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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Seismic monitoring of EGS fracture stimulations at Utah FORGE (Part 1): Time-lapse variations of b-values and Shear-wave Splitting Rates of induced microearthquakes

Characterizing geologic formations near geothermal wells is crucial for efficient extraction of subsurface geothermal energy resources. To monitor effective fracture stimulation of enhanced geothermal systems (EGS), we analyze a catalog of induced microearthquakes to characterize seismicity induced by Phase 2C fracture stimulations of the Utah FORGE project and derive the b-values for 424 induced microearthquakes in three stages of fracture stimulation. Here, we find the time-lapse variations of these b-values. We apply eigenvector rotation and waveform correlation to 3C geophone data to separate fast S 1 and slow S 2 waves, determine their directions, measure their lag time, and calculate the S-wave splitting rate (SSR) for six induced microearthquakes in Stage 1 and 21 in Stage 3. Both SSR values and b-values increase with time. The increase in these values may be related to heavily fractured zones created by fracture stimulations during Stage 2 injections. Large and highly variable SSR values in Stage 3 may reflect heterogeneities in the fracture zones. Time-lapse variations of SSR values and b-values may be one of the most useful approaches to monitoring and characterizing the effectiveness and efficiency of various types of fracture stimulations.

58 GEOSCIENCES↗
DOE OSTI2011

Effect of pH value on particle morphology and electrochemical properties of LiFePO{sub 4} by hydrothermal method

Graphical abstract: The pH value of system is adjusted in the range of 2.5-8.8 by using dilute sulfuric acid and ammonia water. The results indicated that the particle exhibits acute angle diamond flake-like morphology at pH = 2.5. With increase of pH value, the particle gradually becomes to round flake-like and irregular flake-like morphology. The optimal sample synthesized at pH = 6.4 exhibits discharge capacities of 151.8 mAh g{sup -1} at 0.2 C rate and 129.3 mAh g{sup -1} at 3 C rate. Highlights: {yields} The pH value of solution affects greatly on particle morphology. {yields} The solubility product determined the transition of interphases. {yields} The disorder of atoms in crystal is affected by pH value. {yields} LiFePO{sub 4} with high capacity could be synthesized at slight acid or neutral conditions. -- Abstract: Lithium iron phosphate was prepared by hydrothermal synthesis using LiOH.H{sub 2}O, FeSO{sub 4}.7H{sub 2}O and H{sub 3}PO{sub 4} as raw materials. The effects of pH value of reaction solution on particle morphology and electrochemical property were investigated. The pH value of the reaction solution was adjusted in the range of 2.5-8.8 by dilute sulfuric acid and ammonia water. The samples were characterized by field-emission scanning electronic microscope (FE-SEM), X-ray powder diffraction (XRD), constant-current charge/discharge cycling tests and chemical analysis. The results indicated that the particles exhibited acute angle diamond flake-like morphology at pH = 2.5, and as the pH value increased, the particle became hexagon flake-like, round flake-like and irregular flake-like morphology gradually. The optimal sample synthesized at pH = 6.4 exhibited discharge capacities of 151.8 mAh g{sup -1} at 0.2 C rate and 129.3 mAh g{sup -1} at 3 C rate. It was found that pH value affected the morphologies and properties of the product by means of different crystal growth rates.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Evaluation of the 235 U resonance parameters to fit the standard recommended values

A great deal of effort has been dedicated to the revision of the standard values in connection with the neutron interaction for some actinides. While standard data compilation are available for decades nuclear data evaluations included in existing nuclear data libraries (ENDF, JEFF, JENDL, etc.) do not follow the standard recommended values. Indeed, the majority of evaluations for major actinides do not conform to the standards whatsoever. In particular, for the n + 235 U interaction the only value in agreement with the standard is the thermal fission cross section. We performed a resonance re-evaluation of the n + 235 U interaction in order to address the issues regarding standard values in the energy range from 10-5 eV to 2250 eV. Recently, 235 U fission cross-section measurements have been performed at the CERN Neutron Time-o-Flight facility (TOF), known as n_TOF, in the energy range from 0.7 eV to 10 keV. The data were normalized according to the recommended standard of the fission integral in the energy range 7.8 eV to 11 eV. As a result, the n_TOF averaged fission cross sections above 100 eV are in good agreement with the standard recommended values. The n_TOF data were included in the 235 U resonance analysis that was performed with the code SAMMY. In addition to the average standard values related to the fission cross section, standard thermal values for fission, capture, and elastic cross sections were also included in the evaluation. Our paper presents the procedure used for re-evaluating the 235 U resonance parameters including the recommended standard values as well as new cross section measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Variations in pharmacokinetic-pharmacodynamic target values across MICs and their potential impact on determination of susceptibility test interpretive criteria

Abstract Background An antibacterial drug’s susceptibility test interpretive criteria (STIC) are determined by integrating clinical, microbiological and pharmacokinetic-pharmacodynamic (PK-PD) data. PTA analysis plays a pivotal or supportive role in STIC determination and is heavily dependent on the PK-PD target values determined from animal PK-PD studies. Therefore, variations in PK-PD target values may impact STIC determination. Factors contributing to variation in the PK-PD target values include the number of and MICs for bacterial isolates used in animal PK-PD studies. Objectives To analyse the relationship between PK-PD target values and MICs, describe the variations in PK-PD target values of isolates and evaluate whether the proposed/target STICs were within the ranges of the MICs for isolates used in animal PK-PD studies. Methods A database was compiled for this research by screening animal PK-PD study reports submitted to the FDA from 10 new drug applications (NDAs). Results A relationship evaluation between PK-PD target values and MICs for tested isolates for seven drugs (that used AUC/MIC ratio as the PK-PD index) showed that, generally, the AUC/MIC values decreased with an increase in MIC. These target values were highly variable, with the percentage coefficient of variation ranging between 1% and 132% for isolates having the same MIC. For 16/27 (59%) drug/bacteria combinations from all 10 drugs, the proposed/target STICs were higher than the highest MIC for bacteria isolates evaluated, while 6/27 (22.5%) were lower. Conclusions This research suggests that careful considerations related to selection of bacterial isolates for animal PK-PD studies could strengthen the STIC determination process.

Waack, Ursula↗
DOE OSTI2020

Effective Missing Value Imputation Methods for Building Monitoring Data

To understand behaviors of natural and man-made events, such as energy consumption of buildings, which accounts for 40% of energy uses in the US, we deploy automated monitoring devices to record periodic observations. However, such experimental and observation data often contains problems and irregularities that have to be cleaned up before analyses. Due to various conditions affecting sensor operations, the communication channels, recording steps, or the recording media, the recorded data might have missing values, errors, or anomalous values. An effective way to clean up these problems is to replace these missing values, errors and anomalous values with expected values, a process generally known as imputation. In this work, we survey commonly used missing value imputation techniques and compare their performance on a set of building monitoring data. To compare the different types of sensor measurements with widely varying characteristics, we use normalized root mean squared error (NRMSE) as the key metric for the effectiveness of the imputation methods. We additionally consider periodicity and run time when considering comparing methods. Through extensive testing, we find that for small gap sizes, up to 8 consecutive missing values, linear interpolation performs the best; for larger gaps stretching up to 48 consecutive missing values, K-nearest neighbors provides the most accurate imputations; for even larger gaps, more computational intensive methods, such as matrix factorization, achieve the smallest NRMSE. Additionally, we observe that these computationally intensive algorithms not only provide accurate imputations for large gaps, but are also more robust across all types of sensors.

Cho, B↗
DOE OSTI2014

SU-E-I-27: Establishing Target Exposure Index Values for Computed Radiography

Purpose: To develop a standard set of target exposure index (TEI) values to be applied to Agfa Computed Radiography (CR) readers in accordance with International Electrotechnical Committee 62494-1 (ed. 1.0). Methods: A large data cohort was collected from six USAF Medical Treatment Facilities that exclusively use Agfa CR Readers. Dose monitoring statistics were collected from each reader. The data was analyzed based on anatomic region, view, and processing speed class. The Agfa specific exposure metric, logarithmic mean (LGM), was converted to exposure index (EI) for each data set. The optimum TEI value was determined by minimizing the number of studies that fell outside the acceptable deviation index (DI) range of +/− 2 for phototimed techniques or a range of +/−3 for fixed techniques. An anthropomorphic radiographic phantom was used to corroborate the TEI recommendations. Images were acquired of several anatomic regions and views using standard techniques. The images were then evaluated by two radiologists as either acceptable or unacceptable. The acceptable image with the lowest exposure and EI value was compared to the recommended TEI values using a passing DI range. Results: Target EI values were determined for a comprehensive list of anatomic regions and views. Conclusion: Target EI values must be established on each CR unit in order to provide a positive feedback system for the technologist. This system will serve as a mechanism to prevent under or overexposures of patients. The TEI recommendations are a first attempt at a large scale process improvement with the goal of setting reasonable and standardized TEI values. The implementation and effectiveness of the recommended TEI values should be monitored and adjustments made as necessary.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Local patient dose diagnostic reference levels in pediatric interventional cardiology in Chile using age bands and patient weight values

Purpose: To present the results of a patient dose evaluation program in pediatric cardiology and propose local diagnostic reference levels (DRLs) for different types of procedure and age range, in addition to suggesting approaches to correlate patient dose values with patient weight. This study was the first conducted in Latin America for pediatric interventional cardiology under the auspices of the International Atomic Energy Agency. Methods: Over three years, the following data regarding demographic and patient dose values were collected: age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time (FT), and two dosimetric quantities, dose-area product (DAP) and cumulative dose (CD), at the patient entrance reference point. The third quartile values for FT, DAP, CD, number of cine series, and the DAP/body weight ratio were proposed as the set of quantities to use as local DRLs. Results: Five hundred and seventeen patients were divided into four age groups. Sample sizes by age group were 120 for <1 yr; 213 for 1 to <5 yr; 82 for 5 to <10 yr; and 102 for 10 to <16 yr. The third quartile values obtained for DAP by diagnostic and therapeutic procedures and age range were 1.17 and 1.11 Gy cm{sup 2} for <1 yr; 1.74 and 1.90 Gy cm{sup 2} for 1 to <5 yr; 2.83 and 3.22 Gy cm{sup 2} for 5 to <10 yr; and 7.34 and 8.68 Gy cm{sup 2} for 10 to <16 yr, respectively. The third quartile value obtained for the DAP/body weight ratio for the full sample of procedures was 0.17 (Gy cm{sup 2}/kg) for diagnostic and therapeutic procedures. Conclusions: The data presented in this paper are an initial attempt at establishing local DRLs in pediatric interventional cardiology, from a large sample of procedures for the standard age bands used in Europe, complemented with the values of the ratio between DAP and patient weight. This permits a rough estimate of DRLs for different patient weights and the refining of these values for the age bands when there may be large differences in child size. These DRLs were obtained at the largest pediatric hospital in Chile, with an active optimization program, and could be used by other hospitals in the Latin America region to compare their current patient dose values and determine whether corrective action is appropriate.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-305: Clinical Effects of Dosimetric Leaf Gap (DLG) Values Between Matched Varian Truebeam (TB) Linacs

Purpose: The dosimetric leaf gap (DLG) is an important parameter to be measured for dynamic beam delivery of modern linacs, like the Varian Truebeam (TB). The clinical effects of DLG-values on IMRT and/or VMAT commissioning of two “matched” TB linacs will be presented.Methods and Materials: The DLG values on two TB linacs were measured for all energy modalities (filtered and FFF-modes) as part of the dynamic delivery mode commissioning (IMRT and/or VMAT. After the standard beam data was modeled in eclipse treatment planning system (TPS) and validated, IMRT validation was performed based on TG1191 benchmark, IROC Head-Neck (H&N) phantom and sample of clinical cases, all measured on both linacs. Although there was a single-set of data entered in the TPS, a noticeable difference was observed for the DLG-values between the linacs. The TG119, IROC phantom and selected patient plans were furnished with DLG-values of TB1 for both linacs and the delivery was performed on both TB linacs for comparison. Results: The DLG values of TB1 was first used for both linacs to perform the testing comparisons. The QA comparison of TG119 plans revealed a great dependence of the results to the DLG-values used for the linac for all energy modalities studied, especially when moving from 3%/3mm to 2%/2mm γ-analysis. Conclusion: The DLG-values have a definite influence on the dynamic dose, delivery that increases with the plan complexity. We recommend that the measured DLG-values are assigned to each of the “matched” linacs, even if a single set of beam data describes multiple linacs. The user should perform a detail test of the dynamic delivery of each linac based on end-to-end benchmark suites like TG119 and IROC phantoms.1Ezzel G., et al., “IMRT commissioning: Multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119.” Med. Phys. 36:5359–5373 (2009). partly supported by CAMC Cancer Center and Alliance Oncology.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

A Spatial Hedonic Analysis of the Effects of Wind Energy Facilities on Surrounding Property Values in the United States

Previous research on the effects of wind energy facilities on surrounding home values has been limited by small samples of relevant home-sale data and the inability to account adequately for confounding home-value factors and spatial dependence in the data. This study helps fill those gaps. We collected data from more than 50,000 home sales among 27 counties in nine states. These homes were within 10 miles of 67 different wind facilities, and 1,198 sales were within 1 mile of a turbine—many more than previous studies have collected. The data span the periods well before announcement of the wind facilities to well after their construction. We use OLS and spatial-process difference-in-difference hedonic models to estimate the home-value impacts of the wind facilities; these models control for value factors existing before the wind facilities’ announcements, the spatial dependence of unobserved factors effecting home values, and value changes over time. A set of robustness models adds confidence to our results. Regardless of model specification, we find no statistical evidence that home values near turbines were affected in the post-construction or post-announcement/pre-construction periods. Previous research on potentially analogous disamenities (e.g., high-voltage transmission lines, roads) suggests that the property-value effect of wind turbines is likely to be small, on average, if it is present at all, potentially helping to explain why no evidence of an effect was found in the present research.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Influence of Hybridization on the Capacity Value of PV and Battery Resources

Utility-scale systems that combine solar photovoltaic and battery (PV+battery) technologies are growing in popularity on the U.S. bulk power system. The business case for PV+battery systems depends on both their ability to reduce costs and their ability to generate value synergies associated with the provision of energy, capacity, and ancillary services. Capacity value can constitute a significant portion of the value PV+battery hybrids provide to the grid (e.g., through avoided or deferred capacity) and receive through revenues. Throughout this report, we define capacity value as the monetary value of a plant's contribution towards the planning reserve margin, which ultimately depends on market rules and structures. PV+battery hybrids do not always fit into current market structures because of the interactions between the PV and battery components. Unique considerations for the capacity value of PV+battery hybrids include the disparate nature of participation models for PV and battery technologies in existing market rules and the potential influence of a shared interconnection capacity; limitations imposed by a shared inverter; limited ability to charge the battery in advance of capacity events if charging must be sourced from the coupled PV; and challenges or uncertainties associated with co-optimizing the operations of the PV and battery components. Grid operators are currently considering how market structures can be modified to optimally determine the capacity value provided by PV+battery systems, and the rules of how they are integrated into markets are still being written. As with any resource, poorly designed rules could increase the cost of energy and reduce system reliability, while well-designed rules could allow markets to receive the full benefits hybrid systems can offer without overcompensating them for the services they provide. Well-designed rules for PV+battery systems must consider the unique aspects listed above, while leveraging the commonalities with existing resource types. In this report, we summarize the technical capability and market rules that influence the capacity value of PV+battery systems. We further discuss the potential tradeoffs between computational complexity and accuracy for the various ways in which grid operators can credit PV+battery systems for capacity. Finally, we describe markets for capacity, survey current wholesale market rules applying to PV+battery systems, and provide a snapshot of the current regulatory landscape for PV+battery systems.

14 SOLAR ENERGY↗
DOE OSTI2022

Empirical Estimates of Transmission Value using Locational Marginal Prices [Slides]

This study focuses on one potential benefit of transmission infrastructure—congestion relief. It explores historical grid conditions from 2012 through the first half of 2022, and evaluates the marginal value of transmission in facilitating trade within and across regional boundaries by calculating differences in observed nodal wholesale power prices. The study finds that wholesale power prices exhibit stark geographic differences that, in many cases, are stable over time. Many regional and interregional transmission links have significant potential economic value from reducing congestion and expanding opportunities for trade. In fact, many links have hourly average pricing differences in 2021 that exceeded $\$15$/MWh—equivalent to $130 million per year for a 1000 MW link. The value of transmission is correlated with overall energy prices and varies by region and year. Critically, extreme conditions and high-value periods play an outsized role in the value of transmission, with 50% of transmission’s congestion value coming from only 5% of hours. Transmission planners run the risk of understating the benefits of regional and interregional transmission if extreme conditions and high-value periods are not adequately considered. These periods are natural features of actual market operations. As such, the study highlights the need for planners to more-comprehensively assess the value of transmission under both normal and extreme conditions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2023

Cataloging and Quantifying Value Streams from Non-Powered Dam Conversion

Hydropower is a key resource in the United States’ renewable energy transition; however, only 3% of existing dams in the United States currently generate electricity. While many non-powered dams (NPDs) have the potential for energy generation, hydropower addition to these dams has been slow. This is likely due, in part, to perceptions that hydropower development has prohibitively long payback periods, especially in comparison to other renewable energy resources that have shorter development processes. On the other hand, powering some NPDs may unlock new value streams in addition to the value obtained from selling generated energy. There is a need to understand and quantify a wider range of additional value streams to help increase the feasibility of such hydropower projects. In this work, we catalog indirect value streams and difficult-to-quantify direct value streams from NPD retrofitting, specifying which stakeholders are affected, and what kind of impacts (positive or negative) might occur. We identify appropriate quantification methodologies for these indirect value streams and describe the best practices around their implementation for NPD site-level analysis. We also demonstrate the quantification of a few indirect value streams for a selected NPD site, allowing for easier integration of these value streams into future studies by providing basis and background for quantifying these elements.

13 HYDRO ENERGY↗
DOE OSTI2016

NOMINAL VALUES FOR SELECTED SOLAR AND PLANETARY QUANTITIES: IAU 2015 RESOLUTION B3

In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Parallel sort with a ranged, partitioned key-value store in a high perfomance computing environment

Improved sorting techniques are provided that perform a parallel sort using a ranged, partitioned key-value store in a high performance computing (HPC) environment. A plurality of input data files comprising unsorted key-value data in a partitioned key-value store are sorted. The partitioned key-value store comprises a range server for each of a plurality of ranges. Each input data file has an associated reader thread. Each reader thread reads the unsorted key-value data in the corresponding input data file and performs a local sort of the unsorted key-value data to generate sorted key-value data. A plurality of sorted, ranged subsets of each of the sorted key-value data are generated based on the plurality of ranges. Each sorted, ranged subset corresponds to a given one of the ranges and is provided to one of the range servers corresponding to the range of the sorted, ranged subset. Each range server sorts the received sorted, ranged subsets and provides a sorted range. A plurality of the sorted ranges are concatenated to obtain a globally sorted result.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Quantifying Value and Representing Competitiveness of Electricity System Technologies in Economic Models

Evaluating competition between electricity technologies is challenging because it depends on both their costs and their values. While technology costs can typically be estimated from projections of the cost components - capital, fuel, and O&M - estimating a technology's value is more complex due to its dependence on its contributions to multiple different grid services, each with prices that can vary substantially over space and time. In this work, using an electricity model of the contiguous United States, we develop relationships between relative value and share of total generation for major electricity generation technologies which, when paired with projections of technology costs, can be used to estimate technology competitiveness. We identify significant differences in the relationship between relative value and generation share for variable renewable energy (VRE) and non-VRE sources, but we demonstrate that all technologies require consideration of their dynamic values (in addition to cost) when evaluating competitiveness. In addition, we demonstrate that relative value of a technology is substantially impacted by not only its own generation share but also other aspects of the system state, in particular the mix of other technologies present in the system. Finally, we use the developed relative value relationships in combination with projections of future technology costs in a coarse resolution model that competes technologies based on a comprehensive competitiveness metric: profitability-adjusted LCOE (PLCOE). We show that this simple representation of technology competition approximately recovers the generation mix from a detailed model, which is not possible using LCOE alone. Such an approach can be used to improve the representation of technology competition in coarse-resolution models such as integrated assessment models, for which simplified metrics are often needed.

electricity model↗
DOE OSTI2022

The locational value of distributed energy resources: A parcel-level evaluation of solar and wind potential in New York state

We report distributed energy resources (DERs) are poised to play a significant role in evolving power systems because of their flexibility to be sited in areas of high value to the grid. Traditional DER compensation frameworks, specifically net energy metering (NEM), inadequately communicate differences in the locational and temporal value of DER generation to the grid. As a transition from NEM, New York State's (NYS's) Value of Distributed Energy Resources (VDER) framework provides a methodology for calculating different value components that DERs offer the grid. To study the impacts of VDER frameworks on DER deployment, we developed a model to assess the value of distributed solar and wind systems configured as either a behind-the-meter system or a front-of-the-meter system for each parcel of land in NYS. Using parcel-level granularity, we can closely evaluate DER locational value and siting availability, particularly in urban and suburban settings. Our analysis finds while most DER generators would be modestly compensated for deferred transmission and distribution infrastructure upgrades (~0.01 $\$$/kWh for solar PV), a subset of projects receive significant value from this component (0.035 to 0.089 $\$$/kWh for top 5% of parcels for solar PV). Finally, our analysis finds VDER provides less overall compensation than NEM to the average DER generator, however, it increases access to compensation for front-of-the-meter DERs - a large and emerging market.

14 SOLAR ENERGY↗
DOE OSTI2010

High-precision mass measurement of {sup 31}S with the double Penning trap JYFLTRAP improves the mass value for {sup 32}Cl

The mass of {sup 31}S has been measured with the JYFLTRAP double Penning trap mass spectrometer. The new mass excess value of -19 042.55(24) keV deviates from the adopted value of -19 044.6(15) keV by 1.4{sigma}. The mass value of {sup 32}Cl has been revised with the new {sup 31}S result and the latest data from {beta}-delayed proton decay of {sup 32}Cl. The new mass excess value for {sup 32}Cl is -13 334.88(65) keV, which is the most precise value for {sup 32}Cl so far and in agreement with the recent ({sup 3}He,t) data. The isobaric multiplet mass equation has been tested in the T=2 quintet at A=32, and the cubic form of the equation has been found to agree with the experimental data. The Q{sub EC} value for the {beta} decay of T=1/2 mirror nucleus {sup 31}S has been determined as Q{sub EC}=5397.99(24) keV, which slightly deviates from the previously adopted value.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Comparison of Capacity Value Methods for Photovoltaics in the Western United States

This report compares different capacity value estimation techniques applied to solar photovoltaics (PV). It compares more robust data and computationally intense reliability-based capacity valuation techniques to simpler approximation techniques at 14 different locations in the western United States. The capacity values at these locations are computed while holding the underlying power system characteristics fixed. This allows the effect of differences in solar availability patterns on the capacity value of PV to be directly ascertained, without differences in the power system confounding the results. Finally, it examines the effects of different PV configurations, including varying the orientation of a fixed-axis system and installing single- and double-axis tracking systems, on the capacity value. The capacity value estimations are done over an eight-year running from 1998 to 2005, and both long-term average capacity values and interannual capacity value differences (due to interannual differences in solar resource availability) are estimated. Overall, under the assumptions used in the analysis, we find that some approximation techniques can yield similar results to reliability-based methods such as effective load carrying capability.

14 SOLAR ENERGY↗