This thesis describes a geographically- and temporally-resolved, integrated biological and engineering model that estimates algal biomass and lipid production under resource-limited conditions with hourly and county resolution. Four primary resources are considered in this model: sunlight, carbon dioxide, water, and land. The variation in quantity and distribution of these resources affects algae growth, and is integrated into the analysis using a Monod model of algae growth, solar insolation data, and published values for water, carbon dioxide, and land availability. Finally, lipid production is calculated by assuming oil content based on dry weight of the biomass. The model accommodates a range of growth and production scenarios, including water recycling, co-location with wastewater treatment plants and coal-fired generators, and photobioreactor type (open pond or tubular), among others. Results for every county in Texas indicate that between 86 million and 2.2 billion gallons of lipids per year can be produced statewide for the various growth scenarios. The analysis suggests that algal biomass and lipid production does indeed vary geographically and temporally across Texas. Overall, most counties are water-limited for algae production, not sunlight or carbon dioxide-limited. However, there are many nuances in biomass and lipid production by county. Counties in west Texas are typically not solar- or land-limited, but are constrained by either water or carbon dioxide resources. Consequently, counties in east Texas are limited by either water, or land (depending on the fraction of water recycling). Varying carbon dioxide concentration results in higher growth rates, but not always increased biomass and lipid production because of limitations of other resources in each county. / text

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

With the limited reserves of fossil fuels and the environmental problems associated with their use, the world is moving towards cleaner, renewable, and sustainable sources of energy. Biomass is a promising feedstock towards attaining this goal because it is abundant, renewable, and can be considered as a carbon neutral source of energy. Syngas can be further processed to produce liquid fuels, hydrogen, high value chemicals, or it can be converted to heat and power using turbines. Most of the downstream processing of syngas occurs at high pressures, which requires cost intensive gas compression. It has been considered to be techno-economically advantageous to generate pressurized syngas by performing high-pressure gasification. Gasification utilizes high temperatures and an oxidizing gas to convert biomass to synthesis gas (syngas, a mixture of CO and H2). Most of the past studies on gasification used process conditions that did not simulate an industrial gasification operation. This work aims at understanding the chemical and physical transformations taking place during high-pressure biomass gasification at heating rates of practical significance. We have adopted an approach of breaking down the gasification process into two steps: 1) Pyrolysis or devolatalization (fast step), and 2) Char gasification (slow step). This approach allows us to understand pyrolysis and char gasification separately and also to study the effect of pyrolysis conditions on the char gasification kinetics. Alkali and alkaline earth metals in biomass are known to catalyze the gasification reaction. This potentially makes biomass feedstock a cheap source of catalyst during coal gasification. This work also explores catalytic interactions in biomass-coal blends during co-gasification of the mixed feeds. The results of this study can be divided into four parts: (a) pyrolysis of loblolly pine; (b) gasification of pine chars; (c) pyrolysis and gasification of switchgrass; (d) co-gasification of pine/switchgrass with lignite and bituminous coals.

The need to curb increased pollution of environmental resources caused by excessive nitrogen (N) fertilizer application and N fertilizer use inefficiencies in wheat (Triticum aestivum) production systems warrants an inexpensive, sustainable, environmentally sound solution, the root system. Wheat germplasm containing the short arm of rye chromosome 1 (1RS) has recently been found to have larger root system sizes in pot experiments in addition to previously documented higher yields and resistance to leaf, stem and yellow rust. These 1RS lines could therefore be useful in wheat breeding efforts targeting superior root system traits for yield improvements as well as environmental and economic benefits. This dissertation evaluated field root biomass production of Pavon 76 and its wheat-rye (1RS) translocations, effects of root biomass on nitrogen use efficiency, and the temporal variation in their root morphological traits and early growth vigor. The translocation 1RS.1BL had 9 and 23 % higher total root biomass than Pavon 76 at jointing and physiological maturity respectively. Root N uptake peaked at the jointing, where it comprised 22-34% of the total plant N uptake and was lowest at physiological maturity for all genotypes. The inclusion of root N uptake reduced the N utilization efficiency and N harvest index by 6-14 and 7-15% respectively, indicating that the use of only the above ground plant parts over estimates these parameters. In pot experiments, the translocation 1RS .1AL had 12 and 39% higher root biomass than Pavon 76 at anthesis and maturity respectively. 1RS.1BL had 38% higher root mass and 16% longer roots than Pavon76 at physiological maturity. This suggests the existence of differences among the genotypes in below ground partitioning of assimilates at peak nutrient demand (anthesis) for grain filling, and also in rates of root decay and senescence. The lack of differences in root morphological traits among genotypes at early growth stages (6-46 days after sowing) indicates that there are minimal differences in early root growth vigor. The 1RS translocations could therefore expand the wheat breeder's tool box in selections for superior root traits for improved NUE without adverse effects on grain yield.

Über Energie-Biomassepotenziale wird z.T. kontrovers diskutiert. Einerseits ist der Ausbau der Bioenergienutzung politisch gewollt (sowohl hierzulande als auch international), andererseits steht der Energiepflanzenanbau in direkter Konkurrenz zur Nahrungs- und Futtermittelproduktion. In der vorliegenden Arbeit wird der Frage nachgegangen, wie sich Biomassepotentiale bestimmen lassen und welche mathematischen Modellansätze es hierfür gibt. Zunächst wird die grundlegende Funktionsweise von einigen Pflanzenmodellen sowie deren Einsatz für die Biomassepotentialbestimmung erläutert und anhand eines neu entwickelten Modells, dem Modell BioSTAR, näher beschrieben. Das Modell BioSTAR ist ein kohlenstoffbasiertes Pflanzenmodell (Azam-Ali, et al., 1994) und liegt als in Java programmiertes Software-Produkt vor. Mit dem Modell lassen sich die Biomassepotentiale und der Wasserverbrauch von verschiedenen Ackerkulturen in Abhängigkeit von Klima- und Bodenfaktoren ermitteln. Das Modell ist zurzeit für vier Winterungen und drei Sommerungen validiert und wurde im Rahmen dieser Arbeit für eine Energie-Biomassepotentialanalyse für den Raum Niedersachsen herangezogen. Weiterhin wird der Frage nachgegangen, wie ein bereits hoher und nach FAO-Prognosen (FAOSTAT, 2006) weiterhin steigender globaler Fleisch- und Milchproduktkonsum zu Umweltproblematiken im Agrarbereich führt und die für die Welternährung zur Verfügung stehende Agrarfläche unnötig verknappt. Eine Reduzierung des Fleischkonsums auf die DGE (Deutsche Gesellschaft für Ernährung)-Empfehlungsmengen könnte hierzulande große Flächen freisetzen und somit dazu beitragen, die Konkurrenz zwischen dem Energiepflanzenanbau und der Nahrungs- und Futtermittelproduktion zu entschärfen.

The conception of environmental quality is common used in our society. Ecological farming is one of the most quality orientated agricultural system. The experiment was conducted in the Kazliskiai ecological farm of Lithuanian University of Agriculture. There were different kind of investigation determined earlier on the farm, but there were no investigation made on the influence of weedy trench to winter-wheat field. The aim of this work is to determine how weedy trench influences segetic flora and its botanical structure in winter- wheat agrophytocenozis. The tasks, which help to gain the aim: 1. To analyze how the amount of weeds change receding from weedy trench; 2. To analyze how the botanical structure of weeds change receding from weedy trench; 3. To evaluate interrelationship between amount of weeds and their botanical structure due to weedy trench. The object of the research work – the winter-wheat field segetic flora of Kazliskiai ecological farm. The following methods were used in this work: • The analysis of scientific literature; • The calculation of segetic flora amount and its botanical structure in workspaces; • The statistical analysis using EXCEL, DISPERS programs. The results of this work show: The weedy trench has a positive influence on the amount of segetic flora. It is 2-4 times bigger nearby weedy trench than in the middle of the field. The botanical structure changes only in autumn but not numerously.

In order to reduce the discharge of the greenhouse gas CO2, the use of biomass is nowadays promoted as fuel in boilers. Compared to boilers fired with coal and oil the biomass-fired boilers have more complications related to both fouling and corrosion on the heat transfer surfaces. After the combustion, unburned inorganic matter in state of vapour, melts and solid particles are transported in the flue gas and may form deposits on heat transfer surfaces. Deposits on the heat transfer surfaces may result in both increasing corrosion and decreasing boiler efficiency as the heat transfer rate to the superheaters and reheaters decrease by deposits. In order to understand the process of deposit build-up, the whole combustion and transport process had to be analysed including aspects such as, boiler design, fuel properties and combustion environment, followed by particle transport phenomena and the probability for particles to get stuck on the heat transfer tubes. In this thesis numerical simulation of particle trajectories has been conducted as well as measurements of deposits on a special designed deposit probe followed by investigation of on-site measurements of deposit depth on the super-heater tubes in a circulating fluidised bed in Västerås, Sweden. Numerical simulations of particle trajectories in the vicinity of two super-heater tubes were conducted in an Eulerian-Lagrangian mode considering the flue gas and ash particles phase. Particle impingements on the tubes were investigated for different particle sizes. The results from the particle trajectory simulations show that particle larger than 10 µm will mainly impinge on the windward side of the first tube but, however also on the sides of the second tube in the flue gas flow direction. In theory as well as from observations and measurements two tubes can merge together by the deposit build-up. Smaller particles are usually more dispersed due to turbulence and thermophorectic forces, resulting in a more even impingement distribution on the whole surface of the tubes. Probe measurements reveal that the deposit layer growth rate have a significant temperature and time dependence. After the initial deposit build-up a sintering process occurs and sintering is also proven to be dependent on temperature and exposure time. Soot-blowing is the most common method to reduce the effect of deposits on the heat transfer tubes. In the present thesis the soot boiling efficiency is therefore also investigated. The soot-blowing show a strong positive effect on the heat transfer rate in a short time (hours) perspective after a soot-blowing cycle is completed. This positive effect is much weaker when considering a time period of three years. This is an effect of fact that soot-blowing mostly remove the loose part of the deposit material leaving the hard sintered part unaffected. The subject of deposit build up on superheater tubes in large scale boilers involves multi-discipline knowledge and historically, the related research is mostly conducted as measurements and experiments on operating plants. Possibly in the future, theoretical simulations will have a bigger part of research on deposit build-up where the calculations are to be calibrated through measurements on real sites plants.

Ultraviolet-visible chemiluminescent emission features in laboratory-scale flames have been shown by several researchers to correlate well with the flame's equivalence ratio, and it has been suggested that this relation could be used to actively control flames. This study investigated the feasibility of extending this knowledge to the industrial setting. Radiative emissions from basic oxygen furnace (BOF) and thermal generating station burner flames were mainly characterized by thermally-induced greybody spectra; emissions from electronically excited species of OH*, OH*, and CO2* were generally weak and did not offer any unique information that could be used as part of a flame diagnostic system. A sub-study which assessed the impact of biomass cofiring demonstrated that emissions of SO2, NOx, and fossil-CO2 could be reduced with direct fuel replacement. The sensor system could be used as a pyrometer, and as part of a burner balancing strategy to counter increased CO emissions and decreased efficiency.

Ultraviolet-visible chemiluminescent emission features in laboratory-scale flames have been shown by several researchers to correlate well with the flame's equivalence ratio, and it has been suggested that this relation could be used to actively control flames. This study investigated the feasibility of extending this knowledge to the industrial setting. Radiative emissions from basic oxygen furnace (BOF) and thermal generating station burner flames were mainly characterized by thermally-induced greybody spectra; emissions from electronically excited species of OH*, OH*, and CO2* were generally weak and did not offer any unique information that could be used as part of a flame diagnostic system. A sub-study which assessed the impact of biomass cofiring demonstrated that emissions of SO2, NOx, and fossil-CO2 could be reduced with direct fuel replacement. The sensor system could be used as a pyrometer, and as part of a burner balancing strategy to counter increased CO emissions and decreased efficiency.

Pretreatment of recalcitrant lignocellulosic biomass to release sugars for bioconversion into ethanol produces fermentation inhibitors. Increasing yeast inhibitor tolerance should reduce production time and cost. UV mutagenesis followed by genome shuffling using cross mating was performed on Scheffersomyces stipitis strain GS301, a genome shuffled strain with increased tolerance to spent sulphite liquor (SSL). The main fermentation inhibitors in SSL are acetic acid, hydroxymethylfurfural (HMF), and various phenolics. UV mutagenesis resulted in acetic acid tolerant mutants, but they were phenotypically unstable. However, two rounds of UV mutagenesis followed by five rounds of genome shuffling resulted in strains EVB105, EVB205 and EVB505 with increased SSL tolerance and improved acetic acid and HMF tolerance. When fermenting undiluted SSL at pH 5.5, the three strains utilized sugars faster producing higher maximum ethanol than GS301. This study demonstrates that UV mutagenesis with genome shuffling can significantly improve inhibitor tolerance and fermentation performance of yeast. / NSERC Bioconversion Network