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Abstract Castor seed is an important oil seed crop of dryland agriculture. To estimate the energy needs of this crop, two experiments were conducted with three tillage treatments under two farming systems, namely bullock and tractor farming. Under all the selected tillage treatments both for tractor and bullock farming systems, it was found that threshing, harvesting, manual weeding and seed bed preparation were the energy intensive operations. No-tillage treatments was found not only the least energy consuming package of practices but also resulted i n a comparatively high output-input energy ratio despite higher weed intensity. Further, tractor cultivation consumed a higher amount of energy as compared to bullock cultivation but did not result in higher production. The farmer may, therefore, continue with bullock cultivation unless he were to cover larger areas which cannot be commanded by the bullock power resources available to him.

Abstract Biodiesel has gained the forefront of our focus on renewable transportation fuels. This article provides a comprehensive review on the sources used as feedstock and their classification based on generation or type (edible, non-edible, waste resources and animal fats) along with a variety of classical and modern oil extraction techniques. The technical aspects of the various biodiesel production methods currently implemented to the best of our knowledge are discussed here, which include in-situ biodiesel production, both catalysed (homogeneous and heterogeneous systems) and uncatalysed classical production approaches, with emphasis on how each of these approaches are affected by their reaction parameters. The review also highlights the observed drawbacks of each process with a view to assessing the implementation of supercritical and superheated technologies as an alternative, economically feasible advancement. Supercritical process (SCP) has shown great prospect in the obtainment of high quality biodiesel from a wide range of high to low grade feedstock with minimal impacts on the presence of water or FFAs (free fatty acids). From available literature it is shown that these do not affect the process significantly, and various other supercritical fluids such as methyl acetate, tert-butyl methyl ether (MTBE) and dimethyl carbonate can also be used to avoid glycerol formation. The process however, suffers from high initial implementation cost being the most prominent drawback, among others like thermal degradation of the fuel. Another promising technique, the superheated vapour technology (SHV) has emerged as an alternative, with limited literature proving the superiority of either of these processes to be inconclusive. In future works, researchers need to look into various aspects such as developing a spiral reactor for heat recovery, using software based optimization for eliminating redundant experiments analysing production cost for industrial scale-up and improving the fuel’s oxidative stability by adding antioxidants for convenient long-term storage and use.

Energy is essential for industrial production. Because of the past abundance of low-cost energy, historically, the rate of social progress among industrial societies has not been limited by energy availability. Energy cost has not been significant when compared with no energy use. Mechanisation of agriculture, increased use of electrical appliances in the domestic sector and rapid industrialisation to meet the demand of exponentially growing population have resulted in an energy crisis. The raised fossil fuel prices and the environmental factors playing the dominant role in implementation of large scale projects, such as hydro, thermal and nuclear, have aggravated the problem further. In this context, an integrated energy plan for a country seems essential for ecologically sound development of a region. An integrated plan includes strategies to: • improve the efficiencies of end use devices and/or conversion equipment in all sectors; • optimise energy sources (end use matching); • maximise the use of renewable resources; • balance the exploitation of biomass energy resources; and • discourage the use of depletable resources. Conservation through improvement of the efficiencies of end use devices is one of the most effective ways to provide immediate relief for the energy problem. This helps to maintain economic growth and social progress of a region. Environmental problems, resource depletion and growing demand of energy in the state/region make it increasingly imperative that we use energy as efficiently as possible, and planners should take note of this untapped resource. The potential for improved energy efficiency is great, and a substantial part of that potential could be realised in the course of events. The industrial sector constitutes a major consumer of commercial energy. Improvement of energy efficiency in the industrial sector would result in a slower rate of energy growth. A secure energy supply is the major concern of most industrialists. It is, thus, necessary to examine industrial energy use and the economy. The analyses of consumption patterns and the assessment of feasible energy conservation possibilities show that the potential for energy conservation in the industrial sector and in all sectors is substantial. The barriers identified to tap this potential are a lack of information on specific measures and options for achieving energy conservation, lack of capital for schemes involving technology upgrading and efficiency improvements, pricing policies which deviate from rational tariffs and the inadequacy of institutional arrangements for promoting energy conservation in different sectors of the economy. In this regard, research should be sponsored to develop system designs, cost and pricing policies, problems related to system interconnection with public utilities and an assessment of potential energy savings, and research into methods of matching energy resources to work requirements, rather than vice versa, for improved efficiency. It is essential for the planning machinery to foster the integrated approach in energy planning of a region. This paper discusses an attempt made by us to illustrate the industrial energy scene in Karnataka and reveals the possibilities of energy conservation. Analysis of the energy consumption data of Karnataka and India shows that the per capita consumption of energy is low (compared with 56 countries in the world), while for the industrial sector, energy per state domestic product (SDP comparable to GDP) is at least 10–20 times higher than that of industrialised countries. This implies inefficiency in energy utilisation. Detailed investigation of the industrial sector through analysis of the Specific Energy Consumption (SEC)—industry wise and yearly for a seven-year period—reveals that about 27.72% of energy could be saved in the industrial sector. This, when quantified, accounts for savings of 1541 million kWh per year in Karnataka, which is equivalent to the power output of 300 MW (Mega Watts) electric power generating station (hydro/thermal).

Abstract Time is an important factor for bioenergy and bio-product producing industries. Longer process/fermentation times are the major hurdles in making the process more cost effective for any desired product. Integration of different process units were usually carried out to minimize the entire processing time. However, apart from consolidation, microbial adaptation and biomass pretreatment methods plays an important role during product generation. Microorganisms normally take longer time to adapt to the surrounding environment, which certainly affect the entire processing time. Thus, the present work was framed to use mixture of crude and low titre enzymes for lignin degradation and holocellulose hydrolysis followed by fermentation in a single unit to produce second generation ethanol from Kans grass. In the present study, an enzymatic venture was attempted to delignify the recalcitrant lignin molecule and simultaneously hydrolyse the biomass for enhanced sugars generation followed by ethanol production in a common platform. The entire ethanol production process has been optimized through response surface methodology that resulted in 59.96 g/L of ethanol within 24 h. The biomass porosity analysis in terms of surface area, pore size and pore volume of the fermented biomass were found to be decreased that indicates effective action of applied enzymes. Structural characterisation of the fermented biomass showed an extensive surface distortion that revealed the combined action of delignifying and saccharifying enzymes. X-ray diffraction analysis indicates reduced biomass crystallinity after fermentation, which inferred that para-crystalline and crystalline cellulose were utilized maximally for ethanol production. Thus, the results obtained in the present study substantiate the feasibility of the mixed enzymes application in bioprocessing of Kans grass for second generation ethanol production.

We present performance studies of an earth air tunnel cum greenhouse technology in terms of instantaneous thermal efficiency. Analytical expressions have been obtained for heating/cooling conditions of a greenhouse. The results are in accordance with the experimental results obtained for the same system in Greece.

Abstract A simple transient analysis of a solar still is presented incorporating the effect of water flowing over the glass cover. An idea of utilizing the evaporated mass of the water flowing over the glass cover has been suggested and investigated. The effects of other system parameters, like addition of dye, basin water mass and basin liner absorptivity, have also been studied. It is observed that the flow of water over the glass cover enhances the still productivity remarkably and also flowing water at a very low rate and collection of condensed vapour is always advisable to obtain comparably much more distillate output.

In this work, a new methodology of analysis and computation is presented which simplifies calculation of the packed height in a counter current cooling tower, especially for design and cost optimization studies. An algorithm is presented with an implementation in MATLAB to compute the thermodynamic minimum air flow rate for the desired cooling. Combining the Merkel equation and a standard empirical mass transfer correlation, the packed height is shown to be independent of the water flow rate and tower diameter, and dependent only on the excess air flow. The relationship is unique for a given cooling range of water and inlet air wet bulb temperature. A simple power law regression is used to approximate this relationship and results are presented for Vertical Corrugated Packing.

Abstract The trend of using biodiesels in compression ignition engines have been the focus in recent decades due to the promising environmental factors and depletion of fossil fuel reserves. This work presents the effect of Calophyllum inophyllum methyl ester on diesel engine performance, emission and combustion characteristics at different injection pressures. Experimental investigations with varying injection pressures of 200 bar, 220 bar and 240 bar have been carried out to analyse the parameters like brake thermal efficiency, specific fuel consumption, heat release rate and engine emissions of direct injection diesel engine fuelled with 100% biodiesel and compared with neat diesel. The experimental results revealed that brake specific fuel consumption of C. inophyllum methyl ester fuelled engine has been reduced to a great extent with higher injection pressure. Significant reduction in emissions of unburnt hydrocarbons, carbon monoxide and smoke opacity have been observed during fuel injection of biodiesel at 220 bar compared to other fuel injection pressures. However oxides of nitrogen increased with increase in injection pressures of C. inophyllum methyl ester and are always higher than that of neat diesel. In addition the combustion characteristics of biodiesel at all injection pressures followed a similar trend to that of conventional diesel.