Phase stability,fuel properties,and diesel engine performance of palm-oil-based microemulsion biofuels

Microemulsification and blending are two viscosity-modifying techniques of vegetable oils for direct use with diesel engine. In this study, alcohol blends are mixtures of ethanol, diesel, and palm-oil biodiesel while microemulsion biofuels are thermodynamically stable, clear, and single-phase mixtures of diesel, palm oil, and ethanol stabilized by surfactants and cosurfactants. Although there are many studies on biofuels lately, there is limited research on using biodiesel as a surfactant in microemulsion formulations and applied on engine performance at different engine loads. Therefore, the objectives are to investigate phase stability and fuel properties of formulated biofuels (various blends and microemulsions), to determine the engine performance at different engine loads (no load, and from 0.5 to 2.0 kW), and to estimate laboratory-scale cost of the selected biofuels compared to diesel and biodiesel. The results showed that phase stability and fuel properties of selected microemulsion biofuels are comparable to diesel and biodiesel. These microemulsion biofuels can be applied to the diesel engine at different loads while diesel-ethanol blends and palm-oil-biodiesel-ethanol blends cannot be. It was found that the energy efficiencies of the system using microemulsion biofuels were slightly lower than the average energy efficiency of diesel engine. From this study, it can be summarized that microemulsion biofuels can be formulated using palm-oil biodiesel (palm-oil methyl ester) as a bio-based surfactant and they can be considered as environmentally-friendly alternatives to diesel and biodiesel. However, cost considerations showed that the raw materials should be locally available to reduce additional costs of microemulsion biofuels.     

Review of perovskite-structure related cathode materials for solid oxide fuel cells

In this article, different perovskite-structure related materials are reviewed, which could be potential candidates for cathode materials in solid oxide fuel cells. Solid oxide fuel cells provide an alternative, environmentally viable and efficient option to conventional electricity-producing devices. Different properties are required for the materials to qualify as a cathode for solid oxide fuel cells. Therefore, the analysis and review are done based on the process parameters and their effect on the electrical conductivity, electrochemical properties, the coefficient of thermal expansion and mechanical properties of different cathode materials. Fracture toughness and hardness have been the focus while analysing the mechanical properties. The selection of the initial composition, dopants and their valence plays a vital role in deciding the properties mentioned above of cathode materials. The prospective cathode materials classified as cobalt-based and cobalt-free are further bifurcated based on the A-site elements of the perovskite (ABO₃) structure. Also given in this article is the summary of the latest development on the cathode materials. As observed from the properties studied, cobalt-based materials tend to have higher conductivity than cobalt-free materials. While cobalt-free compositions are cost-effective and have a comparable coefficient of thermal expansion with other components of solid oxide fuel cells. The last section of the article gives the future scope of the research.     

Rheological studies on a slurry biofuel to aid in evaluating its suitability as a fuel

Biomass is an often abundant, renewable, low ash and low sulfur fuel. Due to these properties, biofuels are promising alternatives for traditional petroleum-based fuel applications; however, traditional biofuels for internal combustion engines are not cost competitive with gasoline, diesel or fuel oils. One method to reduce the cost of biofuels is to use slurry fuels which have a potential lower cost than liquid biofuels due to high conversion efficiencies. Slurry biofuels, such as a mixture of corn and water, could provide a biofuel alternative for diesel engines, pressurized gasifiers and heating oil applications such as burners or gas turbines. Use of these biomass slurries poses important questions about their stability and suitability for practical applications in internal combustion engines and combustors.This work reports rheology data for stable corn-starch water slurries (CSWS) which used a polyacrylic acid thickener to eliminate settling of the slurry and to provide desirable shear-thinning behavior for most of the compositions evaluated. The effect of shear rate on the viscosity of the CSWS was studied using a BOHLIN-controlled stress (CS) rheometer. The well-known Ostwald—de Waele power law and Sisko models for viscosity fit the data. The effect of corn starch content, thickener content and temperature on the viscosity of CSWS was also studied. The favorable shear thinning properties were observed for starch contents up to 45% starch and should aid pumping, injection and spraying. The lower heating values of the slurries, however, are undesirably low.     

Recent progress in barium zirconate proton conductors for electrochemical hydrogen device applications: A review

Electrochemical hydrogen devices like fuel cells are widely investigated as promising technologies to mitigate the rising environmental challenges and enhance the renewable energy economy. In these devices, proton-conducting oxides (PCOs) are applied as electrolyte materials to transport protons. Excellent physical stability and higher proton transport number are two essential properties of electrolyte materials. Doped BaZrO₃ (BZO) is a solid ion-conducting perovskite material with high chemical stability and good proton-conducting properties at an intermediate temperature range of 400–650 °C. Therefore, BZO is an attractive material among the exciting proton-conducting oxides as electrolyte material. To enhance the proton transport properties and improve the material fabrication process of BZO, techniques such as the use of dopants, sintering aid, synthesis methods are crucial. The present review work highlights the applications of BZO as electrolyte material in electrochemical hydrogen devices such as hydrogen isotopes separation systems, hydrogen sensors, hydrogen pumps, and protonic ceramic fuel cells (PCFCs) or solid oxide fuel cells (SOFCs). The central section of this review summarizes the recent research investigations of these applications and provides a comprehensive insight into the various synthesis process, doping, sintering aid, operating environments, and operating condition's impact on the composition, morphology, and performance of BZO electrolyte materials. Based on the reviewed literature, remarks on current challenges and prospects are provided. The presented information on in-depth analysis of the physical properties of barium zirconate electrolyte's along with output performance will guide aspirants in conducting research further on this field.     

日本藻类生物燃料的研究进展

以藻类为原料的生物燃料不仅可作为石油燃料的替代燃料使用,而且可应对地球温暖化问题、粮食问题及能源安全等问题,因此,藻类生物燃料倍受关注。介绍了藻类生物燃料研究的概况、日本藻类生物燃料的研究情况。     

Applicability of biogas digestate as solid fuel

Biogas digestate is a byproduct in biogas plants. Using the dried digestate as solid fuel seems to be a promising alternative. Objectives were to verify whether digestate from biogas plants is suitable as a solid biomass fuel and to classify the digestate according to current regulations for biofuels. Combustion experiments in a biomass combustion facility were carried out to ascertain both, emissions and combustion behavior.Two different digestates were used as test fuel and pressed into pellets. Net calorific value of digestate pellets were between 15.8 MJ/kg and 15.0 MJ/kg with water content of 9.2% and 9.9%. Ash content was between 14.6% and 18.3%, with softening temperature between 1090 °C and 1110 °C. Major compounds of ash were calcium 13.6-17.0%, phosphorous 20.4-26.7%, silicon 18.0-30.4% and potassium with 8.5-15.5%. The average concentration of carbon monoxide was between 104 mg/m³ and 275 mg/m³ and 334-398 mg/m³ of nitrogen oxides. Average dust concentration of 100-106 mg/m³ has been detected, which was reduced to 40-43 mg/m³ by using an electric filter.Chemical composition and physical properties of digestate fuel pellets depend on the blend of substrates used as feedstock for biogas production. The digestates investigated in this study can be recommended as a fuel for combustion. The calorific value, the ash properties and the emissions allow their use in the investigated solid biomass combustion unit. Further investigations are required to cover a broader range of digestates and combustion techniques.     

Oxidation and low temperature properties of biofuels obtained from pyrolysis and alcoholysis of soybean oil and their blends with petroleum diesel

Diesel-like fuels were synthesized by a pyrolysis method using soybean oil (pyrodiesel, PD) and soybean soapstock (SPD), respectively, as starting material. These pyrodiesel samples were compared with soy biodiesel (BD) samples. All these three biofuels (PD, SPD and BD) and their blends with high sulfur (HSD) and low sulfur (LSD) diesel fuels were evaluated by measuring a number of fuel properties, such as oxidative stability, low-temperature performance, acid value and corrosion properties. Compared to BD blends, PD and SPD and their blends were found to have better oxidative stability, though inferior acid values. SPD and its blends have better flow performance at low-temperature compared to BD and PD blends. All the biofuels and their blends met the copper corrosion requirement prescribed by US and European standard. Based on the results reported here, pyrodiesels from these two-different feedstocks have potential and will require some upgrading or change in pyrolysis conditions, if they are to be used as fuel blending component.     

Storage stability of poultry fat and diesel fuel mixtures: Specific gravity and viscosity

Poultry fat (biofuel) and its 20%, 40%, 60% and 80% mixtures with #2 pump diesel fuel were stored for 1 year at bench scale (1 L) under controlled laboratory conditions at 4, 38, 54.4 °C and at ambient room temperature. Poultry fat (100%) was studied under these same conditions with and without an antioxidant additive. Poultry fat mixtures (20% and 80%) were also stored at pilot scale (250 gallons) under outdoor, ambient conditions. Physical properties and phenomenon relevant to the use of these mixtures as biofuels for industrial boilers were studied and tracked. These properties include specific gravity, dynamic viscosity, sedimentation accumulation and separation (layering). Corrosive effects of these fuels on various metals were also examined. Viscosity and specific gravity of these biofuels changed very little over the course of the 1 year storage period. Sediment accumulation was present in all treatments, with increasing sedimentation correlating with increasing biofuel concentrations. The addition of antioxidant to 100% biofuel minimized changes in physical properties and sedimentation over the course of this study. Layering occurred in all mixtures of poultry fat and diesel fuel. Results also include the approximate amount of energy required to insure proper mixing of each treatment. After mixing, homogenization was maintained for considerable time periods. This suggests that mixing should only be performed immediately before the fuels are utilized. Corrosive properties of these biofuels were generally as expected; brass and copper were susceptible to attack by these fuels where as 316 stainless steel and carbon steel were not.     

Solar energy conversion by photoelectrochemical processes

The basic principles of conversion of solar energy by photoelectrochemical methods are reviewed. A distinction is made between systems used for conversion into electrical energy and those which are applicable for the production of chemical fuel. Besides photogalvanic cells, the main emphasis is put on semiconductor/electrolyte/metal-devices. The various mechanisms involved in these cells, the conversion efficiencies and the stability of the components are discussed in terms of energy schemes. The properties of these systems are compared with those of pure solid state devices. As far as the photolytic decomposition of water for the production of chemical fuel is concerned, the photoelectrochemical reactions in heterogeneous systems are briefly compared with purely photochemical processes in homogeneous solutions. Various conclusions are made concerning the applicability of the systems discussed in this paper.     

Thermodynamic Analysis of Solid Oxide Fuel Cell Gas Turbine Systems Operating with Various Biofuels

Solid oxide fuel cell–gas turbine (SOFC‐GT) systems provide a thermodynamically high efficiency alternative for power generation from biofuels. In this study biofuels namely methane, ethanol, methanol, hydrogen, and ammonia are evaluated exergetically with respect to their performance at system level and in system components like heat exchangers, fuel cell, gas turbine, combustor, compressor, and the stack. Further, the fuel cell losses are investigated in detail with respect to their dependence on operating parameters such as fuel utilization, Nernst voltage, etc. as well as fuel specific parameters like heat effects. It is found that the heat effects play a major role in setting up the flows in the system and hence, power levels attained in individual components. The per pass fuel utilization dictates the efficiency of the fuel cell itself, but the system efficiency is not entirely dependent on fuel cell efficiency alone, but depends on the split between the fuel cell and gas turbine powers which in turn depends highly on the nature of the fuel and its chemistry. Counter intuitively it is found that with recycle, the fuel cell efficiency of methane is less than that of hydrogen but the system efficiency of methane is higher.     

Comparison of micropatterning methods for ceramic surfaces

The fabrication of defined ceramic micropatterns smaller than 100 μm is due to the hardness and brittleness of ceramic materials still very challenging. However, in recent years, micropatterned ceramic surfaces have become highly interesting for biomedical applications or the fabrication of energy converting devices, such as solid oxide fuel or solar cells. In this study we evaluate six modern techniques for ceramic pattern fabrication with feature sizes ranging from 5 to 100 μm. Ceramic materials such as alumina, zirconia, silica and hydroxyapatite are discussed. Advantages and disadvantages for each process are highlighted and compared to the other techniques. Three of these techniques, namely microtransfer molding, modified micromolding and Aerosol-Jet^® printing generate patterns starting with aqueous ceramic suspensions. The other three techniques, micromachining and two different types of laser treatment produce micropatterns by material removal from solid ceramic substrates. The detailed analysis yields that properties such as the desired micropatterning size, shape or the production time are strongly dependant on the chosen technique.     

Neural networks estimation of diesel particulate matter composition from transesterified waste oils blends

The objective of this work is to study the effect of specific fatty acid methyl esters preset in biofuels on particulate matter emissions. A typical diesel fuel supplied in petrol stations (reference), two biofuels composed of methyl esters from the transesterification process of waste oils with different origins and some blends of biofuels with the reference fuel were tested in a commercial direct injection engine reproducing five modes of the European transient urban/extraurban certification cycle.Results from the tests are fitted using neural networks (NN). The equations allow the amount of soluble and insoluble material of Diesel particulates to be determined as a function of engine operating conditions and fuel composition.Simulation from NNs equations proves that the amount of palmitic acid methyl ester in fuels is the main factor affecting the amount of insoluble material emitted due to its higher oxygen content and cetane number.     

Untersuchung von Kraftstoffdampf‐Rückhaltesystemen bei Einsatz von ethanolhaltigen Biokraftstoffen

Fuel vapor restraint systems are used in vehicles to avoid discharge of volatile hydrocarbons from fuel tanks. Until 2020 nearly 10 % of all fossil fuels shall be replaced by biofuels upon which bioethanol plays an important role. The topic of this article is the proper operation of fuel vapor restraint systems depending on the composition of bioethanol‐fuel blends. As a first step, activated carbons commonly used in fuel restraint systems are tested. Received results and measured data serve as input for a mathematical model with the intention to simulate the performance of fuel vapor restraint systems depending on bioethanol‐fuel composition.     

A viable technology to generate third‐generation biofuel

First generation biofuels are widely available because the production technologies are well developed. However, growth of the raw materials conflicts with food security, so that first‐ generation biofuels are not so promising. The second generation of biofuels will not compete directly with food but requires several energy intensive processes to produce them, and also increases land‐use change, which reduces its environmental and economic feasibility. The production of third‐generation biofuels avoids the issues met with first‐ and second‐ generation biofuels, namely food–fuel competition, land‐use change, etc., and is thus considered a viable alternative energy resource. On all dimensions of sustainability (environmental, social and economical), a life cycle assessment approach is most relevant to avoid issues in problem shifting. The utilization of organic waste and carbon dioxide in flue gases for the production of biomass further increases the sustainability of third generation biofuels, as it minimizes greenhouse gas emissions and disposal problems. Copyright © 2011 Society of Chemical Industry     

Rapeseed residues utilization for energy and 2nd generation biofuels

Lignocellulosic biomass is an interesting and necessary enlargement of the biomass used for the production of renewable biofuels. It is expected that second generation biofuels are more energy efficient than the ones of first generation, as a substrate that is able to completely transformed into energy. The present study is part of a research program aiming at the integrated utilization of rapeseed suitable to Greek conditions for biodiesel production and parallel use of its solid residues for energy and second generation biofuels production. In that context, fast pyrolysis at high temperature and fixed bed air gasification of the rapeseed residues were studied. Thermogravimetric analysis and kinetic study were also carried out. The obtained results indicated that high temperature pyrolysis could produces higher yields of syngas and hydrogen production comparing to air fixed bed gasification.     

Application of chemical fractionation methods for characterisation of biofuels,waste derived fuels and CFB co-combustion fly ashes

In the important efforts to decrease the net CO₂ emissions to the atmosphere, new, alternative fuels are being included in the fuel mixes used in utility boilers. However, these fuels have ash properties that are different from those of the traditionally used fuels and in some cases technical problems, such as ash fouling and corrosion occur due to this. Therefore, diagnostic and predictive methods are developed and used to avoid such problems. Determination of the chemical association forms of important elements, such as potassium and sodium, in the fuel by chemical fractionation is a method well defined for coal and biofuels, such as wood pellets, bark and forest residues. Chemical fractionation is a step by step leaching method extracting water soluble salts in the first step, ion exchangeable elements, such as organically associated sodium, calcium and magnesium in the second step and acid soluble compounds such as carbonates and sulfates in the third step. The solid residue fraction consists of silicates, oxides, sulfides and other minerals. The compound extracted in the two first steps is considered reactive in the combustion with a few exceptions. In this work, it has been applied to some waste fuels, i.e. sewage sludge, straw and refuse derived fuel (RDF), as well as to coal and wood. The present work also includes results from combustion tests in a fluidised bed boiler where three blends of the investigated fuels were used. The fractionation results for the fuel blends are weighted results of the fractionations of the pure fuels discussed above which are compared with fractionations of their corresponding fly ashes. The co-combustion strategy gave very good results in reducing ash problems. Possible chemical mechanisms involved are discussed in the article.     

微生物方法选择性生产生物燃料的研究进展

目前,工程荫已经广泛应用于食品、药品及酒精燃料等产品的生产中。尽管如此,工程菌发酵技术的潜力仍然没有充分发掘。交通运输业对于耐用燃料的需求日益增强,迫切地需要开发生物燃料的生产技术。为此,科研人员经过几十年的努力,建起了微生物生理学和途径控制学数据库,使得微生物工程成为生物燃料生产的一项理想技术。虽然目前乙醇在生物燃料市场上占有统治地位,但是它在某些物理性质上存在缺陷,并不足一种理想的燃料。回顾了微生物工程的研究进展,综述了一些新型生物燃料的微生物工程生产。     

沥青快速熔化技术的应用

着重介绍我国炭素生产中沥青快速熔化常用的3种装置。通过对其快速熔化原理的分析,比较了3种形式的装置其对固体沥青的要求、熔化效率、装置清理、控制和日常维护等方面的差别。     

Reduction of diesel smoke opacity from vegetable oil methyl esters during transient operation

This work is focused on the measurement and analysis of the smoke opacity resulting from a Diesel engine fuelled with conventional fuel and biofuels under transient conditions. Methyl esters obtained from used cooking and unused vegetable oils were tested as diesel fuels, pure and blended with 30% and 70% of a commercial diesel fuel which was also used pure. A commercial engine was mounted in a test bench prepared for operating in different transient conditions. A smoke meter AVL 439 allowed for the study of the effect of these fuels on the smoke opacity under varied operating conditions. The thermo chemical properties of the test fuels and the engine parameters, such as fuel/air ratio or exhaust gas recirculation (EGR) ratio, were used for the analysis and interpretation of the results. The engine transient processes studied were (a) engine start, (b) load increase at constant engine speed and (c) engine speed decrease at constant torque. These results suggested that the use of the diesel blends containing vegetable esters is an interesting alternative for a significant reduction in smoke opacity not only in steady conditions but also in transient engine operation, the latter being the most usual condition in passenger vehicles.     

Lipids from food waste as feedstock for biodiesel production: Case Hong Kong

Research on different alternative liquid fuels is rapidly growing because of the environmental concerns and depletion of fossil fuels. As the world confronts a reported food shortage and rising fuel prices, researchers are engaged in developing biofuels that would not convert food crops into energy. In addition, it is apparent that the demand for biodiesel is expected to rise over the coming years. To date, many edible oils are used for biodiesel production. Thus, increasing demand of biodiesel will have a direct impact on food shortage. This underlines the need to use waste materials for biodiesel preparation. In this regard, lipid fraction which can be obtained after hydrolysis of food waste with an enzyme system accumulated in the solid state fungal culture is considered inedible and can be used as a potential source to produce biodiesel.