Biodiesel is one of the prospective alternatives to petroleum fuel resources because of its renewable and environment friendly nature. Transesterficiation process is used for biodiesel production. ...The biodiesel production process mainly depends on five parameters which includes free fatty acid (FFA) content, type of alcohol used and molar ratio (alcohol:oil), catalyst type and its concentration, reaction temperature and time. Methanol and ethanol are commonly used for biodiesel production in presence of different alkaline catalysts like sodium and potassium hydroxides. The production methodology of biodiesel is an important aspect for efficient and cost-effective production of biodiesel. The present study focuses on the various technical aspects of biodiesel production methodology. The study reveals that for optimum biodiesel production reaction temperature should be in range of 50–60°C, molar ratio of alcohol to oil should be in range of 6–12:1 with the use of an alkali catalyst having optimum concentration 1% by weight. The optimal reaction time for transesterification process is 120min.
The demand of energy is increasing at an escalating pace and cannot be fulfilled entirely by conventional energy systems, due to their limited supplies. In addition to this they have a radical impact ...on the environment. In comparison to them hybrid energy systems are a suitable combination of renewable and non-renewable energy systems which keeps into account the advantages of both these systems, thus able to achieve reduction in cost of implementation and maintenance of the system, limited emission levels, improvement in reliability of the overall system etc. Designing of hybrid energy system for a locality and its implementation is an uphill task as the input parameters of the sources considered are randomly varying with time and are also independent of the load requirements. The paper encompasses review on various important sectors needed to be considered while designing and implementation of hybrid energy system; this includes configurations, criteria selection, sizing methodologies and control & energy management. This will help the designer to use suitable design constraints required while implementing hybrid energy system for grid connected or in off grid modes as per the requirement of the locality.
Biodiesel consists of long chain fatty acid esters derived from feed stocks such as vegetable oils, animal fats and used frying oil, etc. which may contain more or less unsaturated fatty acids which ...are prone to oxidation accelerated by exposure to air during storage and at high temperature may yield polymerized compounds. Auto oxidation of biodiesel can cause degradation of fuel quality by affecting the stability parameters. Biodiesel stability includes oxidation, storage and thermal stability. Oxidation instability can led to the formation of oxidation products like aldehydes, alcohols, shorter chain carboxylic acids, insolubles, gum and sediment in the biodiesel. Thermal instability is concerned with the increased rate of oxidation at higher temperature which in turn, increases the weight of oil and fat due to the formation of insolubles. Storage stability is the ability of liquid fuel to resist change in its physical and chemical characteristics brought about by its interaction with its environment and may be affected by interaction with contaminants, light, factors causing sediment formation, changes in color and other changes that reduce the clarity of the fuel. These fuel instabilities give rise to formation of undesirable substances in biodiesel and its blends beyond acceptable quantities as per specifications and when such fuel is used in engine, it impairs the engine performance due to fuel filter plugging, injector fouling, deposit formation in engine combustion chamber and various components of the fuel system.
The present review attempts to cover the different types of fuel stabilities, mechanism of occurrence and correlations/equations developed to investigate the impact of various stability parameters on the stability of the fuel. A review of the use of different types of natural and synthetic antioxidants has also been presented which indicates that natural antioxidants, being very sensitive to biodiesel production techniques and the distillation processes have varying impacts on fuel stability and available literature is very much scarce. The work on the use of synthetic antioxidants on the stability of biodiesel (both distilled and undistilled) from various resources has indicated that out of various 8 synthetic antioxidants studied so far only 3 antioxidants have been found to increase the fuel stability significantly. However, effectiveness of these antioxidants is in the order of TBHQ
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The increasing industrialization and modernization of the world has to a steep rise for the demand of petroleum products. Economic development in developing countries has led to huge increase in the ...energy demand. In India, the energy demand is increasing at a rate of 6.5% per annum. The crude oil demand of the country is met by import of about 80%. Thus the energy security has become a key issue for the nation as a whole. Petroleum-based fuels are limited. The finite reserves are highly concentrated in certain regions of the world. Therefore, those countries not having these reserves are facing foreign exchange crises, mainly due to the import of crude oil. Hence it is necessary to look forward for alternative fuels, which can be produced from feedstocks available within the country.
Biodiesel, an ecofriendly and renewable fuel substitute for diesel has been getting the attention of researchers/scientists of all over the world. The R & D has indicated that up to B20, there is no need of modification and little work is available related to suitability and sustainability of biodiesel production from Jatropha as non-edible oil sources. In addition, the use of vegetable oil as fuel is less polluting than petroleum fuels. The basic problem with biodiesel is that it is more prone to oxidation resulting in the increase in viscosity of biodiesel with respect to time which in turn leads to piston sticking, gum formation and fuel atomization problems.
The report is an attempt to present the prevailing fossil fuel scenario with respect to petroleum diesel, fuel properties of biodiesel resources for biodiesel production, processes for its production, purification, etc. Lastly, an introduction of stability of biodiesel will also be presented.
Summary
The purpose of this article was to review population‐based interventions for preventing childhood obesity carried out in school settings published between 1999 and 2004. A total of 11 such ...interventions were found from USA and UK. The grade of the interventions was from kindergarten, primary grades, middle school to high school. Most of these interventions targeted both physical activity and nutrition behaviours although there were some interventions that focused on only one dimension such as TV watching or restricting drinking of carbonated drinks or increasing physical education time in the school. Most of the interventions were based on some behavioural theory and the most popular theory was social cognitive theory. Most of the interventions focused on individual level behaviour change approaches. Most of the interventions focused on short‐term changes right after the intervention. On the whole, interventions resulted in modest changes in behaviours and mixed results with indicators of obesity. TV watching seems to be most modifiable behaviour, followed by physical activity and nutrition behaviours. The outcome measures such as lowered BMI (body mass index), triceps skin‐fold thickness and waist circumference have not been measured by all studies. Recommendations for enhancing the effectiveness of school‐based childhood obesity interventions are presented.
Due to rapid industrialisation and use of advanced technologies there has been increase in the consumption of fossil fuels, especially petroleum. Increasing needs are reciprocally proportionate to ...diminishing reserves of coal and petroleum. So, the exaggerated to be fulfilled and to curb the problem of increasing fuel prices; researchers are putting their efforts to produce an alternative fuel from replenish able resources on large scale. Biodiesel itself is proving to be a reliable and competent competitor to non-renewable petroleum which is being produced from commonly accustomed plants for instancerapeseed, soybean, sunflower and palm etc. But, complication is that it becomes a problem for in-availability of these oils for foods. Now non-edible raw materials oils such as Pongamia, Jatropha, Mahua, Moringa seed oil etc. have been used to raise the standard of these oils and being produced to complete the level of petroleum and be proven as the best resources for biodiesel production in all approaches both technically and economically. In this paper emphasis has been laid down to review the impact of higher alcohols, use of different raw materials for biodiesel preparation and effect of their composition on Oxidation Stability and Cold Flow properties. Moreover, various production technologies used to produce biodiesel were also reviewed and comparison was done among them for better yield. Further, an attempt has been made to investigate the effect of higher alcohols on biodiesel yield and its properties. The study concludes that oxidation stability depends upon unsaturation mainly linoleic acid and lenolenic acid. Moringa olifera, Moroccan frying oil, Schleichera oleosa L. oil, Moringa peregeria are prospective oils as per oxidative stability characteristics. In contrast to it, cold flow properties depend upon saturation and suggests that having more saturated fatty acids result in poor cold flow properties.
Most abundant form of sulphur in the geosphere has been sulphate. Sulphate, with sulphur in the plus six oxidation state is very stable. Sources of sulphate in groundwater include mineral ...dissolution, atmospheric deposition and other anthropogenic sources (mining, fertilizer, etc.). Gypsum is an important contributor to the high levels of sulphate in many aquifer of the world. Sulphate is not as much as toxic, but it can cause catharsis, dehydration and diarrhoea, and when ingested in higher amount through dietary absorption, the levels of methaemoglobin and sulphaemoglobin are changed in human and animal body. The role of sulphate in aqueous phase and sedimentary phase has been discussed. There is only limited work on sulphate pollution remediation in groundwater at national and international level; therefore, in the light of rising attention in sulphate as a contaminant, different sources of sulphate, its distribution and available different remediation techniques for groundwater system reported so far have been discussed in the present paper. Abiologic processes’ thermochemical sulphate reduction (TSR) also plays significant role in reduction of sulphate.
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