• Energy Research

The synthesis of biodiesel from Jatropha curcas by transesterification is kinetically controlled. It depends on the molar ratio, reaction time, and temperature, as well as the catalyst nature and quantity. The aim of this study was to explore the transesterification of low-cost, inedible J. curcas seed oil utilizing both homogenous (potassium hydroxide; KOH) and heterogenous (calcium oxide; CaO) catalysis. In this effort, two steps were used. First, free fatty acids in J. curcas oil were reduced from 12.4 to less than 1 wt.% with sulfuric acid-catalyzed pretreatment. Transesterification subsequently converted the oil to biodiesel. The yield of fatty acid methyl esters was optimized by varying the reaction time, catalyst load, and methanol-to-oil molar ratio. A maximum yield of 96% was obtained from CaO nanoparticles at a reaction time of 5.5 h with 4 wt.% of the catalyst and an 18:1 methanol-to-oil molar ratio. The optimum conditions for KOH were a molar ratio of methanol to oil of 9:1, 5 wt.% of the catalyst, and a reaction time of 3.5 h, and this returned a yield of 92%. The fuel properties of the optimized biodiesel were within the limits specified in ASTM D6751, the American biodiesel standard. In addition, the 5% blends in petroleum diesel were within the ranges prescribed in ASTM D975, the American diesel fuel standard.

The need for exploring nonfood low-cost sustainable sources for biodiesel production is ever increasing. Commercial and industrial algae cultivation has numerous uses in biodiesel production. This study explores S. elongata as a new algal feedstock for the production of biodiesel that does not compete with food production. The major fatty acids identified in S. elongata oil were oleic (30.5%), lauric (29.9%), myristic (17.0%), and palmitic (14.2%) acids. Transesterification to FAME was conducted using basic (KOH), acidic (HCl), and Zeolitic catalysts for assessment. The yields with acidic (54.6%) and zeolitic (72.7%) catalysts were unremarkable during initial screening. The highest biodiesel yield (99.9%) was achieved using KOH, which was obtained with the optimum reaction conditions of 1.0% catalyst, 60 °C, 4 h, and an oil-to-methanol volume ratio of 1:4. The resulting S. elongata oil methyl esters exhibited densities, CNs, and IVs, that were within the ranges specified in the American (ASTM D6751) and European (EN 14214) biodiesel standards, where applicable. In addition, the high SVs and the moderately high CPs and PPs were attributed to the presence of large quantities of short-chain and saturated FAME, respectively. Overall, the composition and properties of FAME prepared from S. elongaae oil indicate that S. elongata is suitable as an alternative algal feedstock for the production of biodiesel.

Biodiesel from waste cooking oil (WCO) requires antioxidants to meet oxidation stability specifications set forth in ASTM D6751 or EN 14214. In contrast, unrefined cottonseed oil (CSO), containing tocopherols and gossypol, produces biodiesel of higher oxidation stability. However, only a portion of these CSO endogenous antioxidants are suspected to be retained in biodiesel. Because the economics of biodiesel manufacturing rely upon inexpensive sources of triglycerides, emphasis was placed on developing improved alternative processing methods where WCO was the main source of methyl esters (WCOME) and CSO was used as a supplemental source of triglycerides and antioxidants in a 4:1 ratio. This study compared four processing methods for their ability to produce biodiesel of increased oxidative stability prepared from a 4:1 ratio of WCO:CSO. Two novel processing methods developed for this study utilise solvent properties of fatty acid methyl esters and glycerol to avoid additional chemical inventory for biodiesel processors. This study concludes that the two new processing methods resulted in biodiesel that had statistically significant improved oxidation stability when compared to two common industrial processing methods. Another significant finding is that high-shear homogenisation during transesterification reduced reaction time from the published one hour to 16 minutes.

Abstract Fatty acid methyl esters prepared from canola, palm, soybean, and sunflower oils by homogenous base-catalyzed methanolysis were stored for 12 months at three constant temperatures (− 15, 22, and 40 °C) and properties such as oxidative stability, acid value, kinematic viscosity, low temperature operability, and iodine value were periodically measured. Oxidative stability was significantly reduced upon extended storage and acid value as well as kinematic viscosity were increased by only small increments, with these effects more pronounced at elevated temperatures. Iodine value and low temperature operability were essentially unaffected by extended storage. Based on these findings, it is not recommended that acid value or kinematic viscosity be used as indicators of storage stability of biodiesel, nor is it recommended that iodine value be used as a predictor of oxidative stability or indicator of oxidative degradation.

L'impact environnemental des déchets agricoles issus de la transformation des cultures vivrières et fourragères est une préoccupation croissante dans le monde entier. Des efforts concertés sont en cours pour développer des pratiques durables pour l'élimination des résidus de la transformation de cultures telles que le café, la canne à sucre ou le maïs. Le café est crucial pour les économies de nombreux pays car sa culture, sa transformation, son commerce et sa commercialisation fournissent des emplois à des millions de personnes. Dans les pays producteurs de café, l'amélioration de la technologie de traitement des quantités importantes de déchets de café est essentielle pour prévenir les dommages écologiques. Ce mini-examen traite d'un concept de bioraffinerie à plusieurs étapes avec le potentiel de convertir les déchets produits lors des opérations de traitement des cultures, telles que les stations de réduction en pâte de café, en biocarburants et bioproduits précieux à l'aide de technologies de conversion biochimique et thermochimique. L'étape initiale de bioconversion utilise une souche de levure mutante Kluyveromyces marxianus pour produire du bioéthanol à partir de sucres. Les solides appauvris en sucre résultants (principalement des protéines) peuvent être utilisés dans une deuxième étape par la levure oléagineuse Yarrowia lipolytica pour produire de l'ammoniac biosourcé pour l'engrais et sont ensuite dégradés par les protéases Y. lipolytica en peptides et en acides aminés libres pour l'alimentation animale. La fraction lignocellulosique peut être broyée et traitée pour libérer des sucres pour la fermentation dans une troisième étape par un Saccharomyces cerevisiae cellulosique recombinant, qui peut également être modifié pour exprimer des produits peptidiques précieux. Les protéines résiduelles et les solides de lignine peuvent être cuits par jet et passés dans un fermenteur de quatrième étage où Rhodotorula glutinis convertit le méthane en intermédiaires isoprénoïdes. Les résidus peuvent être combinés et transférés dans des réactions de pyrocraquage et d'hydroformylation pour convertir l'ammoniac, les protéines, les isoprènes, les lignines et les huiles en gaz renouvelable. Tout déchet restant peut être thermoconverti en biochar en tant qu'activateur de sol humique. L'intégration de plusieurs technologies pour le traitement des déchets de café a le potentiel de contribuer à la durabilité économique et environnementale. El impacto ambiental de los residuos agrícolas procedentes del procesamiento de cultivos alimentarios y forrajeros es una preocupación creciente en todo el mundo. Se están realizando esfuerzos concertados para desarrollar prácticas sostenibles para la eliminación de residuos del procesamiento de cultivos como el café, la caña de azúcar o el maíz. El café es crucial para las economías de muchos países porque su cultivo, procesamiento, comercio y comercialización proporcionan empleo a millones de personas. En los países productores de café, la mejora de la tecnología para el tratamiento de las cantidades significativas de residuos de café es fundamental para evitar daños ecológicos. Esta mini revisión analiza un concepto de biorrefinería de múltiples etapas con el potencial de convertir los desechos producidos en las operaciones de procesamiento de cultivos, como las estaciones de pulpa de café, en biocombustibles y bioproductos valiosos utilizando tecnologías de conversión bioquímica y termoquímica. La etapa inicial de bioconversión utiliza una cepa de levadura mutante Kluyveromyces marxianus para producir bioetanol a partir de azúcares. Los sólidos agotados en azúcar resultantes (principalmente proteínas) pueden ser utilizados en una segunda etapa por la levadura oleaginosa Yarrowia lipolytica para producir amoníaco de base biológica para fertilizantes y son degradados aún más por las proteasas de Y. lipolytica a péptidos y aminoácidos libres para la alimentación animal. La fracción lignocelulósica puede molerse y tratarse para liberar azúcares para la fermentación en una tercera etapa por una Saccharomyces cerevisiae celulósica recombinante, que también puede modificarse para expresar productos peptídicos valiosos. La proteína residual y los sólidos de lignina se pueden cocinar a chorro y pasar a un fermentador de cuarta etapa donde Rhodotorula glutinis convierte el metano en productos intermedios de isoprenoides. Los residuos se pueden combinar y transferir a reacciones de pirocraqueo e hidroformilación para convertir amoníaco, proteínas, isoprenos, ligninas y aceites en gas renovable. Cualquier residuo restante se puede termoconvertir en biocarbón como potenciador del suelo de humus. La integración de múltiples tecnologías para el tratamiento de los residuos de café tiene el potencial de contribuir a la sostenibilidad económica y ambiental. The environmental impact of agricultural waste from the processing of food and feed crops is an increasing concern worldwide. Concerted efforts are underway to develop sustainable practices for the disposal of residues from the processing of such crops as coffee, sugarcane, or corn. Coffee is crucial to the economies of many countries because its cultivation, processing, trading, and marketing provide employment for millions of people. In coffee-producing countries, improved technology for treatment of the significant amounts of coffee waste is critical to prevent ecological damage. This mini-review discusses a multi-stage biorefinery concept with the potential to convert waste produced at crop processing operations, such as coffee pulping stations, to valuable biofuels and bioproducts using biochemical and thermochemical conversion technologies. The initial bioconversion stage uses a mutant Kluyveromyces marxianus yeast strain to produce bioethanol from sugars. The resulting sugar-depleted solids (mostly protein) can be used in a second stage by the oleaginous yeast Yarrowia lipolytica to produce bio-based ammonia for fertilizer and are further degraded by Y. lipolytica proteases to peptides and free amino acids for animal feed. The lignocellulosic fraction can be ground and treated to release sugars for fermentation in a third stage by a recombinant cellulosic Saccharomyces cerevisiae, which can also be engineered to express valuable peptide products. The residual protein and lignin solids can be jet cooked and passed to a fourth-stage fermenter where Rhodotorula glutinis converts methane into isoprenoid intermediates. The residues can be combined and transferred into pyrocracking and hydroformylation reactions to convert ammonia, protein, isoprenes, lignins, and oils into renewable gas. Any remaining waste can be thermoconverted to biochar as a humus soil enhancer. The integration of multiple technologies for treatment of coffee waste has the potential to contribute to economic and environmental sustainability. يشكل التأثير البيئي للنفايات الزراعية الناتجة عن معالجة المحاصيل الغذائية والعلفية مصدر قلق متزايد في جميع أنحاء العالم. تُبذل جهود متضافرة لتطوير ممارسات مستدامة للتخلص من المخلفات الناتجة عن معالجة محاصيل مثل القهوة أو قصب السكر أو الذرة. البن أمر بالغ الأهمية لاقتصادات العديد من البلدان لأن زراعته ومعالجته وتجارته وتسويقه توفر فرص العمل لملايين الناس. في البلدان المنتجة للبن، يعد تحسين التكنولوجيا لمعالجة الكميات الكبيرة من نفايات البن أمرًا بالغ الأهمية لمنع الضرر البيئي. تناقش هذه المراجعة المصغرة مفهوم التكرير الحيوي متعدد المراحل مع إمكانية تحويل النفايات المنتجة في عمليات معالجة المحاصيل، مثل محطات لب البن، إلى وقود حيوي ومنتجات حيوية قيمة باستخدام تقنيات التحويل البيوكيميائية والكيميائية الحرارية. تستخدم مرحلة التحويل الحيوي الأولية سلالة خميرة Kluyveromyces marxianus متحولة لإنتاج الإيثانول الحيوي من السكريات. يمكن استخدام المواد الصلبة المستنفدة للسكر الناتجة (معظمها بروتين) في مرحلة ثانية بواسطة الخميرة الزيتية Yarrowia lipolytica لإنتاج الأمونيا الحيوية للأسمدة وتتحلل أكثر بواسطة Y. lipolytica proteases إلى الببتيدات والأحماض الأمينية الحرة لتغذية الحيوانات. يمكن طحن الجزء السليولوزي اللجني ومعالجته لإطلاق السكريات للتخمير في مرحلة ثالثة بواسطة السكريات السليولوزية المؤتلفة، والتي يمكن أيضًا هندستها للتعبير عن منتجات الببتيد القيمة. يمكن طهي البروتين المتبقي والمواد الصلبة من اللجنين بالنفث وتمريرها إلى مخمر المرحلة الرابعة حيث تقوم رودوتورولا غلوتيني بتحويل الميثان إلى وسيطات إيزوبرينويد. يمكن الجمع بين المخلفات ونقلها إلى تفاعلات التكسير الحراري والهيدروفورمة لتحويل الأمونيا والبروتين والأيزوبرين واللجنين والزيوت إلى غاز متجدد. يمكن تحويل أي نفايات متبقية إلى فحم حيوي كمعزز للتربة الدبال. إن دمج تقنيات متعددة لمعالجة نفايات البن لديه القدرة على المساهمة في الاستدامة الاقتصادية والبيئية.

Although single-cell oil (SCO) has been studied for decades, lipid production from lignocellulosic biomass has received substantial attention only in recent years as biofuel research moves toward producing drop-in fuels. This review gives an overview of the feasibility and challenges that exist in realizing microbial lipid production from lignocellulosic biomass in a biorefinery. The aspects covered here include biorefinery technologies, the microbial oil market, oleaginous microbes, lipid accumulation metabolism, strain development, process configurations, lignocellulosic lipid production, technical hurdles, lipid recovery, and technoeconomics. The lignocellulosic SCO-based biorefinery will be feasible only if a combination of low- and high-value lipids are coproduced, while lignin and protein are upgraded to high-value products.

Abstract Recently, an “old weed”, pennycress (Thlaspi arvense L.) has become an attractive non-food oilseed crop for Europe and the USA. Pennycress can be produced with existing farm equipment and infrastructure while being grown in the off-season between conventional commodity crops. The adaptation to marginal lands and the satisfactory seed yields make pennycress a viable alternative feedstock for biofuels. In the last decade, pennycress has been extensively studied as a potential oilseed crop in the USA, while receiving far less attention in Europe. Differences in climate and agricultural management between USA and Europe may not permit direct translation of pennycress agronomic knowledge across diverse environments. In the present study, sowing date and seeding rate of pennycress were evaluated in different European (Italy and Greece) and US (Minnesota and Illinois) locations to optimize site-specific production, and determine environmental influence on pennycress-derived biofuel. Pennycress productivity increased with seeding rate up to 1500 m−2 in Europe, but only to 672 m−2 in USA, while sowing in early autumn always improved yields. Seed yield of about 1 Mg ha-1 was achieved only in Greece, where adequate precipitation during the growing season was available. Seed yields were 250% and 140% higher in Greece and Italy, respectively, than Minnesota. Pennycress oil was suitable to convert into biofuel and its composition was influenced by growing environment. In Greece, polyunsaturated fatty acid content was 6% compared to Italy and Illinois. However, the oxidative stability of pennycress oil needs improvement to meet EU and US standards for biodiesel.

A synthetic Candida antarctica lipase B (CALB) gene open reading frame (ORF) for expression in yeast was constructed, and the lycotoxin-1 (Lyt-1) C3 variant gene ORF, potentially to improve the availability of the active enzyme at the surface of the yeast cell, was added in frame with the CALB ORF using an automated PCR assembly and DNA purification protocol on an integrated robotic workcell. Saccharomyces cerevisiae strains expressing CALB protein or CALB Lyt-1 fusion protein were first grown on 2% (w/v) glucose, producing 9.3 g/L ethanol during fermentation. The carbon source was switched to galactose for GAL1-driven expression, and the CALB and CALB Lyt-1 enzymes expressed were tested for fatty acid ethyl ester (biodiesel) production. The synthetic enzymes catalyzed the formation of fatty acid ethyl esters from ethanol and either corn or soybean oil. It was further demonstrated that a one-step-charging resin, specifically selected for binding to lipase, was capable of covalent attachment of the CALB Lyt-1 enzyme, and that the resin-bound enzyme catalyzed the production of biodiesel. High-level expression of lipase in an ethanologenic yeast strain has the potential to increase the profitability of an integrated biorefinery by combining bioethanol production with coproduction of a low-cost biocatalyst that converts corn oil to biodiesel.