Disposal of used creosote-treated railroad ties (RT) is environmentally challenging due to the carcinogenic nature of the creosote. Although the US EPA permits using RT as an energy source in certain combustion units, biomass faces issues with slagging and fouling at high temperatures. In this study, the initial sintering temperature (IST) and melting point of RT ash pellets heated between 600 and 900 °C were determined using a compression strength test (CST). The agglomeration and mineral phase changes were analyzed with BET, FTIR, and XRD, while the slagging and fouling potential were assessed using empirical indices such as the bed agglomeration index, base-to-acid ratio, slag viscosity index, silica-aluminum ratio, alkali index, slagging index, fouling index, and a ternary diagram. CST results show that the IST and melting point are approximately 600 °C and 651 °C, respectively. The BET test indicates gradual agglomeration with increasing temperature. FTIR and XRD confirm calcite decomposes into anhydrite at the IST, aiding sintering and agglomeration. At the melting point, calcite, anhydrite, and silicophosphate transform into vitreous Ca-containing aluminosilicate and aluminophosphate phases, reducing the strength of heated RT ash pellets. Moreover, most indices suggest a high potential for slagging and fouling. Thus, thermal conversion of RT should be operated at or below 651 °C to avoid ash-related problems. Otherwise, the use of additives, leaching, and co-utilization must be explored if the conversion process requires higher operating temperatures. Most creosote-treated wood ties, which are waste materials from railroads, are being reused as feedstock for combustion and gasification. The ash characteristics affect sintering, agglomeration, and slagging in reactors and heat exchange equipment, leading to blockages, inefficiencies, and requiring mandatory operational shutdowns for maintenance. However, there is no data in the literature characterizing the ash behavior of railroad ties at high temperatures. This study aims to evaluate the sintering behavior and mineral transformations of railroad tie ash, as well as its tendencies for slagging and fouling. The results of this work can serve as a baseline for establishing an appropriate operating temperature for the thermal conversion of railroad ties.

Introduction to Renewable Energy Conversions examines all the major renewable energy conversion technologies with the goal of enabling readers to formulate realistic resource assessments. The text provides step-by-step procedures for assessing renewable energy options and then moves to the design of appropriate renewable energy strategies. The goal is for future engineers to learn the process of making resource estimates through the introduction of more than 140 solved problems and over 165 engineering related equations. More than 120 figures and numerous tables explain each renewable energy conversion type. A solutions manual, PowerPoint slides, and lab exercises are available for instructors. Key Features Covers all major types of renewable energy with comparisons for use in energy systems Builds skills for evaluating energy usage versus environmental hazards and climate change factors Presents and explains the key engineering equations used to design renewable energy systems Uses a practical approach to design and analyze renewable energy conversions Offers a solutions manual, PowerPoint slides, and lab activity plans for instructors

The adsorption potential of biochar derived from municipal solid waste (MSW) and coconut husk (CH) for methylene blue (MB) removal was investigated in this study. Both produced biochars exhibited a pHPZC of 8.5 with no observed significant compositional changes (consistent with literature values). The integration of CH in the co-pyrolysis process altered the surface morphology of MSW-BC. Moreover, the post-adsorption images indicated MB deposition on the biochar surfaces. The MCH-BC had 559 m² g−1 specific surface area and about 29 mg g−1 adsorption capacity, and practically indicated superior adsorbent quality than MSW-BC (with corresponding lower values). Furthermore, the adsorption behaviors suggested that the phenomena were (1) potentially influenced by chemisorption from kinetic studies, (2) best fitted the Freundlich isotherm model, denoting a heterogeneous adsorption mechanism, and (3) endothermic and spontaneous from the thermodynamic analysis. The proposed adsorption mechanism was feasibly dominated by physisorption, as indicated by low ΔG° values (−1.234 kJ mol⁻¹ to −4.531 kJ mol⁻¹) and functional groups, likely facilitating hydrogen bonding, which perhaps followed by initially identified chemisorption from kinetic studies. Finally, the study highlighted the potential of co-pyrolyzed MSW and CH biochar as a competitive low-energy synthesis, producing an adsorbent for MB removal.

Developing alternative or new energy sources is essential due to fossil fuel depletion and environmental impacts. Previous studies have synthesized an Ni-functionalized and pyrolyzed rice husk for catalytic refining of oil from microalgae (Scedemus obliquus) and have further optimized the liquid hydrocarbon production. This work further investigated the interacting effects of the operating parameters on gasoline (Y-1) and diesel (Y-2) relative content. The parameters were temperature (A), dodecane-to-oil ratio (B), and pressure (C). The response surface methodology by central-composite design (RSM-CCD) demonstrated that the temperature was the only parameter significantly affecting the relative content of the two fuel products. The previously RSM-CCD optimized condition (A = 246.9 degrees C, B = 3.72, and H-2 pressure = 3.84 MPa), generating the liquid hydrocarbon, produced Y-1 = 77.1 % and Y-2 = 22.9 % with a standard error of +/- 0.7 % and <2.0 % discrepancy from the predicted values. Finally, the specific constituents were further identified as undecane, tridecane, pentadecane, and octadecane for diesel-range products, while octene, octane, nonane, and decane for gasoline-range products. Overall, the study demonstrates the responses of two fuel products under the optimized operating liquid hydrocarbon and further supports the catalytic upgrade considering the identified fuel products.

The sustainable management of municipal solid waste (MSW) and agricultural residues, such as coconut husk (CHK), remains a critical challenge in waste valorization and energy production. This study investigates the co-pyrolysis of MSW and CHK at varying pyrolytic temperatures (350-550 degrees C) to evaluate its effects on product distribution and energy potential, particularly focusing on CHK-blending and underscoring the solid products while also quantifying and characterizing secondary products (i.e., oil and gas). The results indicated that CHK blending had a minimal impact (with no evident synergistic effect) on overall mass yields, possibly due to the comparable lignocellulosic composition of both feedstocks. Char yield (33-60%) was primarily governed by lignin content, which resisted thermal decomposition and favored the aqueous phase over oil generation. Higher temperatures enhanced the formation of combustible gases, including methane, while suppressing less valuable byproducts. The pyrolytic oil phase, rich in phenols, ketones, and furfural, exhibited no distinct trend with temperature, likely due to competing volatilization and decomposition reactions. Furthermore, CHK blending increased fixed carbon content, while elevated temperatures reduced volatile matter and promoted carbonization. Despite these compositional shifts, the pyrolytic products' overall higher heating value (HHV) remained within 2.6-26.0 MJ kg-1, demonstrating their potential as alternative energy sources. These findings highlight the role of co-pyrolysis in promoting sustainable waste-to-energy conversion and material recovery for circular bioeconomy.

With increased worldwide energy demand and carbon dioxide emissions from the use of fossil fuels, severe problems are being experienced in modern times. Energy is one of the most important resources for humankind, and its needs have been drastically increasing due to energy consumption, the rapid depletion of fossil fuels, and environmental crises. Therefore, it is important to identify and search for an alternative to fossil fuels that provides energy in a reliable, constant, and sustainable way that could use available energy sources efficiently for alternative renewable sources of fuel that are clean, non-toxic, and eco-friendly. In this way, there is a dire need to develop technologies for biofuel production with a focus on economic feasibility, sustainability, and renewability. Several technologies, such as biological and thermochemical approaches, are derived from abundant renewable biological sources, such as biomass and agricultural waste, using advanced conversion technologies for biofuel production. Biofuels are non-toxic, biodegradable, and recognized as an important sustainable greener energy source to conventional fossil fuels with lower carbon emissions, combat air pollution, empower rural communities, and increase economic growth and energy supply. The purpose of this review is to explain the basic aspects of biofuels and their sustainability criteria, with a particular focus on conversion technologies for biofuel production, challenges, and future perspectives.

The direct emission of inhalable particulate matters (PM2.5 and PM10) from agricultural sources imposes major concern to human health. It is imperative to keep regular update of the pollutant emissions to scrutinize the sources and take necessary preventive measures. Two representative animal feeding operations, one dairy and one feedlot of Texas were selected during the year 2021 for summer and winter sampling using programmable Federal Reference Method (FRM) samplers and Texas A&M University (TAMU) designed samplers. Additionally, for quick and simple emission concentration determination, handheld particle counters were utilized parallel to the FRM and TAMU designed samplers. The air quality index showed that the PM2.5 pollutant fell into ‘Moderate’ category for about 20.93% times and 13.89% times in the dairy and the feedlot respectively. The maximum mean of daily PM10 concentration observed in the Feedlot during the summer was 1676.3 μg m-3 which can be aggravating. The correlation developed using the emission data from the FRM and handheld samplers demonstrated linear relationship and 0.66 of goodness of fit. During the summer, maximum mean PM2.5 emission factors (EF) of 0.84 kg 1000 hd-1 d-1 and 8.09 kg 1000 hd-1 d-1 were determined for the dairy and for the feedlot respectively. However, the winter and the summer PM10 EF for the dairy did not differ significantly (P>0.05). Although there has not been enough record of PM2.5 annual EF, the current study PM10 annual EF was benchmarked with some of the previously published EFs. This investigation on the air pollutant EFs from the animal feeding operations can greatly benefit in preventing the pollution and updating the most recent EFs. However, continuous monitoring and further research are suggested to improve data quality and develop strategic management practices.

Abstract The dimensions of the of a photobioreactor play a major role in its hydrodynamic and mass transfer characteristics that also affect its growth performance. In this study, a bench-scale airlift photobioreactor (PBR) was designed and fabricated to have a riser-to-diameter ratio (Ar/Ad) equal to 0.42 and an aspect ratio (H/D) equal to 1.53. These dimension ratios are different from typical values wherein most airlift photobioreactors are designed to have Ar/Ad of at least 1.0 and H/D of at least 2.0. It was hypothesized, based on the results of Hwang and Cheng [1], the fabricated PBR in this study will have better hydrodynamic and mass transfer characteristics such as lesser mixing time, better liquid circulation and lesser gas entrainment that may lead to better growth performance. Due to the different dimension ratios from other studies, characterization of the PBR and testing of its performance are required. The hydrodynamic and mass transfer characteristics of the fabricated airlift photobioreactor in this study were measured at varying superficial gas velocities (UGR) from 0.0017 ms−1 to 0.0124 ms−1. The growth parameters of the Spirulina platensis were then tested at different aeration rates to relate the hydrodynamic and mass transfer characteristics to the photobioreactor performance. This study has proven that a photobioreactor that is designed and operated to have the best hydrodynamic and mass transfer characteristics will have the best growth performance at the same light intensity and initial optical density.

As a result of the depletion of fossil resources, ongoing population growth, and the industrialized economy, energy demand has been rising quickly throughout the world. India is now the world's third-largest oil consumer, surpassing Japan and Russia. Today, biofuel research is conducted worldwide because surrounding two essential characteristics: sustainability and renewability. Biofuels have gained considerable significance as a result of dwindling oil sources, worries about energy security, and the escalating environmental issues associated with climate change and greenhouse gas emissions. In most cases, biofuels are produced by subjecting materials that have been densified to the process of heat conversion. In the disciplines of research and development, alternative energy development is a top focus. Due to the depletion of fossil fuel resources, it has become important to find innovative replacements for fossil fuels, such as biofuels, to generate heat and power. Biofuels may be generated using several methodologies, encompassing biological, chemical, and physical approaches. The three steps of densification systems' pre-, during-, and post-pelletization procedures convert biomass into pellets. Several agricultural wastes, such as grain dust, crop leftovers, and fruit tree residues, are available as sources of agricultural energy. Bioenergy from biomass, such as leftovers and energy crops, can be used to produce contemporary energy carriers. This article focuses on an overview of sustainable and renewable biofuel resources and their commercialization.

In this work, designs a novel solar-driven thermochemical conversion reactor to torrefy biomass waste (Ashe Juniper) for further pyrolysis applications. The effect of torrefaction temperature and residence time on the properties of biomass waste was investigated and results showed that torrefaction temperature dominates the properties of product compared to the effect of residence time. The highest energy yield (over 90%) was obtained at 210 degrees C while the highest energy densification (-1.51) was achieved at 360 degrees C. In addition, a two-step kinetic numerical model was used to analyze and predict the experimental process (kinetic rates) and results (C, H, and O contents) based on the experimental results. The analysis results showed that the predicted results are in good agreement with the practical results after torrefaction, indicating the feasibility of this numerical model for torrefaction and pyrolysis applications. The carbon footprint analysis showed that reduction effect of 1.3 -1.6 tCO2/ton-AJ can be obtained by torrefaction of Ashe Juniper. Finally, the prospects for future industrial appli-cations of solar-driven torrefaction reactors discussed as one of affordable and clean energy.

Coconut shells’ abundance in tropical countries, along with its high volatile combustible matter (83.51%) and energy content (18.68 MJ kg-1) make it a good biomass resource and a promising feedstock for gasification. In gasification, different mediums such as air, steam, oxygen, or their combinations can be used to react with the solid carbon and heavy hydrocarbons of biomass. Hence, the effects of using an air-steam mixture as a gasifying agent for the bench-scale fluidized bed gasification of coconut shells were studied. The steam-to-carbon ratio (SCR) was varied to evaluate its effect on the resulting syngas quality and gasification performance, while the equivalence ratio was maintained at 0.25 and the bed temperature was kept at 700°C. Results revealed that the optimum SCR is 0.6, where peak values of hydrogen (H2) and methane (CH4) content, hydrogen-to-carbon monoxide ratio (H2/CO), higher heating value (HHV), cold gas efficiency (CGE), and carbon conversion efficiency (CCE) were observed. Furthermore, the use of the air-steam mixture (SCR 0.6) as a gasifying agent was compared with the conventional air gasification. The study also showed a significant increase in syngas quality in terms of H2 content (4.70 - 5.82%), H2/CO (0.30 - 0.39), and CH4 content (3.53 - 4.38%). The syngas heating value and gasification performance revealed a statistically similar improvement: HHV from 4.95 to 5.41 MJ Nm-3, CCE from 77.64 to 81.75%, and CGE from 47.99 to 51.01%. Moreover, air-steam gasification produced less CO2 (13.42 CO2mol kgbiomass-1) and had higher energy recovery (49.67%).

The potential that biomass energy has to supplement traditional fuels and reduce greenhouse gas emissions has put it front and center in the plan to replace fossil-based fuels with renewable fuels. While much has been written about biomass conversions, no single textbook contains all the information needed to teach a biomass conversion course-until

This study demonstrates the feasibility of a mobile aerial drone particle monitoring system (DPMS) to measure and detect changes in harvest dust levels based on moderate adjustments to harvester settings. When compared to an earlier harvester, a new harvester operated at standard settings produced 35% fewer PM2.5s, 32% fewer PM10s, and 42% fewer TSPs. Increasing the ground speed had an adverse effect on dust mitigation, while reducing it by half only offered a slightly more favorable margin. The mutual effects of some meteorological factors were found to be slightly correlated with PM10 and TSP readings and caused significant variability in PM2.5 readings. The current findings show similar trends to PM reduction estimates of previous studies, with only a nominal difference of 10 to 15% points. Overall, the DPMS was found to perform well within an acceptable statistical confidence level. The use of DPMSs could reduce the logistical needs, complexity issues, and feedback times often experienced using the Federal Reference Method (FRM). Further investigation is needed to verify its robustness and to develop potential correlations with the FRM under different orchard location and management practices. At this stage, the current aerial DPMS should be considered a rapid screening tool not to replace the FRM, but rather to complement it in evaluating the feasibility of dust abatement strategies for the almond industry.