseificação e posterior produção de eletricidade; cenário 3: uso da casca como adubo orgânico. Uma análise econômica e ambiental foi calculada com base nesses três cenários. A tecnologia de gaseificação com casca de café, embora tecnicamente viável, segundo a análise econômica se torna inviável, pois o valor dessa geração elétrica foi superior aos demais valores de geração. Os cenários 2 e 3, que aplicaram práticas sustentáveis, resultaram em valores negativos para os impactos ambientais de esgotamento de água e esgotamento de combustíveis fósseis, comprovando os benefícios de tais práticas. O processo de gaseificação necessita de desenvolvimento tecnológico para tornar o empreendimento economicamente viável. Práticas sustentáveis na cafeicultura trazem benefícios ambientais em curto e longo prazo.

ABSTRACT Brazil is a country of agricultural culture, and for over a hundred years has been the largest coffee producer. Thus, the work proposes alternatives for the use of agricultural residues from coffee production, analyzing them from an environmental and economic point of view. A coffee crop was selected from the municipality of Santa Rosa da Serra (Minas Gerais, Brazil), and three scenarios were established. Scenario 1: husk is discarded outdoors; scenario 2: energy use of the husk for gasification and subsequent production of electricity; scenario 3: use of the husk as an organic fertilizer. An economic and environmental analysis was conducted from these three scenarios. The gasification technology with the coffee husk, although technically feasible, according to the economic analysis becomes unfeasible, since the value of this electric generation was higher than the other generation values. Scenarios 2 and 3 that applied sustainable practices resulted in negative values for the environmental impacts of water depletion and depletion of fossil fuels, proving the benefits of such practices. The gasification process needs technological development to make the enterprise economically viable. Sustainable practices in coffee cultivation bring environmental benefits in the short and long terms.

Resumen El estudio de la gasificación de biomasa ha cobrado gran interés durante las últimas décadas, representando un proceso atractivo para la producción de energía y calor y la producción de hidrógeno y biocombustibles de segunda generación. El objetivo de este trabajo fue caracterizar la composición del gas pobre así como también su potencial energético. Las experiencias se realizan en un gasificador de lecho fijo en escala planta piloto y se usa aserrín a granel de madera de pino como materia prima de gasificación. Se investiga la influencia de la temperatura del proceso (650-900 oC), la tasa de oxígeno (0,3-0,6) y la relación vapor/aserrín sobre la gasificación del aserrín. Los resultados del estudio muestran que el contenido de hidrógeno, los porcentajes de conversión de hidrógeno y carbono, el poder calorífico y la eficiencia térmica del gas aumentan cuando aumenta la temperatura y disminuye la tasa de oxígeno. El uso de vapor en el proceso de gasificación aumenta la eficiencia térmica y el contenido de hidrógeno del gas pobre.

Abstract The study of biomass gasification has gained great interest in recent decades, representing an attractive process for the production of energy and heat and the production of hydrogen and second-generation biofuels. The objective of this work is to characterize the composition of the producer gas, as well as its energy potential. Experiments are carried out in a fixed bed gasifier on a pilot plant scale, and bulk sawdust from pine wood is used as gasification raw material. The influence of process temperature (650-900 oC), oxygen rate (0.3-0.6) and steam / sawdust ratio on the gasification of pine sawdust are investigated. Results of this study show that the hydrogen content, both hydrogen and carbon conversion, the calorific value and the efficiency of the cold gas increase by increasingtemperature and decreasing oxygen rate. The use of steam in the gasification process increasesthermal efficiency and hydrogen content of the producer gas.

A large part of the world's population still depends on firewood for domestic energy needs. If appropriately used, firewood can be considered a renewable energy resource. However, in many rural areas it is burnt in the open and in poorly ventilated kitchens, emitting smoke which is potentially harmful to those exposed to it. Interventions such as wood gasification stoves and electricity seem to have failed. This study evaluated factors influencing firewood consumption in households at the Thulamela local municipality. A household survey collected data from the selected community and it was analysed with Statistical Package for Social Scientists. The chi-square test was used to measure the degree of association between two categorical variables. The study showed a statistically significant association between the source of energy used and gender, education of the household head, employment status, income level, and energy expenditure. The chi-square test determined the association between the variables as the significance level is less than the p-value. The results also indicated that household energy consumption is influenced by level of income, gender, educational level of household head, employment status, number of members employed in a household, and energy expenditure. These factors are linked and mutually dependent. It is recommended that the use of renewable energy and modern energy technologies, such as liquefied petroleum gas, biogas and solar, should be encouraged, with the assistance of the municipality. There is also a need to raise environmental awareness. It is through education that people's perception, attitudes and behaviour towards firewood consumption practices can be changed.

The gasification reactivity of coal char is affected by numerous experimental variables, and char structure is one of the dominant factors. In this work, Raman spectroscopy, powder X-ray diffraction (XRD), and N2 adsorption were used to investigate the physical and chemical structure of char prepared under different pyrolysis conditions. Three kinds of pyrolysis reactors, fluidized-bed reactor (FL), entrained-flow-bed reactor (EF), and fixed-bed reactor (PT), were designed and used to prepare the char samples. Lignite was pyrolyzed in a fixed-bed reactor with a heating rate of 10 ºC min-1, and the final temperature was 1000 ºC. The gasification reactivity of char was characterized in a quartz fixed-bed reactor under CO2, H2O, and their mixtures at 750 ºC. FB reactor produces chars with a smaller interlayer spacing of aromatic layers (d002), and FL reactor produces chars with a larger mean crystallite size along the c-axis (Lc) and aromaticity (ƒa) but inhibits the growth of mean crystallite size along the a-axis (La). The content of small aromatic rings, which is higher in the FL reactor, positively affects the initial intrinsic reactivity.

Taking advantage of the energy contained in the biosolids generated in a wastewater treatment plant (WWTP) is one of the processes of greatest interest due to the opportunity to obtain an energy resources from a waste. The aim of this research was to analyze the environmental sustainability use of biosolids generated in a wastewater-treatment plant for energy-production by fluidized-bed gasification under exergy analysis. The energy-production system was based on previous studies of sustainable-emergy alternatives using biosolids. Sustainability of the process was evaluated by identifying stages in the energy-production system (from drying application to electricity generation) where it is possible to reduce useful energy losses as well as identifying the value of waste streams within the system through exergy analysis. It was illustrated the destroyed exergy and the efficiency by stage and by product in order to assess the effects of inefficiencies in the process sustainability. The mixture of biosolids with coal was identified as a highly sustainable stage of the process, as it presents the highest index of exergy sustainability (0.99), in contrast to the stages of energy-transformation (turbine) and gas-cleaning, which efficiencies are 0.17 and 0.4, respectively. Energy-transformation and gas-cleaning stages are of interest in terms of an improved energy recovery process, making it more efficient by applying new technologies and/or using the waste streams that have high energy potentials.

Abstract: In this work, biochar (BC), a co-product of the fixed bed gasification process of Pinus patula wood pellets (PL) and chips (CH), was characterized as soil amendment. The physicochemical properties and the mineral content of the pellet’s biochar (PL-BC) and the chips biochar (CH-BC) were analyzed following the NTC5167 Colombian technical standard. The BET surface area values of the BCs were 367,33 m2/g and 233,56 m2/g for the PL-BC and the CH-BC, respectively, and the pore volume was 0,20 cm3/g for the PL-BC and 0,13 cm3/g for the CH-BC. These characteristics favor the increase of the BCs water-holding capacity (WHC). Properties such as the pH (8,8-9,0), the WHC (219 %-186,4 %), the total organic carbon (33,8 %-23,9 %), the metalloid presence (Ca, Mg, K, Mn, Al, Si, and Fe), and the ash (1,92wt % - 2,74 wt %) and moisture contents (11,13wt %-11,63 wt %) for both BCs were found to be within the limits set by the standard. Furthermore, the presence of micro and macronutrients, such as Fe and phosphorus (P), and the alkaline pH, make possible the use of these BCs as amendments for acid soils.