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Existing Hydropower Asset (EHA) Annual Gross Generation is a geospatial point-level dataset containing annual gross generation over time (2003-2024) and key characteristics of operational U.S. pumped storage and hybrid plants with 1 megawatt or greater of nameplate capacity. EIA 923 and EHA are the primary sources of the derived data. Hydropower units are excluded.
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Existing Hydropower Asset (EHA) Annual Net Generation is a geospatial point-level dataset containing annual net generation over time (2003-2024) and key characteristics of operational U.S. hydropower plants with 1 megawatt or greater of nameplate capacity. EIA 923 and EHA are the primary sources of the derived data. Pumped storage and hybrid plants are excluded.
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Abstract not provided
With increasing integrations of large‐scale systems based on permanent magnet synchronous generator wind turbine generators (PMSG‐WTGs), the overall inertial response of a power system will tend to deteriorate as a result of the decoupling of rotor speed and grid frequency through the power converter as well as the scheduled retirement of conventional synchronous generators. Thus, PMSG‐WTGs can provide value to an electric grid by contributing to the system's inertial response through the inherent kinetic energy stored in their rotating masses and fast power converter control. In this study, an improved inertial control method based on the maximum power point tracking operation curve is introduced to enhance the overall frequency support capability of PMSG‐WTGs in the case of large supply–demand imbalances. Moreover, this method is implemented in the CART2‐PMSG integrated model in MATLAB/Simulink to investigate its impact on the wind turbine's structural loads during the inertial response process. Simulation results indicate that the proposed method can effectively reduce the frequency nadir, arrest the rate of change of frequency, and alleviate the secondary frequency dip while imposing no negative impact on the major mechanical components of the wind turbine.
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In this paper, we examine and compare the performance of a generator design optimized using additively manufactured NdFeB-SmFeN in nylon-polymer-bonded permanent magnets (PMs) against a generator design with conventional NdFeB sintered PMs. To realize this, a commercially available 15-kW wind generator's rotor is re-optimized using both additively manufactured and sintered NdFeB magnets using simple geometric parameterization that allowed for two specific magnet shapes, namely, arc-shaped and crown-shaped designs. Results showed that for a similar generator performance, the designs with additively manufactured bonded PMs are more cost-competitive in terms of the estimated PM material cost and also have negligible eddy current magnet losses.
A vast majority of utility-scale wind turbine generators in the United States are dependent on foreign- sourced rare-earth permanent magnets that are vulnerable to supply chain uncertainties. Many small wind original equipment manufacturers are motivated to pursue continuous improvements to the generator design to lower the material and production costs and improve performance by lowering cogging torque and increasing the efficiency. Traditional design and manufacturing offer limited opportunities. In this work, we demonstrate advanced design approaches for a 15-kW baseline wind turbine generator by making use of recent progress in three-dimensional (3D) printing of polymer- bonded magnets and, electrical and structural steel. We explore three methods of magnet parametrization using Bezier curves resulting in symmetric, asymmetric and multimaterial magnet designs. We employ a multiphysics approach combining parametric computer-aided design modeling, finite- element analysis and targeted sampling to identify novel designs with more opportunities for reducing rare-earth material, improving efficiency and minimizing cogging torque. The results show that asymmetric-pole design and multimaterial-pole designs offer a greater opportunity to minimize rare-earth magnet materials by up to 35% with similar performance as the baseline generator, suggesting newer opportunities with design freedom beyond traditional limits of symmetry and as allowed by 3D printing.
Iron oxides are a ubiquitous class of compounds that are involved in many biological, geological, and technological processes, and the Fe(III)/Fe(II) redox couple is a fundamental transformation pathway; however, the study of iron oxide surfaces in aqueous solution by powerful spectroscopic techniques has been limited due to "strong absorber problem". In this work, atomic layer deposition (ALD) thin films of polycrystalline alpha-Fe2O3 were analyzed using the Eisenthal chi((3)) technique, a variant of second harmonic generation that reports on interfacial potentials. By determining the surface charge densities at multiple pH values, the point of zero charge was found to be 5.5 +/- 0.3. The interaction of aqueous Fe(II) at pH 4 and in 1 mM NaCl with ALD-prepared hematite was found to be fully reversible and to lead to about 4 times more ferrous iron ions adsorbed per square centimeter than on fused-silica surfaces under the same conditions. The data are consistent with a recently proposed conceptual model for net Fe(II) uptake or release that is underlain by a dynamic equilibrium between Fe(II) adsorbed onto hematite, electron transfer into favorable surface sites with attendant Fe(III) deposition, and electron conduction to favorable remote sites that release and replenish aqueous Fe(II).
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Used nuclear fuel (UNF) separation techniques that strive to separate radiotoxic americium (Am) from trivalent lanthanide fission products through oxidation state control have increased research efforts surrounding Am(V) and Am(VI). However, equivalent knowledge of the tetravalent state, Am(IV), has remained elusive, particularly in conditions more representative of UNF reprocessing, i.e., in concentrated nitric acid (HNO3). With this in mind, we have used electron pulse radiolysis to study the radiation-induced redox reaction of Am(III) with the oxidizing nitrate radical (NO3?) in 6 M HNO3: Am(III) + NO3? ? Am(IV) + NO3? . These experiments enabled us to observe the growth and decay of Am(IV) in a concentrated acidic solution for the first time. The transient Am(IV) species was found to have a lifetime of ~16 µs?sufficiently long-lived to play a critical mechanistic role in UNF reprocessing systems. Additionally, we performed the first-ever temperature-dependent kinetics study of an actinide element, elucidating unprecedented Arrhenius and Eyring activation parameters for the reaction of Am(III) with NO3?. This new knowledge provides much-needed molecular-level insights into the radiation-induced behavior of Am.
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