Continuous increase in world’s population, rapid industrialization, urbanization, and economic growth force for continuously increase in fossil fuel consumption to meet growing energy demand. ...Continuous emissions from burning of fossil fuel will create the need to find the appropriate and sustainable replacement for fossil fuels. Biodiesel is appropriate alternate solution for diesel engine due to its renewable, non-toxic and eco-friendly nature. According to EASAC biodiesel evolution is classified into four generations. Cultivation in arid and semi arid land or water, crop yield, effect on food supply, yield of biodiesel, energy content, carbon-neutral economy, easy availability, and economic viable are the main factors behind the evolution of biodiesel generations. This article highlights a comprehensive assessment of various feedstocks used for different generation biodiesel production with their advantages and disadvantages. Different production methods for biodiesel with yield calculation are also explained. Algae based third generation feedstocks are better in comparison with first and second generation due to their high energy content, high oil content and less polluting nature. Forth generation of biodiesel produced from synthetic biology, which will enhance the various physiochemical properties of biodiesel to achieve carbon neutral economy. Among the all biodiesel production processes; transesterification is the most suitable process, because it produces biodiesel of high yield, comparable properties with diesel. This process is also feasible as per economic point of view. The energy demand of future can be met by the blending of different generation oil feedstocks.
Continuously growing world’s energy demand and global climate change due to green house gas emissions have created need to find out renewable and sustainable energy solution. Biodiesel is one of the ...most promising substitute of diesel fuel that can be produced from vegetable oils, animal fats, waste oils etc. It is broadly classified in four generations i.e. edible oils (first generation), non-edible oils (second generation), waste oils (third generation) and advance solar biodiesel (fourth generation). There are some limitations associated with biodiesel as a fuel in diesel engines like cold flow, oxidation stability etc. Selection of biodiesel due to the above reasons is region specific and depends on the specific properties which are mainly governed by fatty acid composition of that oil. This review discusses the physicochemical properties of different generation biodiesel using 52 types of feedstocks. The chemical composition and physicochemical properties of 31 raw oils have also been discussed. As different fatty acid methyl esters (FAME) structures behave differently, it is not possible to develop a unique approach for obtaining optimum composition of FAME. The low concentration of polyunsaturated FAME and long-chain saturated FAME is more favorable for oxidation stability, low-temperature operability, and satisfactory performance. American Society for Testing and Materials (ASTM), European committee for standardization (CEN), Bureau of Indian Standards (BIS), etc. provided the specifications for the biodiesel and their blends.
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•Classification of biodiesel generations on the basis of the type of feedstocks is covered.•Botanical description and growth condition requirements of jatropha are ...discussed.•Physicochemical properties and fatty acid profile of jatropha biodiesel are analyzed.•Production of biodiesel from jatropha oil with different techniques is summarized.•Performance and emissions characteristics of C.I. engine fuelled with jatropha biodiesel are reviewed.
Due to limited reserves of conventional fossil fuels and their negative impact on global climate and human health, researches are focused to find the alternate energy substitute. Comparable properties of biodiesel make it one of the most promising alternatives of conventional diesel fuel. Jatropha curcas oil (non-edible oil) belongs to the second-generation of biodiesel. In this review, the physicochemical properties, fatty acids distribution, stability of jatropha oil are discussed in detail. The change in fatty acid profile affects the fuel properties, performance and emissions of diesel engines operated on jatropha biodiesel. Oxidation stability of jatropha biodiesel is poor due to the high amount of unsaturated fatty acids. Blending, thermal cracking, micro-emulsification, and transesterification are four basic approaches for production of biodiesel. Transesterification is the most adoptive method due to less expensive operation and high product yield. This article also highlighted the performance and emissions of compression ignition engines operated on jatropha biodiesel and its blends. The lower calorific value of jatropha biodiesel is responsible for the decrease in brake thermal efficiency and an increase in brake specific fuel consumption. High availability of oxygen in jatropha biodiesel reduces HC, CO, and PM emissions, while NOx emission increases significantly. This article provides the most of details of optimum parameters for jatropha biodiesel production and its efficient use in diesel engines.
The path towards energy sustainability is the incremental adoption of available technologies, practices and policies that help to decrease environmental impact of energy sector, with adequate ...standards of energy services.
Trigeneration systems use waste heat from prime movers to generate heating and cooling along with power. They are more efficient, less polluting & more economic than conventional systems. Small scale trigeneration power plants, typically, below 15 kWe, are called micro-trigeneration plants. In such systems, over 80% of fuel energy is converted to useable energy.
Over-exploitation of fossil resources has led to increase in pollutants and CO2 levels in atmosphere, causing severe health hazards. Low carbon society is less dependent on fuels with high carbon content. Also, Kyoto protocol set reduction targets for the nations. Alternative fuels promise sustainable development, energy conservation, efficiency and environmental preservation. Various alternate fuels & micro-trigeneration technologies can be combined, leading to sharp decrease in almost all the emissions.
This paper presents a brief review of micro-trigeneration systems. They are projected as strategic means to achieve energy security and efficiency, with positive impact on economy, simultaneously reducing environmental threats, leading to sustainable development.
•Review of micro-trigeneration systems and technologies is presented.•Attractive option to use waste heat for cooling and heating.•Very efficient on total energy performance, fuel savings and CO2 reduction.•Alternative fuels, like bio-fuels, hydrogen, and wooden-gas can also be used.•Potential sustainable energy systems for residential and small applications.
Presently majority of the world’s energy demand is met by fossil fuels. These fuels are depleting at an alarming rate. Thus in future, our energy systems will need to be renewable and sustainable, ...efficient and cost-effective, convenient and safe. Among the various alternative fuels, hydrogen is a long-term renewable and least polluting fuel (produced from renewable energy sources). Its clean burning characteristics help to meet the stringent emission norms. Majority of the work using hydrogen as a fuel is being done in spark ignition engine, however, in this experimental investigation efforts have been made to utilize it in compression ignition engine.
In this investigation, the performance and emission characteristics were studied on a direct injection, single cylinder, four-stroke, air-cooled, stationary diesel engine coupled to an electric dynamometer. Hydrogen-enriched air with carburetion technique was used as intake charge in the above mentioned engine with 10% & 20% exhaust gas recirculation (EGR). Performance parameters such as specific energy consumption, brake specific fuel consumption, brake thermal efficiency were determined and emissions such as oxides of nitrogen, unburned hydrocarbon, carbon monoxide, carbon dioxide, oxygen and exhaust gas temperature were measured. Dual fuel operation with hydrogen induction coupled with exhaust gas recirculation results in lowered emission level and improved performance level compared to the case of neat diesel operation.
► Main concentration of this investigation is to use of alternate fuels in C.I. engine. ► We use the dual fuel mode (Hydrogen & Diesel) in CI engine. ► We reduce the NOx emission with the use of Exhaust Gas Recirculation technique. ► We conclude that thermal efficiency is increased and emission reduced with the use of hydrogen.
Abstract Magnetic switchbacks are reversals (deflection angle θ B > 90°) in the radial magnetic field B r , accompanied by proton bulk flow v p enhancement. The switchback generation mechanism(s) is ...still debated, though switchback evolution is linked to coronal heating. In this study, we provide an exhaustive investigation of magnetic fluctuations in the first 14 Parker Solar Probe encounters. Our results show (1) enhanced magnetic fluctuations ( θ B ≤ 90°) and (2) clear absence of B r reversals θ B > 90° in sub-Alfvénic solar corona. It is concluded that switchbacks are either generated locally in super-Alfvénic solar wind (in situ) or that a subpopulation of magnetic fluctuations generated in sub-Alfvénic solar corona (ex situ) evolves into switchbacks once in super-Alfvénic solar wind flow. In other words, in situ mechanisms are necessary for switchback formation. It is then hypothesized that interchange reconnection in sub-Alfvénic solar corona can provide both the necessary ex situ trigger and in situ evolution mechanisms for switchback formation, though other trigger mechanisms cannot be ruled out.
The rapid depletion of conventional fuel reserves and the increase in environmental pollution prompted the search for a sustainable energy solution. Biodiesel is one of the most promising energy ...substitutes with similar properties as conventional diesel fuel. Surplus availability of palm oil makes it suitable for biodiesel production. Due to the lack of availability of review articles that cover the entire process of palm biodiesel production and its optimum use in diesel engines, the authors were motivated to write this article. Cultivation parameters of palm trees, extraction of oil, and physicochemical properties of palm oil–based biodiesel are explained in this review. The production of palm biodiesel from raw oil can be done through pyrolysis, micro-emulsification, blending, hydro-esterification, and transesterification processes. For high biodiesel yield and less cost of operation, the transesterification method is adopted. The performance and emission parameters of diesel engines that operated on palm biodiesel and its blends are also explained. There is a decrease in brake thermal efficiency and an increase in brake-specific fuel consumption observed with the use of palm biodiesel in diesel engines. A reduction in CO and HC emissions and an increase in NOx emissions are found due to the oxygenating nature of palm biodiesel. This article provides the scientific approach to find out the optimum parameters for palm biodiesel production and its efficient use in compression ignition engines.
•Potential of renewable fuels as diesel replacement is being emphasized.•Effect of ethanol fumigation on the performance of diesel engine is investigated.•NOx, CO2 and smoke decreases with ...simultaneous increase in HC and CO.•Increase in ignition delay with decrease in combustion duration for ethanol substitution observed.
Dwindling reserves and steeply increasing prices of the fossil-fuels, concern over climatic change due to release of anthropogenic greenhouse gases and the strict environmental regulations have motivated the researchers for the search for renewable alternative fuel that has clean burning characteristics and may be produced indigenously. Alcohols, being oxygenated fuel improve the combustion and reduce greenhouse gas emissions, thus enhancing agrarian economies and encouraging national economy as a whole. The objective of this paper is to investigate the thermal performance, exhaust emissions and combustion behaviour of small capacity compression ignition engine using fumigated ethanol. Fumigated ethanol at different flow rates is supplied to the cylinder during suction with the help of a simplified low cost ethanol fuelling system. With ethanol fumigation, brake thermal efficiency decreased upto 11.2% at low loads due to deteriorated combustion, whereas improved combustion increased efficiency up to 6% at higher loads, as compared to pure diesel. Maximum reduction of 22%, 41% and 27% respectively in nitrogen oxide, smoke and carbon-di-oxide emissions with simultaneous increase in hydrocarbon and carbon-mono-oxide emissions upto maximum of 144% and 139% respectively for different rates of ethanol fumigation have been observed, when compared to pure diesel operation. This is due to the changes in physico-chemical properties of air fuel mixture, viz combustion temperature, oxygen concentration, latent heat of vaporisation, fuel distribution, cetane number and ignition delay, that occurred with addition of ethanol content. The rise in peak pressure of cycle, heat release rate and ignition delay along with decrease in combustion duration for different rates of ethanol fumigation have been observed. The increasing fumigation levels of ethanol results in the increase of maximum rate of pressure rise by 0.3–0.5bar/°crank angle and the crank angle after top dead centre, where peak pressure occurs, shifts by 1–4° of crank angle. It is also observed that maximum heat release rate increases by 2–9J/°crank angle as compared to baseline diesel case. Coefficient of Variance of indicated mean effective pressure increases with ethanol fumigation.
The world is presently confronted with the twin crisis of fossil fuel depletion and environmental degradation. Indiscriminate extraction and lavish consumption of fossil fuels have led to reduction ...in underground based carbon resources. The search for an alternative fuel, which promises a harmonious correlation with sustainable development, energy conservation, management, efficiency, and environmental preservation, has become highly pronounced in the present context. For the developing countries of the world, fuels of bio-origin can provide a feasible solution to the crisis.
The present experimental investigation aims to depict the effect of varying injection opening pressure (IOP) using diesel-mahua oil (raw) blends as fuel on the characteristics of a small agricultural ...engine. The effect of preheated mahua oil and mahua oil methyl ester (MOME) as fuel on engine characteristics has also been investigated. Series of short-term tests were conducted on a single cylinder, 3.7 kW, water cooled, stationary diesel engine and performance and emission characteristics were determined using different diesel-mahua oil blends and also with varying IOP. Optimal IOP as well as blend ratio was determined for maximum efficiency and minimum emission values. Further, a novel pipe in pipe counter flow heat exchanger was designed and fabricated to arrange for preheating the raw mahua oil with exhaust gases of the engine. MOME was also prepared and tested as fuel in engine. Characterisation for major properties of all test fuels was conducted. Performance and emission characteristics of the diesel engine for raw mahua oil blends (unheated) at both rated and optimal IOP were compared with those of diesel, MOME and preheated raw mahua oil. At IOP of 226 bar, maximum brake thermal efficiency was obtained for M10, M20 and M30 blends. Significant reduction in carbon monoxide and hydrocarbon emission were observed. Nitrogen oxides emissions increased marginally. It was also observed that preheated mahua oil as fuel increases efficiency and reduces emissions. The use of M10 even at rated injection pressure and M20 and M30 at 226 bar results in minimum loss of efficiency and generates higher environmental benefits.
