Biofuel production from microalgal biomass offers a clean and sustainable liquid fuel alternative to fossil fuels. In addition, algae cultivation is advantageous over traditional biofuel feedstocks as (i) it does not compete with food production, (ii) it potentially has a much greater areal productivity, (iii) it does not require arable land, and (iv) it can use marginal sources of water not suitable for irrigation or drinking. However, current algae cultivation technologies suffer from (i) low solar energy conversion effiencies, (ii) large thermal fluctuations which negatively affect the productivity, and (iii) large evaporative losses which make the process highly water intensive. This thesis reports a numerical study that address these key issues of planktonic as well as benthic algal photobioreactor technologies. First, radiant energy transfer in planktonic algal photobioreactors containing cells with different levels of pigmentation was studied. Chlamydomonas reinhardtii and its truncated chlorophyll antenna transformant tla1 were used as model organisms. Based on these simulations guidelines are derived for scaling the size and microorganism concentration of photobioreactors cultivating cells with different levels of pigmentation to achieve maximum photosynthetic productivity. To achieve this, the local irradiance obtained from the solution of the radiative transport equation (RTE) was coupled with the specific photosynthetic rates of the microorganisms to predict both the local and total photosynthetic rates in a photobioreactor. For irradiances less than 50 W/m2, the use of genetically modified strains with reduced pigmentation was shown to have negligible effect on increasing photobioreactor productivity. However, at irradiances up to 1000 W/m2, improvements of up to 30% were possible with cells having 63% less pigment concentration. It was determined that the ability of tla1 to transmit light deeper into the photobioreactor was the primary mechanism by which a photobioreactor using the modified strain can achieve greater productivity. Furthermore, it was determined photobioreactors using each strain have dead zones in which the local photosynthetic rate is negligible due to nearly complete light attenuation. These dead zones occur at local optical thicknesses greater than 169 and 275 in photobioreactors using the wild strain and the genetically modified strain, respectively. In addition, a thermal model of an algae biofilm photobioreactor was developed to assess the thermal fluctuations and evaporative loss rate of these novel photobioreactors under varying outdoor conditions. The model took into account air temperature, irradiance, relative humidity, and wind speed as inputs and computed the temperature and evaporative loss rate as a function of time and location in the photobioreactor. The model was run for a week-long period in each season using weather data from Memphis, TN. The range of the daily algae temperature variation was observed to be 13.2C, 12.4C, 12.8C, and 9.4C in the spring, summer, winter, and fall, respectively. Furthermore, without active cooling, the characteristic evaporative water loss from the system is approximately 6.3 L/m2-day, 7.0 L/m2-day, 4.9 L/m2-day, and 1.5 L/m2-day in the spring, summer, fall, and winter, respectively. / text

This action research project focuses on teaching life cycle assessment to engineering students in high school, using biofuels as a relevant application. The study examined the effectiveness of teaching methods related to both the engineering content—life cycle assessment—and the science content—biofuel production. It also examined underlying conceptions that students have about the preferability of some common consumer products from an environmental perspective, as well as their knowledge of ethanol compared to gasoline. The participants in the study consisted of sixteen college students enrolled in an Engineering Energy Systems course while pursuing either an undergraduate or graduate degree related to teaching engineering and science at the secondary level. The students participated in lessons written for a high school engineering science course currently under development in the UTeach Engineering program at The University of Texas at Austin. Data were collected from a pre- and post-unit assessment, observation of student activities and behaviors, and a participant survey. The results of the study suggest that student understanding of the environmental implications of products or processes is deeper after completion of the unit. The study also shows a positive relationship between hands-on sense-building activities and student engagement. As an action research project, the primary goal is the immediate improvement of teaching to increase learning in the classroom. Modifications to the unit and lesson design have been made based on the results of the study in preparation for using the unit with high school students in the following school year. / text

Παρά τη συνολική αύξηση του όγκου των παραγόμενων τροφίμων στον κόσμο, το πρόβλημα της πείνας και του υποσιτισμού, για μεγάλο μέρος των κατοίκων του πλανήτη παραμένει άλυτο. Η ενεργειακή κρίση και η παραγωγή βιοκαυσίμων δίνουν νέα διάσταση στη διατροφική κρίση και στην ακρίβεια τροφίμων. Κατανοώντας λοιπόν τη σπουδαιότητα του θέματος, εκπονήθηκε η παρούσα εργασία. Σκοπός της είναι να διερευνηθεί η σχέση μεταξύ των αγροτικών προϊόντων που προορίζονται για τη διατροφή του ανθρώπου και των βιοκαυσίμων που σχηματίζονται από αυτά. Παράλληλα εξετάζεται και η αλληλεπίδρασή τους με τις τιμές του πετρελαίου. Η εφαρμογή του Υποδείγματος Αυτοπαλίνδρομου Διανύσματος (VAR) καθώς και του Υποδείγματος Aπαρατήρητων ή Σταθερών Επιδράσεων (Fixed Effects Model) βοήθησαν στην εξαγωγή ορισμένων συμπερασμάτων. Σύμφωνα με το πρώτο υπόδειγμα παρουσιάζεται αλληλεπίδραση των τιμών τεσσάρων προϊόντων(καλαμπόκι, ζάχαρη, σογιέλαιο και κραμβέλαιο) με τα βιοκαύσιμα και το πετρέλαιο. Πιο συγκεκριμένα, οι τιμές του καλαμποκιού αντιδρούν αρνητικά το μεγαλύτερο διάστημα σε απρόσμενες μεταβολές του πετρελαίου ενώ θετικά το μεγαλύτερο διάστημα σε μεταβολές της βιοαιθανόλης. Οι τιμές της ζάχαρης αντιδρούν θετικά για μια περίοδο και στη συνέχεια βαίνουν μειούμενες σε αιφνίδια μεταβολή του πετρελαίου. Η αντίστοιχη αντίδραση σε μεταβολές της βιοαιθανόλης, την πρώτη περίοδο είναι θετική, για τις δυο επόμενες αρνητική και στη συνέχεια θετική για τις υπόλοιπες περιόδους. Όσον αφορά στην αντίδραση των τιμών του σογιέλαιου σε απρόσμενη μεταβολή του πετρελαίου τα αποτελέσματα δείχνουν ότι τις πέντε πρώτες περιόδους είναι θετική, μεταξύ πέμπτης και όγδοης αρνητική και στη συνέχεια θετική. Η αντίδραση των τιμών του σογιέλαιου σε μεταβολές του βιοντίζελ είναι αρνητική τις πέντε πρώτες περιόδους, θετική μεταξύ πέμπτης και όγδοης, αρνητική μεταξύ όγδοης και δωδέκατης ενώ στη συνέχεια η διαταραχή αυτή απορροφάται από το σύστημα. Τέλος, η αντίδραση των τιμών του κραμβέλαιου σε μια απροσδόκητη μεταβολή του πετρελαίου, τις πρώτες τέσσερις περιόδους είναι θετική, τις τέσσερις επόμενες αρνητική ενώ τις επόμενες παρατηρείται απορρόφηση της διαταραχής. Η αντίστοιχη αντίδραση σε μια απρόβλεπτη διαταραχή του βιοντίζελ την πρώτη περίοδο είναι θετική, μεταξύ δεύτερης και πέμπτης αρνητική, πέμπτης και δέκατης θετική ενώ στη συνέχεια η διαταραχή αυτή τείνει να απορροφηθεί από το σύστημα. Για τέσσερα προϊόντα (σιτάρι, κριθάρι, σόργο και φοινικέλαιο) η VAR ανάλυση δεν μας παρουσίασε κάποιο αξιόλογο συμπέρασμα λόγω κακής εφαρμογής του μοντέλου αυτού στα συγκεκριμένα προϊόντα. Ωστόσο, σύμφωνα με το υπόδειγμα απαρατήρητων ή σταθερών επιδράσεων (fixed effects) υπάρχει αλληλεξάρτηση ανάμεσα στα προϊόντα (συμπεριλαμβανομένων και εκείνων που η VAR ανάλυση δεν μπόρεσε να ερμηνεύσει), τα βιοκαύσιμα και το πετρέλαιο. Πιο ισχυρή σχέση προέκυψε εκείνη της βιοαιθανόλης με τα προϊόντα και του βιοντίζελ με τα προϊόντα. / Despite the total increase of the produced food in the world, the problem of hunger and malnutrition remains unsolved for a big part of the world population. The energy crisis and the production of biofuels give a new dimension in the food crisis and the high prices of foods. Thus, taking into account the importance of the above subject, the present paper is carried out. The aim of the paper is the analysis of the relation between the agricultural products destinated for human food on the one hand and the biofuels created from them on the other. At the same time their interaction with the prices of oil is also examined. Methodogically speaking, the application of the Vector Autoregressive Model (VAR) as well as the Fixed Effects Model help in the conduct of certain conclusions. According to the first model, an interaction between the prices of four products (corn, sugar, soybean oil, rapeseed oil) as well as the biofuels and oil prices is presented. In particular, the prices of corn react in a negative way to the unforeseen changes of oil prices while they react in a positive way in the bioethanol changes during the longer time period. The sugar prices react positively for a period and afterwards are decreased in a sudden change of oil prices. The corresponding reaction in bioethanol changes for the first period is positive, for the next two periods is negative and afterwards for the rest periods is positive. As far as the reaction of soybean oil prices in an unpredictable change of oil prices are concerned, the results show that in the five first periods is positive, between the fifth and eighth period is negative, and afterwards positive. The reaction of soybean oil prices in biodiesel changes is negative for the first five periods, between the fifth and eighth period is positive, between eighth and twelfth is negative whereas this disturbance is absorbed by the system afterwards. Finally, the reaction of the rapeseed oil in an unexpected change of oil prices, for the first four periods is positive for the four next periods is negative while for the next periods an absorption of disturbance is observed. Respectively, the reaction in an unanticipated disturbance of biodiesel for the first period is positive, between the second and fifth period is negative, between the fifth and tenth period is positive while this disturbance tends to be absorbed from the system afterwards. For the next four products (wheat, barley, sorghum and palm oil) the VAR analysis did not lead to a significant conclusion because of a bad application of the model on the particular products. However, according to the fixed effects model there is an interaction between the products (included also those that the VAR analysis cannot interpret), biofuels and oil. The more powerful relation is proved those of bioethanol with the products and those of the biodiesel with the products.

Fossil fuels are not sustainable due to their worldwide depletion and greenhouse gas (GHG) emissions. Transportation biofuels produced from microalgae are sustainable if GHG emissions are lower than fossil fuels and the sources for materials used during production are sustainable. Four areas were evaluated to address these concerns. First, a study of peer reviewed life-cycle analyses (LCAs) was performed. The purpose of this evaluation was to determine which processing choices during cultivation have the most impacts. Data from nine authors was converted to similar units, and a new LCA was performed to evaluate the impacts. Overall GHG emissions per kg of algae cultivation ranged from 0.1 - 4.4 kg CO₂ eq. / kg algae, with the most of the emissions coming from fertilizer contributions. The second topic evaluated was the GHG emissions from experimental dewatering technologies. The five experimental technology emissions, for acoustic harvesting, membrane filtration, flocculation, electrocoagulation and flocculation plus belt filtration, were compared to a modeled dissolved air flotation technology and a fossil fuel source. For a functional unit of one MJ of renewable diesel (RD), membrane filtration had the lowest GHG emissions at 40.8 g CO₂(eq)/MJ RD. Dissolved air flotation was the highest scenario at 51.9 g CO₂(eq)/MJ RD. All technologies were lower than gasoline at 90.7 g CO₂(eq)/MJ gasoline. The third topic evaluated was the GHG emissions from the materials used for plant construction. A LCA was performed for the infrastructure materials and compared to results from the fuel-cycle. Plastic from pond liners had the largest contribution to GHG emissions for the baseline case. Increasing productivity and lipid content both decreased infrastructure emissions. The final topic evaluated was the sustainability of nitrogen, phosphorus and potassium used for microalgae growth. Results show that the surplus of world fertilizers cannot sustain large scale algae production in the United States. Technology choices that can recycle nutrients lower the overall requirement. Alternative sources of nutrients, like concentrated animal feeding operations, can provide enough nutrients for large scale production of algae.

Fuel availability and security of supply are two of the most important factors in the well functioning of a company like Gävle Energi. Another important factor is the price of the fuels used. The transportation cost plays also an important role when purchasing fuels from different sources. Currently the fuels used in Gävle Energi are mainly woody biofuels, but waste and peat could also be used in the future. The aim of this thesis is to provide an overview of the different available biofuels in the region of Gävle. The fuels considered in the study are: - Bark - Forest Residues - Wood waste - Pellets and Briquettes - Garbage/waste materials - Peat The research is focused on the physical properties of the fuels, their price and transportation cost, environmental and legislation issues and the availability in the region of Gävle. A 10-year perspective is defined for an estimated availability of the different fuels in te region.

Engine exhaust characteristics from two different biodiesel blends, formulated from soy and animal fat biodiesel blended with ultra-low sulphur diesel, were tested during two different test programs with similar operating conditions. Engine exhaust was measured in real-time for nitrogen oxides, total hydrocarbons, particle-bound polyaromatic hydrocarbons, and particle size distribution. Diesel particulate matter was collected on filters and subsequently analyzed for organic carbon, elemental carbon, soluble organic fraction, cations, and anions. The use of biodiesel was found to increase nitrogen oxide emissions, but decrease total hydrocarbons and particulate matter emissions. The most significant impact on emissions was the difference between the engine operating conditions rather than the fuel type. Minor differences were found between the soy and animal fat biodiesel blends through speciation of the diesel particulate matter.

Engine exhaust characteristics from two different biodiesel blends, formulated from soy and animal fat biodiesel blended with ultra-low sulphur diesel, were tested during two different test programs with similar operating conditions. Engine exhaust was measured in real-time for nitrogen oxides, total hydrocarbons, particle-bound polyaromatic hydrocarbons, and particle size distribution. Diesel particulate matter was collected on filters and subsequently analyzed for organic carbon, elemental carbon, soluble organic fraction, cations, and anions. The use of biodiesel was found to increase nitrogen oxide emissions, but decrease total hydrocarbons and particulate matter emissions. The most significant impact on emissions was the difference between the engine operating conditions rather than the fuel type. Minor differences were found between the soy and animal fat biodiesel blends through speciation of the diesel particulate matter.

Antrojoje darbo dalyje aprašyta gaminio paskirtis ir panaudojimo galimybės bei alternatyvos, išnagrinėti pakūrą sudarantys elementai: mazgai, mechanizmai. Atlikta katilo pakūros mazgų konstrukcijos variantų apžvalga – įvairiausių detalių, standartinių gaminių, konstrukcinių sprendimų palyginimas. Atlikti gaminio techniniai skaičiavimai (šiluminės izoliacijos ir nuostolių skaičiavimas, hidrostotelės elementų skaičiavimas, ardelių judinimo hidraulinių cilindrų skaičiavimas, pelenų šalinimo mazgo techniniai skaičiavimai). Trečiojoje darbo dalyje išanalizuota vienos detalės, iš kiekvieno pakūros mazgo, technologiniai maršrutai, nustatyti apdirbimo operacijoms reikalingi įrengimai, apskaičiuotas jų kiekis. Atliktas užlaidų, pjovimo režimų nustatymas bei techninis normavimas. Ketvirtojoje darbo dalyje pateikiama žmonių ir aplinkos saugos reikalavimai eksploatuojant įrenginį, jo ergonomiškumas ir įtaka aplinkai. Penktojoje darbo dalyje atlikti ekonominiai skaičiavimai, kurių pagalba nustatyta ir pagrįsta 1,5 megavato katilo pakūros savikaina. / The aim of the study is to design Boiler-stove furnace of 1,5 megawatt. The first part of bachelor thesis analyses the main technical parameter of boiler-stove furnace of 1,5 megawatt, its operating efficiency, the production volume is provided. The second part describes the function of the product, its usability and possible options, the assemblies and mechanisms - elements constituting the furnace are examined. The review of boiler furnace assembly options design is carried out – various details, standard products, constructive solutions are compared. Technical calculations of the product are performed (calculation of thermal insulation and loss, calculation of hydro-station elements, fire bars moving hydraulic cylinders calculation, technical calculation of ash removal unit). In the third part technological routes of one detail from every furnace component are analyzed, the equipment necessary for processing operations is assigned, calculated its amount. The allowance, determination of cutting regimes and technical rationing is accomplished. The fourth part presents human and environmental safety requirements while operating a device, its ergonomics and environmental impact. Economic calculations are fulfilled in the fifth part. With the help of them the cost of 1,5 megawatt boiler stone Furnace is determined and justified.

The conversion of switchgrass lignin, a renewable source for chemicals and fuels, is investigated using reactions such as depolymerization, hydrodeoxygenation and alkylation. First, the lignin is converted into oils containing phenol, substituted guaiacols and other smaller lignin fragments using formic acid and Pt/C through a batch process. A long reaction time was observed to crucial to yield oils with the highest fraction of lower molecular weight compounds with the lowest O/C and highest H/C molar ratio. Second, the zeolite catalyzed gas phase alkylation of phenol, a model compound for the lignin oil, with propylene was investigated. Zeolite pore topology and acid strength were shown to influence the selectivity for the target product, 2-isopropylphenol. This work shows that the conversion of lignin to useful products is possible and suggests some future work to consider before it can be implemented practically.

Baigiamajame darbe apžvelgiamos organinių medžiagų skaidymo ultragarsu sistemos. Didžiausias dėmesys skiriamas dumblių skaidymo ultragarsu sistemoms. Apžvelgiamos dumblių pritaikymo, jų auginimo ir išgavimo tendencijos. Nagrinėjama išilginių virpesių ultragarsinė dumblių skaidymo sistema „UIP 1000hd”. Darbo tikslas - Standartinio ultragarsinio įrenginio(UIP1000hd Set ) pagalba ištirti botanikos institute auginamų dumblių (augalinių bioląstelių) skaidymo galimybę. Darbo uždaviniai: 1. Įsisavinti naują ultragarsinę įrangą, išmokti naudoti įvairius titaninius koncentratorius, nustatyti reikiamus augalinių bioląstelių skaidymo režimus, išmokti registruoti ultragarsinės sistemos elektrinius ir mechaninius parametrus. 2. Susipažinti su pramoninių dumblių auginimo specifika. Kartu su Botanikos instituto mokslininkais organizuoti tyrimo objekto - dumblių(augalinių bioląstelių) bandomosios partijos užauginimą. 3. Išdirbti dumblių skaidymo lygio vertinimo (tyrimo) metodiką. 4. Išdirbti dumblių skaidymo tyrimo įrenginiu UIP1000hd Set metodiką. 5. Atlikti ultragarsinės sistemos ir kavituojamo skysčio su organine medžiaga virpesių pasiskirstymo analizę ( sistemos kompiuterinis modeliavimas turimomis laboratorijoje programomis). 6. Iš elektrinės ir mechaninės pusės ištirti ultragarsinę sistemą : nustatyti varžines - dažnumines ir amplitudines – dažnumines charakteristikas esant įvairioms elektrin4ms galioms, laisvame ir apkrautame režime. 7. Atlikti 2-3 rūšių pramoninių dumblių... [toliau žr. visą tekstą] / The Master’s Thesis provides an overview on the systems of organic matter decomposition by ultrasound. The focus is on the systems of algal ultrasound decomposition. The tendencies of algae adaptation, cultivation and extraction were reviewed. The ultrasonic algae decomposition system of longitudinal oscillation named “UIP 1000hd” was analyzed. The aims and objectives of the thesis: The aim - is to examine the decomposition possibility of algae (bio cells) growing in the Botanical Institute with the help of standard ultrasound device (UIP1000hd Set). Objectives: 1. To learn about the new ultrasound equipment, learn to use a variety of titanium concentrators, set the required decomposition modes of bio cells, learn to record electrical and mechanical parameters of the ultrasound system. 2. To familiarize with the specifics of industrial algae cultivation. To organize the experimental batch cultivation of the object of the research - algae (plant bio cells) - together with scientists of the Botanical Institute. 3. To master the assessment (research) methodology of the level of algae division. 4. To master the methodology of the algae decomposition equipment UIP1000hd Set. 5. To carry out the distribution of vibration analysis of the ultrasound system and the cativating with the organic matter (the system modeling by computer using programs that are in the Laboratory). 6. To investigate the electrical and mechanical sides of the ultrasound system: to set... [to full text]