>Magister Scientiae - MSc / The depletion of oil reserves and the constant discharge of greenhouse gasses (GHG) that are associated with global warming have forced both political and scientific sectors to pursue alternative, renewable and sustainable fuels that will be blended with petrol and ultimately replace it as the fuel of choice. Bioethanol is a form of fuel that is obtained from natural materials such as biomass. Starch and sugar containing materials are the primary carbon sources for bioethanol production and a range of feedstocks are currently being exploited for this purpose worldwide.This study was aimed at measuring, comparing and analyzing fermentable sugars liberated by sorghum and three other grain crops (maize, barley and wheat) that are grown in South Africa and subsequently analyze ethanol yield after fermentation. Starch was extracted from sorghum, maize, barley and wheat via hot water treatment and hydrolyzed by use of !-amylase, gluco-amylase and a cocktail of both enzymes under various conditions to determine optimum hydrolysis conditions. The resultant liberated soluble sugars were measured with a pocket refractometer and High Performance Liquid Chromatography (HPLC) respectively. Hydrolysates obtained under optimum conditions were fermented with various ethanol producing microbial strains and a high-performing strain was selected. The selected high-performing strain (Saccharomyces cerevisiae NT 53) was used to ferment different grain hydrolysates (sorghum, maize, barley and wheat).The working volumes of the solutions were increased ten-fold (small-scale) and experiments were performed using sorghum grains as substrates and alcohol content was measured with an Alcolyzer Wine M instrument. The optimum hydrolysis conditions for the grain crops were determined and it was found that the enzymes performed well at 70°C and starch was hydrolyzed within the first hour.Sixty grams per litre (60 g/L) of grain solution produced a maximum of 50.8 g/L of glucose when treated with the cocktail treatment. However gluco-amylase facilitated a similar production, at 47.8 g/L glucose. Sorghum and maize produced high glucose amounts and subsequent ethanol amounts, and maximum fermentation efficiencies of 87 % and 98 % respectively when fermented with the high performing NT 53 strain. The NT 53 strain was compared with commercial baker’s yeast and they yielded similar ethanol amounts across the grain types. Under small-scale conditions, sorghum retained the consistency of yielding similar glucose amounts compared to laboratory-scale (50ml) conditions and when analyzed with the Alcolyzer, sorghum yielded a maximum alcohol content of approximately 2 % v/v. This study also showed that gluco-amylase alone was sufficient for starch hydrolysis and sorghum a more favourable and less expensive crop for ethanol production in South Africa.

Biomass energy is the oldest form of energy harnessed by humans. Currently, processed biofuels, which are derived from biomass, are being pursued as a possi- ble route to decarbonize the transport sector - a particularly difficult task for both technological and sociological reasons. In this thesis I explore the impacts that large scale biofuel use could have on atmospheric chemistry. I review the current state of biofuels politically and technologically, focusing on ethanol and biodiesel. I discuss the salient features of tropospheric chemistry and in particular the oxidation of isoprene, an important biogenic volatile organic compound. I examine the impact that including isoprene oxidation has in a new chemistry-climate computer model, UKCA; the response of ozone turns out to depend on local chemical conditions. To evaluate the global model, I use data from the OP3 field campaign in Malaysia and compare it with output from the model chemical mechanism. The mechanism is able to reproduce NOx and ozone measurements well, though is more sensitive to representations of physical rather than chemical processes. I also perform a simple sensitivity study which examines crop changes in the region of Southeast Asia. In the final two chapters, I turn to two distinct phases of the biofuel life cycle. I characterize a potential future atmosphere through an ozone attribution study, then examine the impact of future cropland expansion (phase I of a biofuel life cycle) on tropospheric chemistry. I find that land use change has a large impact on ozone, and that it is more acute than another perturbation (CO2 suppression) to isoprene emissions. I then move to phase III of the life cycle - combustion - and look at the sensitivity of the model chemistry to surface transport emissions from biofuels as a replacement for conventional fuels. I find that biodiesel reduces surface ozone, while ethanol increases it, and that the response has both a linear and nonlinear component.

The diploma thesis deals with the problematics of biofuels as a renewable source of energy in transportation, which has recently gotten under social spotlight. The theoretical part is focused on an explanation of basic terminology, historical development and especially reasons for the need to replace current fosil fuels with respect to an increasing volume of CO2 and shortening oil reserves. The practical part compares characteristics, use, pros and cons of the biofuels of the first and second generation and tries to estimate benefits of the biofuels of the second generation in both economic and environmental area.

En France, la consommation d'énergie finale de bioénergies a crû de 35 % lors de la dernière décennie pour atteindre une part de 8,1 % de la demande finale en 2012. Leur développement a été incité car elles sont une source d'énergie renouvelable, elles permettent de réduire la dépendance aux importations d'énergies fossiles et de diminuer les émissions de gaz à effet de serre (GES). Elles sont aussi un moyen de dynamiser les secteurs agricoles et sylvicoles et de maintenir et de créer des emplois non délocalisables.Mais ce développement est soumis à des incertitudes : compétitivité économique vis-à-vis des ressources fossiles et d'autres alternatives renouvelables, disponibilité de la biomasse, choix technologiques, et mécanismes incitatifs. De plus, il est confronté à des controverses. L'accroissement de la demande en ressources biomasse a créé de la tension sur leurs prix et menacé les usages existants, comme le secteur des panneaux bois pour la construction au niveau français et le secteur de l'alimentation à l'échelle mondiale. Leur bénéfice environnemental a aussi été remis en cause, en termes d'émissions de particules fines pour la valorisation chaleur et électricité et en termes d'émissions de GES pour les biocarburants. De nouveaux procédés de valorisation, ne suscitant pas ces controverses, pourraient être privilégiés par le législateur au détriment des procédés actuels.Le but de cette thèse est de baliser un certain nombre de ces incertitudes afin de proposer des stratégies technologique et réglementaire pour les filières bioénergies françaises. Pour cela, nous avons développé un modèle de prospective qui décrit de façon détaillée le secteur des bioénergies et ses technologies de conversion actuelles et futures. Il est basé sur un paradigme d'optimisation qui permet de calculer les trajectoires technologiques de moindre coût, de 2010 à 2050, selon un grand nombre de contraintes qui représentent les spécificités du secteur : disponibilité et coût des ressources, paramètres techniques, économiques et environnementaux des procédés de conversion, etc.Dans une première partie, la démarche prospective est décrite. Elle consiste à analyser dans le détail les filières bioénergies : leur structure actuelle, les points de controverse et les systèmes techniques prometteurs, puis à développer un modèle de réflexion prospective basé sur ces données.Quatre questions d'intérêt stratégique pour la filière sont discutées dans la suite du document. Premièrement, la question du niveau de la demande à laquelle pourrait répondre le secteur selon deux scénarios contrastés de disponibilité de ressources métropolitaines est envisagée. Les trajectoires technologiques sont aussi analysées. Deuxièmement, l'impact d'une évolution du contexte réglementaire ainsi que les bénéfices environnementaux des biocarburants sont appréhendés. La troisième question est celle de l'impact de l'essor de la chimie du végétal sur les bioénergies. Enfin, les stratégies technologiques des biocarburants sont étudiées à l'aide d'une méthode Monte Carlo afin de comprendre les conditions du déploiement des diverses technologies disponibles. / French bioenergy consumption increased by 35 % over the last decade. It reached an 8.1% share in final energy demand by 2012. Bioenergy has been fostered for its many benefits as it is a renewable energy source that increases energy supply independence and that reduces greenhouse gases (GHG) emissions. This sector also maintains and provides job at local level and promotes agricultural and forestry economic development.But the sustainability of this development is now subject to uncertainties: economic performance in comparison to fossil fuels, biomass availability, technological choices, and level of incentives. In addition, it faces several controversial points. Firstly, rise in global biomass demand has implied a rise in prices and it has threatened existing uses, such as wood panel manufacturing in the French building sector and food supply at a world scale. Secondly, environmental performance has been criticized: biomass combustion could emit fine particulate matter and GHG emissions of current biofuel processes may be higher than initially assessed. Consequently, new bioenergy pathways, avoiding these controversies, could be promoted by the policy maker.This PhD thesis aims at assessing these uncertainties to elaborate technological and regulatory strategies for French bioenergy sector. So, we created a prospective model which precisely describes this sector and its current and future conversion pathways. It relies on linear programming optimization paradigm that calculates least cost technological trajectories, from 2010 to 2050. Bioenergy sector is modelled by a large number of constraints: availability and cost of biomass, technical, economic and environmental parameters of transformation processes, etc.In the first part, we describe the prospective approach. It consists in analysing precisely bioenergy pathways: the current structure, the controversial points and the promising processes. Then, we explicit the conception of the prospective model: its data and its assumptions.In the second part, four main strategic points of bioenergy sector are discussed. Firstly, we assess the level of demand that could be fulfilled according to two contrasting scenarios of French biomass availability. Technological mix is then analysed. Secondly, we investigate the consequences of a change in biofuel regulatory context and a reconsideration of their environmental benefits. Thirdly, bio-based chemistry development impact on bioenergy production is evaluated. Finally, biofuel technological strategies are studied with a Monte Carlo approach to enhance the comprehension of the economic and environmental conditions of technology deployment.

>Magister Scientiae - MSc / There has been a decline in the global fossil fuel reserves, due to an increasing demand for petroleum. Biofuels can be used as an alternative source of energy whereby biomass is converted to liquid fuels such as bioethanol. There is considerable interest in lipolytic enzymes because of their broad substrate range and for this purpose these enzymes have potential in a variety of biotechnological application. Lipolytic enzymes include esterases (E.C 3.1.1.1) and lipases (E.C3.1.1.3). Esterases preferentially hydrolyse short chain (<C10) ester-containing molecules that are partly soluble in water, while lipases hydrolyse a broad range of substrates preferably water-insoluble fatty acyl molecules (>C10). The aim of this study was to express, purify and characterise the lipolytic enzyme present on afosmid, Try 11, previously isolated from a metagenomic library of a Malawian hotspring, which conferred activity on tributyrin and ethyl ferulate. Bioinformatic analysisof the fosmid insert sequence predicted an open reading frame consisting of 951 bp,designated RHgene34, encoding a 317 amino acid protein with 41 % similarity to theα/β hydrolase fold-3 domain protein of Burkholderia sp. The RHgene34 protein contains conserved motifs of esterases/lipases, such as HGGG (residues 95-98),GxSxG (residues 167 - 171) and the putative catalytic triad composed of Ser157,Asp255 and His285. The gene was cloned and expressed in pET21a(+), and transformed into Escherichia coli Rosetta. p-Nitrophenol (p-Np) fatty acyl esters of different carbon chain lengths were used for kinetic characterisation of RHgene34. Kinetic analysis revealed that RHgene34 had a broad range activity on the p-Npesters, from C2 - C14. RHgene34 operates optimally at 45 ºC, pH 9.0 and has a half life of 30 mins at 45 ºC. This study demonstrates that functional screening combined with the sequence analysis is a useful approach for isolating novel enzymes from ametagenome.

Among various sources for biofuels, microalgae provide at least three-orders-of-magnitude higher production rate of biodiesel at a given land area than conventional crop-based methods. However, microalgal biodiesel still suffers from significantly lower harvesting efficiency, making such a fuel less competitive. To increase the separation efficiency of microalgae from cultivation solution, an orbital microchannel was utilized that enabled the isolation of biofuel-algae particles from the effluent. The results obtained showed that the separation efficiency in the microfluidic centrifugal separator can be as high as 76% within a quick separation time of 30 seconds. Multiple parameters of algae behaviors and separation techniques such as initial concentration, pH and temperature were studied and manipulated to achieve better efficiencies. It was found that changing these factors altered the separation efficiency by increasing or decreasing flocculation, or “clumping” of the microalgae within the microchannels. The results suggested that an acidic condition would enhance the separation efficiency since in a basic environment, large flocs of microalgae would block and hinder the separation process. Furthermore, a hot temperature solution (around 33 °C) yielded to a higher separation efficiency. The important characteristics of the separator geometry and the infusion rate on algae separation were also very effective in the separation process. This study revealed that there is an opportunity to improve the currently low efficiency of algae separation in centrifugal systems using much smaller designs in size, ensuring a much more efficient algae harvesting. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

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With the emergence of new biorenewable transportation fuels, the role of heteroatoms in combustion has increased tremendously. While petroleum-based fuels are primarily hydrocarbons, many biorenewable fuels contain heteroatoms such as oxygen and nitrogen, introducing new challenges associated with toxic emissions. A fundamental understanding of the chemical kinetics of combustion of these heteroatomic fuels is necessary to elucidate the pathways by which these toxic emissions are formed and may be achieved through the development of combustion models. Reaction sets, the core of these combustion models, may be assembled for individual fuels through a balance of employing vetted rate constants from prior publications, quantum chemistry calculations, and rate constant estimations. For accuracy, reaction sets should be tested against experimental combustion studies such as low-pressure flame experiments using molecular-beam mass spectrometry (MBMS) or chemiluminescence and high-pressure shock-tube experiments. This dissertation presents the development of a new reaction set to describe gas-phase combustion chemistry of fuels containing only hydrogen, carbon, oxygen, and nitrogen. The foundation of this model was a reaction set to describe combustion of ammonia flames. This reaction set contains only H/N/O chemistry for simplicity. The new reaction set was tested against a pyrolysis shock-tube study, as well as 12 MBMS flame experiments under a variety of conditions, including different mixtures of fuels and oxidizers (NH3, N2O, H2, NO, O2), fuel equivalence ratios (lean to rich), pressures, and concentrations of diluent gas. Additionally, the base H/N/O mechanism was expanded to include carbon chemistry and was tested against flames of dimethylamine, ethylamine, and a methane/ammonia mixture. This reaction set was employed to study heterocyclic biofuels including a fuel-rich flame of tetrahydropyran, the monoether analogue to cyclohexane and the basic ring in cellulose. Additionally, the model was used in a study of morpholine, a 6-membered ring with both ether and amine functionalities, testing the model against fuel-rich flame studies using both MBMS and chemiluminescence techniques and high-pressure shock-tube studies for both oxidation and pyrolysis at elevated temperatures and pressures. Lastly, the model was used to study the combustion of hypergolic rocket fuels, specifically monomethyl hydrazine and tetramethylethyldiamine with red fuming nitric acid.

Lowland switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), indiangrass (Sorghastrum nutans), upland switchgrass (Panicum virgatum), little bluestem (Schizachyrium scoparium), beaked panicum (Panicum capillare), and purpletop (Tridens flavus) all show strong signs of seed dormancy which contributes to extremely poor field establishment. The objective of this work was to reduce seed dormancy by selecting individuals that exhibited reduced pre-stratification dormancy in laboratory tests. The classical breeding method of phenotypic recurrent selection was used to enhance germination. Of the three tall-stature species, lowland switchgrass made the greatest improvement in pre-stratification germination, followed by indiangrass and big bluestem. The four short stature species have shown various results after one cycle of selection at Starkville. A field emergence trial was also conducted to evaluate three cycles of breeding seed with five commercially available cultivars in which Cycle 3 seed produced more plants per hectare than any of the other cultivars or germplasm.

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