Algae are photosynthetic microorganisms that convert carbon dioxide and sunlight into biomass that can be used for biofuel production. Although they are usually cultivated in suspension, these microorganisms are capable of forming productive biofilms over substrata given the right conditions. This dissertation focuses on algal biofilms and their application in biofuel feedstock production. In particular it reports the construction and performance of an algae biofilm photobioreactor, the physico-chemical surface properties of different algal species and adhesion substrata, and cell-surface interactions based on experimental results and theoretical models. A novel algae biofilm photobioreactor was constructed and operated (i) to demonstrate the proof of concept, (ii) to analyze the performance of the system, and (iii) to determine the key advantages and short comings for further research. The results indicated that significant reductions in water and energy requirements were possible with the biofilm photobioreactor. Although the system achieved net energy ratio of about 6, the overall productivity was low as Botryococcus branunii is notoriously slow growing algae. Thus, further studies were focused on identification of algal species capable of biofilm growth with larger biomass and lipid productivities. Adhesion of cells to substrata precedes the formation of all biofilms. A comprehensive study has been conducted to determine the interactions of a planktonic and a benthic algal species with hydrophilic and hydrophobic substrata. The physico-chemical surface properties of the algal cells and substrata were determined and using these data, cell-substrata interactions were modeled with the thermodynamic, Derjaguin, Landau Verwey, Overbeek (DLVO) and Extended Derjaguin, Landau, Verwey, Overbeek (XDLVO) approaches and critical parameters for algal adhesion were identified. Finally, the adhesion rate and strength of algal species were quantified with parallel plate flow chamber experiments. The results indicated that both cell and substrata surface hydrophobicity played a critical role for the adhesion rate and strength of the cells and XDLVO approach was the most accurate model. Finally, based on these findings the physico-chemical surface properties of ten algal species and six substrata were quantified and a screening was done to determine algae species substratum couples favoring adhesion and biofilm formation. / text

This thesis reports the rheological properties of algae slurries as a function of cell concentration for three microalgae species: Nannochloris sp.,Chlorella vulgaris, and Phaeodactylum tricornutum. Rheological properties ofalgae slurries have a direct impact on the agitation and pumping power requirements as well as process design for producing algal biofuels. This study measures the rheological properties of eight diff erent concentrations of each species ranging from 0.5 to 80 kg dry biomass/m³. Strain-controlled steady rate sweep tests were performed for each sample with an ARES-TA rheometer using a double wall couette cup and bob attachment. Shear rates ranged from 5 - 270 s⁻¹, corresponding to typical expected conditions. The results showed that Nannochloris sp. slurry behaved as a Newtonian fluid for concentrations up to 20 kg/m³. Samples with concentrations above 40 kg/m³ behaved as a shear thinning non-Newtonian fluid. The effective viscosity increased with increased biomass concentration for a maximum value of 3.3x10⁻³ Pa-s. Similarly, C. vulgaris slurry behaved as a Newtonian fluid with concentrations of up to 40 kg/m³, above which it displayed a shear thinning non-Newtonianf behavior and a maximum eff ective viscosity of 3.5x10⁻² Pa-s. On the other hand, P. tricornutum slurry demonstrated solely Newtonian fluid behavior, with the dynamic viscosity increasing with increasing biomass concentration for a maximum value of 3.2x10⁻³ Pa-s. The maximum observed e ffective viscosity occurred at a concentration of 80 kg/m³ for all three species. Moreover, an energy analysis was performed where a non-dimensional bioenergy transport e ffectiveness was de termined as the ratio of the energy content of the transported algae biomass to the sum of the required pumping power and the harvesting power. The results show that the increase in major losses due to increase in viscosity was overcompensated by the increase in the transported biomass energy. Also, cultivating a more concentrated slurry requires less dewatering power and is the preferred option. The largest bioenergy transport eff ectiveness was observed for the slurries with the largest initial dry biomass concentrations. Finally, the relative viscosity of algae slurries was modeled using a Kelvin-Voit based model for dilute and concentrated viscoelastic par- ticle suspensions. The model, which depends primarily on the packing factor of the algae species, agrees with the measured viscosity with an average error of 18%, while the concentrated particle suspension model was slightly more accurate than the dilute suspension model. / text

Biofuel is a renewable and sustainable energy source with near-neutral carbon footprint. Algae are an ideal feedstock for biofuel production because they reproduce quickly and have high oil. Algae can be cultivated in non-arable land, and would not impact the food supply. Unfortunately, processing algae into biofuel is more expensive than land crops due to the large volumes of dilute algal suspension that must be harvested and concentrated. In order to improve algae-based biofuel economics, resins were developed that reduce costs associated with water pumping and transport. Hydrophobic resins were developed for binding oil out of an algal suspension so that the residual biomass could be recovered without solvent contamination. Binding behavior displayed lipid species specificity, and binding capacity was improved by ethanol treatment of the biomass. Algae was harvested by binding to anion exchange resin and directly converted into biodiesel. One-step, room temperature in situ transesterification of algae yielded nearly as much biodiesel as two-step, heated transesterification of dried biomass. Elution with transesterification reagent also regenerated the resin for subsequent algal binding. Functionalized resins were developed with high algal binding capacity at neutral pH. Binding was easily reversed, as treatment with buffer with pH higher than pKa of the resin functional group removed the algae and regenerated the resin for subsequent use. The resin bound 10% of its weight in algae and released it as a 100-fold concentrated suspension. The polymers developed can be scaled up for commercial processes and reduce algal harvesting and concentration costs. / text

Biomass fast pyrolysis liquid, also known as bio-oil, is a promising renewable fuel for heat and power generation; however, implementing crude bio-oil in some current combustion systems can degrade combustion performance and emissions. In this study, optimizing fuel properties to improve combustion is considered. Various bio-oils with different fuel properties are tested in a pilot stabilized spray burner under very close flow conditions. Effects of solids, ash and water content of bio-oil as well as ethanol blending were examined. The results show the amount of solids and ash fractions of the fuel were correlated with combustion efficiency. The CO and unburned hydrocarbon emissions decreased with both water and ethanol content. Increasing the fuel’s volatile content by blending in ethanol has been shown to improve flame stability. Also, the organic fraction of particulate matter emissions was found to be a strong function of the thermogravimetric analysis residue of the fuel.

Biomass fast pyrolysis liquid, also known as bio-oil, is a promising renewable fuel for heat and power generation; however, implementing crude bio-oil in some current combustion systems can degrade combustion performance and emissions. In this study, optimizing fuel properties to improve combustion is considered. Various bio-oils with different fuel properties are tested in a pilot stabilized spray burner under very close flow conditions. Effects of solids, ash and water content of bio-oil as well as ethanol blending were examined. The results show the amount of solids and ash fractions of the fuel were correlated with combustion efficiency. The CO and unburned hydrocarbon emissions decreased with both water and ethanol content. Increasing the fuel’s volatile content by blending in ethanol has been shown to improve flame stability. Also, the organic fraction of particulate matter emissions was found to be a strong function of the thermogravimetric analysis residue of the fuel.

Darbe nagrinėta biokuro kūryklų įvairovė, išmetamų teršalų poveikis aplinkai bei žmogui. Pagrindinis darbo tikslas - ištirti biokuro kūryklų (katilo ir krosnies) išmetamų dūmų sudėtį ir teršalų koncentracijas bei įvertinti jų atitikimą normatyviniams dokumentams. Magistriniame darbe apžvelgta biokuro sąvoka, sudėtis ir savybės. Apžvelgta oro ir deguonies kiekio įtaka degimo procesui. Taip pat darbe apžvelgti katilų ir krosnių pagrindiniai elementai bei jų veikimo principai. Nagrinėjama oro taršos problema bei emisijos, deginant biokurą. Darbe pateikiama biokuro degimo tyrimo metodika, veiksniai nuo kurių priklauso biokuro sudegimo pilnumas. Tyrimai atlikti naudojantis dviejų skirtingų namų 2011 m. šildymo sezono duomenimis. Pamatuoti katilo bei krosnies emisijų kiekiai ir palyginta, kuris įrenginys mažiausiai teršia aplinką, remiantis normatyviniais dokumentais. Taip pat matuoti deguonies kiekio dūmuose svyravimai visame degimo procese. Remiantis informacijos šaltiniuose pateiktomis formulėmis apskaičiuotas optimalus oro pertekliaus koeficientas skirtingiems degimo įrenginiams. / This paper analyzes a variety of biofuel furnaces, emissions and the impact on humans. The main aim - to investigate bio flue (boiler and furnace), the composition of the smoke emissions and concentrations of pollutants and to assess their compliance with the normative documents. This thesis covers an overview of the concept of bio-fuels, composition and properties. The theoretical aspects of air and oxygen influence the combustion process. Also look at the boilers and heating elements and their operating principles. The present problem of air pollution and emissions from combustion of biofuels. The paper presents the combustion of biofuels research methodology, the factors which determine the completeness of combustion of biofuels. Investigations were carried out using two different houses in 2011. heating season. Measure the boiler or furnace emissions and compared to plant environmentally friendly, according to legal documents. Also measure the oxygen content of flue variations throughout the combustion process. Based on information provided by sources in the equations estimated optimum excess air ratio for different combustion device.

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<p>The production of biodiesel (methyl esters) from vegetable oils represents analternative means of producing liquid fuels from biomass, and one which is growing rapidly in commercial importance and relevance due to increase in petroleum prices and the environmental advantages the process offers. Commercially, biodiesel is produced from vegetable oils, as well as from waste cooking oils and animal fats. These oils are typically composed of C14-C20 fatty acid triglycerides. In order to produce a fuel that is suitable for use in diesel engines, these triglycerides are usually converted into the respective mono alkyl esters by base-catalyzed transesterification with short chain alcohol, usually methanol. In the first part of this study, the transesterification reactions of three different vegetable oils / sunflower (SFO), soybean (SBO) and waste cooking oil (WCO) with methanol was studied using potassium hydroxide as catalyst in a conventional batch process. The production of biodiesel from waste cooking oil was also studied via continuous operation systems (employing the use of low frequency ultrasonic technology and the jet loop reactor). The characterisation of the feedstock used and the methyl ester products were determined by different analytical techniques such as gas chromatography (GC), high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). The effects of different reaction parameters (catalyst amount, methanol to oil ratio, reaction temperature, reaction time) on methyl ester/FAME yield were studied and the optimum reaction conditions of the different process systems were determined. The optimum reaction conditions for production of methyl esters via the batch process with the fresh oil samples (SFO and SBO) were established as follows: a reaction time of 60 min at 60 &ordm / C with a methanol: oil ratio of 6:1 and 1.0 KOH % wt/wt of oil / while the optimum reaction conditions for the used oil (WCO) was observed at a reaction time of 90 min at 60 &ordm / C, methanol: oil ratio of 6:1 and 1.5% KOH wt/wt of oil. The optimum reaction conditions for the transesterification of the WCO via ultrasound technology applied in a continuous system in this study were: a reaction time of 30 min, 30 &ordm / C, 6:1 methanol/oil ratio and a 0.75 wt% (KOH) catalyst concentration. The ultrasound assisted transesterification reactions performed at optimum conditions on the different oil samples led to higher yields of methyl esters (96.8, 98.32 and 97.65 % for WCO, SFO and SBO respectively) compared to methyl esters yields (90, 95 and 96 % for WCO, SFO and SBO respectively) obtained when using conventional batch procedures. A considerable increase in yields of the methyl esters in the ultrasound assisted reaction process were obtained at room temperature, in a remarkably short time span (completed in 30 min) and with a lower amount of catalyst (0.75 wt % KOH) while the results from the continuous jet loop process system showed even better results, at an optimum reaction condition of 25 min of reaction, a methanol: oil ratio of 4:1 and a catalyst amount of 0.5 wt%. This new jet loop process allowed an added advantage of intense agitation for an efficient separation and adequate purification of the methyl esters phase at a reduced time of 30 min. The use of homogeneous catalysts in conventional processes poses many disadvantages / heterogeneous catalysts on the other hand are attractive on the basis that their use could enable the biodiesel production to be more readily performed as a continuous process resulting in low production costs. Consequently, a solid base catalyst (KNO3/FA) prepared from fly ash (obtained from Arnot coal power station, South Africa) and a new zeolite, FA/Na-X synthesized from the same fly ash were used as solid base catalysts in the transesterification reactions in the conversion of a variety of oil feedstock with methanol to methyl esters. Since fly ash is a waste product generated from the combustion of coal for power generation, its utilization in this manner would allow for its beneficiation (as a catalytic support material and raw material for zeolite synthesis) in an environmentally friendly way aimed at making the transesterification process reasonably viable. Arnot fly ash (AFA) was loaded with potassium (using potassium nitrate as precursor) via a wet impregnation method while the synthesized zeolite FA/Na-X was ion exchanged with potassium (using potassium acetate as precursor) to obtain the KNO3/FA and FA/K-X catalysts respectively. Several analytical techniques were applied for characterization purposes. The results of the XRD and XRF showed that the AFA predominantly contained some mineral phases such as quartz, mullite, calcite and lime. The high concentration of CaO in AFA was apparent to be beneficial for the use of fresh fly ash as a support material in the heterogeneous catalysed transesterification reactions. XRD characterisation of KNO3/FA results indicated that the structure of KNO3/FA gradually changed with the increase in KNO3 loading. The catalyst function was retained until the loading of KNO3 was over 10 %. IR spectra showed that the KNO3 was decomposed to K2O on the fly ash support during preparation at a calcination temperature of 500 &ordm / C. The CO2-TPD of the KNO3/FA catalysts showed that two basic catalytic sites were generated which were responsible for high catalytic abilities observed in the transesterification reactions of sunflower oil to methyl esters. On the other hand, XRD results for the as- received zeolite synthesized from AFA showed typical diffraction peaks of zeolite NaX. SEM images of the FA /NaX showed nano platelets unique morphology different from well known pyramidal octahedral shaped crystal formation of faujasite zeolites and the morphology of the FA /KX zeolite did not show any significant difference after ion exchange. The fly ash derived zeolite NaX (FA /NaX) exhibited a high surface area of 320 m2/g. The application of the KNO3/FA catalysts in the conversion reactions to produce methyl esters (biodiesel) via transesterification reactions revealed methyl ester yield of 87.5 % with 10 wt% KNO3 at optimum reaction conditions of methanol: oil ratio of 15:1, 5 h reaction time, catalyst amount of 15 g and reaction temperature 160 &deg / C, while with the use of the zeolite FA/K-X catalyst, a FAME yield of 83.53 % was obtained for 8 h using the ion exchanged Arnot fly ash zeolite NaX catalyst (FA/KX) at reaction conditions of methanol: oil ratio of 6:1, catalyst amount of 3 % wt/wt of oil and reaction temperature of 65 &ordm / C. Several studies have been carried out on the production of biodiesel using different heterogeneous catalysts but this study has been able to uniquely demonstrate the utilization of South African Class F AFA both as a catalyst support and as a raw material for zeolite synthesis / these catalyst materials subsequently applied sucessfully as solid base catalysts in the production of biodiesel.</p>

Marker-Assisted Verification of Hybrids in Pearl Millet-Napiergrass (Pennisetum glaucum [L.] R. Br. x Pennisetum purpureum Schumach.). (December 2011) Charlie D. Dowling, III, B.S., College of Agriculture and Life Sciences Chair of Advisory Committee: Dr. Russell W. Jessup A high-biomass perennial grass that is directly seeded using existing farm equipment can reduce both planting and overall input costs. Three cytoplasmic male-sterile cms A-lines and four fertile genotypes of pearl millet (Pennisetum glaucum [L.] R. Br.) and one novel pearl millet selection from the Perennial Grass Breeding Program at Texas A&M University were selected to cross with napiergrass (Pennisetum purpureum Schumach.). The pearl millet parents were chosen based on characteristics such as basal tillering, plant height, and days to anthesis. Three napiergrass accessions from the Perennial Grass Breeding Program and the cultivar Merkeron were used as pollinators for these crosses. The cms and fertile pearl millet accessions produced full heads of seed when pollinated with napiergrass. There were a large range of seed sizes and weights for each hybrid family, and the seed were separated into four size classes. The weight differences from the largest to smallest class of seed varied by more than 30%. All of the seed classes germinated, and seed size, in this case, was completely unrelated to the ability to germinate. 100% germination was observed in five seed size classes for both PMN iv hybrids, and 90% germination was observed in three of the eight classes. Essentially all of the hybrid seed recovered from the original pearl millet x napiergrass crosses germinated, but all of the F 1 hybrids were sterile in that none of them produced viable seed. Flow cytometry could not be used to identify the hybrids because the DNA content of pearl millet and napiergrass were essentially the same even though distinct 2C and 4C peaks were seen from the diploid pearl millet. From the 58 EST-SSRs surveyed in the bulked segregate analysis, several were heterozygous dominant and many were homozygous dominant and hemizygous at its particular loci. Seven hemizygous EST-SSRs were identified for Merkeron, seven for PEPU09FL01, eight for PEPU09FL02, and six for PEPU09FL03. These markers are extremely valuable to any pearl millet x napiergrass hybridization program because they provide a means whereby the hybrids can be easily identified. Identification of hemizygous pearl millet markers will also assist in future DNA sequencing and also in a marker-assisted breeding program.

Terpenes comprise a large diverse class of natural products and many of them attract interest because of their physiological function, therapeutic and industrial values. Triterpene oils including squalene (C30), botrycococcene (C30) and their methylated derivatives (C31-C37) generated by the green algae Botryococcus braunii race B, which have recently received significant attention because of their utility for advanced biofuels. However, the slow growth habit of B. braunii makes it impractical as a robust biofuel production system. In this thesis, we firstly evaluated the potential of generating high levels of triterpene (C30) production in tobacco plants by diverting carbon flux from cytosolic MVA pathway or plastidic MEP pathway by overexpressing avian farnesyl diphosphate synthase along with triterpene synthase targeted to the cytoplasm or the chloroplast of cells. Up to 1,000 µg/g fresh weight of squalene and 544 µg/g fresh weight of botryococcene was achieved in our transgenic plants with this metabolism direct to the chloroplasts, which is about approximately 100-times greater than that accumulating in the plants engineered for cytosolic production. To test if methylated triterpenes can be produced in tobacco, we also engineered triterpene methyltransferases (TMTs) into wild type plants and transgenic tobacco plants selected for high level triterpene accumulation. We observed that up to 91% of the total triterpene content was converted to methylated forms (C31, C32) by targeting the TMTs to the chloroplasts of transgenic plants, whereas only 4-14% of total triterpenes were methylated when TMTs were directed to the cytoplasm. Select transgenic lines were growing in field studies from 2011 to 2014 to evaluate their physiological performance under field conditions. Surprisingly, the field studies suggested that the growth and agronomic performance of the transgenic lines accumulating squalene were not compromised, while those accumulating high levels of botryococcene were only 72%-76% as tall, had about 59%-75% of the leaf area, and about 55%-75% of the biomass as wild type plants. Yet, these transgenic plants had photosynthetic capacity equal to the wild type plants.