Search Results (1 - 25 of 103 Results)

Sort By  
Sort Dir
 
Results per page  

Faze, Natasha RanjitLife Cycle And Economic Analysis Comparing Microbial Desalination Cell And Reverse Osmosis Technologies
Master of Science, The Ohio State University, 2015, Food, Agricultural and Biological Engineering
With a growing global population and a higher demand for potable water, society relies on Reverse Osmosis (RO) for large-scale desalination. Reverse Osmosis is currently the most economic and commonly used method to desalinate saline or brackish water to produce potable drinking water. This research investigated the alternative use of Microbial Desalination Cells (MDCs), and compared MDC technology to RO by performing life cycle and economic analyses. The additional advantage of an MDC, as compared with an RO desalination plant, is the production of a small amount of electricity as a by-product of the microorganisms' anaerobic respiration in the MDC device. The goal of this project was to determine if this production of electricity was enough to make MDC technology a more sustainable and economically favorable long term desalination option. A currently operating reverse osmosis plant was analyzed along with a laboratory scale MDC. Given that the RO facility under investigation is much larger than the bench scale MDC, both analyses were normalized on a per cubic meter basis, for implementation in Columbus, Ohio, USA. Results indicate that although the MDC is not currently the more sustainable option, design improvements can be made to the MDC that will make this technology much more promising in the future.

Committee:

Ann Christy (Advisor); Bhavik Bakshi (Committee Member); Matthew Roberts (Committee Member)

Subjects:

Agriculture; Alternative Energy; Environmental Management; Environmental Science; Sustainability; Water Resource Management

Keywords:

Microbial Desalination Cell; MDC;Reverse Osmosis; RO; life cycle analysis; LCA; CBA; Cost Benefit Analysis

Nawarange, Amruta V.Optical Emission Spectroscopy during Sputter Deposition of CdTe Solar Cells and CuTe-Based Back Contacts
Doctor of Philosophy, University of Toledo, 2011, Physics

In this dissertation sputtering processes are studied in detail through optical emission spectroscopy. In order to extract plasma parameters, experimental data and simulations were matched together. We could extract excitation temperatures, vibrational temperatures and rotational temperatures of the plasmas. To explain the simulations and to understand the different mechanisms involved in the sputtering plasmas, relevant aspects of atomic spectroscopy and molecular spectroscopy are reviewed here. A mixture of argon and nitrogen gas was used to sputter a CuxTe target by RF magnetron sputtering. The emission data were then studied as a function of deposition pressure and RF power. These data show many non equilibrium aspects of the plasma; however, in most cases the data are consistent with energy distributions of the rotational, vibrational, and electronic systems that can be characterized individually by distinct temperatures.

We have also used sputter deposition of CuxTe thin-film layers instead of our standard Cu/Au metal layers for back contacts to look for an improved back contact. We prepared three different compositions of CuxTe target material and studied the properties of sputtered films using X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM) and Hall measurements. At optimized deposition conditions for Cu2Te target sputtered films (2 nm thickness and 20 minutes annealing in vacuum) as determined from the thin-film properties, we sputtered this layer onto the back surface of the CdTe of the cell structure. We achieved efficiencies of 13.1% using Cu2Te target sputtered films followed by Au which is very close to our best efficiency achieved with Cu/Au contacts.

Committee:

Alvin Compaan, PhD (Advisor); Alvin Compaan, PhD (Committee Chair); Brian Bagley, PhD (Committee Member); Randall Ellingson, PhD (Committee Member); Sanjay Khare, PhD (Committee Member); Dean Giolando, PhD (Committee Member)

Subjects:

Alternative Energy; Condensed Matter Physics; Experiments; Materials Science; Molecular Physics; Physics; Plasma Physics; Solid State Physics; Theoretical Physics

Keywords:

OES

Garimella, Venkata Naga RavikanthExhaust Emissions Analysis for Ultra Low Sulfur Diesel and Biodiesel Garbage Trucks
Master of Science in Civil Engineering, University of Toledo, 2010, Civil Engineering
The main objective of this experimental thesis is to study the exhaust emissions of in-use garbage trucks for different idling modes fuelled with alternate fuels. The emission concentrations of carbon monoxide, sulfur dioxide, oxides of nitrogen (NO, NO2, and NOX), and carbon dioxide were examined with respect to engine parameters such as fuel temperature, coolant temperature and percent fuel. A Testo350 XL portable emission monitoring instrument was used to collect second by second data for the pollutants. Performance of engine parameters was also monitored simultaneously using on-board diagnostic (OBD) software. The tail pipe emissions from Ultra-Low Sulfur Diesel (ULSD) are compared with emissions from biodiesel blends. Hotter engines produced lower emissions compared to colder engines for all fuel blends and vehicle makes. Significant reductions in emission concentrations were observed due to the inspection and maintenance programs. The performance of biodiesel blends in reducing emission concentrations of pollutants across different vehicle makes was found to be inconsistent. A comprehensive study on various vehicle, fuel and operating parameters that effect the exhaust emission concentrations was conducted to find an alternative to ULSD.

Committee:

Ashok Kumar, PhD (Committee Chair); Brian Randolph, PhD (Committee Member); Dong-Shik Kim, PhD (Committee Member)

Subjects:

Alternative Energy; Automotive Engineering; Civil Engineering; Environmental Engineering; Environmental Health; Environmental Science; Environmental Studies; Experiments; Sustainability; Transportation; Urban Planning

Keywords:

biodiesel; ultra low sulfur diesel; diesel; emission; exhaust; garbage truck; portable emission; blends; Idle engine; Alternative fuels; fuel

Call, IsabelSmall-scale biodiesel production: a feasibility study
BA, Oberlin College, 2005, Economics
The objective of the research presented in this paper is the development of cost curves for small-scale biodiesel production and a comparison of relevant technologies. The three technologies considered are the biodiesel pilot plant at the Iowa Energy Center's Biomass Energy Conversion Center, the commercially-sold Fuelmeister, and the bicycle-powered machine currently under development by students at Oberlin College. The price of biodiesel at which production via these technologies becomes profitable and the relative profitability of each will be determined through the use of a linear program. The importance of resource recovery and energy efficiency and the use of recycled feedstocks will be considered.

Committee:

(Advisor)

Subjects:

Alternative Energy; Economics; Environmental Engineering

Keywords:

biodiesel;cost;curves;price;

Gopu, SusmithaEffect of Phosphotungstic Acid in Electrodes on PEMFC Performance at Elevated Temperature and Low Humidity
Master of Science (MS), Ohio University, 2012, Chemical Engineering (Engineering and Technology)
The aim of this study was to enhance PEMFC performance at elevated temperatures and reduced relative humidity. Such an improvement will advance the efforts made towards the integration of PEMFC technology with existing transportation systems. Addition of Phosphotungstic acid (PWA) in the Nafion® electrolyte membrane has proven to be a promising approach to address this issue. The same concept has been extended to Nafion® in the electrode layer. Improved fuel cell performance from PWA incorporated membrane and electrodes has been observed by estimating the primary sources of losses contributed by activation losses, ohmic resistance and mass transport limitations of the supplied reactants to the reaction sites.

Committee:

Anima Bose, PhD (Advisor); Valerie Young, PhD (Advisor)

Subjects:

Alternative Energy; Chemical Engineering; Chemistry; Inorganic Chemistry; Materials Science; Polymer Chemistry; Polymers; Transportation

Keywords:

PEMFC; Phosphotungstic acid; elevated temperature; low relative humidity; electrode modification; nanocomposite

Singh, ShailendraMethodology for Membrane Fabric Selection for Pilot-Bioreactor
Master of Science (MS), Ohio University, 2011, Mechanical Engineering (Engineering and Technology)
Membrane based photobioreactors hold great promise for CO2 fixation using microalgae. Material performance of the membrane will govern the success of the entire system. This study developed a methodology for membrane material selection. In the proposed model, a modified digital logic method was used to determine the relative importance of key performance characteristics such as wetting, algae growth, adhesion, tensile strength, burst strength, creep rate, and chemical resistance. Multiple tests were performed to evaluate the performance characteristics of the membrane fabrics. Performances of the shortlisted fabrics were normalized to values between 0-1. Finally, the calculated scaled values of individual fabrics together with the weighting factor of each property were used to obtain the overall performance index of each fabric. Results indicate that Polyester 4075 is the leading potential fabric for pilot bioreactor membrane construction, followed by Polyester 4043 and Omnisil. Since the performance indices of fabrics were within a close range, more extensive and pilot-scale testing is recommended to make final material selections.

Committee:

David Bayless, PhD (Advisor); Ben Stuart, PhD (Committee Member); Gregory Kremer, PhD (Committee Member); Morgan Vis, PhD (Committee Member)

Subjects:

Alternative Energy; Engineering; Mechanical Engineering

Keywords:

vertical membrane photobioreactor; membrane selection; modified digital logic method; woven fabric; polyester

Balagurunathan, JayakishanInvestigation of Ignition Delay Times of Conventional (JP-8) and Synthetic (S-8) Jet Fuels: A Shock Tube Study
Master of Science (M.S.), University of Dayton, 2012, Mechanical Engineering
The global depletion of petroleum-based fuels has led the world to more closely examine alternate fuels. Therefore, alternate fuels produced from feedstocks such as coal, soybeans, palm oil or switch grass through methods such as coal liquefaction, biomass gasification, and Fischer-Tropsch synthesis have been tested. Among these techniques, fuels generated using Fischer-Tropsch technologies are of interest because they produce clean burning hydrocarbons similar to those found in commercial fuels. Therefore, in this study the Fischer-Tropsch derived S-8 fuel was evaluated as a drop-in replacement for the jet fuel JP-8. The jet fuel JP-8 is comprised of n-, iso- and cyclo- alkanes as well as aromatics while the S-8 fuel is primarily comprised of n- and iso- alkanes. The composition of the fuel affects its ignition characteristics chemically and physically by either advancement or delay of time to ignition. Since this study focused on the chemical effects, the fuels were completely pre-vaporized and pre-mixed. A high pressure, high temperature heated single pulse shock tube was used for this study. The shock tube is an established experimental tool used to obtain ignition delay data behind reflected shock waves under operating conditions relevant to modern engines. The experiments were conducted over a temperature range of 1000-1600 K, a pressure of 19±2 atm, equivalence ratios of 0.5, 1 and 3, within a dwell time of 7.6±0.2 ms and an argon dilution of 93% (v/v). Ignition delay times were measured using the signal from the pressure transducer on the end plate with guidance from the optical diagnostic signal. Along with JP-8 and S-8, the ignition delay of n-heptane was also studied. N-heptane was chosen to represent the n-alkanes in the fuels for this study since it was present in both fuels and also to prove the fact that the n-alkanes were rate controlling. The results indicate that both S-8 and JP-8 fuels have similar ignition delays at corresponding equivalence ratios. The fuel-rich mixtures ignited faster at lower temperatures (<1150 K) and the fuel-lean mixtures ignited faster at higher temperatures (>1150 K). In the transition period between lower to higher temperatures (~1100-1200 K), the equivalence ratio had no significant effect on the ignition delay time. The results also show that the ignition delay time measurements of S-8 and JP-8 fuels are similar to the ignition delay of n-heptane at the equivalence ratio of Φ=0.5 and thereby indicate that the n-alkanes present in these fuels controlled the ignition under these conditions. The ignition delay results of S-8 and JP-8 at Φ=3.0 from this study were also compared to prior work (Kahandawala et al., 2008) on 2-methylheptane and n-heptane/toluene (80/20 liquid vol.%), respectively and found to be indistinguishable. This data serves to extend the gas phase ignition delay database for both JP-8 and S-8 and is the first known data taken for both these fuels at higher temperatures (>1000 K) for an equivalence ratio of 3.0 with argon as the diluent gas.

Committee:

Sukh Sidhu, Dr (Committee Chair); Philip Taylor, Dr (Committee Member); Moshan Kahandawala, Dr (Committee Member)

Subjects:

Aerospace Engineering; Aerospace Materials; Alternative Energy; Automotive Engineering; Automotive Materials; Chemical Engineering; Chemistry; Energy; Engineering; Environmental Engineering; Mechanical Engineering; Petroleum Engineering; Technology

Keywords:

Ignition delay; shock tube; S-8; JP-8; Jet fuels; Fuel characteristics; heated shock tube; Fischer-Tropsch; Alternate fuels; alkanes; synthetic fuel; fuel; iso-alkanes; jayakishan balagurunathan

Bollin, Patrick M.The Production of Fatty Acid Methyl Esters in Lewis Acidic Ionic Liquids
Master of Science in Chemical Engineering, University of Toledo, 2011, Chemical Engineering

Biodiesel is a direct substitute for petroleum derived fules and can be utilized in diesel equipment with few or no modication (Ma, Hanna, 1999). Traditional sources for biodiesel include plant oils (such as soybean or canola) that are also important food sources; biodiesel derived from plants might therefore not result in substantial displacement of petroleum feedstocks. Algae may present itself as an alternate feedstock for biodiesel production that does not compete with the vital land and water resources needed for traditional agriculture. However, the production of fuels from algae is currently economically unviable due to several technological hurdles, including availability of efficient methods of converting cellular lipids to biodiesel.

The research described herein describes the in-situ transesterification of soy flour triglycerides (surrogate for algal biomass) with methanol to fatty acid methyl esters using a novel ionic liquid (IL) comprised of 1-Ethyl-3-methylimidazolium chloride (EMIMCl) and the metal halide AlCl3. This IL exhibits Lewis acidity and has been shown to be an excellent nonvolatile solvent and catalyst for many chemical reactions including acylations, condensations, esterications, and polymerizations. However, it is now proposed that this IL catalyst is able to perform esterication reactions with the addition of an organic solvent that solubilizes the ionic liquid yet allows it to retain its catalytic properties. This method enables the reaction to experience the benefits of homogeneous catalysis while providing an opportunity for catalyst recovery and reuse.

The influences of biomass concentration, catalyst volume, organic solvent/methanol ratios, reaction time, and temperature on the generation of the desired reaction products has been studied. A traditional mechanistic pathway to account for the observed production of fatty acid methyl esters is proposed and the triglyceride carbon mass balance is closed. The sustained catalytic ability of the ionic liquid was explored and the importance of ionic liquid recovery and reuse will be discussed. In addition, preliminary findings regarding the production of acrylates from biomass and Lewis acidic ionic liquids will be presented.

Committee:

Dr. Sridhar Viamajala (Committee Chair); Dr. Maria Coleman (Committee Member); Dr. Sasidhar Varanasi (Committee Member)

Subjects:

Alternative Energy; Chemical Engineering; Environmental Engineering

Keywords:

Ionic liquid; biodiesel; fatty acid methyl ester

Schafer, Guy M.Identifying Bio-Diesel Production Facility Locations for Home Heating Fuel Applications Within the Midwest Region of the United States
Master of Arts, University of Toledo, 2011, Geography

Amid concerns of rising oil prices, interest into researching alternative renewable energy sources has increased in recent years. A great deal of research has been done to investigate the feasibility of liquid bio-fuels. Ethanol and bio-diesel are currently being used as substitutes for petroleum based fuels. These are primarily used for transportation related applications. Recently bio-diesel has also been used as a substitute for heating fuel in residential homes. The purpose of this study is to identify current production, raw material supply, and potential demand markets within the Midwestern United States. Based on these criteria, facility placement location is identified through the utilization of a weighted location model. The final solution was analyzed utilizing a GIS framework. The analysis demonstrates the Weberian tendency of bio-diesel refineries to be spatially oriented toward the raw material source.

The results indicate that a market for bio-heat does exist in the Mid-western United States. However, the conversion of the entire heating fuel market from petroleum to bio-heat does not seem feasible or probable. Current home heating fuel consumption is approximately 96% of the total bio-diesel production in the region. Therefore total market conversion would require the diversion of bio-diesel feedstock from other uses.

Committee:

Peter Lindquist, Dr. (Committee Chair); Daniel Hammel, Dr. (Committee Member); Neil Reid, Dr. (Committee Member)

Subjects:

Alternative Energy; Geography; Transportation

Keywords:

Bio-Diesel; Location Model; Transportation; Home Heating Fuel

von Deak, Dieter G.Heteroatom-containing Carbon Nanostructures as Oxygen Reduction Electrocatalysts for PEM and Direct Methanol Fuel Cells
Doctor of Philosophy, The Ohio State University, 2011, Chemical and Biomolecular Engineering
The main goal of this work was to undertake a fundamental investigation of precious metal-free carbon catalysts nano-structure modification to enable their use as oxygen reduction reaction (ORR) catalysts in proton exchange membrane (PEM) fuel cells. The sluggish ORR is accelerated by fiscally prohibitive loadings of Pt catalyst. The expense and availability of platinum motivate the development of non-precious metal carbon-nitroge-based ORR catalysts (CNx). The project targets the nature of oxygen reduction reaction active sites and exploring ways to create these sites by molecular tailoring of carbon nano-structures. CNx grown with phosphorous had a significant increase in the ORR active site density. CNx catalyst growth media was prepared by acetonitrile deposition over a Fe and P impregnated MgO. Rotating Ring Disk Electrode (RRDE) Activity and selectivity showed a significant increase in oxygen reduction current with CNx grown with less than a 1:1 molar ratio of P:Fe. Selectivity for the full reduction of dioxygen to water trended with increasing ORR activity for phosphorous grown CNx catalysts. Phosphorus growth altered the morphology of carbon-nitride graphite formed during pyrolysis. The role of the transition metal used to form non-noble metal electrochemical oxygen reduction CNx catalysts was investigated through sulfur and carbon monoxide treatments of the CNx and Pt/carbon electrocatalysts. The intent of poisoning was to show the existence of a non-iron containing electrocatalytic active site in CNx. The sulfur treatment increased the overpotential on a platinum catalyst, but enhanced the current density of the CNx catalyst while leaving the CNx iron phase unchanged. CO in the present of oxygen was found to strongly adsorb to platinum and completely eliminate all oxygen reduction. Under identical conditions, CNx showed a displacement of oxygen due to CO and no oxygen reduction poisoning effect. This suggests that either iron-based active site is sulfur and CO tolerant or that this active site does not participate in the electrocatalytic reduction of oxygen in CNx catalysts. Density functional theory (DFT) calculations of small polycyclic aromatic hydrocarbons (PAHs) that have a similar electronic structure to carbon-nitride catalyst materials were preformed. A strong correlation between B3LYP method N 1s energies and experimental N 1s energies was established for the PAHs studied. Additionally, experimental ionization potentials that would correspond to electron donation trended strongly with the DFT adiabatic and vertical ionization potentials. The testing and setup of fuel cell test station was accomplished. Bench scale membrane electrode assemblies (MEAs) were fabricated cell and achieved comparable performance to a commercial MEA constructed from similar materials. A MEA was constructed with a CNx cathode and was found to have fuel cell performance of the same order of magnitude as other graphitic carbon-nitrogen catalysts heat-treated in the presence of a transition metal. Vulcan carbon and CNx catalysts were compared in accelerated carbon corrosion by examining the current of the electrochemically active surface species hydroquinone/quione with cyclic voltammetry after extended potential holds. CNx was found to be more corrosion resistant than Vulcan carbon that is the most commonly used support in fuel cell electrodes.

Committee:

Umit Ozkan, S (Advisor); David Wood, W (Committee Member); James Rathman, F (Committee Member)

Subjects:

Alternative Energy; Analytical Chemistry; Chemical Engineering; Chemistry; Energy; Engineering; Experiments

Keywords:

catalyst; PEM; fuel cell; oxygen reduction; carbon nitride; graphite; XPS; XAS; corrosion; TEM; phosphorus; sulfur; electrochemistry; RRDE

Flores, Saul DomingoCost benefit analysis of wind turbine investment in Oberlin, Ohio
BA, Oberlin College, 2008, Economics

As concern over global climate change and fears of rising energy costs permeate our collective and individual decision making, more and more private institutions are seeking out innovative and feasible solutions to meet these issues. Many colleges and universities throughout the United States have been among the first private and public institutions to dedicate themselves to positions of climate neutrality and have begun to incorporate the ethics of conservation and commitment to environmental sustainability into their primary objectives. To date nearly five hundred institutions of higher education have signed the American College and Universities Climate Change Commitment, pledging to take immediate and prolonged action to reduce their foot print of carbon dioxide and other greenhouse gas emissions. Undoubtedly many of these schools will be able to implement extensive and inexpensive improvements in the efficiency of current facilities and practices in order to meet their objectives. However for those that have committed to complete climate neutrality, such as Oberlin College, additional measures extending beyond the traditional endeavors of an educational institution may also become necessary. One such option that has received attention from the Oberlin community is the construction of a utility scale wind turbine.

Although there are many other alternatives that the College may investigate, the choice to be considered here is between investing in a wind turbine or purchasing carbon offsets commercially. Naturally the college faces tradeoffs as it allocates its budget between turbines, offsets, and its myriad other operational activities, so a cost benefit analysis is particularly useful in comparing the advantages and disadvantages of investment in various turbine models. This paper addresses several primary objectives. First, the analysis conducted here will update previous research on the topic of the viability of wind power in Oberlin by incorporating spot market electricity prices into the calculations of net benefits and by utilizing a more conservative model of the cost schedule. This paper will also address many of the economic issues inherent in the college's desire to minimize expenditures while decreasing its footprint assuming that it will choose the option with the least cost per unit of emissions offset. Using a standard cost benefit analysis, and exploring the sensitivity of the results to a range of parameters, the results show that a wind turbine in Oberlin will under extremely conservative conditions reduce the carbon emissions footprint at a cost comparable to many commercially available carbon offsets, and that as these conditions are relaxed positive net present values emerge.

The rest of the paper will be organized as follows. The next section reviews relevant literature and focuses the motivation of this study. Section 3 is a statistical summary of the electricity price and wind speed data is presented. Following that a description of the procedures used in calculating generation, revenue, cost, and net present value figures is outlined. In section 4 the results are presented in the subsequent section, and discussion of their sensitivity to various parameters as well as various interpretations follow.

Committee:

Jordan Suter (Advisor); Barbara Craig (Other); Hirschel Kasper (Other); David Cleeton (Other); Shreemoy Mishra (Other); John Scofield (Other)

Subjects:

Alternative Energy; Economic Theory; Economics

Keywords:

wind turbine;Oberlin;Ohio;Oberlin College;reduce;carbon footprint;carbon offsets;wind power;electricity;United States;

Merugula, LauraSupporting Sustainable Markets Through Life Cycle Assessment: Evaluating emerging technologies, incorporating uncertainty and the consumer perspective
Doctor of Philosophy, The Ohio State University, 2013, Chemical and Biomolecular Engineering
As civilization's collective knowledge grows, we are met with the realization that human-induced physical and biological transformations influenced by exogenous psychosocial and economic factors affect virtually every ecosystem on the planet. Despite improvements in energy generation and efficiencies, demand of material goods and energy services increases with no sign of a slowing pace. Sustainable development requires a multi-prong approach that involves reshaping demand, consumer education, sustainability-oriented policy, and supply chain management that does not serve the expansionist mentality. Thus, decision support tools are needed that inform developers, consumers, and policy-makers for short-term and long-term planning. These tools should incorporate uncertainty through quantitative methods as well as qualitatively informing the nature of the model as imperfect but necessary and adequate. A case study is presented of the manufacture and deployment of utility-scale wind turbines evaluated for a proposed change in blade manufacturing. It provides the first life cycle assessment (LCA) evaluating impact of carbon nanofibers, an emerging material, proposed for integration to wind power generation systems as blade reinforcement. Few LCAs of nanoproducts are available in scientific literature due to research and development (R&D) for applications that continues to outpace R&D for environmental, health, and safety (EHS) and life cycle impacts. LCAs of emerging technologies are crucial for informing developers of potential impacts, especially where market growth is swift and dissipative. A second case study is presented that evaluates consumer choice between disposable and reusable beverage cups. While there are a few studies that attempt to make the comparison using LCA, none adequately address uncertainty, nor are they representative for the typical American consumer. By disaggregating U.S. power generation into 26 subregional grid production mixes and evaluating the comparison with respect to a representative range of efficiencies in dishwasher units, a realistic comparison was made. A statistical approach was devised to process the available output by combining a Z-score test with the Cox method for confidence intervals. Despite the common use of LCA software with Monte Carlo analysis, this approach to compare distributions has not been discovered in LCA-related literature and offers a straightforward method for extending analysis under conditions of positive skew approximated by a lognormal distribution, which is common in LCA parameters. The two case studies provide product developer and consumer guidance, respectively. They furthermore may be used to inform policy in both direct and nuanced manners. The encouragement of product reuse is facilitated for individuals and organizations providing food-service facilities. Caution in efforts to increase power generation capacity with renewable energy not coupled with reduction of demand is implied.

Committee:

Bhavik Bakshi (Advisor); Jessica Winter (Committee Member); James Rathman (Committee Member)

Subjects:

Alternative Energy; Climate Change; Environmental Education; Environmental Management; Nanotechnology; Systems Science

Keywords:

life cycle assessment; sustainability; environmental impact; nanotechnology; renewable energy

Amin, Majdi TalalDynamic Modeling and Verification of an Energy-Efficient Greenhouse With an Aquaponic System Using TRNSYS
Doctor of Philosophy (Ph.D.), University of Dayton, 2015, Engineering
Currently, there is no integrated dynamic simulation program for an energy efficient greenhouse coupled with an aquaponic system. This research is intended to promote the thermal management of greenhouses in order to provide sustainable food production with the lowest possible energy use and material waste. A brief introduction of greenhouses, passive houses, energy efficiency, renewable energy systems, and their applications are included for ready reference. An experimental working scaled-down energy-efficient greenhouse was built to verify and calibrate the results of a dynamic simulation model made using TRNSYS software. However, TRNSYS requires the aid of Google SketchUp to develop 3D building geometry. The simulation model was built following the passive house standard as closely as possible. The new simulation model was then utilized to design an actual greenhouse with Aquaponics. It was demonstrated that the passive house standard can be applied to improve upon conventional greenhouse performance, and that it is adaptable to different climates. The energy-efficient greenhouse provides the required thermal environment for fish and plant growth, while eliminating the need for conventional cooling and heating systems.

Committee:

John Kissock (Advisor)

Subjects:

Agricultural Engineering; Agriculture; Alternative Energy; Energy; Engineering; Environmental Science; Mechanical Engineering

Keywords:

Energy-Efficiency, Renewable Energy, Greenhouse, Aquaponics, Efficient-Building, Dynamic Simulation

Snyder, Ryan DanielCombinatorial Analysis of Thermoelectric Materials using Pulsed Laser Deposition
Doctor of Philosophy (Ph.D.), University of Dayton, 2016, Materials Engineering
A high-throughput combinatorial approach for exploratory materials research was developed and applied to thermoelectric materials with complex compositions and crystal structures. This approach allows rapid correlation between the composition, structure, and properties to provide an understanding of how these factors impact thermoelectric performance. Combinatorial samples with graded compositions were successfully deposited using pulsed laser deposition for two thermoelectric materials classes, Ca3Co4O9 and CoSb3. These films were subsequently analyzed using high-throughput analytical tools developed as part of this work. These measurements were supplemented with theoretical models, such as the single parabolic band theory, to provide further explanation as to the sources of variation in the composition-structure-property relationships. Several aspects of these complex relationships, such as the non-parabolic band structure of CoSb3 and the formation of secondary phases in Ca3Co4O9 films, were identified and correlated to observed stoichiometric and thermoelectric property variations using this developed combinatorial method. This work represents a multifaceted approach to combinatorial analysis, which can be extended to other material systems and applications. Further enhancements to the material fabrication process, measurement techniques, or models used for analysis can easily be incorporated into the presented combinatorial framework.

Committee:

Andrey Voevodin, Ph.D. (Committee Chair); Evan Thomas, Ph.D. (Committee Member); Paul Murray, Ph.D. (Committee Member); Christopher Muratore, Ph.D. (Committee Member); Wiebke Diestelkamp, Ph.D. (Committee Member)

Subjects:

Alternative Energy; Engineering; Materials Science

Keywords:

Combinatorial; thermoelectric; thin film; pulsed laser deposition

Del Pilar Albaladejo, JoselynHydrothermal and Ambient Temperature Anchoring of Co (II) Oxygen Evolution Catalyst on Zeolitic Surfaces
Doctor of Philosophy, The Ohio State University, 2014, Chemistry
Nature provides a way to transform the most abundant energetic source, sunlight, to chemical fuel. Artificial photosynthetic systems aim to convert solar energy into chemical fuels such as hydrogen through water splitting. Our group has proposed a zeolite-based system capable of mimicking the natural photosynthetic process such as light harvesting and charge separation. However, water splitting requires a catalyst that promotes the reactions. Catalyst that consist of earth abundant metals, such as cobalt, have been shown to catalyze water oxidation efficiently. We have developed two synthetic methods for the anchoring of cobalt catalyst onto zeolitic surfaces. The methods exploit the zeolite characteristic features such as pore size, high surface area and electronegative framework. The methods are optimized utilizing micron and nano-size zeolite crystals and later applied to zeolite membranes supported on polymeric supports. The first method consists of a three step hydrothermal synthetic route. The successful anchoring of 200 nm plate-like clusters onto the surface of micron-size zeolite is reported. Anchored ß-Co(OH)2 clusters undergo a topotactic transformation to Co3O4 at 125 0C. As a consequence, the catalytic activity of the material decreases due to the thermal oxidation. The hydrothermal method was performed using 40 nm zeolite Y particles. Characterization by Raman and XPS spectroscopy showed that the catalyst is an amorphous Co (II) hydroxide that “coats” the zeolite nanocrystals rather than separate clusters. A 5-fold increase in oxygen evolution yield over the micron-size catalyst was observed. The nano-supported clusters were found to be stable for more than one catalytic cycle. The second method exploits pore diameter as a way to control cobalt cluster size. The ambient temperature synthesis uses three bases which vary in cation size: NaOH, TMAOH and TBAOH. Successful size control was achieved as evidenced by “net-like” clusters in NaOH treated samples and 3 nm particles in TMAOH. No cluster formation was observed for TBAOH. The catalytic performance was found to be TMAOH > NaOH > TBAOH. TMAOH samples are effective due to their higher surface area. The oxygen evolution observed for TBAOH is the result of Co2+ ions that remained in the zeolite cages. TMAOH was found to be unstable due to formation of Co(III)OOH during photo catalysis. The hydrothermal and ambient temperature methods were used to anchor Co(II) catalyst onto zeolite membranes surfaces. Upon hydrothermal anchoring of “plate-like” clusters, zeolite membrane layer is removed from the support resulting in removal of the catalyst. Formation of Co3O4 clusters using this method was observed due to poor anchoring of the clusters. We identified the ambient temperature method as the most effective for Co(II) catalyst anchoring. Catalytic performance for the membranes treated with the different bases was TMAOH >TBAOH > NaOH. The performance is dependent on the surface area of the cluster. TMAOH and TBAOH had spherical particles ranging from 30-60 nm on the surface whereas NaOH membranes showed a “film”. Stability of the catalyst may be improved by transformation to Co3O4 via thermal annealing.

Committee:

Prabir Dutta (Advisor); Claudia Turro (Committee Member); Ann Co (Committee Member); Andrea Wolfe (Committee Member)

Subjects:

Alternative Energy; Analytical Chemistry; Chemistry; Inorganic Chemistry; Materials Science

Keywords:

Water Splitting, Cobalt Catalyst, Zeolite, Water Oxidation, Photocatalysis, Nanozeolites, Cobalt Hydroxides, Cobalt Oxides, Zeolite Membranes, Oxygen Evolution

Zhao, JiaEnhancement of Methane Production from Solid-state Anaerobic Digestion of Yard Trimmings by Biological Pretreatment
Master of Science, The Ohio State University, 2013, Food, Agricultural and Biological Engineering
Anaerobic digestion (AD) is a biological process in which organic matter is decomposed by an assortment of microbes under oxygen-free conditions to produce biogas (about 40-70% CH4 and 30-60% CO2). AD is an efficient and mature waste treatment technology that can can not only achieve the goal of waste disposal, but also generates biomethane, a renewable energy source. Based on its total solids percent (TS), AD can be classified as liquid AD (L-AD) or solid-state AD (SS-AD). Even though L-AD has a faster reaction rate and shorter retention time, SS-AD is generally thought to be advantageous over L-AD due to the smaller volume reactor equipment required, less energy input for heating, and because the solid byproduct weighs less, is more conductive to transportation and storage as compared to typical liquid AD effluents. Yard trimmings are one of the main components of municipal solid waste. They are traditionally recycled by composting or disposed of by landfilling. In both process, energy is lost as heat. SS-AD could provide an alternative solution for the treatment of yard trimmings and the recovery of energy as biogas. The challenge of utilizing lignocellulosic biomass such as yard trimmings for SS-AD, however, is its recalcitrant structure, which impedes the hydrolysis of cellulose and hemicellulose. Lignin is believed to be one of the major factors inhibiting lignocellulose hydrolysis. Therefore, pretreatment aimed at removing lignin from yard trimmings prior to SS-AD may improve the degradability of this feedstock. In this study, two biological pretreatment methods for the enhancement of methane production during SS-AD were evaluated. These included fungal pretreatment by Ceriporiopsis subvermispora and composting. The fungal pretreatment study focused on the effect of moisture content (45%, 60% and 75%) and aeration mode (natural aeration, mechanical aeration for 15 min every 12 h and mechanical aeration for 30 min every 24 h) on the holocellulose and lignin loss and on methane yield during SS-AD. It was found that both aeration mode and moisture content had significant effects on the loss of hemicellulose and lignin. The highest lignin loss (20.9%) was obtained from naturally aerated yard trimmings with 60% moisture content as was the highest methane yield (44.6 L/kg VS(original yard trimmings)). Methane yield was positively linearly correlated with lignin degradation. Compared with the methane yield from original yard trimmings (without fungal pretreatment), fungal pretreatment increased the methane yield by up to154%. In addition, a simulated composting was used to pretreat a mixture of yard trimmings and AD effluent. The composting pretreatment was conducted at 45 °C with moisture content of 55% under natural aeration (no extra mechanical aeration) for 30 days. Composted yard trimmings and additional AD effluent were mixed and then fed into SS-AD reactors and placed at 37 °C for 30 days. The results showed no remarkable lignin loss during the composting process. The methane yield from the composted yard trimmings was not improved compared with the methane yield from original yard trimmings (without composting pretreatment). Therefore composting pretreatment did not appear to be a promising approach to improvement of methane yield of yard trimmings during SS-AD.

Committee:

Yebo Li (Advisor); Jay Martin (Committee Member); Frederick Michel (Committee Member)

Subjects:

Agricultural Engineering; Alternative Energy

Keywords:

Solid-state anaerobic digestion; Methane; Yard Trimmings; Fungal Pretreatment; Composting

Congiu, Brian AlexanderConversion of Carbon Dioxide and Hydrogen into Methane in Bench-scale Microcosms and Packed Column Reactors
Master of Science (MS), Wright State University, 2010, Earth and Environmental Sciences
Escalating energy demands, rising costs, and increasing awareness of the environmental impacts of current energy sources have created an immediate need for sustainable, alternative energy resources and innovative fuel technologies. It is believed that a potential carbon-neutral fuel source can be generated through the microbial production of methane gas by methanogenic archaea. Carbon dioxide captured from the atmosphere and renewable production of hydrogen can be used to support these microorganisms for the large-scale production of methane. Bench-scale investigations involving 160 mL serum bottle batch experiments and two 11L packed-column reactors were conducted to evaluate the feasibility and efficiency of microbial conversion of carbon dioxide and hydrogen to methane. The biogeochemical conditions within the microcosms and reactors were monitored and adjusted in order optimize microbial activity and methane production rates. Parameters such as type of solid support media, hydrogen and carbon dioxide partial pressures, soil/non-soil environments, and reactor circulation rate were experimentally varied in order to determine their effect on microbial methane production. Microbial activity was evaluated based on hydrogen and carbon dioxide consumption, methane production, conversion rates and efficiency, organic acid aqueous concentrations, and reaction mass balance. Rapid and efficient methane production observed in the reactors and microcoms indicated that methanogenic archaea can be supported in optimized environments for the sustained production of methane

Committee:

Abinash Agrawal, PhD (Advisor); Mark Goltz, PhD (Committee Member); Steven Higgins, PhD (Committee Member)

Subjects:

Alternative Energy; Biogeochemistry; Environmental Science; Geochemistry

Keywords:

Carbon Dioxide; Hydrogen; Methane; Microcosms; Packed Column Reactors; Methanogenesis; Methanogen

Bosley, Amber L.Algae Characterization and Processing Techniques
Master of Science in Chemical Engineering, University of Toledo, 2011, Chemical Engineering

The concern over the increasing depletion of our nation’s fossil fuels, high oil prices and greenhouse gas emissions, has motivated research for alternative sources of energy. One alternative energy source, biofuels, provides liquid transportation fuels from biomass derived from plant or animal sources. First generation biofuels are produced from food crops abundant in sugars or lipids such as corn and soy. Second generation biofuels are produced from woody, inedible crops such as poplar and switchgrass. The third generation of biofuels is derived from algae and is of growing interest due to its high yield of energy per unit area, use of carbon dioxide for growth, and minimal contribution as a food product. The main carbon rich components of algal biomass include lipid, carbohydrates and protein. Products such as biodiesel and jet fuel can be derived from lipids. Carbohydrates, in the form of fermentable sugars, can be used to produce bioalcohols. Protein can be used as a dietary supplement or as feed for livestock.

This work addresses algal characterization and processing techniques that are helpful in utilizing algae as a feedstock for bioproduct processing. Methods for lipid analysis are compared to select a technique for small sample sizes and ease of handling. The hydrolysis of soybean oil to convert triglycerides (lipids) to free fatty acids is evaluated. A kinetic model is developed to predict reaction behavior and serve as a platform for algal hydrolysis. Characterization techniques to determine the content of algal biopolymers; lipids, carbohydrates and protein are discussed and applied to multiple algal species. Lastly, protein extraction from alga is investigated to prepare species for successful algal hydrolysis.

Committee:

Constance Schall (Advisor); Dong-Shik Kim (Committee Member); Cyndee Gruden (Committee Member)

Subjects:

Alternative Energy; Chemical Engineering

Keywords:

soybean oil glyceride hydrolysis; free fatty acid autocatalyzed hydrolysis; hydrolysis kinetic model; algae lipid analysis; algal transesterification; algal compositional screening; protein extraction; algal processing

Heck, Elizabeth MariaSynthesis of Poly(p-phenylene vinylene) within Faujasite and Linde Type A Zeolites: Encapsulation for Improved Optical Properties
Master of Science, The Ohio State University, 2011, Chemistry

Thin films of conjugated polymers, like poly(p-phenylene vinylene) (PPV) for example, have been widely integrated into LEDs, photo-voltaic devices, and chemical sensors due to their emissive and conductive properties. One disadvantage to these inexpensive materials, however, is that these conjugated systems are susceptible to degradation in ambient conditions. When exposed to oxygen, the double bonds in the polymer backbone are cleaved resulting in the polymer to lose its conductive properties. The primary focus of this research is to encapsulate the polymer within an inorganic framework that will serve to protect the polymer, thereby improving the optical properties, such as quantum yield, and extend the device lifetime.

Zeolites are aluminosilicate crystalline frameworks that are commonly used for their ion-exchange properties and are widely studied in photochemical host-guest interactions. The negatively charged zeolite framework allows for the incorporation of positively charged ions within the void spaces of the framework. A popular PPV synthesis route involves a sulfonium precursor cation, (α,α’-bis-(tetrahydrothiophenio)-p-xylene), which can be readily exchanged into the zeolite. The precursor is a monomer unit of the polymer and under the right conditions will undergo a ‘ship-in-a-bottle’ synthesis to form encapsulated PPV. The inherent basicity of alkali exchanged faujasite X zeolites (NaX, KX, and CsX) as well as Linde type A zeolite, was utilized to induce the polymerization of the sulfonium precursor, followed by thermal elimination under vacuum at 220°C to form fully conjugated PPV.

Formation of PPV was monitored before and after heating of the samples via electronic and vibrational spectroscopy. Characteristic spectra have been obtained for both types of samples, thereby showing the successful formation of PPV oligomers. However, the emission spectra of post-heat samples are more vibronic in nature, lower in intensity, and red-shifted compared to pre-heat samples. X-Ray diffraction shows that the zeolite maintains its crystalline framework, and is not destroyed by the polymerization. As predicted it appears that encapsulation improves the overall optical efficiency of the polymer, shown by increased quantum yields of the PPV-Zeolite composites when compared to pure polymer thin films.

Differences between effective conjugation length and photoluminescence quenching abilities of PPVs formed within X and A suggests that the building schemes of the two are unique. We hypothesize that the polymer chains while contained within the void space of zeolite A, they also extend out onto the surface and block pore openings. Alternatively in zeolite X, PPV is distributed throughout and allows for entry of other molecules into the framework. The framework organization of X also limits the polymer chain length, whereas A allows for extended linear growth.

Committee:

Prabir Dutta, PhD (Advisor); Terry Gustafson, PhD (Committee Member)

Subjects:

Alternative Energy; Analytical Chemistry; Chemistry

Keywords:

zeolite; PPV; encapsulation; conductive polymers; host-guest chemistry

Triplett, Angela LynnVibration-Based Energy Harvesting with Essential Non-Linearities
Doctor of Philosophy, University of Akron, 2011, Mechanical Engineering

The dependence on electrical power and the advancement of new technology devices has driven new research in the area of alternative energy sources. As electronic devices become smaller and more portable, the use of conventional batteries have become less practical. This has lead to an increase in the study of vibration-based energy harvesting and its use as an alternative source of energy. Previously, linear systems have been developed to harvest energy efficiently when the mechanical oscillator is tuned to the appropriate excitation frequency. This tuning requirement limits the application to a narrow bandwidth of frequencies and puts significant demand on properly designing the system to match a specific excitation. By incorporating non-linearities in the design and analysis of energy harvesting devices, an increase in the performance of the harvester and versatilely of application can be achieved.

This work investigates the role of non-linearities in the mechanical component on the performance of energy harvesting systems, and their advantages compared to a typical linear harvesting system. In particular, an energy harvester that incorporates a piezoelectric element as the attachment and exhibits strong non-linear behavior is analyzed through numerical and analytical simulations, as well as an experimental validation of the simulations. The harvester is subjected to an excitation of ambient vibrations of either a periodic impulsive or harmonic manner. Strong non-linearities are obtained by either the geometric design of the system or by attaching non-linear springs to the primary mass of a spring-mass-damper system. Under certain operating conditions, the resulting unique dynamic behavior of the non-linear system increases the efficiency in comparison to a single degree-of-freedom linear energy harvester.

The use of strongly non-linear energy harvesters as vibration absorbers was also investigated. Vibration absorbers have been shown to be efficient over a wide bandwidth of frequencies when multiple non-linear masses are attached to the primary mass of a linear oscillator. In this work, the conventional vibration absorber described by [21], is enhanced by the insertion of an energy harvester in series with with the non-linear spring. The results indicate an increase in the efficiency of the vibration absorber, while simultaneously creating a proficient energy harvester.

Committee:

D. Dane Quinn, Dr. (Advisor); Tom Hartley, Dr. (Committee Member); Curtis Clemons, Dr. (Committee Member); Jiang Zhe, Dr. (Committee Member); Ernie Pan, Dr. (Committee Member)

Subjects:

Alternative Energy; Applied Mathematics; Energy; Engineering; Mechanical Engineering; Technology

Keywords:

energy harvesting; NES; non-linear; elliptic functions; method of averaging; impulse; piezoelectrics

Esbenshade, Aaron JDifferential Protein Expression and Butanol Production using Clostridium beijerinckii
Master of Science in Biological Sciences, Youngstown State University, 2012, Department of Biological Sciences
Current events demand new forms of renewable energy. Ethanol from fermentation has been the standard in biofuel for years, but not for long. It has become apparent that ethanol has serious drawbacks. Ethanol is more corrosive to engines and only has approximately 60% the energy content of gasoline per gallon. This problem may be remedied by the use of butanol. Butanol is far less corrosive than ethanol and holds 95% the energy of gasoline per gallon. Our research uses the bacterium Clostridium beijerinckii as the model for the fermentative production of butanol using discarded lignocellulose from biomass, specifically wood. The wood biomass (wood chip), is processed by treatment with high temperature and pressure, resulting in a hydrolysate consisting of free sugars and other breakdown products of cellulose and hemi-cellulose. We have been able to grow C. beijerinckii in media containing xylose or glucose as the principle sugars, both which are present in the wood extract. We had limited success growing bacteria in media whose only carbon source (sugar). is wood hydrolysate. Analysis has shown that the sugar concentrations in these wood extracts were too low to support significant growth. More highly concentrated versions of the hydrolysate appeared to kill the organism completely presumably due to the increased inhibitory compounds. We continued to study the bacterial proteome in efforts to identifying key proteins that play role in the overall process of butanol fermentation. In the future we hope to genetically engineer microorganisms to efficiently carry out butanol fermentation at commercially significant levels. We were also able to find that the scaled up version of the reaction provided significantly higher production of butanol, presumably due to a more consistent growth environment.

Committee:

Gary Walker, Ph.D. (Advisor); Douglas Price, Ph.D. (Committee Member); Jonathan Caguiat, Ph.D. (Committee Member)

Subjects:

Alternative Energy; Biology; Microbiology; Molecular Biology

Keywords:

Clostridium Beijerinckii;butanol;biofuel;differential protein

Kennedy, Edward NelsonThe Electrochemical Behavior Of Molybdenum And Tungsten Tri-Nuclear Metal Clusters With Ethanoate Ligands
Doctor of Philosophy (PhD), Wright State University, 2017, Environmental Sciences PhD
The goal of this research was to study the electrochemical behavior of tri-nuclear clusters of molybdenum and tungsten. In addition, the feasibility of using these clusters as catalysts for the purpose of oxidizing ethanol was investigated. Four tri-nuclear cluster compounds were studied: hexa-µ2-acetatotriaquadi-µ3-oxotrimolybdenum (IV, IV, IV) trifluoromethanesulfonate [Mo3O2(O2CCH3)6(H2O)3](CF3SO3)2, hexa-µ2-acetatotriaquadi-µ3-oxodimolybdenum (IV, IV) tungsten (IV) trifluoromethanesulfonate [Mo2W2O2(O2CCH3)6(H2O)3](CF3SO3)2, hexa-µ2-acetatotriaquadi-µ3-oxomolybdenum (IV) ditungsten (IV, IV) trifluoromethanesulfonate [MoW2O2(O2CCH3)6(H2O)3](CF3SO3)2, and hexa-µ2-acetatotriaquadi-µ3-oxotritungsten (IV, IV, IV) trifluoromethanesulfonate [W3O2(O2CCH3)6(H2O)3](CF3SO3)2. Data was gathered from experimental results with cyclic voltammetry for the four tri-nuclear clusters. Initially, an ionic liquid, EMIBF4 (1-ethyl-3-methylimidazolium tetrafluoroborate), was used as the solvent. Subsequent solvents for use with these clusters were investigated, including ACN (acetonitrile) and NMF (N-methylformamide). The secondary solvent system settled on was the DMSO-TBAHFP solvent system. Each tri-nuclear cluster displayed a reversible redox reaction and one or more irreversible reduction reactions. The redox peak potentials were found to be Ep,a: -0.44V and Ep,c: -0.42V for Mo3, Ep,a: -0.32V and Ep,c: -0.43V for Mo2W, Ep,a: -0.31 V and Ep,c: -0.44 V for MoW2, and Ep,a: -0.42 and Ep,c: -0.46 for the W3 tri-nuclear cluster. The irreversible reduction reactions for each tri-nuclear cluster were observed at Ep,c(2): -0.74 for Mo3, Ep,c(2): -1.15 for Mo2W, Ep,c(2): -1.14 for MoW2, and Ep,c(2): -0.84 for the W3 tri-nuclear cluster. The diffusion coefficients in DMSO were determined to be DMo3 = 9.105E-06 cm2s-1, DMo2W = 1.743E-05 cm2s-1, DMoW2 = 1.764E-05 cm2s-1, and DW3 = 1.991E-05 cm2s-1. Exploring the electrocatalytic capability of these compounds was another effort made, by attempting to electroplate the compounds on platinum electrodes. Although some types of deposition events did appear to occur, it is unlikely they were of the intact tri-nuclear clusters. Thus far, the ethanol molecule has been partially oxidized, but breaking the carbon-carbon bond in the molecule proved to be a challenge that was not achieved.

Committee:

Vladimir Katovic, Ph.D. (Advisor); Jay Johnson, Ph.D. (Advisor); Suzanne Lunsford, Ph.D. (Committee Member); William Heineman, Ph.D. (Committee Member); Christopher Barton, Ph.D. (Committee Member); Doyle Watts, Ph.D. (Committee Member)

Subjects:

Alternative Energy; Chemistry; Environmental Science; Materials Science

Keywords:

Tri-nuclear clusters; diffusion coefficient; cyclic voltammetry; electrodeposition; molybdenum; tungsten

Vadlamani, AgasteswarEnhanced Biomass and Lipid Productivities of Outdoor Alkaliphilic Microalgae Cultures through Increased Media Alkalinity
Doctor of Philosophy, University of Toledo, 2016, Engineering
A major challenge to the economic viability of outdoor cultivation of microalgae is the high cost of CO2 supply, even when microalgae farms are co-located with point sources of CO2 emissions. In addition, the global capacity for algae biofuel generation is severely restricted when farm locations constrained by proximity to CO2 sources along with the additional limitations of low slope lands and favorable climate. One potential solution to the impediments of CO2 cost and availability is through the cultivation of microalgae in highly alkaline pH solutions (pH>10) that are effective at scavenging CO2 from the atmosphere at high rates. The extreme alkaline pH media would also mitigate culture crashes due to microbial contamination and predators. In this thesis, we report the indoor and outdoor cultivation of a microalgae isolate (Chlorella sp. str. SLA-04) adapted to grow in unusually high pH environments. The isolate was cultivated in a growth medium at pH>10 without any inputs of concentrated CO2. Initial cultivation studies (both indoor and outdoor) resulted in biomass and lipid productivities that were comparable to those reported for other microalgae cultures cultivated in near-neutral media (pH 7-8.5). SLA-04 cultures also showed high lipid productivity and high glucose-to-lipid conversion efficiency when cultivated indoors mixotrophically in the presence of glucose as an organic carbon source. Following this, experiments were performed to determine the effect of pH and bicarbonate (HCO3-) concentrations on biomass productivity of str. SLA-04. Increased HCO3- concentrations in the culture medium resulted in an increase in the overall biomass productivity of str. SLA-04 (22 g-biomass·m-2·d-1). Simultaneously, the high medium pH (pH >10) led to increased mass transfer rates of CO2 from the atmosphere. The improved CO2 uptake rates from the atmosphere resulted in the replenishment of HCO3- utilized during the growth of SLA-04. The quantum yields and photosynthetic parameters were also analyzed under high pH and HCO3- conditions. Maximum quantum yield (Fv/Fm), an indicator of stress for microalgae, was > 0.65, suggesting that high pH conditions did not affect the photosynthetic activity of str. SLA-04. Further, high HCO3- concentrations in the culture medium also improved the effective quantum yield (Y II) and electron transfer rates (ETR). The increase in Y (II) and ETR would suggest that high cellular dissolved inorganic carbon (HCO3-) flux under high HCO3- medium conditions could have driven the light-dependent reactions (in the thylakoid membrane) towards higher production of NADPH for use in carbon fixation. Finally, large-scale cultivation studies were conducted to verify the reproducibility of biomass productivity of SLA-04 cultures under high pH and HCO3- medium conditions. Our results showed that high biomass and lipid productivities (~20 g-biomass·m-2·d-1 and 2.3 g-FAMEs·m-2·d-1) were obtained and were similar to the results achieved in small raceway open ponds. Overall, our phototrophic cultivation studies demonstrate that biomass and lipid productivities can be improved under high pH and HCO3- conditions without additional concentrated CO2 inputs. Though high phototrophic productivities were achieved in the highly alkaline media, we recognized that achieving consistently high productivities throughout the year is difficult, especially during winter months due to shorter days and colder temperatures. One potential strategy to improve overall productivity and/or maintain consistently high productivity in the winter months is through mixotrophic cultivation. However, the high probability of rapid microbial contamination in outdoor reactor systems containing organic substrates have precluded the use of this approach by others. Since extreme alkaline pH media is expected to mitigate detrimental microbial contamination and predators, we assessed the feasibility of outdoor open pond mixotrophic cultivation of str. SLA-04 in a high pH growth medium (>10) supplemented with glucose. Three cultivation trials (of 10-12 d duration each) were performed in outdoor non-sterile raceway ponds. SLA-04 cultures grew well during all trials and no detrimental bacterial contamination was detected. The mixotrohically grown cultures showed significantly higher biomass and lipid productivities when compared to previously reported outdoor phototrophic cultivation studies. The lipid yield was measured to be 0.36 g-FAMEs·g-glucose-1. To further improve the glucose-to-lipid conversion efficiency, a lipid-boost strategy was implemented wherein str. SLA-04 was first allowed to grow phototrophically until N-depletion followed by addition of glucose. The lipid-boost strategy significantly improved the lipid yields to 0.46 g-FAMEs·g-glucose-1. Compared to the glucose conversion efficiencies for previously reported microalgae as well as oleaginous yeast, the conversion efficiencies obtained under both mixotrophic and lipid-boost conditions were high. Overall, our results suggest that extreme growth conditions (pH>10) of str. SLA-04 enabled high-productivity mixotrophic and lipid-boost cultivation, even under non-sterile outdoor conditions.

Committee:

Sridhar Viamajala (Committee Chair); Sasidhar Varanasi (Committee Member); Patricia Relue (Committee Member); Arunan Nadarajah (Committee Member); Ronald Fournier (Committee Member)

Subjects:

Alternative Energy; Chemical Engineering

Keywords:

microalgae, biofuel, alkaliphilic, phototrophic, mixotrophic, lipid-boost, photosynthesis, lipid, outdoor cultivation, raceway ponds, photobioreactor, carbon dioxide, mass transfer rates

Baral, Nawa RajTechno-economic Analysis of Butanol Production through Acetone-Butanol-Ethanol Fermentation
Doctor of Philosophy, The Ohio State University, 2016, Food, Agricultural and Biological Engineering
Butanol is a next generation liquid biofuel, which can be produced through acetone-butanol-ethanol (ABE) fermentation using lignocelluloses including agricultural residues, forest residues, and energy crops. While butanol is superior to ethanol in terms of fuel properties, its commercial production is still encumbering due to low product yield, energy intensive recovery method and butanol toxicity to microbes. However, recent developments of simultaneous saccharification, fermentation and recovery techniques have potential to reduce these problems and improve butanol yield. Before commercial deployment, these recent developments on ABE fermentation technology require a thorough assessment of techno-economic feasibilities and bottlenecks. Thus, the main objective of this research was to assess the techno-economic feasibility of a biorefinery producing 113.5 million liters per year (30 million gallons per year) butanol through ABE fermentation. This study compared different components of butanol production system including feedstock supply logistics, pretreatment, fermentation and recovery, and stillage utilization methods. All the techno-economic models were developed in modeling software-SuperPro Designer. Different process and operating parameters for different components were gathered from existing literature and used as the main input to the models. Corn stover feedstock supply logistics cost ($/metric ton, dry) was estimated to be 112.1 when corn stover feedstock was assumed to be directly transported from field edge to biorefinery. This mode of feedstock transportation was found to be feasible for the biorefinery capacity considered in this study. Sulfuric acid pretreatment was found to be the most economic process with sugar production cost ($/kg) of 0.42 when compared to other most common pretreatment processes considered in this study such as steam explosion, ammonia fiber explosion, ionic liquid and biological. Based on current state of these different recovery methods, such as conventional distillation, vacuum recovery, gas stripping and liquid-liquid extraction, the lower butanol production cost ($/L) of 1.27 ($1.54/L-gasoline equivalent) was found under gas stripping recovery method. Other recovery methods require further research and development efforts to be competitive with gas stripping. Moreover, estimated stillage processing cost ($/L-butanol produced) of direct combustion system and fast pyrolysis system were found to be 0.15 and 0.17, respectively. Based on current state of technology, stillage utilization with direct combustion was found to be an economic stillage utilization method due to the lower stillage utilization cost. Integrating the most economic options discussed so far, the butanol production cost ($/L) at 95 % confidence interval was found to be 0.69-1.57 and 1.34-2.53 with and without considering byproducts’ credit, respectively. Energy conversion efficiency for the overall butanol production process was about 53.83 %. With further improvement in butanol yield of 30 g/100 g fermentable sugars, 98 wt% butanol recovery, glucose and xylose yield of 90 g/100 g initial glucan and xylan, feedstock supply cost of $64/metric ton (dry) and commercial selling value for acetone of $0.79/L, butanol production cost through ABE fermentation could be reduced to $0.47/L-butanol ($0.57/L-gasoline equivalent). This cost is very optimistic at present state of technology, which requires further research and development efforts to be economically competitive with last two years average corn ethanol cost of $0.37/L ($0.55/L-gasoline equivalent) and last 15 years average gasoline price of $0.65/L.

Committee:

Ajay Shah (Advisor); Frederick C. Michel (Committee Member); John P. Fulton (Committee Member); Thaddeus C. Ezeji (Committee Member)

Subjects:

Agricultural Engineering; Alternative Energy

Keywords:

Corn stover; feedstock supply logistics; pretreatment; ABE fermentation; butanol recovery; stillage utilization; techno-economic analysis

Niechayev, Nicholas AlexanderThe Environmental Productivity and Photosynthetic Light Response of Agave americana: A Potential Semi-Arid Biofuel Feedstock
Master of Science (MS), Ohio University, 2016, Environmental Studies (Voinovich)
The potential for the desert succulent species Agave americana (L.) as an advanced biofuel crop in water limited regions has recently been recognized. However, the potential productivity of A. americana in the United States is not yet fully understood. This study developed an environmental productivity index (EPI) model that can be used to estimate the actual growth of A. americana based on the seasonal patterns of water, temperature, and photosynthetically active radiation (PAR) on a monthly time scale for any given region. Previously published research was used to construct indices that predict growth responses of A. americana to water and temperature. Light responses, however, have not previously been determined for this species, and this study is the first to experimentally resolve the physiological response of A. americana to varying intensities of PAR. The photosynthetic response to light was determined by measuring gas exchange over 24 hours in plants that were acclimated to varied light levels over 10 days. Results were used to derive a predictive index of the growth response to light. Maximum CO2 fixation rates were observed at a light intensity of 1250 µmol photons m-2 s-1. A monthly EPI was calculated as the product of the water, temperature, and light indices appropriate for the monthly environmental conditions in Maricopa, AZ, where the first trial of A. americana was recently completed. Growth predicted using the EPI was compared to actual production. The summed EPI values were highly correlated (R2 = 0.99) with the average total biomass of healthy 2 and 3 year old plants. Quantitative relationships derived here between environmental conditions and production of A. americana provide a simple tool to estimate and compare potential productivity across regions where this species has not yet been grown, and to determine potential geographic ranges in the future as climate changes.

Committee:

Sarah Davis, Dr. (Advisor); David Rosenthal, Dr. (Advisor); Ahmed Faik, Dr. (Advisor)

Subjects:

Agriculture; Agronomy; Alternative Energy; Biochemistry; Biology; Botany; Cellular Biology; Energy; Environmental Science; Environmental Studies; Horticulture; Plant Biology; Plant Sciences

Keywords:

crassulacean acid metabolism; light response; Li-Cor 6400; environmental productivity index; abiotic responses; agave americana; CAM; arid; semi-arid; bioenergy; climate change; PEPC; phosphoenolpyruvate carboxylase; scyphophorus acupunctatus; range; GIS

Next Page