Power and Energy Commons^™

Energy-Based Analysis Of Utility Scale Hybrid Power Systems, Kwame Agyenim-Boateng

UNLV Theses, Dissertations, Professional Papers, and Capstones

The promise of large-scale use of renewables such as wind and solar for supplying electrical power is tempered by the sources' transient behavior and the impact this would have on the operation of the grid. Among the methods cited for addressing some of those concerns are exploring the complementary nature of solar and wind power generation, and through the use of supplemental energy storage. While the technology for the latter has not been proven to be economical on a large scale at the present time, some assessments of what magnitude is required can be made. An energy-based analysis of utility …

Improving The Efficiency Of Organic Solar Cells By Varying The Material Concentration In The Photoactive Layer, Kevin Anthony Latimer

Electrical & Computer Engineering Theses & Dissertations

Polymer-fullerene bulk heterojunction solar cells have been a rapidly improving technology over the past decade. To further improve the relatively low energy conversion efficiencies of these solar cells, several modifications need to be made to the overall device structure. Emerging technologies include cells that are fabricated with interfacial layers to facilitate charge transport, and tandem structures are being introduced to harness the absorption spectrum of polymers with varying bandgap energies.

When new structures are implemented, each layer of the cell must be optimized in order for the entire device to function efficiently. The most volatile layer of these devices is …

Correlations Of Capacitance-Voltage Hysteresis With Thin-Film Cdte Solar Cell Performance During Accelerated Lifetime Testing, David S. Albin, Joseph A. Del Cueto

Publications (E)

In this paper we present the correlation of CdTe solar cell performance with capacitance-voltage hysteresis, defined presently as the difference in capacitance measured at zero-volt bias when collecting such data with different pre-measurement bias conditions. These correlations were obtained on CdTe cells stressed under conditions of 1-sun illumination, open-circuit bias, and an acceleration temperature of approximately 100 ºC.

Effect Of Hysteresis On Measurements Of Thin-Film Cell Performance, David S. Albin, Joseph A. Del Cueto

Publications (E)

Transient or hysteresis effects in polycrystalline thin film CdS/CdTe cells are a function of pre-measurement voltage bias and whether Cu is introduced as an intentional dopant during back contact fabrication. When Cu is added, the current-density (J) vs. voltage (V) measurements performed in a reverse-to-forward voltage direction will yield higher open-circuit voltage (V_oc), up to 10 mV, and smaller short-circuit current density (J_sc), by up to 2 mA/cm², relative to scanning voltage in a forward-to-reverse direction. The variation at the maximum power point, Pmax, is however small. The resulting variation in FF can be …

Use Of 2nd And 3rd Level Correlation Analysis For Studying Degradation In Polycrystalline Thin-Film Solar Cells, David S. Albin, Joseph A. Del Cueto, S. H. Demtsu, S. Bansal

Publications (E)

The correlation of stress-induced changes in the performance of laboratory-made CdTe solar cells with various 2^nd and 3^rd level metrics is discussed. The overall behavior of aggregated data showing how cell efficiency changes as a function of open-circuit voltage (V_oc), shortcircuit current density (J_sc), and fill factor (FF) is explained using a two-diode, PSpice model in which degradation is simulated by systematically changing model parameters. FF shows the highest correlation with performance during stress, and is subsequently shown to be most affected by shunt resistance, recombination and in some cases voltage-dependent collection. Large decreases …

High Efficiency, Low Cost Solar Cells Manufactured Using ‘Silicon Ink’ On Thin Crystalline Silicon Wafers October 2009 - November 2010, Homer Antoniadis

Publications (E)

The objectives of Phase I (Feb – Oct 2009) include the development and demonstration of a 17% efficient 25mm x 25mm crystalline Silicon solar cell and a 16% efficient 125mm x 125mm crystalline Silicon solar cell, both produced by Ink-jet printing Silicon Ink on a thin crystalline Sil-icon wafer. To achieve these objectives, processing approaches were developed to print the Silicon Ink in a predetermined pattern to form a high efficiency selective emitter, remove the solvents in the Silicon Ink and fuse the deposited particle Silicon films. Additionally, standard solar cell manufacturing equipment with slightly modified processes were used to …

Hybrid Cooling Systems For Low-Temperature Geothermal Power Production, Andrea Ashwood, Desikan Bharathan

Publications (E)

The overall objective of this investigation is to identify and evaluate methods by which the net power output of an air-cooled geothermal power plant can be enhanced during hot ambient conditions using minimal amounts of water.

Geothermal power plants that use air-cooled heat rejection systems experience a decrease in power production during hot periods of the day. This decrease in power output typically coincides with the time when utilities need power to address high air conditioning loads. Hybrid cooling options, which use both air and water, have been studied for this report to assess how they might mitigate the net …

"Buried-Anode" Technology Leads To Advanced Lithium Batteries, National Renewable Energy Laboratory

Publications (E)

A technology developed at the National Renewable Energy Laboratory has sparked a start-up company that has attracted funding from the Advanced Projects Research Agency-Energy (ARPA-E). Planar Energy, Inc. has licensed NREL's "buried-anode" technology and put it to work in solid-state lithium batteries. The company claims its large-format batteries can achieve triple the performance of today's lithium-ion batteries at half the cost, and if so, they could provide a significant boost to the emerging market for electric and plug-in hybrid vehicles.

Commercial Program Development For A Ground Loop Geothermal System: Energy Loads, Gui, Turbulent Flow, Heat Pump Model And Grid Study, Paul A. Gross Ii

Browse all Theses and Dissertations

The use of the earth's thermal energy to heat and cool building space is nothing new; however, the heat transfer approximations used in modeling geothermal systems, leave uncertainty and lead to over sizing. The present work is part of a Wright State effort to improve the computer modeling tools used to simulate ground loop geothermal heating and cooling systems. The modern computer processor has equipped us with the computation speed to use a finite volume technique to solve the unsteady heat equation with hourly time steps for multi-year analyses in multiple spatial dimensions. Thus we feel there is more need …

Commercial Program Development For A Ground Loop Geothermal System: G-Functions, Commercial Codes And 3d Grid, Boundary And Property Extension, Kyle L. Hughes

Browse all Theses and Dissertations

The rise in fossil fuel consumption and green house gas emissions has driven the need for alternative energy and energy efficiency. At the same time, ground loop heat exchangers (GLHE) have proven capable of producing large reductions in energy use while meeting peak demands. However, the initial cost of GLHEs sometimes makes this alternative energy source unattractive to the costumer. GLHE installers use commercial programs to determine the length of pipe needed for the system, which is a large fraction of the initial cost. These commercial programs use approximate methods to determine the length of pipe mainly due to their …

Ab Initio Simulations Of Graphene-Based Nanosensor For Detecting No2 And Li, Ahmed Jama Hassan

Browse all Theses and Dissertations

Nanosensors, i.e., sensors based on nanomaterials, have the potential of superior performance owing to their size effect, and can have significant effects on detection of pollutants in the environment. Various nanowires have been used in this context. Here we investigate the possibility of NO2 and Li detection using the quantum conductance change in graphene nanoribbon. Quantum conductance modification in graphene nanoribbon upon NO2/Li adsorption was calculated using ab initio methods. The optimized structures of the adsorbed NO2 indicated two different geometries where either nitrogen or oxygen was closer to the graphene lattice. The former resulted in charge transfer from NO2 …