• Energy Research

[EN] This study proposes a predictive equivalent consumption minimization strategy (P-ECMS) that utilizes velocity prediction and considers various dynamic constraints to mitigate fuel cell degradation assessed using a dedicated sub -model. The objective is to reduce fuel consumption in real -world conditions without prior knowledge of the driving mission. The P-ECMS incorporates a velocity prediction layer into the Energy Management System. Comparative evaluations with a conventional adaptive-ECMS (A-ECMS), a standard ECMS with a well -tuned constant equivalence factor, and a rule -based strategy (RBS) are conducted across two driving cycles and three fuel cell dynamic restrictions (|di/dt|max <= 0.1, 0.01, and 0.001 A/cm2s). The proposed strategy achieves H2 consumption reductions ranging from 1.4% to 3.0% compared to A-ECMS, and fuel consumption reductions of up to 6.1% when compared to RBS. Increasing dynamic limitations lead to increased H2 consumption and durability by up to 200% for all tested strategies. This research is part of the project TED2021-131463B-I00 (DI-VERGENT) funded by MCIN/AEI/10.13039/501100011033 and the European Union "NextGenerationEU"/PRTR.

[EN] As the world intensifies its efforts to reduce the adverse effects of global warming, the shift towards a fully developed hydrogen-based economy is emerging as a core strategy. This transition involves the strategic blending of hydrogen with conventional fossil fuels such as natural gas (HCNG), allowing for adaptation to hydrogen availability. Nevertheless, the environmental impact of HCNG vehicles in realistic scenarios with variable hydrogen content remains unexplored. This study focuses on evaluating the global warming impact of the transition of light-duty passenger cars from CNG to H2 vehicles using HCNG blends from 2020 to 2050 and different realistic scenarios. The results in the present study were obtained through a combination of an experimental testing campaign that allowed obtaining how the performance and emissions of HCNG vehicles change with the H2 content and a life cycle assessment methodology. Based on the findings, the scenario in which hydrogen was mostly produced from SMR-dominant, was found to have the potential to reach and outperform the zero-emission concept due to the utilization of biogas. From the results of this study, the recommended H2 content in HCNG blends that offers low environmental impact while avoiding the overdemand of hydrogen in the short term for the 2020-2030 decade is 25% H2 content, increasing to 50% by 2030, and to 75%-100% during the 2040-2050 decade, thus reaching the transition towards pure-H2 technology that minimizes environmental impact. This research has been partially funded by FEDER and the Spanish Government through project RTI2018-102025-B-I00 (CLEAN-FUEL) . M. Olcina-Girona is partly supported by the grant CIACIF/2021/437 of the "Subvenciones para la contratacion de personal investigador pre-doctoral (ACIF) "of the Conselleria d'Innovacio, Universitats, Ciencia i Societat Digital de la Generalitat Valenciana, Spain.

[EN] At the present time, the critical climate situation has raised awareness about the importance of developing carbon-free technologies. In this context, fuel cell systems (FCS) have become one of the key technologies in the pathway to decarbonization. Given that road transport is a major contributor to greenhouse gas (GHG) emissions, this paper focuses on a specific segment of this sector: light commercial vehicles (LCVs). The current market situation shows that LCV manufacturers have not yet decided what is the appropriate powertrain architecture for this kind of vehicle. Thus, the current paper studies a wide range of possible FCS-based propulsive system designs, changing the size of the FCS, electric battery and H2 tank. These propulsive system architectures are analyzed concerning the performance of the vehicle, in terms of consumption and range, and the durability of its FCS. The evaluation of these different designs will be highly valuable for the LCV industry and manufacturers, as it allows to understand the optimal powertrain solution. The study demonstrates that a significant increase in range can be achieved with only a minor penalty in hydrogen consumption. Additionally, the research indicates that it is feasible to employ one of the most durable FCS designs while meeting LCV mission requirements with minimal consumption penalty. In conclusion, this paper provides valuable data to the ongoing research in this field, offering a detailed analysis of the impact of H2 consumption, autonomy, and durability of the FCS across various vehicle architectures under typical LCV driving conditions. This research has been partially funded by Universitat Politecnica de Valencia through the support program for research and de-velopment (PAID-01-22) and by the Generalitat Valenciana (Conselleria d'Innovacio, Universitats, Ciencia i Societat Digital) as a part of the DEFIANCE research project (CIPROM/2021/039) through the PROMETEO funding program. The activities of this work are also part of TED2021-131463B-I00 (DIVERGENT) funded by MCIN/AEI/10.13039/501100011033 and the European Union "NextGenerationEU"/PRTR .

[EN] Fuel cell (FC) technology has been identified as a technically attractive solution to decarbonize the transportation sector, especially for heavy-duty vehicles. In this context, the industry and the scientific community are in need of advanced fuel cell systems (FCS) models that are able to replicate real-world operating conditions. Due to the scarcity of said models in the open literature, this study aimed to develop a comprehensive methodology to calibrate and validate multi-physics dynamic FCS models. Therefore, the key contribution of this paper is the detailed description of the calibration process for each component and the calibration order. The specific focus here was to accurately describe the behavior of the FC stack as well as the cathode, anode, and cooling circuits of the balance of plant. The model was calibrated with the aid of experimental data from a Toyota Mirai FC electric vehicle, which was predominantly retrieved from the vehicle¿s Controller Area Network (CAN) bus system thereby negating the need for major intrusion into the powertrain system. The validation process was deemed successful with the model being able to truthfully replicate the characteristics of the FC vehicle operated on the World-wide harmonized Light duty Test Cycle (WLTC) 3b and US06 driving cycle. The time-resolved physical parameters such as the cathode pressure, mass flow, or the FC stack temperature were captured with high fidelity, while the overall performance parameters such as the H2 consumption in the stack and the system, and the compressor energy consumption were predicted accurately with a deviation lower than 0.47%, 1.75% and 1.89% with respect to the experimental data, respectively. This research is part of the project TED2021-131463B-I00 (DI-VERGENT) funded by MCIN/AEI/10.13039/501100011033 and the European Union "NextGenerationEU"/PRTR. It has also been partially funded by the Spanish Ministry of Science, Innovation, and University through the University Faculty Training (FPU) program (FPU19/00550) . Toby Rockstroh and Ram Vijayagopal acknowledge support through the US DOE Vehicle Technologies Program. Argonne National Laboratory is operated by UChicago Argonne, LLC under Contract no. DE-AC02-06CH11357. The US Government retains for itself, and others acting on its behalf, a paid-up non-exclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly, by or on behalf of the Government. The authors would like to express their gratitude to Kevin Stutenberg from Argonne National Laboratory for the informative discussions surrounding the experimental test campaign.

[ES] A la luz de la crisis medioambiental y del creciente interés en el uso del H2 para avanzar hacia la Economía del Hidrógeno, esta tesis tiene como objetivo analizar y optimizar nuevas arquitecturas de sistemas propulsivos de FCV para aplicaciones en turismos y vehículos pesados en términos de rendimiento, durabilidad e impacto medioambiental. Para ello, se ha desarrollado una plataforma de modelado de FCV multifísica y flexible que integra un modelo de pila de combustible validado junto con los componentes del BoP, los componentes mecánicos y eléctricos del vehículo y el sistema propulsivo, un modelo de degradación de FC semi-empírico informado por tendencias físicas diseñado para ser utilizado en condiciones de conducción y un optimizador de EMS en tiempo real que ofrece el mejor rendimiento dado un diseño de sistema propulsivo y un ciclo de conducción, de tal forma que todas las arquitecturas propuestas para una aplicación determinada sean comparables en términos justos. La discusión de los resultados puede dividirse en tres partes diferentes. La primera está orientada a la optimización del rendimiento del FCS. Los resultados de esta parte ayudaron a identificar la estrategia de gestión del aire que, dado un conjunto de restricciones impuestas en los componentes del BoP, maximizaba la potencia neta del FCS (eficiencia) para cada valor de densidad de corriente. El balance energético resultante, que comprende la potencia producida por la pila de combustible, las perdidas electroquímicas y el consumo de los componentes del BoP, fue analizado y utilizado para determinar y diseñar la estrategia de control de los actuadores del BoP para condiciones de conducción. La segunda parte se centra en la evaluación y optimización, cuando es posible, de la arquitectura FCREx para aplicaciones de turismos y la configuración multi-FCS para aplicaciones de vehículos de transporte pesado. Desde el punto de vista del rendimiento, la arquitectura FCREx ofrecía un consumo mínimo de H2 con una elevada potencia de la pila de combustible y una gran capacidad de la batería, pero este diseño podría ser prohibitivo en términos de costes. Podía ofrecer hasta un 16.8-25% menos de consumo de H2 y un 6.8% menos de consumo de energía. La limitación en la dinámica de esta arquitectura aumento la durabilidad de la FC en un 110% con una penalización en el consumo de H2 del 4.7%. La arquitectura multi-FCS para aplicaciones pesadas podría funcionar con una dinámica aún menor, con un aumento de la durabilidad de la pila del 471% con una penalización en el consumo de H2 del 3.8%, ya que el perfil de conducción de los vehículos pesados suele ser menos dinámico. El control y el dimensionamiento diferencial solo podrían aportar beneficios en términos de impacto ambiental o de coste, pero no de rendimiento. La última parte considera los resultados obtenidos en términos de rendimiento y durabilidad para analizar el impacto medioambiental de cada arquitectura. La estrategia de producción de H2 afecta significativamente a las emisiones del ciclo de vida en ambas aplicaciones sobre cualquier otra elección de diseño. El diseño óptimo para la arquitectura FCREx que minimiza las emisiones tiene una alta potencia de la pila de combustible y una capacidad moderada de la batería. En el caso de la aplicación para vehículos pesados, se identificó la dinámica de control óptima para cada diseño y estrategia de producción de H2, y se determinó que la estrategia de diseño de dimensionado diferencial solo proporcionaba beneficios si se consideraba una tecnología de pila de combustible diferente para las distintas pilas integradas en el sistema propulsivo. [CA] A la llum de la crisi mediambiental i del creixent interés en l'ús de l'H2 per a avançar cap a l'Economia de l'Hidrogen, aquesta tesi té com a objectiu analitzar i optimitzar noves arquitectures de sistemes propulsius de FCV per a aplicacions en turismes i vehicles pesants en termes de rendiment, durabilitat i impacte mediambiental. Per a això, s'ha desenvolupat una plataforma de modelatge de FCV multifísica i flexible que integra un model de pila de combustible validat juntament amb els components del BoP, els components mecànics i elèctrics del vehicle i el sistema propulsiu, un model de degradació de pila de combustible semi-empíric informat per tendències físiques dissenyat per a ser utilitzat en condicions de conducció i un optimitzador d'EMS en temps real que ofereix el millor rendiment donat un disseny de sistema propulsiu i un cicle de conducció, de tal forma que totes les arquitectures proposades per a una aplicació determinada siguen comparables en termes justos. La discussió dels resultats pot dividir-se en tres parts diferents. La primera està orientada a l'optimització del rendiment del FCS. Els resultats d'aquesta part van ajudar a identificar l'estratègia de gestió de l'aire que, donat un conjunt de restriccions imposades en els components del BoP, maximitzava la potència neta del FCS (eficiència) per a cada valor de densitat de corrent. El balanç energètic resultant, que comprén la potència produïda per la pila de combustible, les pèrdues electroquímiques i el consum dels components del BoP, va ser analitzat i utilitzat per a determinar i dissenyar l'estratègia de control dels actuadors del BoP per a condicions de conducció. La segona part se centra en l'avaluació i optimització, quan ¿es possible, de l'arquitectura FCREx per a aplicacions de turismes i la configuració multi-FCS per a aplicacions de vehicles de transport pesat. Des del punt de vista del rendiment, l'arquitectura FCREx oferia un consum mínim d'H2 amb una elevada potència de la pila de combustible i una gran capacitat de la bateria, però aquest disseny podría ser prohibitiu en termes de costos. Podia oferir fins a un 16.8-25% menys de consum d'H2 i un 6.8% menys de consum d'energia. La limitació en la dinàmica d'aquesta arquitectura va augmentar la durabilitat de la pila en un 110% amb una penalització en el consum d'H2 del 4.7%. L'arquitectura multi-FCS per a aplicacions pesades podria funcionar amb una dinàmica encara menor, amb un augment de la durabilitat de la pila del 471% i una penalització en el consum d'H2 del 3.8%, ja que el perfil de conducció dels vehicles pesants sol ser menys dinàmic. El control i el dimensionament diferencial només podrien aportar beneficis en termes d'impacte ambiental o de cost, però no de rendiment. L'última part considera els resultats obtinguts en termes de rendiment i durabilitat per a analitzar l'impacte mediambiental de cada arquitectura. L'estratègia de producció d'H2 afecta significativament a les emissions del cicle de vida en totes dues aplicacions sobre qualsevol altra elecció de disseny. El disseny òptim per a l'arquitectura FCREx que minimitza les emissions té una alta potència de la pila de combustible i una capacitat moderada de la bateria. En el cas de l'aplicació per a vehicles pesants, es va identificar la dinàmica de control `optima per a cada disseny i estratègia de producció d'H2, i es va determinar que l'estratègia de disseny de dimensionament diferencial només proporcionava beneficis si es considerava una tecnologia de pila de combustible diferent per a les diferents piles integrades en el sistema propulsiu. [EN] In light of the environmental crisis and the growing interest in the use of H2 to advance toward the Hydrogen Economy, this thesis aims at analyzing and optimizing novel FCV powerplant architectures for passenger car and heavy-duty vehicle applications in terms of performance, durability, and environmental impact. For that purpose, a multi-physics flexible FCV modeling platform was developed integrating a validated FC stack model together with the BoP components, the mechanical and electrical components of the vehicle and powertrain, a semi-empirical physics-informed FC degradation model designed to be used in driving conditions and a real-time EMS optimizer that offers the best performance given a powerplant design and driving cycle so that all the proposed architectures for a given application are comparable. The discussion of the results can be divided into 3 different parts. The first one is oriented towards the FCS performance optimization. The results in this part helped to identify the air management strategy that, given a set of constraints imposed in the BoP components, maximized the FCS net power output (efficiency) for each value of current density. The resulting energy balance comprising the FC stack power produced, the electrochemical losses, and the consumption of the BoP components was analyzed and used to determine and design the control strategy of the BoP actuators for driving cycle conditions. The second part is focused on the evaluation and optimization, when possible, of the FCREx architecture for passenger car applications and the multi-FCS configuration for heavy-duty vehicle applications. Performance-wise the FCREx architecture offered minimum H2 consumption with high FC stack power and high battery capacity, but this design could be prohibitive in terms of costs. It could offer up to 16.8-25% lower H2 consumption and 6.8% lower energy consumption. Limiting the dynamics of this architecture increased the FC durability by 110% with a penalty in H2 consumption of 4.7%. The multi-FCS architecture for heavy-duty applications could operate with even lower dynamics, with an increase in the FC durability of 471% with a penalty in H2 consumption of 3.8%, since the driving profile of heavy-duty vehicles is usually more steady. Differential control and sizing could only provide benefits in terms of environmental impact or cost, not performance. The last part considers the results obtained in terms of performance and durability to analyze the environmental impact of each architecture. The H2 production pathway affected significantly the life cycle emissions of both applications over any other design choice. The optimum design for FCREx architecture that minimized emissions had high FC stack power and moderate battery capacity. In the case of heavy-duty application, the optimum control dynamics for each design and H2 production pathway were identified, and the differential sizing design strategy was determined to only provide benefits if different FC stack technology was considered for the various stacks in the powerplant.

[EN] Aiming to reduce global warming and emissions in general, cleaner technologies are the spotlight of research and industry development. Among them, fuel cell vehicles (FCV) are gaining interest to decarbonize the transport sector. Plug-in FCV or FCV in range-extender configuration (FCREx) is an interesting option to reduce the total cost of ownership (TCO) and the energy usage per km. The aim of this study was to generate design spaces of FCREx by varying the FC stack maximum power output, the battery capacity, and the H-2 tank capacity to understand the implications of this architecture in range, consumption, and cost (estimated with a WLTP driving cycle). Unlike other studies, the approach was focused on a novel architecture for passenger vehicles and was focused on the development of the validated FC system model and the energy management strategy (EMS) optimization for each design, based on the Pontryagin Minimum Principle (PMP). Consumption was found to decrease with increasing battery capacity and FC maximum power due to the higher efficiency of the systems. The design spaces showed how with 5 kg of H-2 and >= 50 kWh of battery capacity the maximum range of FCREx could be over 700 km. The results of this study showed how FCREx architecture could provide overall energy consumption saving up to 6.8% and H-2 consumption saving ranging from 16.8% to 25%, compared to current commercial FCVs. The optimum FCREx design, not only based on performance, should have similar to 30 kWh of battery capacity and >= 80 kW of FC maximum power to minimize manufacturing costs while maximizing efficiency. This research has been partially funded by FEDER, Spain and the Spanish Government through project RTI2018-102025-B-I00 (CLEANFUEL) and through the University Faculty Training (FPU) program

[EN] In the new scenario where the transportation sector must be decarbonized to limit global warming, fuel cell-powered aerial vehicles have been selected as a strategic target application to compose part of the urban fleet to minimize road transport congestion and make goods and personal transportation fast and efficient. To address the necessity of clean and efficient urban air transport, this work consists of the conceptual development of a lightweight rotary-winged transport vehicle using a hydrogen-based fuel cell propulsion system and the optimization of its energy balance. For that purpose, the methods for integrating the coupled aerodynamic and propulsion system sizing and optimization was developed with the aim of designing concepts capable of carrying 0 (unmanned aerial vehicle - Design 1) and 1 (Aerotaxi - Design 2) passengers for a distance of 300 km at a cruise altitude of 500 m with a minimum climbing rate capability of 6 m s-1 at 1000 m. The results show how these designs with the desired performance specifications can be obtained with a vehicle mass ranging from 416 to 648 kg, depending on the application, and with specific range and endurance respectively within 46.2-47.8 km/kg and 20.4-21.3 min/kg for design 1 and 33.3-33.8 km/kg and 12.5-13.9 min/kg for design 2. This research has been partially funded by the Spanish Ministry of Science, Innovation, and University through the University Faculty Training (FPU) program (FPU19/00550) and FEDER and the Generalitat Valenciana, Consellerfa d'Innovacio, Universitats, Ciencia i Societat Digital through project IDIFEDER/2021/039. Funding for open access charge: CRUE-Universitat Politecnica de Valencia.

[EN] Fuel cell (FC) technologies for mobility are gaining interest as promising options to decarbonize the transport sector in line with the current progress towards the H-2 economy. Previous studies show how the fuel cell range extender (FCREx) powertrain architecture can offer flexible and efficient operation along with the potentially low total cost of ownership (TCO) in passenger car applications. Cradle-to-grave emissions of these vehicles have not been estimated, nor their variation with the components sizing or the H-2 production pathway analyzed. In this study, the life cycle assessment (LCA) and sizing methodologies were combined to address these knowledge gaps. The design spaces were generated by varying the FC maximum power, the battery capacity and the H-2 tank capacity and by simulating the resulting designs with the WLTC 3b driving cycle. Then, the lifetime H-2 and energy consumption results and design parameters were calculated and used as inputs to estimate the greenhouse gases (GHG) and NOX emissions on the manufacturing and fuel production cycles. From the results, it was proven how considering steam methane reforming (SMR) with carbon capture and storage (CCS) as the H-2 production pathway could decrease by 60% and 38% GHG-100 and NOX emissions respectively, with respect to electrolysis where electricity is generated with the EU mix. The optimum design, in terms of emissions, was found to be with low-moderate battery capacity and moderate-high FC maximum power in contrast to the optimum design for performance, which had high battery capacity and high FC stack power. This research has been partially funded by the Spanish Ministry of Science, Innovation and University through the University Fac-ulty Training (FPU) program (FPU19/00550) . Funding for open access charge: CRUE-Universitat Politecnica de Valencia