BUSCADOR RECOLECTA

This paper analyses the potential reduction of electric energy generated with fossil fuels with 40 GW of PV power and 40 GW of wind power in the existing Spanish electric system and its integration by making use of existing hydroelectric power and reserves with different levels of flexibility. We use 10-minute data for 2 years and we firstly assume that hydro power remains the same as originally, observing an already high reduction in fossil fuel use in the electric mix. Then we increasingly allow more flexibility in hydro power use, i.e., we allow to use hydro reserves with different time horizons, and we analyze the incremental reduction in fossil fuel generation as we increase this flexibility. We observe that we can obtain notable gains in terms of fossil fuel reduction when increasing flexibility just slightly showing how hydro power can integrate large amounts of variable renewable energy in Spain with only a small change in the reserves profile., This project has received funding from the European Union´s H2020 research and innovation programme under Maria Sklodowska-Curie grant agreement No 101034285. Additionally, this work has been supported by the Spanish State Research Agency (AEI) and ERDF-UE under grants PID2022-142179OB-I00 and PID2022-139914OB-I00.

Re-utilizing lithium-ion batteries from electric vehicles reduces their environmental impact. To ensure their optimal sizing and safe use, identifying the current state of the battery and predicting its remaining useful life is essential. This work analyzes the degradation mechanisms involved and proposes an aging model that utilizes a semi-empirical approach to accurately reproduce the battery's state of health within a range of 75-45 %. Calendar aging includes dependencies on temperature and state of charge while cycling aging is modeled based on depth of discharge, medium SOC, temperature, and Crate. The model is validated against experimental data from 14 LMO/LNO cells previously used in actual Nissan Leaf vehicles and an RMSE bellow 2.5 % is achieved in every case., This work is part of the projects PID2022-139914OB-I00, funded by MICIU/ AEI/10.13039/501100011033/ and by 'ERDF/EU' , TED2021-132457BI00, funded by MICIU/AEI/10.13039/501100011033/ and by the European Union 'NextGenerationEU/PRTR', STARDUST (H2020-SCC-2016/17- 774094), funded by the European Union's Horizon 2020 research and innovation program, HYBPLANT (0011-1411-2022-000039), funded by the Government of Navarre, and Lion2H2 (PJUPNA2023-11380), funded by the Public University of Navarre.

An increasing number of applications with diverse requirements incorporate various battery technologies. Selecting the most suitable battery technology becomes a tedious task as several aspects need to be taken into account. Two of the key aspects are the battery characteristics under temperature variations and their degradation. While numerous contributions using tailored assessment methods to evaluate both aspects for a particular application exist in the literature, a general methodology for analysis is necessary to enable a quantitative comparison between different technologies. We propose in this paper a novel methodology, based on performance indicators, to quantify the potential and limitations of a battery technology for diverse applications sharing a similar operational profile. A quantification of phenomena such as the influence of high and low temperatures on the battery, or the effect of cycling and state of charge on battery aging is obtained. In pursuit of these indicators, an experimental procedure and the fitting of aging model parameters that allow their calculation are proposed. As an additional outcome of this work, a general aging model that allows comprehensive analysis of aging behavior is developed and the trade-off between experimental time and accuracy is analyzed to find an optimal experimental time between 2 and 4 months, depending on the studied battery technology. Finally, the proposed methodology is applied to four battery technologies in order to show its potential in a real case-study., This work was supported by grants PID2022-139914OB-I00 funded by MICIU/AEI/10.13039/501100011033/ (Spain) and by ERDF/EU (European Union), TED2021-132457B-I00 funded by MICIU/AEI/10.13039/501100011033/ (Spain) and by the NextGenerationEU/PRTR (European Union), HYBPLANT (0011-1411-2022-000039) funded by the Government of Navarre (Spain), and Lion2H2 (PJUPNA2023-11380) funded by the Public University of Navarre (Spain). Elisa Irujo was supported by a predoctoral contract from the Public University of Navarre (Spain).

Thyristor rectifiers are currently the most common solution for supplying high-power electrolyzers. These rectifiers typically include a dc inductance, which significantly increases system costs. However, this inductance can be avoided by relying solely on ac-side inductances, required for grid current harmonic filtering, although this approach introduces specific challenges. Traditional analytical models of thyristor rectifiers are unable to determine the electrolyzer operating point for a given firing angle and may lead to incorrect system sizing, ultimately preventing the converter from delivering nominal power. This limitation arises from the fact that existing models are formulated for inductive or constant-current loads, whereas electrolyzers exhibit electrical behavior closer to constant-voltage loads. In this paper, a novel analytical model of 6- and 12-pulse thyristor rectifiers with constant-voltage load is developed. The model enables the analysis and optimal sizing of thyristor rectifiers directly connected to electrolyzers without a dc-side inductance. Its accuracy has been validated through both simulations and experimentally using a laboratory-scale prototype. Furthermore, the model has been applied to optimally size a 12-pulse rectifier supplying a 5.5 MW electrolyzer, demonstrating its suitability for the design of thyristor rectifier systems in industrial-scale electrolysis applications and highlighting its advantages over traditional approaches., This work is part of the projects PID2022-142791OB-I00 and PID2022-139914OB-I00 funded by MICIU/AEI/10.13039/501100011033 and by "ERDF/EU", and has also been supported by the Public University of Navarra under a Ph.D. scholarship.

Publicado 2024-07-30, Experimental studies of lithium-ion batteries are very often based only on deep charge and discharge cycles. However, these test profiles do not fully reflect the actual operation of the battery in an electric vehicle or in stationary applications, where the battery is not only loaded during the main charging and discharging profiles, but it is also stressed by the current throughput caused by renewable power fluctuations or by auxiliary services. These cycles, which are superimposed to the main charge and discharge processes and have a depth of discharge not exceeding 2%, are called micro-cycles. Although there are several simulation studies that attempt to capture this issue, there is still no comprehensive experimental study that has the phenomena that occur during micro-cycling. This paper presents an experimental analysis of micro-cycles, providing a detailed view of the different processes taking place in the battery during aging, by means of a detailed analysis of the results from electrochemical impedance spectroscopy (EIS). By studying the single electrochemical processes in detail, this paper explains the benefits of micro-cycling in terms of extending the lifetime of the battery., This research was funded by the Czech Technical University student's grant project number SGS24/136/OHK3/3T/13 and by the project 'The Energy Conversion and Storage', funded as project No. CZ.02.01.01/00/22-008/0004617 by Programme Johannes Amos Comenius, call Excellent Research. Moreover, this work is part of the projects PID2022-139914OB-I00, funded by MCIN/AEI/10.13039/501100011033/FEDER, UE, TED2021-132457B-I00, funded by MCIN/AEI/10.13039/501100011033/ and by the European Union NextGenerationEU/PRTR, and HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre.

This paper investigates the impact of power supply and dc current ripple on the efficiency of water electrolyzers and demonstrates that optimally sized thyristor rectifiers meeting grid power quality regulations can effectively supply high-power electrolyzers with minimal impact on electrolyzer efficiency. Firstly, an equivalent electrical model for the electrolyzer is developed, and the efficiency reduction caused by dc current ripple is analyzed. This is validated by means of experimental data from a 5-kW alkaline electrolyzer operated with both thyristor- and IGBT-based rectifiers. Next, the paper explores the operation of high-power electrolyzers supplied by 6- and 12-pulse thyristor rectifiers complying with grid power quality standards. Results show that with optimal sizing of ac-side source voltage and filtering inductances, these solutions exhibit negligible dc current ripple impact on electrolyzer efficiency. These findings, validated through simulation of a 5.5 MW electrolyzer, highlight the viability of thyristor rectifiers in high-power electrolysis applications, and emphasize the importance of an optimal power supply design and sizing for enhancing water electrolyzers' performance., This work is part of the projects PID2022-142791OB-I00 and PID2022-139914OB-I00 funded by MICIU/AEI/10.13039/501100011033/ and by 'ERDF/EU', and has also been supported by the Public University of Navarra under a Ph.D. scholarship. It has also been supported by Ingeteam Power Technology. The authors also thank the Agencia Nacional de Investigación y Desarrollo (ANID) FONDECYT Regular grant number 1220556, the Centre for Multidisciplinary Research on Smart and Sustainable Energy Technologies for Sub-Antarctic Regions under Climate Crisis ANID/ATE220023, Fondap SERC 1522A0006 and IRCF 24932270 project from the University of Nottingham.

Extensive use of lithium-ion batteries and scarcity of lithium are leading to re-emergence of sodium-ion batteries as a promising candidate, side-by-side with LIBs, to cover increasing demand of energy storage systems. Thus, development and commercialization of SIBs have been recently accelerated. Scientific research on first commercialized cells has been published regarding its fundamental parameters, aging and thermal performance. However, SIBs still require experimental study to continue developing and maturing their technology. For that reason, this work presents an electrical characterization and aging analysis of a commercial 1.3 Ah 18650 SIB. Based on experimental results obtained, this contribution reveals energy efficiencies of around 92% and an open circuit voltage with a plateau at a SOC of 35%. Regarding aging, samples full cycled at 0.5C exhibit a capacity loss of 15% after 310 cycles and stored cells age at a speed of 0.01 %/day., This work is part of the projects PID2022-139914OB-I00, funded by MICIU/ AEI/ 10.13039/501100011033/ and by 'ERDF/EU', TED2021-132457BI00, funded by MICIU/AEI/10.13039/501100011033/ and by the European Union 'NextGenerationEU/PRTR', STARDUST (H2020-SCC-2016/17-774094), funded by the European Union's Horizon 2020 research and innovation program, HYBPLANT (0011-1411-2022-000039), funded by the Government of Navarre, Lion2H2 (PJUPNA2023-11380), funded by the Public University of Navarre, and has also been supported by the Public University of Navarra under a Ph.D. scholarship.

Safety issues associated with lithium-ion batteries (LIBs) jeopardize their widespread adoption in both stationary applications and electric vehicles. One of the factors that can most affect the safety of a LIB is its chemistry. For this reason, this article aims to evaluate the safety of the two main current chemistries, LFP and NMC. In particular, the safety of both technologies is examined from the perspective of the areas of abuse that characterize their behavior beyond the safe operation area. A commercial 5 Ah pouch cell with LFP chemistry is subjected to various overtemperature and overcharge abuses at different conditions. The results obtained for LFP chemistry cell are discussed together with those for NMC cell from a previous work of the authors. Identification of the abuse areas allows for a comparative analysis of the safety of both chemistries, providing a valuable tool for classifying the abuse behavior of LIBs., This work is part of the projects PID2022-139914OB-I00, funded by MICIU/AEI/ 10.13039/501100011033/ and by 'ERDF/EU', TED2021-132457BI00, funded by MICIU/AEI/10.13039/501100011033/ and by the European Union 'NextGenerationEU/PRTR', STARDUST (H2020-SCC-2016/17-774094), funded by the European Union's Horizon 2020 research and innovation program, HYBPLANT (0011-1411-2022-000039), funded by the Government of Navarre, and has also been supported by the Spanish Ministry of Science and Innovation under a Ph.D. scholarship (PRE2020-095314).

The electric mobility industry is booming. In order to reduce the environmental impact of this boom, there is the potential to reuse the batteries from electric vehicles. However, the technical and economic feasibility of the second-life of lithium-ion batteries remains in question. This is due to the intricate non-linear mechanisms that occur during battery degradation, leading to capacity and power loss. Ongoing research aims to create models that can predict the state of battery degradation. However, most studies have focused on the battery's first life, operating within a limited state of health range and requiring constant monitoring of the battery's exposure conditions. While these models provide satisfactory results for the battery's performance in vehicles, they cannot be directly applied to second-life scenarios. In response to this issue, this article proposes a degradation modeling method for second-life batteries based on identifying and linearizing different degradation trends within the battery. This approach allows the application of the model without prior knowledge of the battery's history. It has been validated for a state of health range of 95% to 20%, through both conventional charge-discharge tests and a real-world scenario involving a smart charging station for urban buses. The results obtained with the developed model are overall satisfactory, achieving a MAPE below 3% for capacity and 1.4% for internal resistance in the real-world scenario., This work was supported by grants PID2022-139914OB-I00 funded by MICIU/AEI/10.13039/501100011033/ (Spain) and by ERDF/EU (European Union), TED2021-132457B-I00 funded by MICIU/AEI/10.13039/501100011033/ (Spain) and by the NextGenerationEU/PRTR (European Union), HYBPLANT (0011-1411-2022-000039) and PRIDEBAT (PC24-PRIDEBAT-014-002) funded by the Departamento de Universidad, Innovación y Transformación Digital (Department of University, Innovation and Digital Transformation) of the Goverment of Navarre (Spain), and Lion2H2 (PJUPNA2023-11380) funded by the Public University of Navarre (Spain).