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Landfills are one of the most common ways to dispose the solid urban waste in many countries due to their relatively simple technical requirements, operational costs and low investment. Moreover, biogas produced in landfills can be used as a renewable energy source for power generation. The Valencian Region is one of the largest solid urban waste producers in Spain, and therefore, it has an unexplored potential of landfill biogas production. This paper aims to estimate the potential of biogas landfill production for power generation in the Valencian Region. Statistical data from solid urban waste in landfills in the provinces of Alicante, Castellón, and Valencia was gathered. Then the potential of landfill biogas production was estimated by means of waste classification for each province. To provide information related to the use of landfill gas as an alternative source of energy, results presented in this work show that the Valencian Region has an important potential to use landfill biogas from solid urban waste as a renewable source for power generation, and also provide information to the regional government, academic researches, policy makers and investors.

Abstract Charge transfer reaction across the electrode/electrolyte interface and hydrogen diffusion in the negative MH alloy electrode dominate the high-rate discharge capability of the metal hydride electrode in a nickel metal hydride (Ni/MH) battery. The mass transfer process in the MH electrode mainly involves hydrogen diffusion in the bulk MH alloy. The charge transfer reaction in the negative electrode reflects the capability of hydrogen reduction and oxidation reactions at the surface of the MH alloy powder. In this study, an AB 5 -type hydrogen-absorbing alloy was used as the negative electrode material. The rate-determining mass transfer process in the bulk MH alloy electrode was studied and analyzed using anodic polarization measurements. The exchange current density, which is related to the charge transfer reaction, was analyzed by using the hydrogen equilibrium pressure. The estimation of hydrogen diffusion coefficient in the MH alloy is strongly dependent on the value of the effective reaction area of charge transfer reaction at the surface of the alloy powder.

The increasing energy consumption, mostly supplied by fossil fuels, has motivated the research and development of alternative fuel technologies to decrease the humanity’s dependence on fossil fuels, which leads to pollution of natural sources. Small-scale biomass gasification, using air-steam blends for partial oxidation, is a good alternative since biomass is a neutral carbon feedstock for sustainable energy generation. This research presents results obtained from an experimental study on coffee husk (CH) gasification, using air-steam blends for partial oxidation in a 10 kW fixed-bed gasifier. Parametric studies on equivalence ratio (ER) (1.53 < ER < 6.11) and steam-fuel (SF) ratio (0.23 < SF < 0.89) were carried out. The results show that increasing both SF and ER results in a syngas rich in CH4 and H2 but poor in CO. Also, decreased SF and ER decrease the peak temperature (Tpeak) at the gasifier combustion zone. The syngas high heating value (HHV) ranged from 3112 kJ/SATPm3 to 5085 kJ/SATPm3 and its maximum value was obtained at SF = 0.87 and ER = 4.09. The dry basis molar concentrations of the species, produced under those operating conditions (1.53 < ER < 6.11 and 0.23 < SF < 0.89), were between 1.12 and 4.1% for CH4, between 7.77 and 13.49% for CO, and between 7.54 and 19.07% for H2. Other species were in trace amount.

Modeling and simulation of internal variables such as temperature and relative humidity are relevant for designing future climate control systems. In this paper, a mathematical model is proposed to predict the internal variables temperature and relative humidity (RH) of a growth chamber (GCH). Both variables are incorporated in a set of first-order differential equations, considering an energy-mass balance. The results of the model are compared and assessed in terms of the coefficients of determination (R2) and the root mean squared error (RMSE). The R2 and RMSE computed were R2 = 0.96, R2 = 0.94, RMSE = 0.98 °C, and RMSE = 1.08 °C, respectively, for the temperature during two consecutive weeks; and R2 = 0.83, R2 = 0.81, RMSE = 5.45%RH, and RMSE = 5.48%RH, respectively, for the relative humidity during the same period. Thanks to the passive systems used to control internal conditions, the growth chamber gives average differences between inside and outside of +0.34 °C for temperature, and +15.7%RH for humidity without any climate control system. Operating, the GCH proposed in this paper produces 3.5 kg of wet hydroponic green forage (HGF) for each kilogram of seed (corn or barley) harvested on average.

Abstract This document presents a performance assessment of the three-phase two-level voltage source converter (VSC) model of the real-time digital simulator RTDS/RSCAD. This evaluation is conducted through two case studies. One case is a simple two-bus power electronic-based system, and the second case is a three-bus system with a frequency-dependent transmission line model and a closed-loop controlled VSC with communication delay. The results obtained reveal that the RTDS/RSCAD VSC model presents some issues on stability, harmonic spectrum, ripple, and power quality in general, as compared with the PSCAD VSC solutions. These results also suggest the need for better power electronic components models.

This study is aimed at the analysis of the pyrolysis kinetics of Nanche stone BSC (Byrsonima crassifolia) as an agro-industrial waste using non-isothermal thermogravimetric experiments by determination of triplet kinetics; apparent activation energy, pre-exponential factor, and reaction model, as well as thermodynamic parameters to gather the required fundamental information for the design, construction, and operation of a pilot-scale reactor for the pyrolysis this lignocellulosic residue. Results indicate a biomass of low moisture and ash content and a high volatile matter content (≥70%), making BCS a potential candidate for obtaining various bioenergy products. Average apparent activation energies obtained from different methods (KAS, FWO and SK) were consistent in value (~123.8 kJ/mol). The pre-exponential factor from the Kissinger method ranged from 105 to 1014 min−1 for the highest pyrolytic activity stage, indicating a high-temperature reactive system. The thermodynamic parameters revealed a small difference between EA and ∆H (5.2 kJ/mol), which favors the pyrolysis reaction and indicates the feasibility of the energetic process. According to the analysis of the reaction models (master plot method), the pyrolytic degradation was dominated by a decreasing reaction order as a function of the degree of conversion. Moreover, BCS has a relatively high calorific value (14.9 MJ/kg) and a relatively low average apparent activation energy (122.7 kJ/mol) from the Starink method, which makes this biomass very suitable to be exploited for value-added energy production.

El aumento de la demanda energética, así como de las emisiones contaminantes ha generado un incremento de la investigación de tecnologías que permitan mitigar ambas problemáticas a nivel mundial. Dentro de las alternativas para mejorar la eficiencia de los procesos térmicos, el régimen de combustión sin llama se presenta como una de las alternativas más promisorias, puesto que permite obtener altos valores del rendimiento térmico mediante el mejoramiento de la transferencia de calor y del proceso de combustión, con la consiguiente reducción de las emisiones contaminantes. Debido a esto, en el presente estudio se realiza una revisión del estado del arte de dicha tecnología, haciendo énfasis en los aspectos fenomenológicos asociados, las principales características del régimen y su estabilidad, pasando por los mecanismos de obtención y la presentación de una serie de estudios, tanto a nivel nacional como internacional, en los que se utilizaron combustibles fósiles y alternativos. La revisión finaliza con la discusión de algunos casos en los cuales se ha implementado el régimen a nivel industrial.

Based on a recently published theoretical model, in this work we experimentally studied the problem of gravity water drainage due to continuous steam injection into an elliptical porous chamber made of glass beads and embedded in a metallic, quasi-2D, massive cold slab. This configuration mimics the process of steam condensation for a given time period during the growth stage of the steam-assisted gravity drainage (SAGD) process, a method used in the recovery of heavy and extra-heavy oil from homogeneous reservoirs. Our experiments validate the prediction of the theoretical model regarding the existence of an optimal injected steam mass flow rate per unit length, ϕopt, to achieve the maximum recovery of a condensate (water). We found that the recovery factor is close to 85% when measured as the percentage of the mass of water recovered with respect to the injected mass. Our results can be extended to actual oil-saturated reservoirs because the model involves the formation of a film of condensates close to the chamber edge that allows for gravity drainage of a water/oil emulsion into the recovery well.