Thesis (Doctor of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2017. / The search for alternatives to fossil fuel is necessary with a view to reducing the negative environmental impact of fossil fuel and most importantly, to exploit an affordable and secured fuel source. This study investigated the viability of municipal solid waste gasification for a fuel cell system. Potential solid fuels obtained from the study in the form of refuse-derived fuel (RDF) had high heating value (HHV) between 18.17 MJ/Kg - 28.91 MJ/Kg with energy density increased from 4142.07 MJ/m3 to 10735.80 MJ/m3. The molecular formulas of RDF derived from Ladies Smith drop-off site, Woodstock drop-off site and an average molecular formula of all thirteen municipal solid waste (MSW) disposal facilities were CH1.43O1.02, CH1.49O1.19, and CH1.50O0.86 respectively. The comparative ratios of C/H were in the range of 7.11 to 8.90. The Thermo Gravimetric Analysis showed that the dehydration, thermal decompositions, char combustions were involved in the production of gaseous products but flaming pyrolysis stage was when most tar was converted to syngas mixture. The simulation of RDF gasification allowed a prediction of the RDF gasification behaviour under various operating parameters in an air-blown downdraft gasifier. Optimum SFR (steam flowrate) values for RDF1, RDF2 and RDF3 were determined to be within these values 2.80, 2.50 and 3.50 and Optimum ER values for RDF1, RDF2 and RDF3 were also determined to be within these values 0.15, 0.04 and 0.08. These conditions produced the desired high molar ratio of H2/CO yield in the syngas mixture in the product stream. The molar ratios of H2/CO yield in the syngas mixture in the product stream for all the RDFs were between 18.81 and 20.16. The values of H2/CO satisfy the requirement for fuel cell application. The highest concentration of heavy metal was observed for Al, Fe, Zn and Cr, namely 16627.77 mg/Kg at Coastal Park (CP), 17232.37 mg/Kg at Killarney (KL), 235.01 mg/Kg at Tygerdal (TG), and 564.87 mg/Kg at Kraaifontein (KF) respectively. The results of quantitative economic evaluation measurements were a net return (NR) of $0.20 million, a rate of return on investment (ROI) of 27.88 %, payback time (PBP) of 2.30 years, a net present value (NPV) of $1.11 million and a discounted cash flow rate of return (DCFROR) of 24.80 % and 28.20 % respectively. The results of the economic evaluations revealed that some findings of the economic benefits of this system would be viable if costs of handling MSW were further quantified into the costs analysis. The viability of the costs could depend on government responsibility to accept costs of handling MSW.

California is experiencing a rapid increase in interest for the potential of converting ocean waves into clean electricity. Numerous applications have been submitted for the permitting of such renewable energy projects; however the profitability, practicability, and survivability have yet to be proven. Wave energy conversion technology has steadily matured since its naissance in the 1970’s, several wave energy power installations currently exist, and numerous plans for commercial power plant are in the works on the shores of multiple continents. This study aims to assess the economic viability of two proposed commercial wave energy power plant projects on the Central California Coast. A theoretical 25 MW capacity wave energy plant located at a site five nautical miles off of Point Arguello, in Santa Barbara County is compared to a site five nautical miles off of Morro Bay, in the County of San Luis Obispo. The Pacific Gas and Electric Company and Green Wave Energy Solutions, LLC have proposed full-scale commercial wave power plants at these sites, and are currently undergoing the federal permitting processes. Historical wave resource statistics from 1980 to 2001 are analyzed with performance specifications for the AquaBuOY, Pelamis P1, and WaveDragon wave energy converters (WECs) to calculate the annual electrical output of each device at each site. Sophisticated computer modeling of the bathymetric influence on the wave resource at each site is presented using the program Simulating Waves Nearshore (SWAN) developed by the Delft University of Technology. The wave energy flux, significant wave height, and peak period are computed at each site for typical summer and winter swell cases, using seafloor depth measurements at a 90 meter rectangular grid resolution. The economic viability of commercial electricity generation is evaluated for each WEC at each site by the calculation of the net present value of an estimated 25-year project life-cycle, the internal rate of return, and the required cost of electricity for a 10-year project simple payback period. The lowest required price of electricity is $0.13/kWh and occurs at the Point Arguello site using the AquaBuOY WEC. The highest annual capacity factor is 18% using the Pelamis WEC. The net present value and internal rate of return calculations suggest that the AquaBuOY WEC is profitable at both sites for electricity prices above $0.14/kWh. Shallow water wave propagation SWAN modeling demonstrated favorable wave energy flux states for WEC operation and power generation at both sites, with typical winter energy fluxes of 30-37 kW/m.

A Metal-Insulator-Metal (MIM) diode is a high frequency device used for energy harvesting purpose in the RECTENNA. The main objective of this thesis work is to design, fabricate and characterize a thin-film MIM diode. A key issue associated in this research work is the development MIM diode with nanometer thin insulator region. The reason for the development of MIM diode is to rectify a wide spectrum of AC signal to usable DC power. In this thesis work, a planar MIM diode with Aluminum/Aluminum-Oxide/Gold has been fabricated. The thickness of the insulator region obtained was about 3nm. The Metal and insulator depositions were done by sputtering and plasma oxidation, respectively. I-V Characteristics of the diode was measured by making use of in-house set-up and 70% of the devices on a single wafer yielded with better result. Most of the I-V curves obtained were highly non-linear and asymmetric. Based on the I-V measurement, the logarithmic derivative of I vs. V was plotted and the tunneling behavior was also observed.

Variable electrical generation (VG) sources such as wind farms are an increasing percentage of total electrical generation in the Bonneville Power Administration (BPA) balancing area and are starting to impact the ability of the regional balancing authority to control the electric grid. Wind farms are not dispatchable and challenge historical electric grid control methods. Successful integration of VG at high penetration levels of wind needs to address increased overall system variability and the rapid power ramp rates caused by wind. One of the new control paradigms needed is accurate wind speed prediction which directly relates to wind farm power output. With an accurate wind speed forecast other generation sources can be dispatched as needed to ensure grid stability. This work uses BPA metrology station (MS) data to make predictions for short-term wind speed where short-term is defined as a one hour prediction horizon. It is shown that, using the available metrology station data and several different prediction methodologies, only small improvements in short-term wind speed prediction can be achieved with the available data for the algorithms analyzed. / Graduation date: 2013

No description available.

A molten carbonate fuel cell (MCFC) is an electro-chemical energy conversion technology that runs on natural gas and employs a molten salt electrolyte. In order to keep the electrolyte in this state, the cell must be kept at a temperature above 500 C, eliminating the need for precious metals as the catalyst. There has been only a limited amount of research on modelling the transport processes inside this device, mainly due to its limited ability for mobile applications. In this thesis, three one-dimensional models of a MCFC are presented based on different types of diffusion and convection. Comparisons between models are performed so as to assess their validity. Regarding ion transport, it is shown that there exists a limiting case for ion migration across the cathode that depends on the conductivity for the liquid potential. Finally, an optimization of the diffusivity across the cathode is carried out in an attempt to increase the cell performance and its longevity. / UOIT

All electric machines have two mechanical operations, motoring and braking. The nature of braking can be regenerative, where the kinetic energy of the rotor is converted into electricity and sent back to the power source or non-regenerative, where the source supplies electric power to provide braking. This thesis investigates several critical issues related to regenerative braking in both DC and AC electric machines, including the determination of boundaries in the torque-speed plane defining the regenerative braking capability region and the evaluation of operating points within that capability region that result in maximum regenerative braking recharge current. Electric machines are used in the powertrains of electric and hybrid-electric vehicles to provide motoring or braking torque in response to the driver's request and power management logic. Since such vehicles carry a limited amount of electrical energy on-board their energy storage systems (such as a battery pack), it is important to conserve as much electrical energy as possible in order to increase the range of travel. Therefore, the concept of regenerative braking is of importance for such vehicles since operating in this mode during a braking event sends power back to the energy storage system thereby replenishing its energy level. Since the electric machine assists the mechanical friction braking system of the vehicle, it results in reduced wear on components within the mechanical friction brake system. As both mechanical friction braking and electric machine braking are used to provide the requested vehicle braking torque, braking strategies which relate to splitting of the braking command between the two braking mechanisms are discussed. The reduction in energy consumption of a test vehicle along different driving schedules while using different braking strategies is also studied.

Wind generation has become one of the most popular choices of technology for adding new generation capacity to power systems worldwide. Several factors have contributed to the increased integration of wind generation, including environmental concerns and the continual increase in fossil fuel prices. As well, recent regulations have moved toward limitations on greenhouse gases, especially in the European Union (EU). Similar laws are currently under consideration in the US and other parts of the world. Other factors have also promoted the use of wind energy, such as advances in manufacturing and control technology and the attractiveness of wind as a “green” source of energy. The large-scale integration of wind power into an electricity system introduces planning and operational challenges because of the intermittent nature of wind speed and the difficulty involved in predicting it. For these reasons, wind energy is often considered an unreliable energy source. Additional problems are associated with the integration of large-scale wind farms into an electrical grid, among which wind power fluctuation is the most challenging. To maximize the penetration level of wind energy in a grid, a reliable technology must be developed in order to eliminate or at least decrease wind power fluctuation. The primary goal of this thesis was to develop methods of maximizing the penetration level of wind energy conversion systems (WECSs) into a grid, which requires mitigating wind power fluctuation. A robust control technique has therefore been developed for mitigating wind power fluctuation. This control technique exploits historical environmental data collected over a number of years in order to evaluate the profile of the output power of a variety of wind energy conversion systems (WECSs). The developed control technique was applied to Types A and C WECSs modifying the pitch angle controller of Type A WECS and the back-to-back converter control of Type C WECS. The Attachment of a storage device to the WECSs after the control technique is applied was investigated from both an economic and a technical point of view. The optimum sizing and siting of the wind energy conversion system equipped with the proposed control technique was also studied. This research is expected to contribute to the advancement of WECS technology by presenting a feasible solution to the problems associated with the integration of large-scale WECSs into electrical grids.

A scaled direct energy conversion device was built to convert kinetic energy of singly ionized helium ions into an electric potential by the process of direct conversion. The experiments in this paper aimed to achieve higher potentials and higher efficiencies than ever before. The predicted maximum potential that could be produced by the 150 kV accelerator at the Texas A&M Ion Beam Lab was 150 kV, which was achieved with 92% collection efficiency. Also, an investigation into factors affecting collection efficiency was made. It was concluded that charge was being lost due to charge exchange occurring near the surface of the target which caused positive target atoms to be ejected from the face and accelerated away. Introducing a wire mesh near the face of the target with an electric potential, positive or negative, which aimed to control secondary ion emissions, did not have an effect on the collection efficiency of the system. Also, it was found that the gas pressure inside the chamber did not have an effect on the collection efficiency. The goal of achieving higher electric potentials and higher efficiencies than previous direct conversion work was met.

Limited worldwide energy supplies demand the improved utilization of thermal energy, which is the dominant form of all primary energy sources used today. Large quantities of waste heat are routinely exhausted wherever thermo-mechanical energy conversion occurs, providing an opportunity to improve utilization. Two waste-heat-driven cycles are analyzed: an absorption/compression cascade cooling cycle and a coupled Rankine/compression cycle. The absorption/compression cascade provides an environmentally-sound option for a common approach to thermal energy recovery: the use of absorption cycles for cooling applications. To achieve cooling at temperatures below 0ºC, ammonia-water is the overwhelming choice for the working fluid. However, concerns about the toxicity and flammability of ammonia sometimes limit its application in sensitive arenas. In this study, a lithium bromide-water absorption cycle is coupled with a carbon dioxide vapor compression cycle to realize the benefits of high-lift cooling without the concerns associated with ammonia. This cycle utilizes a waste heat stream at temperatures as low as 150°C to provide cooling at -40°C. The topping absorption cycle achieves a coefficient of performance (COP) of about 0.77, while the bottoming cycle achieves a COP of about 2.2. The coupled Rankine/compression cycle provides a mechanical expansion and compression approach to achieve thermally activated cooling, again driven by waste heat. The power produced in the turbine of the Rankine cycle is directly coupled to the compressor of a vapor-compression cooling cycle to generate cooling to be utilized for space-conditioning. The refrigerant R245fa is used throughout the cycle. Even with low grade waste heat sources, a Rankine cycle efficiency of about 11-12 percent can be achieved. When coupled to the bottoming compression cycle with a COP of about 2.7, this yields an overall waste heat to cooling conversion efficiency of about 32 percent at nominal conditions.