• Energy Research

Abstract Torrefaction enhances physical properties of lignocellulosic biomass and improves its grindability. Energy densification, via fuel pellets production, is one of the most promising uses of torrefaction. Lignin contributes to self-bonding of wood particles during pelletization. In biomass thermal pretreatment, part of lignin (in the form of lignin liquid intermediates – LLI) migrates from the cell wall and middle lamella and deposits on the fibers’ surfaces and/or inner surface of the secondary cell wall. This material can play an important role on bonding particles during wood pelletization as well as production of wood composites. The objective of this paper was to investigate the influence of torrefaction conditions on amount, composition, molecular weight, and pattern of deposition of LLI on wood cells. Torrefaction of extracted ponderosa pine in the range of temperatures 225–350 °C was conducted in a tube furnace reactor and the torrefied wood was extracted with dichloromethane (DCM) to isolate the lignin-rich soluble material. A maximum yield of DCM-soluble material was observed in wood torrefied at approximately 300 °C for 30 min. ESI/MS revealed that the molecular weight of the removed material is less than 1200 g mol −1 and decreases as torrefaction temperature augments. Semiquantitative Py-GC/MS of the DCM-soluble material suggests that this lignin-rich material migrates and deposits on cells’ surfaces in amounts that depend on the torrefaction conditions. Py-GC/MS of the solid fraction after the DCM process showed a progressive reduction of products of the pyrolysis of lignin and levoglucosan as torrefaction temperature increased, revealing that lignin content in the solid decreased due in part to migration. SEM of torrefied particles helped to show the apparent formation of LLI during torrefaction. Results suggest that it is possible to control the thermal pretreatment conditions to increase or reduce the amount of lignin-rich material on fiber surfaces as required for downstream processes (e.g., fuel pellets or wood composites manufacture).

Research on using biochar for environmental applications has witnessed unprecedented advances in the past decade. Biochar is universally considered one of the best alternatives to store carbon to fight global warming. Thus, the sequential use of biochar in environmental remediation compatible with carbon sequestration is receiving growing attention. One of the reasons for such huge interest is the possibility to engineer biochar with targeted properties (e.g., surface area and chemistry) relevant to existing environmental issues. These properties can be achieved by selecting appropriate raw materials, processing conditions, carbonization technology, and the possibility of selecting postproduction modification approaches. The objective of this review is to summarize strategies to enhance biochar properties relevant to its use in environmental services (e.g., water purification, air/gas cleaning, construction materials, soil amendments) and the corresponding results on the use of this material for these applications. The main methods for enhancing biochar properties for environmental applications reviewed include activation (physical and chemical), oxidation, metal and metal oxide modification, metal-free heteroatom doping, and biological modification. Both modified and unmodified biochars have been used for soil amendments as adsorbents of pollutants in the aqueous phase (e.g., removal of P and N, heavy metals, and organic pollutants), adsorbents of pollutants in the gas phase (e.g., biogas cleaning), as a catalyst, as an additive for improving anaerobic digestion, and as an admixture to cementitious/construction materials, with promising results in all cases. New opportunities for using biochar are being reported as the science of biochar production, modification, and use advances.

Abstract This paper presents a pre-feasibility study of producing and using electrolytic hydrogen in Ecuador as part of a strategy towards a low carbon economy. Hydrogen could be produced using hydropower either alone or combined with other renewable energy sources. For this study, we analyzed two scenarios of energy availability based on data from the largest hydroelectric power plant in the country. The first scenario assumes that an amount of water equivalent to 30% of that spilled in 2011 could be used to generate additional electricity. Thus, an additional amount of energy equivalent to 5% of the energy produced in 2011 could be available. The second scenario doubles this amount of energy. Economic analysis showed that to obtain low-cost hydrogen (3.00 US$/kg) it is necessary to operate the electrolysis plants 24 h/day, using low-cost electricity (30 US$/MWh). A continuous supply of energy could be possible when new hydroelectric utilities start operating or by integrating hydropower with solar and wind. Three possibilities for using hydrogen are discussed: 1) production of ammonia as a raw material for nitrogenous fertilizers, 2) hydro-treating heavy oils and bio-oils in oil refineries, and 3) as an energy storage medium to offset natural instability and unpredictability of renewables.

This paper reviews the literature related to the complex chemical composition and multiphase nature of bio-oils and their practical implications. Over time, bio-oil forms separated phases due to purely physical phenomena (phase stability) or chemical composition changes in storage (aging reactions). Bio-oil multiphase behavior and the formation of separated phases are controlled by the complex chemical composition of these oils. Fast pyrolysis oils from woody biomass are typically observed in a single phase. However, feedstocks with high extractives content and/or high ash content commonly produce oils with more than one phase (an aqueous phase, an upper layer, and a decanted heavy oily phase). The first part of this Review focuses on the effects of feedstock composition, particle size, type of pyrolysis reactor, and condensation systems on bio-oil chemical composition and their impact on stable oils production. The second section reviews our current understanding of fresh bio-oil multiphase behavior and ...

Banana is one of the most important agricultural products of Ecuador. It relies on intensive monoculture cropping systems with a large volume of standing biomass and large amounts of residual biomass that can be used for carbon sequestration. This study was performed (1) to quantify the yearly residual biomass generation, (2) to quantify the carbon stock of standing banana biomass, (3) to estimate the carbon sequestration potential by using the residual biomass generated yearly, and (4) to propose a biomass prediction model for banana crops in Ecuador. The study was conducted between March 2018 and January 2019 in the three main banana-producing provinces of Ecuador (Los Ríos, Guayas, and El Oro). Samples of rachis, pseudostem, leaves, and flowers from 36 banana plants of the variety Musa AAA Cavendish were taken for laboratory tests. Physical measurements such as height, circumferences, number of leaves, and weights were determined for the 36 plants. Results showed an average residue-to-product ratio of 3.79 and a country's yearly biomass generation of 2.65 Mt on a dry basis. The carbon stock of the standing biomass was estimated as 4.18 ± 1.02 Mg/ha, 5.44 ± 0.96 Mg/ha, and 5.13 ± 1.11 Mg/ha for Los Ríos, Guayas, and El Oro, respectively. The estimated carbon abatement capacity of the residual biomass is 3.92 MtCO2/year. Three biomass estimation models were developed in Python®, using the data collected in this study and least squares fitting for exponential models of the form: Y = AXn + C. The models showed good prediction capacity for Ecuadorian banana plants, with R2 up to 0.85. It is expected that this study could serve as the basis for studies on developing sustainable conversion processes of banana residual biomass.

Abstract The objective of this paper is to report our results on the behavior of an Otto engine working with gasoline blended with a fraction rich in esters of carboxylic acids derived from biomass pyrolysis bio-oil, hereby called as “Bioflex”. Sugarcane trash undergoes a fast pyrolysis process at the PPR-200 pilot plant to produce the bio-oil at Unicamp (Brazil). The process of separating carboxylic acids from bio-oil, the production of esters from these acids, the process of blending these esters with gasoline as well as the results of the use of this blend in an Otto engine of 4 kW capacity – component of a 2 kW e generator – are described. Trial tests determined that it is possible to blend up to 14 vol.% of Bioflex with gasoline type C used in Brazil. The engine performance with this blend compared to the performance of the engine working with pure gasoline resulted in identical power output and fuel consumption. The results showed that it is technically feasible to use blends of carboxylic acid esters derived from the biomass pyrolysis bio-oil with gasoline in conventional Otto engines.

AbstractIn recent years, the “new car smell” has been linked to materials off‐gassing toxic volatile organic compounds (VOCs) within the chamber of vehicles. Previous studies collected air samples directly from the vehicle chamber and analyzed them using gas chromatography–mass spectrometry (GC–MS). However, there is a lack of data regarding which materials are responsible for each compound and the resulting concentrations. This preliminary research was focused on analysis of VOC emissions emitted from basalt fiber and hemp hurd‐reinforced polypropylene (PP) panels, glass fiber reinforced PP panels, and PP panels intended for interior automotive applications such as dashboards and door panels. The panels were subjected to various temperatures and UV radiation that may be experienced within a vehicle. Results showed increasing concentrations as temperature increased, and a reduction in off‐gassing in the presence of UV radiation. The major compounds detected were acetaldehyde (<41 μg/m3), acetone (<29 μg/m3), and various alkanes (<6786 μg/m3). Overall, the concentrations detected from all panels were below the suggested standards and limitations.

Cet article fournit une revue des technologies de pyrolyse, en se concentrant sur les conceptions de réacteurs et les entreprises commercialisant ces technologies. Le regain d'intérêt pour la pyrolyse est motivé par le potentiel de conversion des matériaux lignocellulosiques en bio-huile et en biochar et l'utilisation de ces intermédiaires pour la production de biocarburants, de produits biochimiques et de biochars d'ingénierie pour les services environnementaux. Cette revue présente la pyrolyse lente, intermédiaire, rapide et micro-ondes comme des technologies complémentaires qui partagent certains points communs dans leurs conceptions. Alors que les technologies de pyrolyse lente (fours de carbonisation traditionnels) utilisent des troncs de bois pour produire des morceaux de charbon pour la cuisson, les systèmes de pyrolyse rapide traitent les petites particules pour maximiser le rendement en bio-huile. La prise de conscience des enjeux environnementaux liés à l'utilisation des technologies de carbonisation et les difficultés techniques d'exploitation des réacteurs à pyrolyse rapide utilisant du sable comme milieu de chauffage et de grands volumes de gaz porteur, ainsi que les problèmes de raffinage des huiles hautement oxygénées résultantes, obligent la communauté de la conversion thermochimique à repenser la conception et l'utilisation de ces réacteurs. Les réacteurs de pyrolyse intermédiaire (également appelés convertisseurs) offrent des opportunités pour la production équilibrée à grande échelle de charbon et de bio-huile. La capacité de ces réacteurs à traiter les déchets forestiers et agricoles sans trop de prétraitement est un avantage évident. La pyrolyse par micro-ondes est une option pour les petits appareils autonomes modulaires pour la gestion des déchets solides. Ici, l'évolution de la technologie de pyrolyse est présentée d'un point de vue historique ; ainsi, les conceptions innovantes anciennes et nouvelles sont discutées ensemble. Este documento proporciona una revisión de las tecnologías de pirólisis, centrándose en los diseños de reactores y las empresas que comercializan estas tecnologías. El renovado interés en la pirólisis está impulsado por el potencial de convertir materiales lignocelulósicos en bioaceite y biochar y el uso de estos intermedios para la producción de biocombustibles, bioquímicos y biochars diseñados para servicios ambientales. Esta revisión presenta la pirólisis lenta, intermedia, rápida y de microondas como tecnologías complementarias que comparten algunos puntos en común en sus diseños. Mientras que las tecnologías de pirólisis lenta (hornos de carbonización tradicionales) utilizan troncos de madera para producir trozos de carbón para cocinar, los sistemas de pirólisis rápida procesan partículas pequeñas para maximizar el rendimiento del bioaceite. La realización de los problemas ambientales asociados con el uso de tecnologías de carbonización y las dificultades técnicas de operar reactores de pirólisis rápida utilizando arena como medio de calentamiento y grandes volúmenes de gas portador, así como los problemas con el refinado de los aceites altamente oxigenados resultantes, están obligando a la comunidad de conversión termoquímica a repensar el diseño y uso de estos reactores. Los reactores de pirólisis intermedia (también conocidos como convertidores) ofrecen oportunidades para la producción equilibrada a gran escala de carbón y bioaceite. La capacidad de estos reactores para procesar residuos forestales y agrícolas sin mucho preprocesamiento es una clara ventaja. La pirólisis por microondas es una opción para pequeños dispositivos autónomos modulares para la gestión de residuos sólidos. En este documento, se presenta la evolución de la tecnología de pirólisis desde una perspectiva histórica; por lo tanto, se discuten juntos los diseños innovadores antiguos y nuevos. This paper provides a review of pyrolysis technologies, focusing on reactor designs and companies commercializing these technologies. The renewed interest in pyrolysis is driven by the potential to convert lignocellulosic materials into bio-oil and biochar and the use of these intermediates for the production of biofuels, biochemicals, and engineered biochars for environmental services. This review presents slow, intermediate, fast, and microwave pyrolysis as complementary technologies that share some commonalities in their designs. While slow pyrolysis technologies (traditional carbonization kilns) use wood trunks to produce char chunks for cooking, fast pyrolysis systems process small particles to maximize bio-oil yield. The realization of the environmental issues associated with the use of carbonization technologies and the technical difficulties of operating fast pyrolysis reactors using sand as the heating medium and large volumes of carrier gas, as well as the problems with refining the resulting highly oxygenated oils, are forcing the thermochemical conversion community to rethink the design and use of these reactors. Intermediate pyrolysis reactors (also known as converters) offer opportunities for the large-scale balanced production of char and bio-oil. The capacity of these reactors to process forest and agricultural wastes without much preprocessing is a clear advantage. Microwave pyrolysis is an option for modular small autonomous devices for solid waste management. Herein, the evolution of pyrolysis technology is presented from a historical perspective; thus, old and new innovative designs are discussed together. تقدم هذه الورقة مراجعة لتقنيات الانحلال الحراري، مع التركيز على تصاميم المفاعلات والشركات التي تقوم بتسويق هذه التقنيات. إن الاهتمام المتجدد بالتحليل الحراري مدفوع بإمكانية تحويل المواد اللجنوسليلوزية إلى زيت حيوي وفحم حيوي واستخدام هذه المواد الوسيطة لإنتاج الوقود الحيوي والكيماويات الحيوية والفحم الحيوي الهندسي للخدمات البيئية. تقدم هذه المراجعة الانحلال الحراري البطيء والمتوسط والسريع والموجات الدقيقة كتقنيات تكميلية تشترك في بعض القواسم المشتركة في تصميماتها. في حين أن تقنيات التحلل الحراري البطيء (أفران الكربنة التقليدية) تستخدم جذوع الخشب لإنتاج قطع الفحم للطهي، فإن أنظمة التحلل الحراري السريع تعالج الجسيمات الصغيرة لزيادة إنتاجية الزيت الحيوي. إن إدراك القضايا البيئية المرتبطة باستخدام تقنيات الكربنة والصعوبات الفنية لتشغيل مفاعلات التحلل الحراري السريع باستخدام الرمل كوسيط تسخين وكميات كبيرة من الغاز الحامل، بالإضافة إلى مشاكل تكرير الزيوت عالية الأكسجين الناتجة، تجبر مجتمع التحويل الكيميائي الحراري على إعادة التفكير في تصميم واستخدام هذه المفاعلات. توفر مفاعلات التحلل الحراري الوسيطة (المعروفة أيضًا باسم المحولات) فرصًا للإنتاج المتوازن على نطاق واسع للفحم والنفط الحيوي. وتعد قدرة هذه المفاعلات على معالجة نفايات الغابات والنفايات الزراعية دون الكثير من المعالجة المسبقة ميزة واضحة. يعد التحلل الحراري بالموجات الدقيقة خيارًا للأجهزة المستقلة الصغيرة المعيارية لإدارة النفايات الصلبة. هنا، يتم تقديم تطور تقنية الانحلال الحراري من منظور تاريخي ؛ وبالتالي، تتم مناقشة التصاميم المبتكرة القديمة والجديدة معًا.