PhD Theses (Energy Science and Engineering)
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Item Investigations in Enhanced Production of Bioalcohols and Their Derivatives Using Experimental and in-Silico Approach(2024) Kumar, KaranThis thesis presents a comprehensive scientific investigation focusing on the challenges and advancements in bioalcohol (mainly biobutanol) synthesis through Clostridia , emphasizing enhancing production efficiency from sustainable resources. Emp loying a multidisciplinary approach, the research encompasses comparative genomic analysis, in depth exploration of cell central metabolism during ABE fermentation, experimental examination of butanol production from lignocellulosic hydrolysates using Clos tridial co culture systems, development of genome scale metabolic models (GSMs), and innovative investigations into production of value added bioalcohol using sono enzymatic processes.Item Lignocellulosic bioethanol production from delignified rice straw using tailor-made crude recombinant hydrolytic enzyme cocktail and Saccharomyces cerevisiae MTCC170(2024) Devi, Maibam PremeshworiiThe thesis work includes a review of the literature on lignocellulosic bioethanol production from rice straw. Screening of suitable pretreatment methods for rice straw biomass from various chemical and physico-chemical pretreatment methods for maximum lignin removal in the pretreated rice straw was carried out. Further, the selected pretreatment method i.e. DES solvent system of ChCl and acetic acid (AA) was statistically optimized for maximal delignification and retainment of the total carbohydrate content (TCC) in the pretreated RS considering three significant pretreatment parameters; ChCl: AA molar ratio, time and temperature. For the efficient saccharification of choline chloride: acetic acid-pretreated RS, enzyme cocktail was formulated using crude (unpurified) recombinant bacterial hydrolytic enzyme cocktail consisting of cellulases (cellobiohydrolase, CtCBH5A and cellulolytic chimeric enzyme, CtGH1-L1-CtGH5-F194A with a bi-functional activity of β-1,4-endoglucanase and β-1,4-glucosidase) and xylanases (endo-1,4-β-xylanase, CtXyn11A and exo-1,4-β-xylosidase, BoGH43A) for the optimal proportion of each constituting enzyme for the efficient saccharification of choline chloride: acetic acid pretreated rice straw (CApRS) biomass. Finally, the CApRS biomass was used for bioethanol production using the formulated crude recombinant enzyme cocktail and Saccharomyces cerevisiae MTCC170. Pre-saccharification and simultaneous saccharification and fermentation of delignified CApRS biomass for bioethanol production were statistically optimized considering pre-saccharification time, enzyme dosage and fermentation temperature as a significant variable for maximizing ethanol yield and ethanol productivity.Item (A) Non-intrusive and Non-destructive Technique for Condition Assessment of Transformer Liquid Insulation(2024) Rohith, SangineniThis thesis presents a high frequency signal based condition assessment technique that can detect and estimate the moisture content (MC) and total acid number (TAN) in insulating oil samples. It addresses the applicability of the developed technique to alternate insulating oils such as nanofluids (NFs), ester oil (EO), and blended oils (BO). A non-intrusive and non-destructive technique (NINDT) which uses an S-band horn antenna to radiate the signals onto the oil samples for detecting and estimating the MC and TAN in mineral oil (MO) is developed. The reflected signal from the samples is analyzed to study the resonant frequency corresponding to MC and TAN. Electromagnetic interference on the measurements is avoided by placing the test setup in an anechoic chamber. Undesired reflections from the oil-test vessel boundaries are avoided by making the test cell with a material having impedance and relative permittivity close to that of the oil. The technique is applied to various laboratory-aged samples and linear prediction graphs are deduced from the obtained reflection coefficient. These linear prediction graphs are used to predict the MC and TAN in service-aged MO samples to evaluate the effectiveness of the developed technique. The alternative insulation such as EO, BO, and NFs are studied extensively to support the fact that the proposed technique is being used on validated insulation rather than arbitrarily selected samples. MO and a commercial EO (FR3) are mixed in various ratios to prepare BOs. The electrical and physiochemical properties such as MC, AC breakdown voltage, dissipation factor, relative permittivity, specific resistance, flash points, interfacial tension and density of the BOs are studied. The long term performance of the BOs is also studied by oxidative aging them according to ASTM D1934. The partial discharge in the fresh and aged oils is studied according to the IEC 60270 standard and the inception, extinction voltages, phase resolved partial discharge patterns are presented. Further, the fresh and oxidative aged MO, EO, and BOs are subjected to multiple electrical sparks and the gases produced are noted. The classical ratio methods such as Rogers, IEC, and Dornenburg ratios are used to predict the type and intensity of fault in the BOs from the collected data. Further, the prediction of the type and intensity of fault is attempted by using graphical methods such as Duval’s triangles and pentagons. The total dissolved combustible gases produced in the oils are also presented. Further, solid insulation is aged in the EO to study the gelling phenomenon and the surface profile of the insulation. Although extensive literature is available on the physiochemical and electrical properties of NFs, their magnetic behavior is unclear. Therefore, the magnetic response of the NPs, base oils, and NFs to the quasi-static and dynamic magnetic fields is studied at room temperature conditions and various magnetic parameters of the NPs and NFs are extracted. After the extensive investigation and substantiation of the insulation, the NINDT and the linear graphs are investigated for their applicability to detect and estimate the MC and TAN in the NFs and BOs. The percentage error between the predicted and actual value is reported and the applicability of the NINDT for the BOs and NFs is commented upon.Item Design and Development of Efficient Electrodes for Rigid and Flexible Solar Cells(2024) Dawo, ChandanPhotovoltaic technology has been regarded as a renewable power source which converts sunlight directly into electricity with least impact on the environment. Dye sensitized solar cells (DSSCs) is one such 3rd generation photovoltaic technology which drawn a significant attention due to its low manufacturing cost, simple preparation methodology compared to other technologies. It is an electrochemical cell consist of working electrode/photoanode, dye, electrolytes and counter electrodes. The electrodes in DSSCs play a significant role in charge transport and collection during operation. Dye (N719) in DSSCs harvests solar Energy Science and Engineering and transfer electrons to a semiconductor material (TiO2) for the generation of electricity. DSSCs assembled with abundant and cheap materials seems to be a substantial contributor for commercial development in the near future. The thesis focuses on the development of economically competitive rigid and flexible electrodes with the motivation to further enhance Energy Science and Engineering conversion efficiency of DSSCs.Item Microalgal Wastewater Treatment, Enhanced Biomass Productivity, and Biofuel Conversion Under a Biorefinery Approach(2021) Mishra, SanjeevIn view of globalization and Energy Science and Engineering consumption, an economic and sustainable biorefinery model is essential to address Energy Science and Engineering security and climate change. Recently, biofuel production from microalgae under the biorefinery approach had gained wide attention. However, the economic viability of the process at its current state is not considered sustainable. In this context, the present study aimed to develop a sustainable biorefinery model that includes producing microalgal biomass using wastewater, converting biomass to biofuel via chemical and thermochemical processes, and valorizing waste to produce co-products. In the present study, eight native microalgal strains were isolated from domestic sewage wastewater and its screening study showed that Monoraphidium sp. KMC4 had superior biomass (1.47 ± 0.08 g L-1) and lipid (436 ± 0.06 mg L-1) yield followed by 88-100% removal of ammonia, nitrate, phosphate, and COD. The process optimization had significantly enhanced biomass yield to 2.49 g L-1, 3.62 g L-1 and 6.14 g L-1 in batch, fed-batch and semi-continuous mode of growth study in the photobioreactor. The harvested biomass was further processed for biofuel productions such as biodiesel (FAME) and biocrude. The biocrude production via co-hydrothermal liquefaction (Co-HTL) process used domestic sewage sludge as a co-feedstock. The optimized Co-HTL had resulted in a 39.38 wt% biocrude yield that had 10.13% of heavy naphtha, 23.92% of kerosene, and 27.09% of gas oil fractions. In addition, the present study also valorized solid residues and liquid effluents for the production of value-added products under a circular bioeconomy based biorefinery modelItem Design and Development of Renewable Plant Microbial Fuel Cell for Bioelectricity Generation(2023) Sarma, Pranab JyotiIn recent times, mankind is undergoing a momentous transition, facing a significant Energy Science and Engineering demand while grappling with issues like biodiversity loss and climate change, which make our world challenging to inhabit. The present work is focused of generation of sustainable, renewable, green, ecofriendly and cost effective bioelectricity by plant microbial fuel cell technology and it in turns helps to mitigate various indoor air pollutants and purify air. Out of the the four different indoor plants Philodendron erubescens showing the highest electricity generation capabilities, followed by Epipremnum aureum, Anthurium andreanum, and Dracaena braunii. A long-term performance study for over six month showed that the better root development and adaptability of plant species under moist conditions enhanced PMFC performance and stability, reducing the cell's internal resistance. The study emphasizes the importance of different operating conditions in influencing plant growth and development, thereby impacting PMFC performance.Item Design, Development and Testing of Solar Air Heater for Drying Applications(2023) Sureandhar, GThe study focuses on the arc rib embedded SAH configuration, which has shown promising thermo-hydraulic performance. Analytical analysis and experimental investigations reveals a decline in heat transfer rate and thermal efficiency along the SAH ductItem Process Development for Microalgal Cultivation System Towards Enhancement of CO2 Fixation and Biochemical Production Efficiency(2024) Chauhan, Deepesh SinghMicroalgae present a promising avenue for CO₂ sequestration and biofuel production due to their rapid growth and high lipid content. However, their commercial viability faces challenges, such as low CO₂ capture efficiency, sensitivity to environmental stresses, and high water and nutrient demands. This thesis aims to overcome these challenges by focusing on strain selection, optimizing cultivation conditions, ensuring CO₂ utilization stability, achieving high biomass productivity, cost-effective harvesting, and water reuse strategies.Item Design, Optimization, and Intensification of a Biological Gas to Liquid (BioGTL) Process for Methane Conversion to Methanol(2024) Priyadarshini, AradhanaThis study investigates the methane bioconversion to methanol using biological gas-to-liquid (BioGTL) technique and especially addresses the United nation’s SDG 7 (Affordable and clean energy) and SDG 13 (Climate action). The principal aim of the present thesis is to design, optimize and intensify a bio-process for conversion of methane into methanol. Chapter 1 introduces and discusses impact of methane in climate change and why methane bioconversion to methanol is essential. The critical bioconversion of methane to methanol is made possible by soluble methane monooxygenases (sMMO) and particulate methane monooxygenase (pMMO). Chapter 2 studies and reports the potential of methanotrophic consortium enriched from rice field soil in methanol production. The consortium achieved a high methanol production titre of 130 mM (4.16 g/L). The maximum methanol titre of 160 mM was obtained using the Methylomicrobium buryatense 5G. Further, Methylotuvimicrobium buryatense 5GB1C was studied for their methanol accumulation capability in Chapter 3. This study attempted to maximize the methanol production using statistical optimization of the crucial fermentation parameters (phosphate buffer concentration, pH and temperature) resulting in a methanol titre of 8.54 mM in 24 h. Further investigation employed a methanol dehydrogenase inhibitor to prevent methanol breakdown, leading to an increased accumulation of 10.37 mM. The process was scaled up to a 3.7 L bioreactor, and significantly improved both methanol concentration (23.7 mM) and methane conversion efficiency (47.8%).Item Applications of Passion Fruit Extracts as Bioactive Pharmaceuticals, Biodiesel Additive for Oxidation Stability and Corrosion Resistance(2023) Purohit, SukumarFruits and vegetables are frequently consumed because of their contents - minerals, dietary fibers, vitamins, and antioxidants which are beneficial for the health. In developing countries there are very limited to negligible waste management policies. As a result, most of the waste materials are directly exposed to the open environment causing severe environmental pollution. Agro-waste materials are having enormous potential for valorization as they contain abundant bioactive phytochemicals, including polyphenols, anthocyanins, tannins, glycosides, vitamins, alkaloids, and many more. These compounds have also profound therapeutic values as antidiabetic, antimicrobial, anticancer, and so on. Moreover, the natural antioxidant extracted from this waste can also be utilized as natural additives to second-generation biofuels (biodiesel) for their quality improvement as oxidative stabilizers and corrosion inhibitors. Northeast India is bestowed with two biodiversity hotspots with variety of flora and fauna. Passion fruit is a less popular plant cultivated in these regions. The main edible part of this fruit is its flavourful and nutritious juice. The rest of the parts i.e. rind and seed make upto 60% of the total weight of fruit and are disposed directly without any treatment.Thus, the present work aims to explore the antioxidant potential of these two varieties of passion fruit (yellow and purple passion fruit) from Northeast India for various applications. The entire thesis work has been divided into four major parts. The first part of the thesis presents the collection, morphological and physico-chemical characterization of the rind and seed of yellow passion fruit and purple passion fruit collected from Northeast India. The second part of the thesis discusses the phytochemical profile of the rind and seed extracts from yellow and purple passion fruit and their role as antioxidant and antibacterial agents. In this context, the samples were extracted using four different solvents such as ethyl acetate, acetone, methanol and water. Phytochemical mining study revealed presence of many phytochemicals from the passion fruit sample. Further, in the subsequent part of the thesis, role of the antioxidant rich passion fruit extracts for increasing oxidation stability of different biodiesel was elaborated. Biodiesel is prone to oxidation because of high moisture content and unsaturated fatty acid composition.Item Aerodynamic Design and Wind Tunnel Testing of Small Horizontal-axis Wind Turbine for Multirotor Configurations(2023) Siram, OjingThe present investigation explores the applicability of small horizontal-axis wind turbines (SHAWTs) to be employed as a power-generating source in places where Energy Science and Engineering demand isminimal or as a potential off-grid power source. The design and testing of SHAWT have been carried out at low λ (0.5 < λ < 6) and low Re (0.3×105 ≤ Re ≤ 3×105) conditions. The rotor blades were designed using the blade element momentum theory and fabricated using the 3D printer. The rotors’ performance was tested in the wind tunnel using the rotary torque sensor (RTS). Based on the literature review, airfoil E216 (M1), SG6043 (M2), NACA63415(M3), and NACA0012 (M0) have been chosen for developing the model rotors. From BEMT analysis and experimental investigation, the M1 rotor shows maximum power coefficient of 0.37 and 0.34, respectively. The complexity of the BEMT rotor necessitates the development of a non-BEMT rotor, which in the present study are straight and linear tapered (SLT rotors). The SLT rotors with the root-to-tip chord (Cr/Ct) of 1:1 show favourable results. Furthermore, an in-depth investigation of wake propagation using particle image velocity (PIV) has been carried out. The near wake (x/R < 6) study shows the formation of a W-shape. The time-resolve and timeaveraged stream wise PIV assessment reveal Gaussian-like (skew) distribution and the presence of two opposite crests, marking the flow movement. The high-fidelity PIV data were then used to develop an ANN-based wake model. It is observed that experimental and ANN-based models can produce much better and more reliable results than their analytical counterparts.Item Study of Algal Biofilm to Enhance Biomass and Lipid Accumulation(2023) Devi, Nongmaithem DebeniMicroalgal biomass for the production of biodiesel is emerging at the forefront in the relevant research realm. They are considered the most versatile biomass due to certain characteristics such as (1) the ability to convert carbondioxide (CO2) into biomass through transesterification, (2) short life-cycle, (3) high growth rate, and (4) microalgae cultivation that does not compete for fertile fields with food crops. Biodiesel production can be improved by increasing biomass and lipid yield (LY), as well as optimizing downstream processing. Studies have shown various approaches to increase microalgae biomass and lipid production. High biomass productivity (BP) and LY depends on the potential of strains and cultivation strategy. The goal of this thesis is to investigate the potential of microalgae species that are native to North-Eastern, India for biodiesel production and to assess their ability to treat wastewater and produce biomass that can be used for animal feed. The freshwater microalga, Scenedesmus sp. DDVG I was selected as a potential strain for biomass production. The freshwater cyanobacterium, Limnothhrix sp. DDVG II was used as an auto-flocculating strain. The BioEnergy Science and Engineering Lab isolated both strains from a swampy region of the Indian Institute of Technology Guwahati (IITG), Indai. DDVG I and DDVG II microalgal isolates were molecularly characterized using 18S and 16S rRNA gene sequence analysis. The sequences were submitted to NCBI GenBank as MN630585 and MN630310, respectively. DDDVG I and DDVG II strains grew the fastest in a normal BG11 medium at pH 7 and 27 °C, with specific growth rates of 0.12±0.005 d-1 and 0.11±0.00 d-1, respectively. Further supplementation of the medium with 1.05 g/L urea, 0.04 g/L K2HPO4, and 6 g/L glucose resulted in increased biomass and LY of up to 8.5 g/L & 39.5% for DDDVG I and 3.3 g/L & 19.9% for DDVG II, respectively.Item Studies on Spirulina Species NCIM 5143 for Microbial Fuel Cell Applications(2023) Quadir, Mohd Golam AbdulThis study utilizes Spirulina species NCIM 5143 procured from National Collection of Industrial Microorganisms, Pune, India. The phylogenetic analysis from 16S rRNA revealed its identity closer to Spirulina subsalsa BGLR6. The species was cultured in inorganic Zarrouk medium supplemented with trace elements in white light of 2500 lux at temperature of 32°C at 180 revolutions per minute. The specific growth rate and doubling time were found to be 0.0771 day-1 and 8.98 days respectively. The species was found to be a helical filament in structure with a diameter of 3 μm and pitch length of 1 μm. It exhibited gliding motility and moved towards light exhibiting phenomenon of positive phototaxis. This property influences the pattern of biofilm formation by the cyanobacteria and the configuration of filamentous cells within it, depending on the direction of illumination. The static culture always formed a network of filaments on walls that developed into biofilms over time and stuck to the walls. This natural biofilm formation capacity was utilized and the wet weight was inoculated into an H- type biofuel cell setup, leading to the formation of a biofilm over the electrodes. Interestingly, a subpopulation of bacteria was detected in the vicinity of the Spirulina filaments, and a few cells were directly attached to the filament structures. This close physical association indicates that crucial metabolite and nutrient exchange might occur between the host and bacterial cells. Four distinct heterotrophic colonies were isolated and identified through 16S rRNA sequencing as Halomonas saliphila, Halomonas campaniensis, Alcanivorax pacificus, and Pelagibacterium lentulum. We inferred, that these pure culture strains were the dominant members of the Spirulina-associated bacterial community as they could form colonies on the zarrouk medium plate devoid of any organic carbon source, thriving on residual extracellular organic carbon and metabolites exuded by the phototrophic host (Spirulina). These associations indicate a copiotrophic habitat typical of a phytoplankton bloom or matured phototrophic biofilm. We believe that this combination of predominant bacterial species isolated by us might be involved in efficient carbon and nitrogen cycling assisting the sustained growth of the host cyanobacterium (Spirulina subsalsa).Item Development and Performance Assessment of Gaseous fuel based Porous Radiant Burners(2023) Kumar, M ArunThis thesis presents the development and performance testing of Porous Radiant Burners (PRBs) using different fuels, including LPG, natural gas, and biogas, for cooking and industrial applications. These PRBs show promise in enhancing thermal efficiency and reducing emissions compared to conventional burners. In addition, an analytical model was developed to determine the factors influencing the primary air entrainment in a PRB. And experimental investigations were performed to check the validity of the developed analytical expression. Further, performances of the developed PRBs were assessed in terms of thermal efficiency and emissions. Through experimental investigations, it was found that the developed LPG-PRB and NG-PRB, exhibit improved thermal efficiency and fuel savings. Furthermore, a BG-PRB cookstove for domestic use was developed and demonstrated substantial gains in thermal efficiency and reduced emissions compared to conventional biogas burners. Environmental and economic assessments of the developed PRBs were conducted, highlighting the environmental benefits and cost savings associated with the use of these innovative PRBs. This research work contributes to the sustainable Energy Science and Engineering transition and offers practical solutions for cleaner and more efficient Energy Science and Engineering utilization in cooking and Industrial applications.Item Distributed Microgrid System Design and Control Algorithms for Oil and Gas fields(2023) Bishnoi, DeepikaGas flaring is an issue of serious environmental concern worldwide. Globally approximately 100 BCM (Billion Cubic Metres) of natural gas is flared every year, which leads to 400 million tons of CO2 (Carbon Dioxide) emissions and wastage of nearly 20 million dollars annually. The burning of expensive natural gas is not just an economical loss, it also poses a severe environmental threat to the flora and fauna and a risk of health abnormalities for human settlements around oil and gas fields, petroleum refineries, and petrochemical plants. Almost all the gas flaring sites are situated at remote locations because of which unreliable electricity is another major issue faced in the region.Item Design And Fabrication Of Solid State TiO2|Ag Structure For Developing Efficient Plasmonic Photo-Electric Conversion Device(2024) Devi, Kshetrimayum PriyalakshmiThe global shift towards renewable energy sources, propelled by environmental concerns, has ignited a surge in research aimed at developing efficient solar energy technologies. This thesis is dedicated to the creation of a solid-state plasmonic energy harvesting device using low cost methodologies. Initial simulations compare various noble metal nanoparticles for their plasmonic resonance properties, with silver identified as particularly advantageous due to its sensitivity and electronic characteristics. Semiconductor substrates are synthesized through a simplified Sol-Gel technique, resulting in the production of TiO2 thin films tailored for solar applications. Subsequently, a solid-state energy harvesting device is fabricated, leveraging metal/semiconductor heterojunctions to achieve promising cell performances. Furthermore, the thesis delves into an environmentally friendly approach to synthesizing silver-graphene nanocomposites, which holds significant potential for enhancing device efficiency. These findings represent a significant stride forward in the design and implementation of efficient plasmonic energy harvesting devices, paving the way for sustainable advancements in solar power generation.Item Development and Performance Evaluation of Methanol and Ethanol Operated Cookstoves(2023) Maurya, PratibhaThe present thesis emphasizes on the need for clean cooking fuel sources in developing countries where 2.8 billion people rely on solid fuels, posing health hazards due to indoor air pollution. Although liquefied petroleum gas (LPG) and biogas are cleaner alternatives, they face adoption barriers, including cost and availability. Methanol and ethanol have gained traction as a cleaner cooking source, and several countries have launched programs promoting their use. However, conventional methanol and ethanol cookstoves have drawbacks, such as low firepower and soot formation. In this regard, the thesis aims to evaluate the performance, safety, and sustainability of Free Flame Combustion based (FFC) methanol cookstoves, develop a Porous Media Combustion (PMC) based methanol cookstove, assess the feasibility of ethanol as a cooking fuel in FFC and PMC based cookstove, analyse indoor air quality due to use of PMC based cookstoves and compare it with the existing FFC based cookstove, and develop an Indian standard for the use of methanol and ethanol cookstoves.Item Design and Development of Hybrid Nanomaterials for Efficient Photocatalysis(2024) Devi, Thongam DebikaWater is our life and its quality degradation has imposed a major threat to the health and environment with the emerging contaminants. Photocatalytic advanced oxidation processes (AOP) using reactive oxygen species (OH¯, •OH, H2O2, HO2•, O2•¯, O22¯) provide complete degradation of these persistent pollutants by using nanomaterials triggered by light absorption. However, its real-time application is limited by the use of high-power light sources to trigger the reaction and its limited performance. Thus, this thesis focuses on understanding and addressing these bottlenecks by― (a) designing and developing a sunlight-responsive photocatalyst to harvest natural sunlight, (b) developing heterostructure photocatalysts for enhanced efficiency by developing interfacial charge transfer, and (c) studying and discovering ways to enhance charge transfer by manipulating heterostructure photocatalyst responsive to natural sunlight. To achieve efficient photocatalysis, different sunlight-responsive photocatalysts were synthesized by varying― synthesis mediums and methods introducing surface defects and producing different nanoparticle morphologies. The dependence of the charge transfer, charge carrier lifetimes, surface structures, induced defects, and morphologies on the photocatalytic efficiencies were discussed elaborately. Variable ZnO samples were synthesized using DMF or DEG solvents using solvothermal and chemical synthesis methods showing different properties― morphologies, surface, and chemical properties. The influence of the charge transfer pathways in the photocatalytic efficiencies is discussed and explored with different charge transfer methods― self-assembled ZnO nanoparticles on three electronically different SWCNTs (metallic-SWCNT/ZnO, semiconducting-SWCNT/ZnO, and pristine-SWCNT/ZnO); Type I ZnO/Fe3O4 and Type II ZnO/TiO2 composite heterostructures; g-C3N4 & Z-scheme g-C3N4/ZnO composites, and other composites― g-C3N4/SWCNT, and g-C3N4/ZnO/SWCNT. By taking RhB as a model pollutant, these nanoparticles were used as the floating photocatalyst by coating on the face-mask fabric showing variable efficiencies up to 99% of 10 ppm RhB degradation within the 100 min natural sunlight exposure.Item Optimal Operating Parameters for Performance Improvement of a Biogas Fueled Spark Ignition Engine(2023) Hotta, Santosh KumarThe environmental concerns and the uncertainties associated with the future availability of fossil fuel are driving the interest of utilizing renewable biofuels in the internal combustion (IC) engines. Among the renewable gaseous fuels, biogas is an attractive source of energy in rural areas and is mainly composed of CH4 (50-70%), CO2 (25-50%), H2 (1-5%), N2 (0.3-3%) with traces of H2S. Direct use of biogas as a standalone fuel in CI engine is almost impossible due its properties such as higher self-ignition temperature, higher resistance to auto ignition and knock. But, the physical and chemical characteristics of biogas have a great resemblance on the octane fuels in higher compression ratio (CR) SI engines. Although SI engines are best suitable for renewable or non-renewable high-octane fuels, they need special attention to accommodate biogas. The combustion process in a SI engine is greatly influenced by the operating parameters. Various techniques such as alteration in CR and IT, preheating, pre-chamber ignition, etc. were proposed to enhance the performance, combustion and emission characteristics of the biogas fueled SI engine. Thus, one of such techniques, with proper optimization of operational parameters, can be employed to develop an efficient biogas-based SI engine. The current research is mainly focused to determine the optimal operating parameters (optimum compression ratio, maximum brake torque timing, throttle position and optimum air-fuel ratio) of a biogas fueled SI engine through a multi fuel, variable compression ratio (VCR), spark ignited research engine setup for effective implementation in a commercial SI engine.Item Exploring potential genetic routes for enhancing lipid accumulation in microalgae for biofuel application(2022) Sharma, Prabin KumarTo harness the benefit of microalgal biotechnology for biofuel application, genetic manipulation of metabolic pathways is essential, requiring an efficient genetic transformation method. Besides, an efficient gene transfer system in microalgae would allow a way to understand cellular metabolism regulation by characterizing the genes involved through a reverse genetics approach. A. tumefaciens-mediated genetic transformation is a method of choice for ease in transformation and its ability to precisely integrate low copy number transgene into transcriptionally active genomic regions. However, in C. sorokiniana, the lack of a reliable and efficient Agrobacterium-mediated gene transfer method limits its potential uses in commercial scale utilization. We described an efficient A. tumefaciens-mediated genetic transformation in C. sorokiniana. For the first time in C. sorokiniana, it highlighted the reliable detection of stable transgene integration and expression in C. sorokiniana, which opens up limitless possibilities in biofuel production and other commercially valuable commodities. Further, as higher lipid biosynthesis and accumulation are essential to achieve sustainable production of biofuel in microalgae. The green microalgae Chlorella sorokiniana was genetically engineered with a rate-limiting enzyme of neutral lipid biosynthesis, diacylglycerol acyltransferase 1 from Jatropha curcas (JcDGAT1) and a transcription factor WRINKLED 1 from Arabidopsis thaliana known to involve in lipid biosynthesis in higher plants, to enhance the lipid content. The results offer a valuable strategy for enhancing oil production and might facilitate a platform strain with industrial potential. Our results suggest genetic means to increase neutral lipids and unsaturated fatty acids in C. sorokiniana for biofuel production. In conclusion, this research provides proof of concepts to make microalgae an economically viable source for biodiesel production. A similar technique may be helpful for the biosynthesis of certain high-value compounds in microalgae.