Effects of mixing system and pilot fuel quality on diesel–biogas dual fuel engine performance

This paper describes results obtained from CI engine performance running on dual fuel mode at fixed engine speed and four loads, varying the mixing system and pilot fuel quality, associated with fuel composition and cetane number. The experiments were carried out on a power generation diesel engine at 1500 m above sea level, with simulated biogas (60% CH₄–40% CO₂) as primary fuel, and diesel and palm oil biodiesel as pilot fuels. Dual fuel engine performance using a naturally aspirated mixing system and diesel as pilot fuel was compared with engine performance attained with a supercharged mixing system and biodiesel as pilot fuel. For all loads evaluated, was possible to achieve full diesel substitution using biogas and biodiesel as power sources. Using the supercharged mixing system combined with biodiesel as pilot fuel, thermal efficiency and substitution of pilot fuel were increased, whereas methane and carbon monoxide emissions were reduced.     

Development and quantification of biodiesel production from chicken feather meal as a cost-effective feedstock by using green technology

Increased urbanization and increase in population has led to an increased demand for fuels. The result is the prices of fuels are reaching new heights every day. Using low-cost feedstocks such as rendered animal fats in biodiesel production will reduce biodiesel expenditures. One of the low-cost feedstocks for biodiesel production from poultry feathers. This paper describes a new and environmentally friendly process for developing biodiesel production technology from feather waste produced in poultry industry. Transesterification is one of the well-known processes by which fats and oils are converted into biodiesel. The reaction often makes use of acid/base catalyst. If the material possesses high free fatty acid then acid catalyst gives better results. The data resulted from gas chromatography (GC) revealed these percentages for fatty acid compositions: myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and arachidonic acid. The biodiesel function group was analyzed by using FTIR. This study concluded that the rooster feathers have superior potential to process them into biodiesel than broiler chicken feathers fat because of fatty acid composition values and it has important properties of biodiesel.     

Biogas production: current state and perspectives

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. Most often applied are wet digester systems using vertical stirred tank digester with different stirrer types dependent on the origin of the feedstock. Biogas is mainly utilized in engine-based combined heat and power plants, whereas microgas turbines and fuel cells are expensive alternatives which need further development work for reducing the costs and increasing their reliability. Gas upgrading and utilization as renewable vehicle fuel or injection into the natural gas grid is of increasing interest because the gas can be used in a more efficient way. The digestate from anaerobic fermentation is a valuable fertilizer due to the increased availability of nitrogen and the better short-term fertilization effect. Anaerobic treatment minimizes the survival of pathogens which is important for using the digested residue as fertilizer. This paper reviews the current state and perspectives of biogas production, including the biochemical parameters and feedstocks which influence the efficiency and reliability of the microbial conversion and gas yield.     

Extraction of oil from microalgae for biodiesel production: A review

The rapid increase of CO(2) concentration in the atmosphere combined with depleted supplies of fossil fuels has led to an increased commercial interest in renewable fuels. Due to their high biomass productivity, rapid lipid accumulation, and ability to survive in saline water, microalgae have been identified as promising feedstocks for industrial-scale production of carbon-neutral biodiesel. This study examines the principles involved in lipid extraction from microalgal cells, a crucial downstream processing step in the production of microalgal biodiesel. We analyze the different technological options currently available for laboratory-scale microalgal lipid extraction, with a primary focus on the prospect of organic solvent and supercritical fluid extraction. The study also provides an assessment of recent breakthroughs in this rapidly developing field and reports on the suitability of microalgal lipid compositions for biodiesel conversion.     

Comparative life cycle assessment of autotrophic cultivation of Scenedesmus dimorphus in raceway pond coupled to biodiesel and biogas production

Life cycle assessment (LCA) of indigenous freshwater microalgae, Scenedesmus dimorphus, cultivation in open raceway pond and its conversion to biodiesel and biogas were carried out. The LCA inventory inputs for the biogas scenario was entirely based on primary data obtained from algal cultivation (in pilot scale raceway pond), harvesting, and biogas production; while only the downstream processing involved in biodiesel production namely drying, reaction and purification were based on secondary data. Overall, eight scenarios were modeled for the integrated process involving: algae-based CO₂ capture and downstream processing scenarios for biodiesel and biogas along with impact assessment of nutrient addition and extent of recycling in a life cycle perspective. The LCA results indicated a huge energy deficit and net CO₂ negative in terms of CO₂ capture for both the biodiesel and biogas scenarios, majorly due to lower algal biomass productivity and higher energy requirements for culture mixing. The sensitivity analysis indicated that variability in the biomass productivity has predominant effect on the primary energy demand and global warming potential (GWP, kg CO₂ eq.) followed by specific energy consumption for mixing algal culture. Furthermore, the LCA results indicated that biogas conversion route from microalgae was more energy efficient and sustainable than the biodiesel route. The overall findings of the study suggested that microalgae-mediated CO₂ capture and conversion to biodiesel and biogas production can be energy efficient at higher biomass productivity (> 10 g m⁻² day⁻¹) and via employing energy-efficient systems for culture mixing (< 2 W m⁻³).

     

Engineering challenges in biodiesel production from microalgae

In recent years, the not too distant exhaustion of fossil fuels is becoming apparent. Apart from this, the combustion of fossil fuels leads to environmental concerns, the emission of greenhouse gases and issues with global warming and health problems. Production of biodiesel from microalgae may represent an attractive solution to the above mentioned problems, and can offer a renewable source of fuel with fewer pollutants. This review presents a compilation of engineering challenges related to microalgae as a source of biodiesel. Advantages and current limitations for biodiesel production are discussed; some aspects of algae cells biology, with emphasis on cell wall composition, as it represents a barrier for fatty acid extraction and lipid droplets are also presented. In addition, recent advances in the different stages of the manufacturing process are included, starting from the strain selection and finishing in the processing of fatty acids into biodiesel.     

生物柴油原料资源高油脂微藻的开发利用

生物柴油作为化石能源的替代燃料已在国际上得到广泛应用。至今生物柴油的原料主要来自油料植物, 但与农作物争地的情况以及较高的原料成本限制了生物柴油的进一步推广。微藻作为高光合生物有其特殊的原料成本优势, 微藻的脂类含量最高可达细胞干重的80%。利用生物技术改良微藻, 获得的高油脂基因工程微藻经规模养殖, 可大大降低生物柴油原料成本。介绍了国内外生物柴油的应用现状, 阐述了微藻作为生物柴油原料的优势, 对基因工程技术调控微藻脂类代谢途径的研究进展, 以及在构建工程微藻中面临的问题和应采取的对策进行了综述和展望。     

Microbial utilization of crude glycerol for the production of value-added products

Energy fuels for transportation and electricity generation are mainly derived from finite and declining reserves of fossil hydrocarbons. Fossil hydrocarbons are also used to produce a wide range of organic carbon-based chemical products. The current global dependency on fossil hydrocarbons will not be environmentally or economically sustainable in the long term. Given the future pessimistic prospects regarding the complete dependency on fossil fuels, political and economic incentives to develop carbon neutral and sustainable alternatives to fossil fuels have been increasing throughout the world. For example, interest in biodiesel has undergone a revival in recent times. However, the disposal of crude glycerol contaminated with methanol, salts, and free fatty acids as a by-product of biodiesel production presents an environmental and economic challenge. Although pure glycerol can be utilized in the cosmetics, tobacco, pharmaceutical, and food industries (among others), the industrial purification of crude glycerol is not economically viable. However, crude glycerol could be used as an organic carbon substrate for the production of high-value chemicals such as 1,3-propanediol, organic acids, or polyols. Microorganisms have been employed to produce such high-value chemicals and the objective of this article is to provide an overview of studies on the utilization of crude glycerol by microorganisms for the production of economically valuable products. Glycerol as a by-product of biodiesel production could be used a feedstock for the manufacture of many products that are currently produced by the petroleum-based chemical industry.     

Liquid and gaseous fuels from biotechnology: challenge and opportunities

Abstract: This paper presents challenging opportunities for production of liquid and gaseous fuels by biotechnology. From the liquid fuels, ethyl alcohol production has been widely researched and implemented. The major obstacle for large scale production of ethanol for fuel is the cost, whereby the substrate represents one of the major cost components. Various scenarios will be presented for a critical assessment of cost distribution for production of ethanol from various substrates by conventional and high rate processes. The paper also focuses on recent advances in the research and application of biotechnological processes and methods for the production of liquid transportation fuels other than ethanol (other oxygenates; diesel fuel extenders and substitutes), as well as gaseous fuels (biogas, methane, reformed syngas). Potential uses of these biofuels are described, along with environmental concerns which accompany them. Emphasis is also put on microalgal lipids as diesel substitute and biogas/methane as a renewable alternative to natural gas. The capturing and use of landfill gases is also mentioned, as well as microbial coal liquefaction. Described is also the construction and performance of microbial fuel cells for the direct high-efficiency conversion of chemical fuel energy to electricity. Bacterial carbon dioxide recovery is briefly dealt with as an environmental issue associated with the use of fossil energy.     

Second Generation Biofuels: High-Efficiency Microalgae for Biodiesel Production

The use of fossil fuels is now widely accepted as unsustainable due to depleting resources and the accumulation of greenhouse gases in the environment that have already exceeded the “dangerously high” threshold of 450 ppm CO₂-e. To achieve environmental and economic sustainability, fuel production processes are required that are not only renewable, but also capable of sequestering atmospheric CO₂. Currently, nearly all renewable energy sources (e.g. hydroelectric, solar, wind, tidal, geothermal) target the electricity market, while fuels make up a much larger share of the global energy demand (～66%). Biofuels are therefore rapidly being developed. Second generation microalgal systems have the advantage that they can produce a wide range of feedstocks for the production of biodiesel, bioethanol, biomethane and biohydrogen. Biodiesel is currently produced from oil synthesized by conventional fuel crops that harvest the sun’s energy and store it as chemical energy. This presents a route for renewable and carbon-neutral fuel production. However, current supplies from oil crops and animal fats account for only approximately 0.3% of the current demand for transport fuels. Increasing biofuel production on arable land could have severe consequences for global food supply. In contrast, producing biodiesel from algae is widely regarded as one of the most efficient ways of generating biofuels and also appears to represent the only current renewable source of oil that could meet the global demand for transport fuels. The main advantages of second generation microalgal systems are that they: (1) Have a higher photon conversion efficiency (as evidenced by increased biomass yields per hectare): (2) Can be harvested batch-wise nearly all-year-round, providing a reliable and continuous supply of oil: (3) Can utilize salt and waste water streams, thereby greatly reducing freshwater use: (4) Can couple CO₂-neutral fuel production with CO₂ sequestration: (5) Produce non-toxic and highly biodegradable biofuels. Current limitations exist mainly in the harvesting process and in the supply of CO₂ for high efficiency production. This review provides a brief overview of second generation biodiesel production systems using microalgae.     

Influence of tall oil biodiesel with Mg and Mo based fuel additives on diesel engine performance and emission

The purpose of this study is to investigate influences of tall oil biodiesel with Mg and Mo based fuel additives on diesel engine performance and emission. Tall oil resinic acids were reacted with MgO and MoO(2) stoichiometrically for the production of metal-based fuel additives (combustion catalysts). The metal-based additives were added into tall oil biodiesel (B60) at the rate of 4 micromol/l, 8 micromol/l and 12 micromol/l for preparing test fuels. In general, both of the metal-based additives improved flash point, pour point and viscosity of the biodiesel fuel, depending on the rate of additives. A single cylinder DI diesel engine was used in the tests. Engine performance values did not change significantly with biodiesel fuels, but exhaust emission profile was improved. CO emissions and smoke opacity decreased by 56.42% and by 30.43%, respectively. In general, low NO(x) and CO(2) emissions were measured with the biodiesel fuels.     

Selection and Characterization of Biofuel-Producing Environmental Bacteria Isolated from Vegetable Oil-Rich Wastes

Fossil fuels are consumed so rapidly that it is expected that the planet resources will be soon exhausted. Therefore, it is imperative to develop alternative and inexpensive new technologies to produce sustainable fuels, for example biodiesel. In addition to hydrolytic and esterification reactions, lipases are capable of performing transesterification reactions useful for the production of biodiesel. However selection of the lipases capable of performing transesterification reactions is not easy and consequently very few biodiesel producing lipases are currently available. In this work we first isolated 1,016 lipolytic microorganisms by a qualitative plate assay. In a second step, lipolytic bacteria were analyzed using a colorimetric assay to detect the transesterification activity. Thirty of the initial lipolytic strains were selected for further characterization. Phylogenetic analysis revealed that 23 of the bacterial isolates were Gram negative and 7 were Gram positive, belonging to different clades. Biofuel production was analyzed and quantified by gas chromatography and revealed that 5 of the isolates produced biofuel with yields higher than 80% at benchtop scale. Chemical and viscosity analysis of the produced biofuel revealed that it differed from biodiesel. This bacterial-derived biofuel does not require any further downstream processing and it can be used directly in engines. The freeze-dried bacterial culture supernatants could be used at least five times for biofuel production without diminishing their activity. Therefore, these 5 isolates represent excellent candidates for testing biofuel production at industrial scale.     

研究开发燃料油植物生产生物柴油的几个策略

能源短缺和环境污染是目前人类社会所面临的巨大挑战, 而生物柴油的应用和推广正是现阶段解决能源替代问题的较佳手段。现今国外生物柴油产业发展十分迅速, 产量逐年增长, 而我国的生物柴油产业才刚刚起步。本文介绍了极具潜力的5种木本油料植物麻疯树(Jatropha curcas)、光皮树(Cornus wilsoniana)、文冠果(Xanthoceras sorbifolia)、黄连木(Pistacia chinensis)和欧李(Cerasus humilis)和1种野生草本油料植物海篷子(Salicornia bigelivii), 进而提出运用转基因技术提高燃料油植物种子含油量的优势, 归纳总结了生产生物柴油的4种不同工艺。最后建议政府应对燃料油植物种植和生产加工产业实施补贴和免税等扶植政策。本文对我国生物质能源产业的发展提供了有价值的实施策略, 具有重要的借鉴和参考价值。     

生物柴油利用概况及其在中国的发展思路

石化燃料是当前人类使用的主要能源,但其日益消耗殆尽,同时造成了严重的温室效应和环境污染问题,因此,生物柴油被当作石化燃料的绿色替代品,许多国家都在大力研发。该文阐述了生物柴油的本质及其较石化柴油咱使用上的优良特性,综述了生物柴油主要在欧美国家中的发展现状及其它国家的研发动态,特别是以大豆(Glycine max)和油菜(Brassica campestris)等油料作物为主的生物柴油原料生产状况。在分析了我国油料生产与食用消费现状、受国际生物柴油大力发展的影响的程度及油料作物与粮食生产对耕地资源的激烈竞争矛盾的基础上,提出了充分利用盐碱地、贫瘠、荒漠与退耕还林地,通过种植抗逆性强的油料植物发展我国生物柴油的思路。     

生物柴油研究进展

介绍了国内外生物柴油的发展现状,探讨了我国发展生物柴油的原料来源途径,包括木本油料植物、转基因油料作物、废弃油脂、微生物油脂和微藻油脂等,综述了制备生物柴油的化学法、酶法、超临界法等生产技术及其进展,概括了当前生物柴油主要的品质问题与改性对策,分析了生物柴油副产物的高值化利用策略,指出了我国生物柴油产业化面临的原料、技术和生物炼制方面的主要问题。     

Oleaginous yeasts for biodiesel: Current and future trends in biology and production

Production of biodiesel from edible plant oils is quickly expanding worldwide to fill a need for renewable, environmentally-friendly liquid transportation fuels. Due to concerns over use of edible commodities for fuels, production of biodiesel from non-edible oils including microbial oils is being developed. Microalgae biodiesel is approaching commercial viability, but has some inherent limitations such as requirements for sunlight. While yeast oils have been studied for decades, recent years have seen significant developments including discovery of new oleaginous yeast species and strains, greater understanding of the metabolic pathways that determine oleaginicity, optimization of cultivation processes for conversion of various types of waste plant biomass to oil using oleaginous yeasts, and development of strains with enhanced oil production. This review examines aspects of oleaginous yeasts not covered in depth in other recent reviews. Topics include the history of oleaginous yeast research, especially advances in the early 20th century; the phylogenetic diversity of oleaginous species, beyond the few species commonly studied; and physiological characteristics that should be considered when choosing yeast species and strains to be utilized for conversion of a given type of plant biomass to oleochemicals. Standardized terms are proposed for units that describe yeast cell mass and lipid production.     

Biodiesel from microalgae

Continued use of petroleum sourced fuels is now widely recognized as unsustainable because of depleting supplies and the contribution of these fuels to the accumulation of carbon dioxide in the environment. Renewable, carbon neutral, transport fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable and carbon neutral alternative to petroleum fuels. Unfortunately, biodiesel from oil crops, waste cooking oil and animal fat cannot realistically satisfy even a small fraction of the existing demand for transport fuels. As demonstrated here, microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Like plants, microalgae use sunlight to produce oils but they do so more efficiently than crop plants. Oil productivity of many microalgae greatly exceeds the oil productivity of the best producing oil crops. Approaches for making microalgal biodiesel economically competitive with petrodiesel are discussed.     

研究开发燃料油植物生产生物柴油的几个策略

能源短缺和环境污染是目前人类社会所面临的巨大挑战,而生物柴油的应用和推广正是现阶段解决能源替代问题的较佳手段。现今国外生物柴油产业发展十分迅速,产量逐年增长,而我国的生物柴油产业才刚刚起步。本文介绍了极具潜力的5种木本油料植物麻疯树（Jatropha curcas）、光皮树（Cornus wilsoniana）、文冠果（Xanthoceras sorbifolia）、黄连木（Pistacia chinensis）和欧李（Cerasus humilis）和1种野生草本油料植物海篷子（Salicornia bigelivii）,进而提出运用转基因技术提高燃料油植物种子含油量的优势,归纳总结了生产生物柴油的4种不同工艺。最后建议政府应对燃料油植物种植和生产加工产业实施补贴和免税等扶植政策。本文对我国生物质能源产业的发展提供了有价值的实施策略,具有重要的借鉴和参考价值。     

Biodiesel from microalgae beats bioethanol

Renewable biofuels are needed to displace petroleum-derived transport fuels, which contribute to global warming and are of limited availability. Biodiesel and bioethanol are the two potential renewable fuels that have attracted the most attention. As demonstrated here, biodiesel and bioethanol produced from agricultural crops using existing methods cannot sustainably replace fossil-based transport fuels, but there is an alternative. Biodiesel from microalgae seems to be the only renewable biofuel that has the potential to completely displace petroleum-derived transport fuels without adversely affecting supply of food and other crop products. Most productive oil crops, such as oil palm, do not come close to microalgae in being able to sustainably provide the necessary amounts of biodiesel. Similarly, bioethanol from sugarcane is no match for microalgal biodiesel.     

Biodiesel production,properties, and feedstocks

Biodiesel, defined as the mono-alkyl esters of vegetable oils or animal fats, is an environmentally attractive alternative to conventional petroleum diesel fuel (petrodiesel). Produced by transesterification with a monohydric alcohol, usually methanol, biodiesel has many important technical advantages over petrodiesel, such as inherent lubricity, low toxicity, derivation from a renewable and domestic feedstock, superior flash point and biodegradability, negligible sulfur content, and lower exhaust emissions. Important disadvantages of biodiesel include high feedstock cost, inferior storage and oxidative stability, lower volumetric energy content, inferior low-temperature operability, and in some cases, higher NO _x exhaust emissions. This review covers the process by which biodiesel is prepared, the types of catalysts that may be used for the production of biodiesel, the influence of free fatty acids on biodiesel production, the use of different monohydric alcohols in the preparation of biodiesel, the influence of biodiesel composition on fuel properties, the influence of blending biodiesel with other fuels on fuel properties, alternative uses for biodiesel, and value-added uses of glycerol, a co-product of biodiesel production. A particular emphasis is placed on alternative feedstocks for biodiesel production. Lastly, future challenges and outlook for biodiesel are discussed. Disclaimer: Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.