The supercritical water gasification (SCWG) and carbon dioxide gasification of agro-industrial and urban waste residues—Coffee Husk, Eucalyptus Biochar, Energy Sugarcane, and Refuse-Derived Fuel (RDF)—were studied using TeS® v.2 software, which employs a non-stoichiometric thermodynamic model to minimize Gibbs free energy and predict equilibrium compositions. The effects of temperature (873.15–1273.15 K), pressure (220–260 bar), biomass feed (18–69%), and gasifying agents on hydrogen and methane formation were analyzed. Higher temperatures and biomass feed percentages favored hydrogen production, while lower temperatures increased methane formation. At 1273.15 K, RDF showed the highest hydrogen yield in SCWG, rising from 0.43 to 1.42 mol, followed by Energy Sugarcane (0.39 to 1.23 mol), Coffee Husk (0.34 to 0.74 mol), and Eucalyptus Biochar (0.33 to 0.62 mol). In CO2 gasification, hydrogen yields were lower but followed a similar trend. At 873.15 K, RDF also exhibited the highest methane increase in SCWG, from 0.14 to 0.91 mol, followed by Energy Sugarcane (0.12 to 0.65 mol), Coffee Husk (0.11 to 0.36 mol), and Eucalyptus Biochar (0.11 to 0.29 mol). Methane formation in CO2 gasification was significantly lower, with RDF increasing from 0.0035 to 0.35 mol, followed by Energy Sugarcane (0.0024 to 0.24 mol), Coffee Husk (0.0002 to 0.058 mol), and Eucalyptus Biochar (0.0002 to 0.028 mol). On the other hand, a slight increase in hydrogen formation was observed as pressure decreased, while the opposite effect was observed for methane formation, with a small increase in its production as pressure increased. The impact of pressure change on the equilibrium compositions was not as significant as the effect observed by varying temperature; this behavior was observed in both gasification processes studied. Additionally, the behavior of the H2/CO molar ratio for each biomass in the studied gasification processes was analyzed to assess the potential uses of the produced syngas. It was observed that the SCWG resulted in significantly higher H2/CO molar ratios compared to CO2 gasification.

This work evaluates the impact of air renewal on energy consumption for indoor environments. For this purpose, an analysis of the problem of air renewal at a Brazilian level was carried out, as well as research into the energy impact of air renewal without energy recovery and the different existing technologies for recovering energy from renewed air. On the other hand, the influence of heat-recovery systems was analyzed in three Brazilian cities (Manaus, São Paulo, and Brasília) for different environments, where a classroom in Manaus has an approximately 50% external air factor and a 42% sensible heat factor. However, classrooms in São Paulo and Brasília have a lower external air factor (27% and 8%, respectively) and a higher sensible heat factor (61% and 78%, respectively). Considering a system with heat recovery, the external air factor decreases to 23%, 10%, and 3% for Manaus, São Paulo, and Brasília, respectively. This allows us to understand the influence of heat-recovery systems, which reduce the external air factor and increase the sensible heat factor.

The sludge generated in sanitary sewage treatment, mainly during all stages of sewage treatment, is a waste that can be used for energy purposes. The sewage sludge can contain many toxic substances, such as pathogens, metals, and organic contaminants, which can cause severe environmental pollution. Therefore, the adequate treatment and possible energy recovery (generation of electricity and/or heat), in addition to representing a noble destination for sanitary sludge, is aligned with the concept of circular economy. To assess the potential for using sewage sludge as an energy source, various analyses were carried out for its characterization, such as proximate and ultimate analysis, calorific value determination, granulometric analysis, and surface adhesion tension. Among the results obtained, the lower heating value (LHV) stands out, with an average value of about 17 MJ/kg, which is a close result to the LHV of conventional biomass. Furthermore, the tests and sludge characterization results show that the drying method proposed in this study is more interesting than the convective method, given that it produces a smaller particle size in the material, for example.

While the aviation sector is trying to reach the net zero-carbon status in 2050, sustainable aviation fuel (SAF) is a possible strategy to help achieve this target. The present study compares alternative SAF production routes to meet future demands in the Brazilian and World markets. One possible SAF production chain includes the internationally approved alcohol-to-jet (ATJ) technology using the well-established Brazilian first-generation (1G) sugarcane ethanol as raw material (scenario I). This alternative was compared with technologies that utilize the excess lignocellulosic residues of the 1G sugarcane ethanol production either to produce SAF through gasification and Fischer-Tropsch (FT) synthesis combination (scenario II) or to produce more ethanol in an integrated first- and second-generation plant (1G2G) to serve as input to the ATJ process (scenario III). The assessment and comparison of the proposed SAF production alternatives were performed by adapting and using the models included in the Virtual Biorefinery (VB) platform developed by the LNBR/CNPEM to simulate the various biochemical and thermochemical integrated value chains. The major performed activities were: (i) technical, economic, and environmental assessments of sugarcane production and straw recovery; (ii) simulation of 1G and 1G2G ethanol production processes; (iii) simulation of the SAF production processes considered for the ATJ and FT alternative routes; (iv) economic and Life Cycle Assessment (LCA) of SAF production. The economic assessment results indicated that scenario I has the lower minimum selling price (MSP) for SAF (0.85 US$/L) attributed to the lower investments for the process, while scenarios II (1.10 US$/L) and III (1.07 US$/L) confirmed that the MSP of all scenarios was higher than the fossil fuel price (0.54 US$/L). Nevertheless, the technical results showed that scenario III presented a higher SAF production (135.3 million L/year) than scenarios I and II (98.5 and 114.3 million L/year, respectively). Regarding LCA, it could be mentioned that SAF emissions obtained in all scenarios (the lowest is 20.1 gCO2eq/MJ for scenario II) were lower than fossil fuel (87.5 gCO2eq/MJ). Finally, it can be indicated that the availability of sugarcane in Brazil converts the country into a potentially essential participant for the deployment of large-scale projects for SAF production, which can reduce greenhouse gas emissions compared with the conventional kerosene production chain. Furthermore, the learning curve of new technologies included in scenarios II and III, as well as the implementation of policies associated with the production of biofuels, could strongly reduce the MSP of SAF produced in integrated chains.

A reaction-front assessment and char characterization of a mixture of oil sludge and palm kernel shell in a fixed -bed reverse-downdraft gasifier using air as the oxidizing agent has been performed. The investigation was focused on assessing the effect of airflow (from 30 up to 60 L/min) on the reaction front as well as on the characterization of char derived from the thermochemical treatment. The thermochemical conversion process was described by output parameters such as fuel consumption rate, flame front velocity (Vff), maximum process temperature (Tmax), air-fuel equivalence ratio, and char yield. The char was characterized regarding its surface structure by determining Brunauer, Emmett, and Teller (BET) surface area, pore volume, and pore size distri-bution. The results demonstrated that as the airflow rate increased from 30 to 60 L/min, Vff and Tmax augmented from 4.36 to 6.49 mm/min, and from 967 to 1090 degrees C, respectively, as the process approached a combustion regime. In parallel, the char yield decreased from 13.4 to 4.5 % for the same airflow range due to the higher temperatures, which favors oxidation reactions. The char characterization showed that the BET surface area reached a maximum value of 269.8 m2/g at 50 L/min and subsequently decreased, which was attributed to the thermal deformation of the pore structure as the process temperature increased. Furthermore, pore size distri-bution showed that the char was mainly composed of micropores. Besides providing useful information related to the operation of gasifiers and char production, this analysis is particularly relevant for solutions aimed at mitigating environmental impacts, as it involves renewable sources and energy recovery.

This work aims to evaluate the gasification of oily sludge (OS) and the potential use of produced gas as feedstock for ammonia production. For this purpose, a computational gasification model was developed and validated in Aspen Hysys® v. 11.0 software to evaluate the influence of air/steam mixtures as gasification agents on the studied parameters. The Lower Heating Value (LHV) of the producer gas varied between 5 and 10 MJ/m3 for equivalence ratios greater than 0.3. The molar concentration of H2 increased to 24.9% at 1380°C and decreased to 21.5% at 1700°C. Finally, the producer gas was used to synthesize ammonia, where a conversion of more than 90% was obtained at a pressure of 100 bar and a temperature of 450°C. The results showed that oil sludge gasification could be a viable alternative to efficiently converting refinery waste into valuable products.

In this work, a comprehensive energetic and exergetic comparative assessment is presented for the simple solar organic Rankine cycle (SORC), regenerative solar organic Rankine cycle (RORC), and dual-loop solar organic Rankine cycle (DORC), considering parameters such as the net power produced, exergy destruction, exergy, and energy efficiency in four zones located in Colombia due to their high solar irradiation potential. The energetic and exergetic balances were applied for each system component, using toluene as the working fluid. The RORC system showed a 2% increase in efficiency over the SORC, while the DORC cycle was lower than the SORC (45.85%) and RORC (46.90%) systems. Finally, for the exergy analysis, the results revealed that the SORC (5.3%) and RORC (5.2%) systems had the highest efficiency compared to DORC systems. Additionally, the highest exergy destruction (89%) was related to the collector, followed by the evaporators (1–2%), pumps (0.1%), and turbines (1.12%).

The thermal conversion of oil sludge has been presented as a promising alternative for treating this residue in the petroleum industry. The chemical and energetic characterization of residues is essential in determining the most suitable thermochemical conversion process for their treatment and the appropriate operational parameters for the process. In this sense, this study focuses on a non-isothermal thermo-kinetic analysis of oil sludge to determine the influence of temperature and heating rate on the composition of the evolved gases produced during pyrolysis. Using the thermogravimetric analysis coupled with a Fourier-Transform Infrared Spectroscopy (FTIR), the kinetic and thermodynamic analysis of oil sludge were carried out by applying the Kissinger, Friedman, Ozawa-Flynn-Wall, and the Coats-Redfern methods, leading to the determination of oil sludge activation energy (Ea) consonant with its pyrolysis. In a dry nitrogen atmosphere, four different heating rates were used (5, 10, 20, and 50 K min−1). The active region occurs between 373 and 873 K. The overall pyrolysis process was considered a two-step process with two conversion stages. The first one ranges from 5 to 55

En el presente trabajo se estudió la pirólisis de residuos de yuca a través de un análisis termogravimétrico (TGA). Para este propósito, la biomasa seleccionada (yuca) fue caracterizada a partir de su poder calorífico, análisis inmediato y elemental. Para los experimentos fueron usadas tres velocidades de calentamiento (50, 75 y 100 K/min) en una atmósfera inerte con una rampa de calentamiento desde la temperatura ambiente (~25 °C) hasta 900 °C. Los resultados de la caracterización inicial mostraron un contenido de cenizas del 1,8%, y poder calorífico del 15,2 MJ/kg, convirtiendo este residuo en un candidato potencial para su uso energético a través de procesos de conversión termoquímica. Por otro lado, durante el tratamiento térmico en atmósfera inerte, el residuo de yuca experimentó un evento de pérdida de masa principal a 339,57 °C para 50 y 75 K/min (la mayor pérdida de masa fue a 50 K/min, resultando en un 12,15% del carbón) y se desplazó 34 °C cuando se trató la muestra a 100 K/min. Del análisis cinético se observó que la energía de activación aumenta conforme aumenta la conversión, donde el método Friedman que presenta altas energías de activación de 93,98, 190,98 y 182,1 kJ/mol en 0,15, 0,85 y 0,95 respectivamente. Los métodos Ozawa–Flynn–Wall (OFW) y Kissinger–Akahira–Sunose presentan un comportamiento similar para la dependencia de la energía de activación frente a la conversión y la variación es pequeña entre los resultados obtenidos con cada uno de ellos.

The present work studied the pyrolysis of cassava residues through a thermogravimetric analysis (TGA). For this purpose, the selected biomass (cassava) was characterized by its calorific value, immediate analysis, and elemental analysis. For the experiments, three heating rates (50, 75, and 100 K/min) were used under in an inert atmosphere with a heating ramp from room temperature (similar to 25 degrees C) to 900 degrees C. The initial characterization results showed an ash content of 1.8% by mass and a calorific value of 15.2 MJ/kg, making this residue a promising candidate for energy use through thermochemical conversion processes. On the other hand, during heat treatment under an inert atmosphere, the cassava residue experienced a major mass loss event at 339.57 degrees C for 50 and 75 K/min (the greatest mass loss was at 50 K/min, resulting in 12.15% of the char) and displaced 34 degrees C when the sample was treated at 100 K/min. From the kinetic analysis, it was observed that the activation energy increases as the conversion increases, whereas the Friedman method which presents high activation energies of 93.98, 190.98 and 182.1 kJ/mol at 0.15, 0.85 and 0.95 respectively. OFW and KAS methods present a similar behavior for the activation energy dependence on conversion, and the variation is minor between the results obtained with each of them.

A review of desiccant dehumidification technologies for improving air quality is presented, mainly focusing on alternatives for air conditioning systems for minimizing Sick Building Syndrome. The principles and types of desiccant wheels, as well as the existing selection software for these types of equipment, were reviewed and comparatively evaluated. The study focused on the Brazilian context; thus, information about this country's air conditioning systems and laws were evaluated. Possible applications of desiccant wheels, such as their integration into cooling cycles and the sensible heat wheel, were also analyzed. Finally, several examples of commercial desiccant wheel selection software that are useful in many situations were evaluated. Nevertheless, it was evidenced that the available software could not perform an operation analysis for only a specific period. Therefore, creating computational tools to select desiccant wheels is essential when considering the data from the different Brazilian regions for a year.

Heavy oil and biomass co-gasification has been analyzed through a model developed in Aspen Plus™ v 11.0 software. The model was used to assess main gasification parameters, such as cold gas efficiency, yield, low heating value (LHV), and producer gas composition, using air and oxygen as gasification agents. Subsequently, producer gas energy use in the Rankine cycle was performed using a model developed in GateCycle™ v11.1.2.4.850 software. Likewise, the economic indicators of the integrated Rankine cycle-gasification system were calculated. The economic evaluation was developed through Monte Carlo simulation using Crystalball™. The results showed a LHV producer gas decreasing trend as the equivalence ratio (ER) increased, oscillating between 6.37 and 3.63 MJ/Nm3 for ER values greater than 0.30 in the air co-gasification case, while the scenario that used oxygen presented better LHV results, ranging from 9.40 to 11.79 MJ/Nm3. For air co-gasification, the Rankine cycle efficiency range was between 13.0% and 9.5%, while for oxygen co-gasification, values between 14.0% and 13.2% were obtained. Regarding the economic assessment, the two scenarios evaluated (with a reliability of 95%) have a probability higher than 92.1% of economic losses due mainly to the lower electrical power and the local electricity rate.

This work focuses on the energy and economic evaluation of a power generation system composed of a downdraft gasifier and gas microturbine. The gasification process was studied using wood pellets as fuel, while the influence of two gasification agents (air and oxygen-enriched air) on parameters, such as low heating value (LHV), composition, and yield of syngas, were analyzed. The syngas produced from oxygen-enriched air gasification in a downdraft gasifier had an LHV higher than 8 MJ/Nm3, being suitable to be supplied in the gas microturbine. Subsequently, syngas use in the gas microturbine was evaluated, and the results demonstrated that microturbine efficiency dropped from 33.00% to 21.35%, while its power decreased from 200 kW to 81.35 kW. The power generation system was modeled using Aspen Plus® v 11.0 software and validated using results obtained from published experimental studies. Accordingly, the integrated generation system presented an overall efficiency of 11.82% for oxygen-enriched air gasification cases. On the other hand, an economic assessment through risk analysis using Monte Carlo simulations was performed using Crystal Ball® v11.1.2.4.850 software. The economic results indicated that the implementation of a generation system was economically unfeasible, however, if the electricity rate price was increased by 63%, the proposed configuration could be feasible.

An energetic and environmental assessment of producer gas production from oil sludge (OS) gasification and an analysis of its potential use for electricity generation has been performed. A computational model of OS gasification was developed and two gasification agent (oxygen and air/steam mixture) cases were analyzed. To determine the energy recovery potential of OS, a computational model involving a gas microturbine powered with the producer gas from OS gasification was developed. Results showed that oxygen gasification produced a gas LHV (11.1-7.2 MJ/Nm(3)) higher than air/steam gasification (9.9-3.8 MJ/Nm(3)). These differences influenced the microturbine electricity generation index values, which ranged from 0.423 to 0.407 kWh/kg-OS with oxygen, and from 0.42 to 0.393 kWh/kg-OS, using air/steam mixtures. For environmental impacts estimation of gasification/gas-microturbine integration, eight environmental impact categories were assessed by using the Life Cycle Assessment methodology. Among these, oxygen gasification showed higher reductions in comparison to air/steam gasification, in the nonrenewable energy (77%), respiratory organics (85%), and carcinogens (85%) categories. When energy recovery from syngas was considered, both cases have a lower carbon footprint (379-569 kg CO2-eq/ton OS) than incineration process (1045 kg CO2-eq/ton OS), which indicates that gasification system is an environmentally attractive option for OS treatment. (c) 2022 Elsevier Ltd. All rights reserved.

Given the imminent energy transition towards more sustainable and renewable energy systems, bioenergy represents an indispensable short and medium-term alternative. However, a key factor for developing the global bioindustry is establishing and consolidating integrated multi-product systems capable of efficiently and sustainably converting some organic materials into biofuels, bioelectricity, and other affordable bioproducts. Under this horizon, this work aims to evaluate and compare, through the thermodynamics precepts (1st and 2nd law), fixed capital investment, and life cycle analysis, different integrated bioenergetic complexes in which lignocellulosic material from oil palm and sugarcane cultures are processed simultaneously. These systems were structured for the Brazilian scenario, a country with a prominent role in bioenergy conversion, given its recognized soil and climate potential, large territory, and expertise in the bioenergy field. Consequently, this work presents a study of three scenarios: the first (CI), conventional palm oil biodiesel and sugarcane ethanol system; the second (CII) oilpalm-sugarcane biorefinery annexed to a lignocellulosic biomethanol plant; and the third (CIII) which is an extension of the second, but in this one, the concepts of advanced gas turbine integrated biomass gasification (BIG-GTCC) cycles are inserted. In this sense, a systematic analysis methodology is developed and implemented, which allows characterizing and measuring the energy, exergy, and environmental aspects related to the lignocellulosic material energy conversion, providing indicators that enable and facilitate the evaluation and selection of technologies that contribute to global energy decarbonization. The results obtained from the ther-modynamic evaluation expose the advantage of getting a more prominent energy portfolio from various raw materials, with CIII standing out before the other scenarios, with superior performance in Global plant efficiency (53.4 %), Surplus Electricity Index (86.6 kWh ton(MP)(-1)), and Global plant exergy efficiency (62.7 %), associated with BIG-GTCC integrating, verifying how attractive it is for agribusinesses. From an economic point of view, integration is not feasible; however, it could be significantly improved through fiscal incentives founded on fossil energy use reduction, enhanced conversion yielding, and improvements in conversion technologies. On the other hand, the LCA results showed the potential environmental benefits associated with the fossil diesel partial substitution by biodiesel (considering methanol derived from lignocellulosic material), both in sugarcane and palm culture, enabling the fossil energy consumption reduction by 79.6 % (sugarcane) and 69.2 % (palm) by the methyl route. Consequently, Fossil Energy Ratio (FER) increases to 9 energy units and Life Cycle Energy Effi-ciency (LCEE) up to 52.6 % are achieved in the oilpalm-sugarcane biorefinery.