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New design methodology for the calculation of the feed sections into which the acceleration track of a hyperloop vehicle is divided
No full textThis paper presents the design methodology used to optimize the number of sections into which the acceleration track of a Hyperloop-type vehicle is divided. In these types of vehicles, a pre-acceleration system is necessary to reach a speed close to cruising speed before the main propulsion system can operate. For this purpose, a switched reluctance linear motor (LSRM), divided into what are called unitary machines (UMs) connected in series, is proposed along with a converter to control thrust force generated by the motor. The methodology is applied to a specific case (mission) where a mass of 250 kg needs to be accelerated over a distance of 60 m to reach a speed of 120 km/h. As a result of the proposed methodology, the number of sections into which the linear motor is divided, the number of UMs per section, and the optimal turn-on and turn-off angles of the LSRM phases are determined to achieve the target force profile
PRODUCTION AND CHARACTERIZATION OF Cr-DOPED UO2 AS AN ATF SURROGATE BY DRY POWDER METHOD (IONMAT PROJECT. SUBTASK 2.1)
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A New Index Assessing the Viability of PAR Application Projects Used to Validate PAR Models
Full text linkPhotosynthetically active radiation (PAR) is a useful variable to estimate the growth of biomass or microalgae. However, it is not always feasible to access PAR measurements; in this work, two sets of nine hourly PAR models were developed. These models were estimated for mainland Spain from satellite data, using multilinear regressions and artificial neural networks. The variables utilized were combinations of global horizontal irradiance, clearness index, solar zenith angle cosine, relative humidity, and air temperature. The study territory was divided into regions with similar features regarding PAR through clustering of the PAR clearness index (kPAR). This methodology allowed PAR modeling for the two main climatic regions in mainland Spain (Oceanic and Mediterranean). MODIS 3 h data were employed to train the models, and PAR data registered in seven stations across Spain were used for validation. Usual validation indices assess the extent to which the models reproduce the observed data. However, none of those indices considers the exceedance probabilities, which allow the assessment of the viability of projects based on the data to be modeled. In this work, a new validation index based on these probabilities is presented. Hence, its use, along with the other indices, provides a double and thus more complete validation
Measurement of the ??-ratio and (n,??) cross section of U-235 from 0.2 to 200 eV at n_TOF
Full text linkWe measured the neutron capture-to-fission cross-section ratio (alpha-ratio) and the capture cross section of U-235 between 0.2 and 200 eV at the n_TOF facility at CERN. The simultaneous measurement of neutron-induced capture and fission rates was performed by means of the n_TOF BaF2 Total Absorption Calorimeter (TAC), used for detection of ??-rays, in combination with a set of micromegas detectors used as fission tagging detectors. The energy dependence of the capture cross section was obtained with help of the Li-6(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the U-235(n,f) cross section between 7.8 and 11 eV was then used for its absolute normalization. The alpha-ratio, obtained with slightly higher statistical fluctuations, was determined directly, without need for any reference cross section. To perform the analysis of this measurement we developed a new methodology to correct the experimentally observed effect that the probabilities of detecting a fission reaction in the TAC and the micromegas detectors are not independent. The results of this work have been used in a new evaluation of U-235 performed within the scope of the Collaborative International Evaluated Library Organisation (CIELO) Project, and are consistent with the ENDF/B-VIII.0 and JEFF-3.3 capture cross sections below 4 eV and above 100 eV. However, the measured capture cross section is on average 10% larger between 4 and 100 eV
Analysis of spatial and temporal variability of the PAR/GHI ratio and PAR modeling based on two satellite estimates
Full text linkThe main objectives of this work are to address the analysis of the spatial and temporal variability of the ratio between photosynthetically active radiation (PAR) and global horizontal irradiance (GHI), as well as to develop PAR models. The analysis was carried out using data from three stations located in mainland Spain covering three climates: oceanic, standard Mediterranean, and continental Mediterranean. The results of this analysis showed a clear dependence between the PAR/GHI ratio and the location; the oceanic climate showed higher values of PAR/GHI compared with Mediterranean climates. Further, the temporal variability of PAR/GHI was conditioned by the variability of clearness index, so it was also higher in oceanic than in Mediterranean climates. On the other hand, Climate Monitoring Satellite Facility (CM-SAF) and Moderate-Resolution Imaging spectroradiometer (MODIS) data were used to estimate PAR as a function of GHI over the whole territory. The validation with ground measurements showed better performance of the MODIS-estimates-derived model for the oceanic climate (root-mean-square error (RMSE) around 5%), while the model obtained from CM-SAF fitted better for Mediterranean climates (RMSEs around 2%)
Comparative Analysis of Photosynthetically Active Radiation Models Based on Radiometric Attributes in Mainland Spain
Full text linkThe aims of this work are to present an analysis of quality solar radiation data and develop
several hourly models of photosynthetically active radiation (PAR) using combinations of radiometric
variables such as global horizontal irradiance (GHI), diffuse horizontal irradiance (DHI), and direct
normal irradiance (DNI) from their dimensionless indices atmospheric clearness index (kt), horizontal
diffuse fraction (kd), and normal direct fraction (kb) together with solar elevation angle ( ). GHI,
DHI, and DNI data with 1-minute frequencies in the period from 2016 to 2021 from CEDER-CIEMAT,
in a northern plateau, and PSA-CIEMAT in the southeast of the Iberian Peninsula, were used to
compare two locations with very different climates according to the K??ppen???Geiger classification.
A total of 15 multilinear models were fitted and validated (with independent training and validation
data) using first the whole dataset and then by kt intervals. In most cases, models including the
clearness index showed better performance, and among them, models that also use the solar elevation
angle as a variable obtained remarkable results. Additionally, according to the statistical validation,
these models presented good results when they were compared with models in the bibliography.
Finally, the model validation statistics indicate a better performance of the interval models than the
complete models
Advances in the location and repairing of ribbon interruptions in photovoltaic modules
Full text linkOne of the most frequent failures in PV modules is the total or partial interruption of ribbons that connect the cells in the module. In the case of modules with cells that have two ribbons on their surface, it is possible to distinguish between single interruptions (affecting only one ribbon of a cell) and twin interruptions (affecting both ribbons of a cell). In the case of repairing twin interruptions, it is possible to restore a significant part of the expected power, according to the nominal values of the module, which in modules with three diodes is in the order of a multiple of 1/3 of the nominal module power. In the case of repairing single interruptions, the recovered power reaches more modest values, up to 6 percentage points of the power prior to the repair. This article also shows the benefits to module fill factor depending on the repairs made and discusses metastable interruptions and the occurrence of new interruptions that can occur after initial repairs are made. A classification of single interruptions is proposed based on their type, and several methods to determine their location are described, highlighting one in particular for its simplicity and low cost. Finally, the relevance of carrying out a total repair (twin and single interruptions) or a partial repair (twin interruptions only) is discussed
Photovoltaic Waste Generation in the Context of Sustainable Energy Transition in EU Member States
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Open AccessArticle
Photovoltaic Waste Generation in the Context of Sustainable Energy Transition in EU Member States
by Mar??a Beatriz Nieto Morone 1,2,*ORCID,F??lix Garc??a Rosillo 1ORCID,Miguel ??ngel Mu??oz-Garc??a 2ORCID andMaria del Carmen Alonso-Garc??a 1ORCID
1
Unidad de Energ??a Solar Fotovoltaica, Departamento de Energ??a, CIEMAT, Av. Complutense, 40, 28040 Madrid, Spain
2
Laboratorio de Propiedades F??sicas y T??cnicas Avanzadas en Agroalimentaci??n (LPF-TAGRALIA), Escuela T??cnica Superior de Ingenier??a Agron??mica, Alimentaria y de Biosistemas (ETSIAAB), Universidad Polit??cnica de Madrid, Av. Puerta de Hierro, 2, 28040 Madrid, Spain
*
Author to whom correspondence should be addressed.
Resources 2025, 14(3), 37; https://doi.org/10.3390/resources14030037 (registering DOI)
Submission received: 14 January 2025 / Revised: 18 February 2025 / Accepted: 21 February 2025 / Published: 26 February 2025
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Abstract
The European Union (EU) is witnessing an expansion in solar capacity, aligning with its commitment to achieving climate neutrality by 2050. However, deploying solar capacity introduces significant environmental complexities, such as managing photovoltaic waste when the modules reach their end of life. This study presents an assessment of PV waste mass generation, integrating the latest data from the revised targets of the National Energy and Climate Plans (NECPs) of EU Member States presented in December 2023. Annual and cumulative PV waste mass is presented, analyzing the results in terms of the PV capacity deployment in each country and their recycling needs to face the treatment of the generated PV waste. According to the reviewed targets, the analysis reveals significant variations in PV waste mass generation across EU countries. The revisions show a substantial increase in the amount of waste generated in Europe. Lithuania and Ireland are anticipated to face substantial challenges, particularly under the early-loss scenario, whereas Germany, Italy, France, and Spain continue to be the countries that will generate the most PV waste mass in Europe. These findings emphasize the necessity for formulating and implementing effective waste management strategies to address the increasing generation of PV waste and mitigate its environmental impact. Furthermore, the study underscores the need to reassess projections to accommodate evolving energy policies and targets, ensuring alignment with sustainability objectives in this dynamic field
