Investigation on low and high temperature fuel cell components and their evaluation in short stack configuration

La ricerca sulle celle a combustibile ad ossidi solidi (SOFC) ed a membrana ad elettrolita polimerico è attualmente indirizzata al miglioramento delle performance e della loro vita utile, così come alla riduzione dei costi. Tali aspetti sono importanti per rendere questi dispositivi più interessanti per il mercato, sia nelle applicazioni stazionarie che automotive. Da questo punto di vista, per la tecnologia PEMFC sembra necessario un incremento della temperatura (da 80°C a 110-120°C, high temperature PEMFC o HT-PEMFC). Ciò porterebbe ad una migliore resistenza alle impurezze di CO nel fuel, un migliore thermal and water management ed una migliore efficienza per la co-generazione. Al contrario, la tecnologia SOFC va verso temperature intermedie (IT-SOFC); ciò permetterebbe una riduzione dei costi nello sviluppo di celle planari, grazie a processi di fabbricazione meno onerosi ed ad un incremento della stabilità. Questi modi di estendere l'applicazione sono ben studiati per celle singole, ma il processo di scale-up verso dispositivi di potenza necessita di ulteriori specifici approfondimenti. Inoltre, tecnologie differenti necessitano di procedure di test differenti, adattate a specifici settori applicativi. In questa tesi di Dottorato, sono stati testati dispositivi a celle a combustibile basati su tecnologia ad ossidi solidi od ad elettrolita polimerico per applicazioni specifiche. In particolare, sono stati studiati stack di fuel cells di potenza nominale pari ad 1kW, per verificare la possibilità dell'utilizzo di fuel cell per applicazioni di piccola taglia. Attualmente, i dispositivi basati su HT-PEMFC stanno suscitando interesse per lo sviluppo delle celle a combustibile. Nonostante una profonda conoscenza delle proprietà dei materiali, la valutazione degli stessi a livello di stack è stata oggetto di un piccolo numero di studi. In questa attività di ricerca è stato approfondito proprio questo aspetto. La tecnologia IT-SOFC è considerata adatta per applicazioni stazionarie e per la produzione di energia distribuita, poiché può usare combustibile poco costoso in processi elettrochimici ad elevata efficienza. Inoltre, per applicazioni relative ad utenze residenziali, i dispositivi studiati possono essere considerati come la base per lo sviluppo di un sistema turn-key e non come la versione downscaled per studi da laboratorio. Questa tesi di Dottorato include considerazioni per applicazioni sia stazionarie che automotive, analizzando stack di fuel cells di potenza sufficiente per essere considerati come proof-of-concept. In altre parole, la potenza è sufficiente per studiare i principali fenomeni che appaiono in stack di dimensioni superiori orientate ad applicazioni pratiche. L'intera attività può essere suddivisa in due parti: 1) test di short stack HT-PEMFC per la valutazione delle performance in condizioni tipiche del settore automovtive (corrente, temperatura, umidificazione, pressione) e per individuare il punto di lavoro ottimale; 2) test di stack IT-SOFC in gas naturale per valutare la perdita di prestazioni per fenomeni legati a cicli redox che possono avvenire durante l'uso reale. Tecniche di diagnosi, come il metodo di interruzione di corrente e la spettrocopia d'impedenza hanno completato lo studio fornendo informazioni circa l'ottimizzazione dell'assemblaggio degli stack. La sperimentazione è stata interamente condotta in laboratorio, per controllare in maniera accurata le variabili di processo; nonostante ciò, le prestazioni ottenute sono comunque utili per applicazioni concrete, una volta che siano state definite condizioni di lavoro appropriate come compromesso tra prestazioni e costi.Research activities on solid oxide (SOFC) or polymer electrolyte membrane (PEMFC) fuel cells are currently focused on performance and lifetime enhancement as well as costs reduction. These aspects are relevant to make such systems more attractive for the market, both for stationary and automotive applications. From this point of view, an increase of temperature (from 80°C to 110-120°C) appears necessary for PEMFC technology (high temperature PEMFC, or HTPEMFC). This would allow more resistance to CO contaminants in the fuel, better thermal and water management and a better efficiency for co-generation. On the contrary, SOFC technology is moving towards intermediate temperature (IT-SOFC); this would allow cost reduction while developing planar cells, due to less critical construction processes and an increase of stability. These ways to enhance the fuel cells applications are well studied for single cell but the scale-up process to significant power production devices needs specific investigations. Moreover, different technologies need different field test procedures, tailored on the specific application sectors. In this Ph.D. thesis, fuel cell devices exploiting either solid oxide or polymer electrolyte technologies, were tested for specific applications. In particular, 1kW fuel cell stacks were tested in order to verify the possibility of fuel cell use in small size applications. Nowadays, HT-PEMFC devices are creating lot of interest for FC technology development. Anyway, despite a deep knowledge of material properties, the assessment of the new materials at stack level have undergone only few studies. In this research activity this aspect was investigated. Moreover, IT-SOFC technology is considered valuable for stationary applications and distributed energy production, using cheap fuels and a highly efficient electrochemical process. Nevertheless, for residential energy consumption, the studied SOFC device can be considered not as a downscaled device for laboratory study, but as the base to develop a complete system. This Ph.D. thesis involves considerations for both stationary and automotive applications, by analysing fuel cells stack with a size large enough to be considered a proof-of-concept. In other words, the size appears sufficient to investigate main phenomena visible in larger stack oriented to real world applications. The whole activity can be divided in two lines: 1) tests of HT-PEMFC short stacks that were carried out to evaluate their performance in typical automotive working conditions (current, temperature, humidification, pressure) and to establish an optimal operating point. 2) tests of IT-SOFC stacks in natural gas, in order to evaluate performance decay and its response to detrimental effects due to thermal and redox cycles that can appear in "out of laboratory" usage. Diagnostic analysis such as current interrupt method and electrochemical impedance spectroscopy completed the study by supplying information about the optimization of stack assembling procedure. The whole experimental activities were carried out in laboratory, to accurately control the process variables; nevertheless, the recorded performances are anyway meaningful with respect to real world applications, once defined tailored working conditions by a good compromise between performances and costs

Caso studio italiano: Valutazione del potenziale “Green Hydrogen” da Power-to-gas

Il documento descrive l’applicazione del tool realizzato all’interno del progetto SuperP2G da CNR-ITAE e UNIBO in riferimento a due casi d’uso (nazionale e regionale), riguardanti la penetrazione della mobilità ad idrogeno sul territorio italiano. Il tool di pianificazione sviluppato fornisce come principali risultati l’allocazione ottima degli impianti di produzione di idrogeno verde basati sull’elettrolisi e la loro taglia, in funzione delle rinnovabili e della domanda di idrogeno presenti in un dato territorio. Inoltre, gli output di calcolo rilasciano anche una caratterizzazione economica delle soluzioni trovate in termini di “cost breakdown”, in riferimento ai costi d’investimento, quelli relativi alla connessione alla rete elettrica, al trasporto di idrogeno verso gli utilizzatori, senza tralasciare i costi operativi d’impianto. Elementi chiave per l’applicazione del tool a casi reali sono la stima della domanda di idrogeno e la definizione dei costi che entrano in gioco in riferimento alle specifiche tecnologie. A tal proposito è stato necessario sviluppare scenari futuri che tengano conto di una penetrazione del vettore idrogeno rilevante ai fini dell’applicazione del tool, considerando le proiezioni di mercato sia in termini di sviluppo e scale-up delle tecnologie che di possibile domanda di idrogeno. Si è scelto di analizzare i due scenari di riferimento attuali così come previsto nella strategia europea sull’idrogeno e nel “New Green Deal” con i relativi target al 2030 e al 2050. Nello specifico i due casi studio sviluppati riguardano: 1) Penetrazione del vettore idrogeno a livello nazionale nella mobilità veicolare al 2030 e al 2050. Questo caso studio è basato sulla conversione (parziale) in idrogeno delle attuali stazioni di rifornimento di carburante presenti sulle autostrade italiane. 2) Penetrazione del vettore idrogeno a livello regionale nella mobilità veicolare al 2030 e al 2050. Questo caso studio è basato sulla conversione (parziale) in idrogeno delle attuali stazioni di rifornimento di carburante presenti nella regione Puglia

Hybrid cascade heat pump and thermal-electric energy storage system for residential buildings: experimental testing and performance analysis

The need for innovative heating and cooling systems to decarbonize the building sector is widely recognized. It is especially important to increase the share of renewables at building level by maximizing self-consumption and reducing the primary energy demand. Accordingly, in the present paper, the results on a wide experimental campaign on a hybrid system are discussed. The system included a sorption module working as the topping cycle in a cascade configuration with a DC-driven vapor compression heat pump. A three-fluids heat exchanger with a phase change material (PCM), i.e., RT4 with nominal melting temperature of 4 °C, was installed on the evaporator side of the heat pump, for simultaneous operation as thermal storage and heat pumping purposes. The heat pump was connected to a DC-bus that included PV connection and electricity storage (batteries). Results showed that the energy efficiency of the heat pump in cascade operation was double compared to compression-only configuration and that, when simultaneously charging and discharging the latent storage in cascade configuration, no penalization in terms of efficiency compared to the compression-only configuration was measured. The self-sufficiency of the system was evaluated for three reference weeks in summer conditions of Athens climate and it was found that up to 100% of the electricity needed to drive the system could be self-produced for a modest cooling demand and up to 67% for the warmer conditions with high cooling demand.This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 768824 (HYBUILD). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31) and by the Ministerio de Ciencia, Innovación y Universidades—Agencia Estatal de Investi-gación (AEI) (RED2018-102431-T). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia program

Perspectives on green hydrogen in Europe—during an energy crisis and towards future climate neutrality

Hydrogen and regional energy infrastructure are significant for the European Green Deal and was the focus of the SuperP2G research Project (Synergies Utilising renewable Power Regionally by means of Power to Gas). Five national projects (Denmark, Netherlands, Germany, Austria, and Italy) cooperated to investigate power-to-gas feasibility. The energy crisis due to the war in Ukraine peaked during the project. The demand for green hydrogen increased as natural gas was reduced. In 2022, the cost of blue hydrogen was 9.5–12.6 €/kg. Higher electricity prices impacted the cost of green hydrogen less. Considering the 2021–22 level of electricity and gas prices, and the potential flexibility of electrolysers, electrolytic hydrogen was on a par with blue hydrogen. On the long term, green hydrogen is assumed to be competitive around 2030. A fast ramping up and favourable electricity cost development could halve the hydrogen production cost until 2040 with investment being the major contributor to a cost reduction. Meanwhile, the smart operation of a wind/electrolyser system might achieve 24% reduction of its operation cost. The following measures are recommended to introduce green hydrogen on a large scale: 1) certification of green and low carbon hydrogen and a uniform CO2 price; 2) ensuring a level playing field across markets; 3) enabling policies to enhance European security of supply by increasing domestic production and diversifying imports; 4) fast ramping of renewable electricity generation; and 5) coordinated planning of hydrogen, methane, and electricity infrastructures

A New Geographic Information System (GIS) Tool for Hydrogen Value Chain Planning Optimization: Application to Italian Highways

Optimizing the hydrogen value chain is essential to ensure hydrogen market uptake in replacing traditional fossil fuel energy and to achieve energy system decarbonization in the next years. The design of new plants and infrastructures will be the first step. However, wrong decisions would result in temporal, economic losses and, in the worst case, failures. Because huge investments are expected, decision makers have to be assisted for its success. Because no tools are available for the optimum design and geographical location of power to gas (P2G) and power to hydrogen (P2H) plants, the geographic information system (GIS) and mathematical optimization approaches were combined into a new tool developed by CNR-ITAE and the University of Bologna in the SuperP2G project, aiming to support the interested stakeholders in the investigation and selection of the optimum size, location, and operations of P2H and P2G industrial plants while minimizing the levelized cost of hydrogen (LCOH). In the present study, the tool has been applied to hydrogen mobility, specifically to investigate the conversion of the existing refuelling stations on Italian highways to hydrogen refuelling stations (HRSs). Middle-term (2030) and long-term (2050) scenarios were investigated. In 2030, a potential demand of between 7000 and 10,000 tons/year was estimated in Italy, increasing to between 32,600 and 72,500 tons/year in 2050. The optimum P2H plant configuration to supply the HRS was calculated in different scenarios. Despite the optimization, even if the levelized cost of hydrogen (LCOH) reduces from 7.0–7.5 €/kg in 2030 to 5.6–6.2 €/kg in 2050, the results demonstrate that the replacement of the traditional fuels, i.e., gasoline, diesel, and liquefied petroleum gases (LPGs), will be disadvantaged without incentives or any other economic supporting schemes

Li-ion Battery Modeling and State of Charge Estimation Method Including the Hysteresis Effect

In this paper, a new approach to modeling the hysteresis phenomenon of the open circuit voltage (OCV) of lithium-ion batteries and estimating the battery state of charge (SoC) is presented. A characterization procedure is proposed to identify the battery model parameters, in particular, those related to the hysteresis phenomenon and the transition between charging and discharging conditions. A linearization method is used to obtain a suitable trade-off between the model accuracy and a low computational cost, in order to allow the implementation of SoC estimation on common hardware platforms. The proposed characterization procedure and the model effectiveness for SoC estimation are experimentally verified using a real grid-connected storage system. A mixed algorithm is adopted for SoC estimation, which takes into account both the traditional Coulomb counting method and the developed model. The experimental comparison with the traditional approach and the obtained results show the feasibility of the proposed approach for accurate SoC estimation, even in the presence of low-accuracy measurement transducers

Framework di pianificazione territoriale per lo sfruttamento del “Green Hydrogen” attraverso tecnologie P2G

Il progetto SuperP2G-Italy con CNR-ITAE (capofila) e Università di Bologna ha conseguito l’obiettivo proposto, ovvero lo sviluppo di un tool open-source e Web-Gis finalizzato all’ottimizzazione della supply chain dell’idrogeno dalla produzione agli utenti finali. In particolare, il tool sviluppato ottimizza la posizione e la taglia delle centrali di produzione dell’idrogeno da elettrolisi minimizzando i costi di produzione e di trasporto dell’idrogeno che può essere realizzato su gomma oppure all’interno di condotte. In accordo agli obiettivi di progetto, il tool è attualmente disponibile in una versione “alpha test”, ovvero, prima di poter essere messa a disposizione agli utenti (versione beta) dovranno essere completate attività di sviluppo del software principale così come dovranno essere integrate funzionalità aggiuntive, sinteticamente riportate nella sezione finale del documento. Obiettivo del documento è quello di illustrare brevemente il framework del tool mentre nell’ultima sezione si riportano le limitazioni che attualmente sono presenti e i potenziali sviluppo futuri che gli autori si auspicano di implementare per aumentare la flessibilità di utilizzo

Optimal Design of Grid Integration of a Net Zero Energy Building trough Electrochemical Energy Storage and Fuel Cell Utilization

The integration of electrochemical energy storage, renewable energy production, and fuel cell systems can play a key role in the development of more efficient eco-friendly systems, spanning all sectors of energy management, from stationary to mobile. In particular, residential sector consumed 19% of worldwide energy production in 2015, resulting the third energivorous sector after transport and industry. Distributed energy systems, which efficiently use local resources, can reduce problems in regions with lack of a stable network and more in general help the growth of a sustainable development. In this case, the impact of PV-Lithium Batteries-SOFC integration in a NZEB (Net Zero Energy Builiding) is investigated by using software simulation, developed in Matlab/Simulink environment, to find optimal compromise between environment benefits, electricity grid independence, and costs. The NZEB was realized at CNR-ITAE laboratories by using eco-friendly technologies such as low environmental impact renewable FRP (Fiber Reinforced Pultruded) materials for its manufacturing, high efficiency PV panels, custom innovative multi-source inverter, advanced LiFeMgPO4 batteries, Solid Oxide Fuel Cell, optimized HVAC (Heating, Ventilation and Air Conditioning). Software simulation helps to evaluate and forecast the impact of all of the systems described upon, aiming to obtain an efficient energy management. At first, a monitoring campaign has been launched to evaluate loads consumption, PV production during the year and performances of single elements. After this, all data collected have been used to create models of all the systems present inside the building. The model developed permits to evaluate improvement parameters such as CO2 reduction, Load Cover Factor, Supply Cover Factor, estimate effective energy consumption and costs, and choose the right algorithm for energy management

Computer Fluid Dynamics Assessment of an Active Ventilated Façade Integrating Distributed MPPT and Battery

Ventilated Façades integrated with photovoltaic panels have become a popular way to improve both the thermal-physical performances of the existing built environment. The increased usage of not-programmable renewable energy sources implies the adoption of energy storage systems to mitigate the mismatch between the power generation and the building’s demand. Aiming at properly integrates a photovoltaic panel and a battery (Lithium based) as a module of an active ventilated façade, the prototype design has been carried out in terms of thermo-fluid dynamics performance. Based on experimental setup, a numerical study of flow through the air cavity of the active ventilated façade has been carried out by the fluid-dynamics Finite Volume code-Ansys-Fluent. The calibrated model was lastly used to perform a wide range of parametric analyses on different climate and boundary conditions to explore the viability of the prototype

Perspectives on green hydrogen in Europe - during an energy crisis and towards future climate neutrality

Hydrogen and regional energy infrastructure are significant for the European Green Deal and was focus ofthe SuperP2G research Project (Synergies Utilising renewable Power Regionally by means of Power to Gas). Five national projects (Denmark, Netherlands, Germany, Austria, and Italy) cooperated to investigate Power-to-Gas feasibility. The energy crisis due to the war in Ukraine peaked during the project. The demand for green hydrogen increased as natural gas was reduced. In 2022, the cost of blue hydrogen was 9.5-12.6 EUR/kg. Higher electricity prices impacted the cost of green hydrogen less. Considering the 2021-2022 level of electricity and gas prices, and the potential flexibility of electrolysers, electrolytic hydrogen was on a par with blue hydrogen. On the long term, green hydrogen is assumed to be competitive around 2030. A fast ramping up and favourable electricity cost development could halve the hydrogen production cost until 2040 with investment being the major contributor to a cost reduction. Meanwhile, the smart operation of a wind/electrolyser system might achieve 24% reduction of its operation cost. The following measures are recommended to introduce green hydrogen on large scale: 1) Certification of green and low carbon hydrogen and a uniform CO2 price; 2) Ensuring a level playing field across markets; 3) Enabling policies to enhance European security of supply by increasing domestic production and diversifying imports; 4) Fast ramping of renewable electricity generation; 5) Coordinated planning of hydrogen, methane and electricity infrastructures