A novel electrode was constructed and tested in a bio-battery. This configuration consisted of a composite electrode with immobilized bacteria (Escherichia coli K-12) in the anode and a composite electrode with immobilized Carbon Nanoparticles (CNP) and algae (Chlorella vulgaris/Scenedesmus sp.) suspended in the cathode. The composite electrode consisted of three parts: a 304L stainless steel mesh base, an electro-polymerized layer of pyrrole, and an electro-polymerized layer of methylene blue. The bacteria were immobilized on the anode electrode using a technique incorporating CNP and a Teflontm emulsion. The anode and cathode electrodes were tested separately in conjunction with chemical cathodes and anodes respectively. The composite electrode with immobilized bacteria was tested in a bioanode setup. The cathode chamber of the cell contained a potassium ferricyanide and buffer solution with a graphite electrode. Factors affecting electrode performance, such as Teflontm and carbon nanoparticle concentration, were investigated to find optimum values. The maximum power density generated by the composite electrode with immobilized bacteria and a chemical cathode was 378 mW/m2. This electrode configuration produced approximately 69% more power density and 53% more current density than composite electrodes with bacteria suspended in solution. Electrochemical Impedance Spectroscopy analysis determined that a significant portion of the bio-battery’s resistance to charge transfer occurred at the surface of the anode and this resistance was significantly lowered when using immobilized bacteria (51% lower than bio-batteries with suspended bacteria). Similarly, biocathodes containing composite electrodes coated with CNP were tested using two algae species, Chlorella vulgaris and Scenedesmus sp., suspended in solution. This electrode configuration was compared with composite electrode without CNP coating. The anode chamber contained potassium ferrocyanide solution with a graphite counter electrode. The composite electrode with CNP produced approximately 23% more current density than composite electrode without CNP. A complete bio-battery was designed using a composite electrode with immobilized bacteria anode and a CNP coated composite electrode with algae suspended in the cathode. EIS analysis showed that the resistance was higher in the biocathode than in the bioanode and a significant portion of the ohmic resistance was contributed by the membrane.

Microbial fuel cells (MFCs) are novel green technologies that convert chemical energy stored in biomass into electricity through microbial metabolisms. Both fossil fuel depletion and environmental concern have fostered significant interest in MFCs for both wastewater treatment and electricity generation. However, MFCs have not yet been used for practical applications due to their low power outputs and challenges associated with scale-up. High throughput screening devices for parallel studies are highly necessary to significantly improve and optimize MFC working conditions for future practical applications. Here in this research, microfabricated platforms of microbial fuel cell array as high throughput screening devices for MFC parallel studies have been developed. Their utilities were described with environmental sample screening to uncover electricigens with higher electrochemical activities. The first version of the MFC arrays is a batch-mode miniaturized 24-well MFC array using ferricyanide as catholyte. Several environmental species that showed higher electricity generation capabilities than Shewanella oneidensis MR-1 (SO) were uncovered using the developed MFC array, with one environmental electricigen, Shewanella sp. Hac353 (dq307734.1)(7Ca), showing 2.3-fold higher power output than SO. The second MFC array platform developed is an air-cathode MFC array using oxygen in air as electron acceptor, which is sustainable compared to ferricyanide that depletes over time. Environmental electricigen screenings were also conducted, showing parallel comparison capabilities of the developed array. The third MFC array platform is a microfluidic-cathode MFC array that enables long-term operations of miniature MFC arrays with improved power generation abilities. The capability of the microfluidic-cathode MFC array to support long-term parallel analysis was demonstrated by characterizing power generation of SO and 7Ca, proving extended operation time and improved power outputs compared to batch-mode MFC array. The fourth MFC array platform enables both catholyte and anolyte replenishments for long-term characterization of various carbon substrate performances. Finally, the 24-well microfluidic MFC array was further scaled up to 96 wells, which greatly increased the throughput of MFC parallel studies. The developed MFC arrays as high throughput screening platforms are expected to greatly impact how current MFC studies are conducted and ultimately lead to significant improvement in MFC power output.

Fuel cell technology has undergone significant development in the past 15 years, spurred in part by its unique energy conversion characteristics; directly converting chemical energy to electrical energy. As fuel cell technology has past through the prototype/pre-commercialisation development, there is increasing interest in manufacturing and application issues. Of the six different fuel cell types pursued commercially, the Proton Exchange Membrane (PEM) fuel cell has received the greatest amount of research and development investment due to its suitability in a variety of applications. A particular application, to which state-of-the art PEMFC technology is suited, is backup/uninterruptible power supply (UPS) systems, or stand-by power systems. The most important feature of any backup/UPS system is reliability. Traditional backup power systems, such as those utilising valve regulated lead acid (VRLA) batteries, employ remote testing protocols that acquire battery state-of-health and state-of-charge information. This information plays a critical role in system management and reliability assurance. A similar testing protocol developed for a PEM fuel cell would be a valuable contribution to the commercialization of these systems for backup/UPS applications. This thesis presents a novel testing and analysis procedure, specifically designed for a PEM fuel cell in a backup power application. The test procedure electronically probes the fuel cell in the absence of hydrogen. Thus, the fuel cell is in an inactive, or passive, state throughout the testing process. The procedure is referred to as the passive state dynamic behaviour (PSDB) test. Analysis and interpretation of the passive test results is achieved by determining the circuit parameter values of an equivalent circuit model (ECM). A novel ECM of a fuel cell in a passive state is proposed, in which physical properties of the fuel cell are attributed to the circuit model components. Therefore, insight into the physical state of the fuel cell is achieved by determining the values of the circuit model parameters. A method for determining the circuit parameter values of many series connected cells (a stack) using the results from a single stack test is also presented. The PSDB test enables each cell in a fuel cell stack to be tested and analysed using a simple procedure that can be incorporated into a fuel cell system designed for backup power applications. An experimental system for implementing the PSDB test and evaluating the active performance of three different PEM fuel cells was developed. Each fuel cell exhibited the same characteristic voltage transient when subjected to the PSDB test. The proposed ECM was shown to accurately model the observed transient voltage behaviour of a single cell and many series connected cells. An example of how the PSDB test can provide information on the active functionality of a fuel cell is developed. This method consists of establishing baseline performance of the fuel cell in an active state, in conjunction with a PSDB test and identification of model parameter values. A subsequent PSDB test is used to detect changes in the state of the fuel cell that correspond to performance changes when the stack is active. An explicit example is provided, where certain cells in a stack were purposefully humidified. The change in state of the cells was identified by the PSDB test, and the performance change of the effected cells was successfully predicted. The experimental test results verify the theory presented in relation to the PSDB test and equivalent circuit model.

The growth of distributed energy resources together with the incorporation of new technologies in the generation and storage of energy are imposing new control and operational strategies. Due to its storage capability and that it is considered to be clean energy; fuel cell (FC) is one of the most promissory technologies as a stationary energy source in micro grids and also in transportation applications. Therefore, two main issues are addressed in this work; the conception, design, and setup of a fully instrumented test bench for proton exchange membrane (PEM) FC stacks and the design and experimental test of a new dynamic energy-exchange control strategy for multi source and multi load systems. To define the test bench instrument requirements, in the first part a complete dynamic model review is given. In the next section, relevant information regarding the setup of the FC test bench design and implementation is included, i.e., specification criteria of the instruments and acquisition and data display system. Some experimental results are performed in order to demonstrate the potentialities of the setup. In the following chapter, a new dynamic energy exchange control strategy (DSER) is introduced and tested in a two port system via simulation and experimentation. In order to establish a comparison and integrate the DSER in a FC application, in the fifth chapter a three port system - including a static model of FC - and two different control approaches, are tested via simulation. The thesis is closed with some concluding remarks and some potential research topics generated from this work.

Solid oxide fuel cells (SOFCs) are promising power generation devices due to its high efficiency and low pollutant emissions. SOFCs operate with a wide range of fuels from hydrogen (H2) to hydrocarbons, and are mainly intended for stationary power generation. Compared to combustion systems, SOFCs have significantly lower environmental impacts. However, the full scale commercialization of SOFCs is impeded by high cost and problems associated with long-term performance and durability. The cell performance can be affected by various internal losses, involving cathode, anode and electrolyte. Anodic losses make a significant contribution to the overall losses, practically in anode-supported cells. Therefore, it is desirable to reduce the anodic losses in order to enhance the overall cell performance. Knowledge of the actual elementary reaction steps and kinetics of electrochemical reactions taking place on the anode is critical for further improvement of the anode performance. Since H2 and carbon monoxide (CO) are the primary reforming products when hydrocarbons are used as SOFC fuels, investigation of electrochemical reactions involving H2 and CO should provide a better understanding of SOFC electrochemical behavior with hydrocarbon feeds. However, still exist uncertainties concerning both H2 and CO electrochemical reactions. The overall objective of this research is to investigate the mechanistic details of H2 and CO electrochemical reactions on SOFC anodes. To achieve this objective, Ni/YSZ pattern anodes were used in the experimental study and as model anodes for the simulation work due to their simplified 2-D structure. The Ni/YSZ pattern anodes were fabricated using a bi-layer resist lift-off method. Imaging resist nLOF2035 and sacrificial resist PGMI SF11 were found to be effective in the bi-layer photolithographic process. Suitable undercut size was found critical for successful pattern fabrication. A simple method, involving taking microscopic photographs of photoresist pattern was developed, to check if the undercut size is large enough for the lift-off; semi-circle wrinkles observable in photographs indicate whether the undercut is big enough for successful pattern anode fabrication. The final product prepared by this method showed straight and clear Ni patterns. A systematic study was performed to determine the stable conditions for Ni/YSZ pattern anode performance. The microstructure and electrochemical behavior changes of the pattern anode were evaluated as a function of Ni thickness, temperature and H2O content in H2 environment. Ni/YSZ pattern anodes with 0.5 µm thick Ni were tested in dry H2 at 550°C without significantly changing the TPB line. Ni/YSZ pattern anodes with Ni thickness of 0.8 µm were tested at 550°C under dry and humidified H2 (3-70% H2O) conditions without TPB line change. For 0.8 µm thick patterns, the TPB length showed pronounced changes in the presence of H2 with 3-70% H2O at 700°C. Significant increase in TPB length due to hole formation was observed at 800°C with 3% and 10% H2O. Ni/YSZ pattern anodes with 1.0 µm thick Ni were stable in H2 with 3% H2O in the range 500-800°C, with only slight changes in the TPB line. Changes of TPB line and Ni microstructure were observed in the presence of 3-70% H2O above 700C. Stabilization of the pattern anode performance depends on temperature. To accelerate stabilization of the cell, pre-treatment of the cell in H2 with 3% H2O for ~22 hrs at 750°C or 800°C could be performed. In addition, comprehensive data sets for H2 and CO electrochemical oxidation reactions on Ni/YSZ pattern anodes were obtained under stable test conditions. For the H2/H2O system, the polarization resistance (Rp) increases as temperature, overpotential, H2 partial pressure, TPB length decreases. Rp is also dependent on H2O content. When the H2O content is between 3% and 30-40%, Rp decreased with increasing H2O content. However, Rp is less affected with further increases in H2O content. For the CO/CO2 system, polarization resistance depends on partial pressure of CO and CO2, temperature and overpotential. Moreover, the polarization resistance decreases when the partial pressure of CO2 and temperature increase. The partial pressure of CO has a positive effect on the polarization resistance. The polarization resistance decreases to a minimum when the overpotential is 0.1 V. For both H2 and CO electrochemical oxidations, charge transfer reactions contribute to the rate limiting steps. A 1-D dynamic SOFC half-cell model considering multiple elementary reaction kinetics was developed. The model describes elementary chemical reactions, electrochemical reactions and surface diffusion on Ni/YSZ pattern anodes. A new charge transfer reactions mechanism proposed by Shishkin and Ziegler (2010) based on Density Functional Theory (DFT) was investigated through kinetic modeling and pattern anode experimental validation. This new mechanism considers hydrogen oxidation at the interface of Ni and YSZ. It involves a hydrogen atom reacting with the oxygen ions bound to both Ni and YSZ to produce hydroxyl (charge transfer reaction 1), which then reacts with the other hydrogen atom to form water (charge transfer reaction 2). The predictive capability of this reaction mechanism to represent our experimental results was evaluated. The simulated Tafel plots were compared with our experimental data for a wide range of H2 and H2O partial pressures and at different temperatures. Good agreements between simulations and experimental results were obtained. Charge transfer reaction 1 was found to be rate-determining under cathodic polarization. Under anodic polarization, a change in rate-limiting process from charge transfer reaction 1 to charge transfer reaction 2 was found when increasing the H2O partial pressure. Surface diffusion was not found to affect the H2 electrochemical performance.

The University of Waterloo Alternative Fuels Team (UWAFT) is a student team that designs and builds vehicles with advanced powertrains. UWAFT uses alternatives to fossil fuels because of their lower environmental impacts and the finite nature of oil resources. UWAFT participated in the EcoCAR Advanced Vehicle Technology Competition (AVTC) from 2008 to 2011. The team designed and built a Hydrogen Fuel Cell Plug-In Hybrid Electric Vehicle (FC-PHEV) and placed 3rd out of 16 universities from across North America. UWAFT design projects offer students a unique opportunity to advance and augment their core engineering knowledge with hands-on learning in a project-based environment. The design of thermal management systems for powertrain components is a case study for design engineering which requires solving open ended problems, and is a topic that is of growing importance in undergraduate engineering courses. Students participating in this design project learn to develop strategies to overcome uncertainty and to evaluate and execute designs that are not as straightforward as those in a textbook. Electrical and control system projects require students to introduce considerations for reliability and robustness into their design processes that typically only focus on performance and function, and to make decisions that balance these considerations in an environment where these criteria impact the successful outcome of the project. The consequences of a failure or unreliable design also have serious safety implications, particularly in the implementation of powertrain controls. Students integrate safety into every step of control system design, using tools to identify and link together component failures and vehicle faults, to design detection and mitigation strategies for safety-critical failures, and to validate these strategies in real-time simulations. Student teams have the opportunity to offer a rich learning environment for undergraduate engineering students. The design projects and resources that they provide can significantly advance student knowledge, experience, and skills in a way that complements the technical knowledge gained in the classroom. Finding ways to provide these experiences to more undergraduate students, either outside or within existing core courses, has the potential to enhance the value of program graduates.

The scalable syntheses of functional, porous nanostructures with tunable three-dimensional morphologies is a significant challenge with potential applications in chemical, electrical, electrochemical, optical, photochemical, and biochemical devices. As a result, several bio-enabled and synthetic approaches are explored in this work (with an emphasis on peptide-enabled deposition) for the generation of aligned nanotubes of nanostructured titania for application as electrodes in dye-sensitized solar cells and biofuel cells. As part of this work, peptide-enabled deposition was used to deposit conformal titania coatings onto porous anodic alumina templates under ambient conditions and near-neutral pH to generate aligned, porous-wall titania nanotube arrays that can be integrated into dye-sensitized solar cells where the arrays displayed improved functional dye loading compared to sol-gel-derived nanotubes. A detailed comparison between synthetic and bioorganic polyamines with respect to titania film properties deposition rate provided valuable information for future titania coating experimental design given specific applications. The development of template-based approaches to single-wall titania nanotube arrays led to the development of a new synthetic method to create aligned, multi-walled titania nanotube arrays. Lastly, peptide-enabled deposition methods were extended beyond inorganic mineral and used for enzyme immobilization by cross-linking the peptide with the multicopper oxidase laccase. Peptide-laccase hybrid enzyme coatings improved both the amount of enzyme adsorbed onto carbon nanotube “buckypaper” and allowed the enzyme to retain more activity upon immobilization onto the surface.

This thesis explores the integration and dynamics of residential scale renewable-regenerative energy systems which employ hydrogen for energy buffering. The development of the Integrated Renewable Energy Experiment (IRENE) test-bed is presented. IRENE is a laboratory-scale distributed energy system with a modular structure which can be readily re-configured to test newly developed components for generic regenerative systems. Key aspects include renewable energy conversion, electrolysis, hydrogen and electricity storage, and fuel cells. A special design feature of this test bed is the ability to accept dynamic inputs from and provide dynamic loads to real devices as well as from simulated energy sources/sinks. The integration issues encountered while developing IRENE and innovative solutions devised to overcome these barriers are discussed. Renewable energy systems that employ a regenerative approach to enable intermittent energy sources to service time varying loads rely on the efficient transfer of energy through the storage media. Experiments were conducted to evaluate the performance of the hydrogen energy buffer under a range of dynamic operating conditions. Results indicate that the operating characteristics of the electrolyser under transient conditions limit the production of hydrogen from excess renewable input power. These characteristics must be considered when designing or modeling a renewable-regenerative system. Strategies to mitigate performance degradation due to interruptions in the renewable power supply are discussed. Experiments were conducted to determine the response of the IRENE system to operating conditions that are representative of a residential scale, solar based, renewable-regenerative system. A control algorithm, employing bus voltage constraints and device current limitations, was developed to guide system operation. Results for a two week operating period that indicate that the system response is very dynamic but repeatable are presented. The overall system energy balance reveals that the energy input from the renewable source was sufficient to meet the demand load and generate a net surplus of hydrogen. The energy loss associated with the various system components as well as a breakdown of the unused renewable energy input is presented. In general, the research indicates that the technical challenges associated with hydrogen energy buffing can be overcome, but the round trip efficiency for the current technologies is low at only 22 percent.

Liquid water management has a major impact on the performance and durability of the polymer electrolyte membrane fuel cell (PEMFC). The gas diffusion layer (GDL) of a PEMFC provides pathways for mass, heat, and electronic transport to and from the catalyst layers and bipolar plates. When the GDL becomes flooded with liquid water, the PEMFC undergoes mass transport losses that can lead to decreased performance and durability. The work presented in this thesis includes contributions that provide insight into liquid water transport behaviour in and on the surface of the GDL, as well as insight into how future GDLs could be designed to enhance water management. The effects of compression on liquid water transport in the GDL and on the microstructure of the GDL are presented. It was found that compressed regions of the GDL provided preferential locations for water breakthrough, while scanning electron microscopy (SEM) imaging revealed irreversible damage to the GDL due to compression at typical fuel cell assembly pressures. The dynamic behaviour of droplet emergence and detachment in a simulated gas flow channel are also presented. It was found that on an initially dry and hydrophobic GDL, small droplets emerged and detached quickly from the GDL surface. However, over time, this water transport regime transitioned into that of slug formation and channel flooding. It was observed that after being exposed to a saturated environment, the GDL surface became increasingly prone to droplet pinning, which ultimately hindered droplet detachment and encouraged slug formation. A pore network model featuring invasion percolation with trapping was employed to evaluate the breakthrough pattern predictions of designed porous media. These designed pore networks consisted of randomized porous media with applied diagonal and radial gradients. Experimental microfluidic pore networks provided validation for the designed networks. Diagonal biasing provided a means of directing water transport in the pore network, while radially biased networks provided the additional feature of reducing the overall network saturation. Since directed water transport and reduced saturation are both beneficial for the PEMFC GDL, it was proposed that biasing of this nature could be applied to improved GDL designs. Lastly, recommendations for future extensions of this research are proposed at the end of this thesis.

Fibre-optic sensing techniques for application in polymer electrolyte fuel cells (PEMFC) are presented in this thesis. Temperature, relative humidity (RH) and air-water two-phase flow sensors are developed and demonstrated based on optical fibre Bragg gratings (FBG). Bragg gratings offer the following characteristics that warrant their development for application in PEMFCs: small size, environmental compatibility and the possibility of multiplexed multi-parameter sensing. Contributions of this work are in novel sensor development and implementation strategies. Important installation design considerations include the sensor proximity to the catalyst layer, sensor strain relief and minimal bending of the fibre. With these considerations, the dynamic and steady-state performance of FBG temperature sensors distributed throughout the flow-field of a single cell PEMFC was validated with a co-located micro-thermocouple. In the development of FBGs for in situ measurement of relative humidity, a polyimide-coated FBG based RH sensor is presented with significantly improved response time and sensitivity over previously reported designs. The RH inside a PEMFC under transient operating conditions is monitored. Step increases in current induce significantly larger increases in RH near the outlet than near the inlet of the cell, and associated transients within the fuel cell are found on a time scale approaching the sensor response time. Finally, to complete the suite of FBG sensors for water management in PEMFCs, an evanescent field based FBG sensor embedded in a microchannel for the measurement of two-phase flow dynamics is presented. Using high speed video for validation, it is established that the novel sensor enables the measurement of droplet average velocity and size in flow regimes representative of an operating fuel cell. / Graduate