It was obtained that the yeast Torulaspora globosa VKPM Y-953 is suitable for the production of biodiesel fuel. Zinc plays an important regulatory role in the metabolism of the studied strain. The study of the growth parameters and the fatty acid profile of the yeast T. globosa showed that the limitation of its growth by ethanol, at different concentrations of zinc in the medium, considerably influences the chemical composition and the energy content of yeast cells, but not their yield by weight (Yx/s). The increased concentrations of zinc in the medium, in combination with the yeast growth limitation by ethanol, elevated the content of lipids in the cells by 28% and diminished the content of proteins by 14%. At the same time, the limitation of yeast growth by zinc decreased Yx/s and energy (ηX/S) by 2.6 and 3.1 times, respectively. In this case, the content of lipids in cells fell by 72%, while that of proteins rose by 65%. The fatty acid profile of the T. globosa cells was used to es... [more]

Electrification is considered an optimal long-term solution for the decarbonization of the transport sector. However, in the medium period, propulsion systems will continue to dominate urban mobility, thus requiring the shift from fossil fuels toward low carbon fuels. In this regard, the request from the EU to achieve carbon neutrality by 2050 is encouraging the use of innovative fuels and powertrains. Alcohols such as ethanol and methanol are particularly suitable for spark ignition engines. This paper investigates the effect of ethanol/methanol blends on the performance and emissions of a turbocharged direct injection spark ignition engine running on the worldwide harmonized light vehicles test cycle. Three blends were considered, consisting of 10% v/v ethanol (E10), 25% v/v ethanol (E25) and 5% v/v ethanol with 15% v/v methanol (E5M15). Gaseous and particle emissions were measured at the exhaust. The main novelty of the study regards the investigation of the behavior of alcohol blen... [more]

Cellulosic fibers from date palm are among the most promising lignocellulose feedstock for biorefinery purposes. The world production is between 1.9 and 2.4 million t/year. Initially, a pretreatment with dilute-sulphuric acid of these fibers was performed using a response surface methodology, with temperature and process time as factors. The aim is to produce bioethanol from young and old fibers from date palm, Phoenix dactylifera L. Optimal thermochemical pretreatment conditions for both fibers palms were 220 °C in hydrothermal conditions (without acid); in these conditions pretreated young fibers presented a maximum content in holocelluloses of 45.18% and old fibers 61.97%. Subsequently, during the enzymatic hydrolysis a maximum yield of total reducing sugars (TRS) was reached, 46.32 g/100 g for pretreated dry young fibers and 48.54 g/100 g for pretreated dry old fibers. After enzymatic saccharification, hydrolysates were fermented by Pachysolen tannophilus (ATCC 32691) to ethanol, r... [more]

The worldwide consumption of fossil hydrocarbons in the road transport sector in 2020 corresponded to roughly half of the overall consumption. However, biofuels have been discreetly contributing to mitigate gaseous emissions and participating in sustainable development, and thus leading to the extending of the commercial utilization of internal combustion engines. In this scenario, the present work aims at exploring the effects of alternative fuels containing a blend of 15% ethanol and 35% biodiesel with a 50% fossil diesel (E15D50B35) or 50% Fischer−Tropsch (F-T) diesel (E15FTD50B35) on the engine combustion, exhaust emissions (CO, HC, and NOx), particulate emissions characteristics as well as the performance of an aftertreatment system of a common rail diesel engine. It was found that one of the blends (E15FTD50B35) showed more than 30% reduction in PM concentration number, more than 25% reduction in mean particle size, and more than 85% reduction in total PM mass with respect to con... [more]

Oxygenated fuels, in this case short carbon-chain alcohols, have been investigated as alternative fuels to power compression ignition engines. A major advantage of short-chain alcohols is that they can be produced from renewable resources, i.e., cultivated commodities or biomass-based biorefineries. However, before entering the market, the effects of short-chain alcohols on engine performance, exhaust emissions, noise and sound quality need to be understood. This work sheds light on the relationship between the physicochemical properties of the alcohol/diesel fuel blends (ethanol and 1-propanol) on engine performance, exhaust emissions and, for the first time, on noise and sound quality. It has been demonstrated that when the content of alcohol in blends increased, soot and soluble organic material emissions drastically decreased, mainly due to the increase of oxygen content in the fuel. Reduction in soot emissions combined with higher thermodynamic efficiency of alcohol fuels, with re... [more]

An increasing percentage of ethanol in fuel leads to significant changes in polarity and solubility, which makes conventional gasoline deposit control additives (DCAs) difficult to dissolve in ethanol fuels, resulting in the formation of deposits on engine elements. Critical areas of deposit formation in an engine are constituted by inlet valves, combustion chambers, and fuel injectors. As a consequence, operational parameters of the engine are disturbed to a large extent by the total effect of the deposits. To prevent the aforementioned phenomena, in the operation of engines fueled with ethanol-containing blends, it is necessary to use specifically prepared DCAs. The paper briefly presents a process of development of DCAs dedicated to high-ethanol fuels. Each of the prepared DCA formulations contained a substance having detergent-emulsifying properties (referred to in the text as DEM), a carrier oil, and a solvent. The composition and ratios of components used in the DCA, by testing t... [more]

This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean combustion in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied in an optically accessible engine working in PFS mode for two fuels and two different durations of pilot injection at the time of spark: 210 µs and 330 µs for E30 (gasoline blended with ethanol by 30% volume fraction) and gasoline, respectively. In both conditions, early injections during the intake stroke were used to generate a well-mixed lean background. The results were compared to rich, stoichiometric and lean well-mixed combustion with different spark timings. In the PFS combustion process, it was possible to detect a non-spherical and highly wrinkled blue flame, coupled with yellow diffusive flames due to the combustion of rich zones near the spark plug. The initial flame spread for both PFS ca... [more]

This case study investigates the potentials, greenhouse gas (GHG), and energy performance of forest residue biofuels produced by new and emerging production technologies, which are commercially implemented in Sweden for heavy transport. The biofuel options included are ethanol (ED 95), hydro-processed vegetable oil (HVO), and liquefied biogas (LBG) produced from logging residues in forestry and sawdust generated in sawmills. The calculated life cycle GHG emissions, based on the EU Renewable Energy Directive calculation methodology, for all three pathways are in the range of 6−11 g CO2eq./MJ, corresponding to 88−94% GHG emission reductions as compared to fossil fuel. Critical parameters are the enzyme configuration for ethanol, hydrogen supply systems and bio-oil technology for HVO, and gasifier size for LBG. The energy input is ranging from 0.16 to 0.43 MJ/MJ biofuel and the total conversion efficiency from the feedstock to biofuel, including high-value by-products (excluding heat), va... [more]

Starting from bioethanol it is possible, by using an appropriate catalyst, to produce ethyl acetate in a single reaction step and pure hydrogen as a by-product. Two molecules of hydrogen can be obtained for each molecule of ethyl acetate produced. The mentioned reaction is reversible, therefore, it is possible to hydrogenate ethyl acetate to reobtain ethanol, so closing the chemical cycle of a Liquid Organic Hydrogen Carrier (LOHC) process. In other words, bioethanol can be conveniently used as a hydrogen carrier. Many papers have been published in the literature dealing with both the ethanol dehydrogenation and the ethyl acetate hydrogenation to ethanol so demonstrating the feasibility of this process. In this review all the aspects of the entire LOHC cycle are considered and discussed. We examined in particular: the most convenient catalysts for the two main reactions, the best operative conditions, the kinetics of all the reactions involved in the process, the scaling up of both eth... [more]

The effect of temperature was studied on the synthesis of fatty acid alkyl esters by means of transesterification of waste beef tallow using ethanol and, iso-butanol and 1-butanol at supercritical conditions. These alcohols are proposed for the synthesis of biodiesel in order to improve the cold flow properties of alkyl esters. Alcohol−beef tallow mixtures were fed to a high-pressure high-temperature autoclave at a constant molar ratio of 45:1. Reactions were carried out in the ranges of 310−390 °C and 310−420 °C for ethanol and iso-butanol, respectively; meanwhile, synthesis using 1-butanol was assessed only at 360 °C. After separation of fatty acid alkyl esters, these samples were characterized by nuclear magnetic resonance (NMR) and gas chromatography coupled to mass spectrometry (GC-MS) to quantify yields, chemical composition, and molecular weight. Results indicated that yields enhanced as temperature increased; the maximum yields for fatty acid ethyl esters (FAEEs) were attained... [more]

Food waste has a great potential for resource recovery due to its huge yield and high organic content. Oriented fermentation is a promising method with strong application prospects due to high efficiency, strong robustness, and high-value products. Different fermentation types lead to different products, which can be shifted by adjusting fermentation conditions such as inoculum, pH, oxidation-reduction potential (ORP), organic loading rate (OLR), and nutrients. Compared with other types, lactic acid fermentation has the lowest reliance on artificial intervention. Lactic acid and volatile fatty acids are the common products, and high yield and high purity are the main targets of food waste fermentation. In addition to operational parameters, reactors and processes should be paid more attention to for industrial application. Currently, continuously stirred tank reactors and one-stage processes are used principally for scale-up continuous fermentation of food waste. Electro-fermentation a... [more]

Ethanol is a widely produced fuel, as well as a fuel additive. Its price is closely related to the price of gasoline, its major substitute. This paper focuses on the impacts of the related variables on regional ethanol prices. Additionally, the length of the price dataset made it possible to isolate the impacts of COVID-19 on the ethanol prices. Using multiple regression and Confirmatory Factor Analyses, we found no significant correlation between the European and US ethanol prices because the major influencing factors were regionally different. In the case of the European ethanol markets, the positive factors were wheat, maize, and potassium chloride prices, while the European sugar and diammonium phosphate prices were negative. In the US markets, gasoline, sugar, and most of the artificial fertilizer prices were positive, while wheat prices were negative. Based on factor analysis, artificial fertilizers and maize factors proved to be important to the European markets, while US ethano... [more]

Hydrogen is the most common molecule in the universe. It is an excellent fuel for thermal engines: piston, turbojet, rocket, and, going forward, in thermonuclear power plants. Hydrogen is currently used across a range of industrial applications including propulsion systems, e.g., cars and rockets. One obstacle to expanding hydrogen use, especially in the transportation sector, is its low density. This paper explores hydrogen as an addition to liquid fuel in the detonation chamber to generate thermal energy for potential use in transportation and generation of electrical energy. Experiments with liquid kerosene, hexane, and ethanol with the addition of gaseous hydrogen were conducted in a modern rotating detonation chamber. Detonation combustion delivers greater thermal efficiency and reduced NOx emission. Since detonation propagates about three orders of magnitude faster than deflagration, the injection, evaporation, and mixing with air must be almost instantaneous. Hydrogen addition h... [more]

Microwave heating offers a lot of advantages compared to conventional heating methods in the chemical reactions field due to its positive effects on reaction time and selectivity. Dielectric properties, and in particular permittivity, of substances and mixtures, are important for the optimization of microwave heating processes; notwithstanding this, specific databases are poor and far from being complete, and in the scientific literature very little data regarding these properties can be found. In this work, impedance measurements were carried out using a specially designed system to get the real and imaginary parts of the dielectric constant. The apparatus was tested in the estimation of permittivity of water−ethanol and water−NaCl mixtures, varying their composition to obtain a wide range of permittivity values. The results were compared to literature data and fitted with available literature models to verify the correspondence between them, finding that permittivity dependence on mi... [more]

The bioethanol industry continues improving sustainability, specifically focused on plant energy and GHG emission management. Dried distiller grains with solubles (DDGS) is a byproduct of ethanol fermentation and is used for animal feed. DDGS is a relatively low-value bulk product that decays, causes odor, and is challenging to manage. The aim of this research was to find an alternative, value-added-type concept for DDGS utilization. Specifically, we aimed to explore the techno-economic feasibility of torrefaction, i.e., a thermochemical treatment of DDGS requiring low energy input, less sophisticated equipment, and resulting in fuel-quality biochar. Therefore, we developed a research model that addresses both bioethanol production sustainability and profitability due to synergy with the torrefaction of DDGS and using produced biochar as marketable fuel for the plant. Our experiments showed that DDGS-based biochar (CSF—carbonized solid fuel) lower calorific value may reach up to 27 MJ∙... [more]

This paper proposes and analyzes a mathematical model for the production of bioethanol in a continuous bioreactor with recycling. The kinetics correspond to the use of Saccharomyces bayanus for the fermentation of sugars found in wastewater from soft drinks. The proposed model considers product growth latency, which was experimentally found in batch studies of ethanol production. Furthermore, the inhibition effect of ethanol is expressed by a modified version of the classical Andrew’s model for substrate inhibition. The proposed model consists of only three ordinary differential equations containing a minimal number of operating parameters, which include the bioreactor residence time, glucose feed concentration, recycle ratio and the fraction of biomass removed from the reactor by the flow. The positivity and the boundedness of solutions of the model were confirmed under reasonable restrictions of parameters. The stability analysis showed that there is a value of residence time at whic... [more]

Biofuels provide high oxygen content for combustion and do modify properties that influence the engine operation process such as viscosity, enthalpy of vaporization, and cetane number. Some requirements of performance, fuel consumption, efficiency, and exhaust emission are necessary for the validation of these biofuels for application in engines. This work studies the effects of the use of diethyl ether (DEE) in biodiesel-ethanol blends in a DI mechanical diesel engine. The blends used in the tests were B80E20 (biodiesel 80%-ethanol 20%) and B76E19DEE5 (biodiesel 76%-ethanol 19%-DEE 5%). Fossil diesel (D100) and biodiesel (B100) were evaluated as reference fuels. The results revealed similar engine efficiencies among tested fuels at all loads. The use of B100 increased CO and NOx and decreased THC compared to D100 at the three loads tested. B80E20 fuel showed an increase in NOx emission in comparison with all fuels tested, which was attributed to higher oxygen content and lower cetane... [more]

In this study, low-quality rapeseed was used as a raw material for biodiesel fuel production. The application of such seeds with an enzyme catalyst is a green approach to producing renewable biodiesel fuel. During the in situ transesterification process, mineral diesel was selected as an extraction solvent for the simultaneous extraction and transesterification of rapeseed oil (RO). This allowed, at the end of the process, for the production of a mixture of mineral diesel and biodiesel fuel. Energy is saved using this process, as the need to extract the oil separately is eliminated and extraction and transesterification take place together in the in situ process. In this study, 11 different lipases were analyzed from which to select the most effective biocatalyst according to the chosen experimental conditions. The most suitable lipase for in situ transesterification was Lipozyme TL IM (Thermomyces lanuginosus). The impact of the temperature and duration of the reaction was investigate... [more]

Simultaneous saccharification and fermentation (SSF) at high solid loading is a potential approach to improve the economic feasibility of cellulosic ethanol. In this study, SSF using high loading of rice straw was assessed using a vertical ball mill reactor. First, the conditions of temperature and number of glass spheres were optimized at 8% (w/v) initial solids (41.5 °C, 18 spheres). Then, assays were carried out at higher solid loadings (16% and 24% w/v). At 8% or 16% solids, the fermentation efficiency was similar (ηF~75%), but the ethanol volumetric productivity (QP) reduced from 1.50 to 1.14 g/L.h. By increasing the solids to 24%, the process was strongly affected (ηF = 40% and QP = 0.7 g/L.h). To overcome this drawback, three different feeding profiles of 24% pre-treated rice straw were investigated. Gradual feeding of the substrate (initial load of 16% with additions of 4% at 10 and 24 h) and an inoculum level of 3 g/L resulted in a high ethanol titer (52.3 g/L) with QP of 1.1... [more]

The present study aimed to assess and classify energy-environmental efficiency levels to reduce greenhouse gas emissions in the production, commercialization, and use of biofuels certified by the Brazilian National Biofuel Policy (RenovaBio). The parameters of the level of energy-environmental efficiency were standardized and categorized according to the Energy-Environmental Efficiency Rating (E-EER). The rating scale varied between lower efficiency (D) and high efficiency + (highest efficiency A+). The classification method with the J48 decision tree and naive Bayes algorithms was used to predict the models. The classification of the E-EER scores using a decision tree using the J48 algorithm and Bayesian classifiers using the naive Bayes algorithm produced decision tree models efficient at estimating the efficiency level of Brazilian ethanol producers and importers certified by the RenovaBio. The rules generated by the models can assess the level classes (efficiency scores) according... [more]

A greenhouse gas (GHG) emission reduction obligation system has been implemented in the Swedish road transport sector to promote the use of biofuels. For transportation fuel suppliers to fulfil this obligation, the volume of biofuel required decreases with decreasing life cycle GHG emission for the biofuel, linking lower GHG emission to higher economic value. The aim of this study was to investigate how the economic competitiveness of a Swedish emerging lignocellulosic-based ethanol production system would be influenced by the reduction obligation. The life cycle GHG emission for sawdust-based ethanol was calculated by applying the method advocated in the EU Renewable Energy Directive (RED II). The saving in GHG emissions, compared with fossil liquid transportation fuels, was 93% for a potential commercial production system in southern Sweden. This, in turn, will increase the competitiveness of sawdust-based ethanol compared to the mainly crop-based ethanol currently used in the Swedis... [more]

Adsorption refrigeration has become an attractive technology due to the capability to exploit low-grade thermal energy for cooling power generation and the use of environmentally friendly refrigerants. Traditionally, these systems work with pure fluids such as water, ethanol, methanol, and ammonia. Nevertheless, the operating conditions make their commercialization still unfeasible, especially owing to safety and cost issues as a consequence of the working pressures, which are higher or lower than 1 atm. The present work represents the first thermodynamic insight in the use of mixtures for adsorption refrigeration and aims to assess the performance of a binary system of ammonia and ethanol. According to the Gibbs’ phase rule, the addition of a component introduces an additional degree of freedom, which allows to adjust the pressure of the system varying the composition of the mixture. The refrigeration process was simulated with isothermal- isochoric flash calculations to solve the pha... [more]

Cellulosic insulation paper is usually used in oil-immersed transformer insulation systems. In this study, the molecular dynamics method based on reaction force field (ReaxFF) was used to simulate the pyrolysis process of a cellobiose molecular model. Through a series of ReaxFF- Molecular Dynamics (MD) simulations, the generation path of ethanol at the atomic level was studied. Because the molecular system has hydrogen bonding, force-bias Monte Carlo (fbMC) is mixed into ReaxFF to reduce the cost of calculation by reducing the sampled data. In order to ensure the reliability of the simulation, a model composed of 20 cellobioses and a model composed of 40 cellobioses were respectively established for repeated simulation in the range of 500−3000 K. The results show that insulating paper produced ethanol at extreme thermal fault, and the intermediate product of vinyl alcohol is the key to the aging process. It is also basically consistent with others’ previous experiment results. So it ca... [more]

The optimum nitrogen concentration for media supplementation and strain dominance are aspects of key importance to the industrial production of ethanol with a view to reducing costs and increasing yields. In this work, these two factors were investigated for four ethanologenic Saccharomyces cerevisiae strains (CLQCA-INT-001, CLQCA-INT-005, CLQCA-10-099, and UCLM 325), selected from the screening of 150 isolates, mostly from Ecuadorian yeast biodiversity. The effect of nitrogen concentration was assessed in terms of cellular growth, glucose consumption and ethanol production, and the yeast strains’ dominance was evaluated in continuous co-fermentation with cellular recycling by mitochondrial DNA analyses. Among the four selected yeast strains under study, CLQCA-INT-005 presented the highest glucose consumption at a nitrogen supplement concentration as low as 0.4 g·L−1, attaining an ethanol yield of up to 96.72% in 24 h. The same yeast strain was found to be highly competitive, showing a... [more]

In Europe, diesel combustion is being banned due to the NOx and PM2.5 emissions impact on air quality. The bus sector is being electrified and is increasing its use of alternative fuels, such as natural gas (in spark ignition engines) and bioethanol (in compression ignition engines), to reduce such harmful emissions. Even if a diesel bus is equipped with selective catalytic reduction (SCR), its NOx emissions are reduced its but produces more NH3 emissions that are PM2.5 precursors. In developing countries, the air quality is still barely monitored, however, the air quality issue is well known and is being addressed. Moreover, the Ecuadorian sugar cane industry is seeking ways to increase its ethanol production. This is the ideal framework to explore a new technology and energy source in developing economies such as Ecuador. This paper explores the impact of the Ecuadorian diesel bus fleet conversion to hybrid compression ignition ethanol (HEV-ED95), hybrid diesel and plug-in hybrid fle... [more]