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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Optimising implementation strategies for fuel cell powered road transport systems in the United Kingdom

Lane, Benjamin M. January 2002 (has links)
No description available.
2

Hydrogen Fuel Cell on a Helicopter: A System Engineering Approach

January 2016 (has links)
abstract: Hydrogen fuel cells have been previously investigated as a viable replacement to traditional gas turbine auxiliary power unit onboard fixed wing commercial jets. However, so far no study has attempted to extend their applicability to rotary wing aircrafts. To aid in the advancement of such innovative technologies, a holistic technical approach is required to ensure risk reduction and cost effectiveness throughout the product lifecycle. This paper will evaluate the feasibility of replacing a gas turbine auxiliary power unit on a helicopter with a direct hydrogen, air breathing, proton exchange membrane fuel cell, all while emphasizing a system engineering approach that utilize a specialized set of tools and artifacts. / Dissertation/Thesis / Masters Thesis Engineering 2016
3

Polyaniline based metal-organic framework composites for hydrogen fuel cells

Ramohlola, Kabelo Edmond January 2017 (has links)
Thesis (M. Sc. (Chemistry)) -- University of Limpopo, 2017. / In order to meet the great demand of energy supply globally, there must be a transition from dependency on fossil fuel as a primary energy source to renewable source. This can be attained by use of hydrogen gas as an energy carrier. In the context of hydrogen fuel cell economy, an effective hydrogen generation is of crucial significant. Hydrogen gas can be produced from different methods such as steam reforming of fossil fuels which emit greenhouse gases during production and from readily available and renewable resources in the process of water electrolysis. Hydrogen generated from water splitting using solar energy (photocatalysis) or electric energy (electrocatalysis) has attracted most researchers recently due to clean hydrogen (without emission of greenhouse gases) attained during hydrogen production. In comparison with photocatalytic water splitting directly using solar energy, which is ideal but the relevant technologies are not yet commercialized, electrolysis of water using catalyst is more practical at the current stage. The platinum group noble metals (PGMs) are the most effecting electrocatalysts for hydrogen evolution reactions (HER) but their scarcity and high cost limit their application. In this study, we presented the noble metal free organic-inorganic hybrid composites and their HER electrocatalysis performances were investigated. Polyaniline-metal organic framework (PANI/MOF) composite was prepared by chemical oxidation of aniline monomer in the presence of MOF content for hydrogen production. The properties of PANI, MOF and PANI/MOF composite were characterised for their structure and properties by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Raman, transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), atomic absorption spectroscopy (AAS), square wave (SWV) and cyclic voltammetry (CV). There was a clear interaction of MOF on the backbone of the PANI matrix through electrostatic interaction as investigated by both Raman and FTIR. The MOF exhibited irregular crystals with further wrapping of MOF by PANI matrix as evidenced by both SEM and TEM analyses. The PANI composite exhibited some nanorods and microporous structure. x The determined energy band gap of the composite was in good agreement with previously reported catalysts for hydrogen evolution reaction (HER). The thermal stability of PANI increased upon addition of MOF. Experiments probing the electrochemical, HER and photophysical properties revealed that the composite was very stable and robust with significant improvement in properties. The resulting composite is a promising low-cost and environmentally friendly hydrogen production material. In this work we also reported about novel poly (3-aminobenzoic acid)-metal organic framework referred as PABA/MOF composite. Spectroscopic characterisations (UV-vis and FTIR) with support of XRD and TGA revealed a successful interaction between PABA and MOF. Morphological characterisation established that PABA is wrapping MOF and the amorphous nature of the materials were not affected. The catalytic effect of PABA and PABA/MOF composites on HER was studied using exchange current density and charge transfer coefficient determined by the Tafel slope method. A drastic increase in catalytic H2 evolution was observed in PABA and composite. Moreover, they merely require overpotentials as low as ~-0.405 V to attain current densities of ~0.8 and 1.5 Am-2 and show good longterm stability. We further demonstrated in the work the electrocatalytic hydrogen evolution reaction of MOF decorated with PABA. These novel MOF/PABA composites with different PABA loading were synthesised via in situ solvothermal synthesis of MOF in the presence of PABA. It was deduced that PABA with different loading amount have an influence on the morphologies, optical properties and thermal stabilities of MOF. Interestingly, the MOF/PABA composites exhibited the great significant on the HER performance and this is potentially useful in HER application for hydrogen fuel cell. / Sasol Inzalo foundation and National Research Foundation of South Africa
4

Techno-Economic Analysis of Hydrogen Fuel Cell Systems Used as an Electricity Storage Technology in a Wind Farm with Large Amounts of Intermittent Energy

Sanghai, Yash 01 January 2013 (has links) (PDF)
With the growing demand for electricity, renewable sources of energy have garnered a lot of support from all quarters. The problem with depending on these renewable sources is that the output from them is independent of the demand. Storage of electricity gives us an opportunity to effectively manage and balance the supply and demand of electricity. Fuel cells are a fast developing and market capturing technology that presents efficient means of storing electricity in the form of hydrogen. The aim of this research is to study the impact of integrating hydrogen fuel cell storage system with a wind farm to improve the reliability of the grid for allowing higher penetration of renewable energy sources in the power system. The installation of energy storage systems strongly depends on the economic viability of the storage system. We identified four types of fuel cells that could be used in a hydrogen fuel cell storage system. We bring together a range of estimates for each of the fuel cell systems for the economic analysis that is targeted towards the total capital costs and the total annualized costs for the storage system for individual applications like rapid reserve and load shifting. We performed sensitivity analysis to determine the effect of varying the rate of interest and cost of fuel cell on the total annualized cost of the storage system. Finally, we compared the costs of hydrogen based storage system with other storage technologies like flywheel, pumped hydro, CAES and batteries for the individual application cases.
5

SOLID STATE NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY OF CHEMICALLY MODIFIED GRAPHITIC MATERIALS FOR THE PERFORMANCE ENHANCEMENT OF HYDROGEN FUEL CELLS

MacIntosh, Adam Robert January 2018 (has links)
Solid-state nuclear magnetic resonance (ssNMR) spectroscopy was used to anal- yse numerous graphene-sheet based materials in an attempt to study their effects on the performance of polymer electrolyte membrane fuel cell (PEM-FC) mate- rials. It has been noted in the literature that fuel cells which incorporated these materials (e.g. functionalized graphene, doped carbon nanotubes (CNTs), etc.) displayed increased performance over a wider range of environmental conditions, chiefly temperature and relative humidity. The inter-material interactions behind this phenomenon are poorly described at best. Due to its extreme site speci ficity and sensitivity to minute differences in nuclear electromagnetic environments, ss- NMR is an ideal tool for investigating the complicated interactions at work in these systems. While the electronically conductive, amorphous, non-stoichiometric, and low spin-density nature of these materials presented challenges to the collection of NMR spectra, the results presented here display the remarkable utility of this method in the study of analogues and derivatives of graphene. Graphene Oxide (GO), a derivative of graphene, has intrinsic proton conduc- tivity which is similar to Na fon, the most popular proton exchange membrane material currently used in fuel cells. Research into acid-functionalized graphene oxides and determining the role of acidic groups in increasing proton conductivity will help to improve polymer electrolyte membrane performance in fuel cell sys- tems. Multinuclear solid-state NMR (ssNMR) spectroscopy was used to analyse the structure and dynamics of GO and a number of sulfonic acid derivatives of GO, both novel and previously reported. 13C spectra showed the disappearance of surface-based oxygen groups upon GO functionalization, and can be used to identify linker group carbon sites in previously synthesized and novel functional- ized GO samples with high speci city. Dehydration of these samples allows the collection of 1H spectra with resolved acidic proton and water peaks. The effect of dehydration on the proton spectrum is partially reversible through rehydration. Deuteration of the acidic groups in high temperature and acidic conditions was virtually unsuccessful, indicating that only the surface and not the intercalated functional groups play a role in the enhanced proton conductivity of ionomer / functionalized GO composites. Increased surface area and increased delamination of functionalized GO is suggested to be important to improved PEM-FC perfor- mance. This synthesis and method of analysis proves the utility of ssNMR in the study of structure and dynamics in industrially relevant amorphous carbon ma- terials, despite the obvious di culties caused by naturally broad signals and low sensitivity. Graphene and carbon nanotubes (CNTs) have been investigated closely in re- cent years due to their apparent positive effect on the electrochemical performance of new fuel cell and battery systems as catalyst stabilizers, supports, or as metal- free catalysts. This is particularly true for doped graphene and CNTs, where only a small amount of doping with nitrogen and/or phosphorus can have a re- markable effect on materials performance. A direct link between structure and function in these materials is, as of yet, unclear. Doped graphene and CNTs were synthesized using varied chemical vapour deposition (CVD)-based methods, and ssNMR was used to unambiguously identify dopant atom sites, revealing that these particular synthesis methods result in highly homogeneous populations of installed phosphorus and nitrogen atoms. We present the first experimental 15N spectrum for graphitic nitrogen in N-doped graphene. 15N-labeled nitrogen doped graphene synthesized as reported here produces mainly graphitic nitrogen sites located on the edges of sheets and around defect sites. 1H-1H and 1H-15N corre- lations were also used to probe dopant nitrogen sites in labelled and unlabelled N-doped graphene. A nearly homogeneous population of phosphorus in P-doped graphene is found, with an overwhelming majority of graphitic phosphorus and a small amount of phosphate oligomer. Similar findings are noted for the phos- phorus sites in phosphorus and nitrogen co-doped CNTs with a minor change in chemical shift, as would be expected from two chemically similar phosphorus sites in carbon allotropes (CNTs versus graphene sheets) with signifi cantly different electronic structures. Ionomeric sulfonated polyether ether ketone (SPEEK) membranes were doped with functionalized graphenes, and the proton conductivities of these composite membranes was measured at fuel cell operational temperatures and percent relative humidities (%RH). The differences in proton conductivity between pure SPEEK membranes and composites with different dopants and doping levels at varied conditions were investigated through high-fi eld 1H ssNMR. It was found that high- speed MAS was able to dehydrate membranes under water-saturated conditions, and so lower %RH conditions were better able to produce reliable ssNMR results. The addition of graphitic dopants appeared to have an overall detrimental effect on the bulk proton conductivity of membranes, while concurrently these doped membranes had a broadened operational temperature window. In an attempt to explore the positive influence of nitrogen doping on the effec- tive lifetime of carbon-supported platinum catalysts used in automotive hydrogen fuel cell systems, solid-state NMR was employed to probe the difference (if any) between doped catalyst supports made from different carbon and nitrogen sources. 1H spectroscopy showed a variety of sites present in the doped samples; some likely from residual starting material but others from novel sites within the doped cat- alyst supports. Double-quantum and 2D 1H experiments were used to examine the structure of these catalysts, while 13C CPMG experiments (see Chapter 2) revealed subtle differences in the nuclear relaxation rates of these materials, poten- tially related to their electronic conductivity. The results of the ssNMR analysis were insuffcient to provide an unambiguous picture of the dopant sites within these carbon black samples; this was due in equal parts to the lack of isotopically labelled dopants, the effects of electronic induction and ring current shifts on data acquisition and analysis, and the broad array of different 13C chemical shift en- vironments present in the carbon black itself. While the data is still interesting spectroscopically, suggestions are made at the end of this chapter to expand upon the lessons learned through this study to produce more useful results from similar samples in the future. / Thesis / Doctor of Philosophy (PhD) / Solid-state nuclear magnetic resonance (ssNMR) spectroscopy was used to anal- yse numerous graphene-sheet based materials in an attempt to study their effects on the performance of polymer electrolyte membrane fuel cell (PEM-FC) materials. It has been noted in the literature that fuel cells which incorporated these materials (e.g. functionalized graphene / graphite, doped carbon nanotubes (CNTs), etc.) displayed increased performance over a wider range of environmental conditions, chiefly temperature and relative humidity. The inter-material interactions behind this phenomenon are poorly described at best. Due to its extreme site specifi city and sensitivity to minute differences in nuclear electromagnetic environments, ss- NMR is an ideal tool for investigating the complicated interactions at work in these systems. While the electronically conductive, amorphous, non-stoichiometric, and low spin-density nature of these materials presented challenges to the collection of NMR spectra, the results presented here display the remarkable utility of this method in the study of analogues and derivatives of graphene. Covalently functionalized graphene / graphite was synthesized, and the struc- tures of several derivatives were recorded with remarkable resolution, such that functional group carbons were resolvable. The proton dynamics of this material were remarkably slow, and so improvements in composite PEM ion conductiv- ity were proposed to be caused by surface interactions between dopant and poly- mer. The proton dynamics of ionomer graphene composites were also investigated through ssNMR. A number of graphene and CNT samples doped with phosphorus and 15N-labelled nitrogen were also analysed, and the synthesis methods employed were found to produce chemically homogeneous dopant sites with few by-products. Absent isotopic labelling, nitrogen dopant sites in carbon black samples were found to affect the relaxation properties of protons within nitrogen doped carbon black.
6

Design and Control of a Unique Hydrogen Fuel Cell Plug-In Hybrid Electric Vehicle

Giannikouris, Michael January 2013 (has links)
The University of Waterloo Alternative Fuels Team (UWAFT) is a student team that designs and builds vehicles with advanced powertrains. UWAFT uses alternatives to fossil fuels because of their lower environmental impacts and the finite nature of oil resources. UWAFT participated in the EcoCAR Advanced Vehicle Technology Competition (AVTC) from 2008 to 2011. The team designed and built a Hydrogen Fuel Cell Plug-In Hybrid Electric Vehicle (FC-PHEV) and placed 3rd out of 16 universities from across North America. UWAFT design projects offer students a unique opportunity to advance and augment their core engineering knowledge with hands-on learning in a project-based environment. The design of thermal management systems for powertrain components is a case study for design engineering which requires solving open ended problems, and is a topic that is of growing importance in undergraduate engineering courses. Students participating in this design project learn to develop strategies to overcome uncertainty and to evaluate and execute designs that are not as straightforward as those in a textbook. Electrical and control system projects require students to introduce considerations for reliability and robustness into their design processes that typically only focus on performance and function, and to make decisions that balance these considerations in an environment where these criteria impact the successful outcome of the project. The consequences of a failure or unreliable design also have serious safety implications, particularly in the implementation of powertrain controls. Students integrate safety into every step of control system design, using tools to identify and link together component failures and vehicle faults, to design detection and mitigation strategies for safety-critical failures, and to validate these strategies in real-time simulations. Student teams have the opportunity to offer a rich learning environment for undergraduate engineering students. The design projects and resources that they provide can significantly advance student knowledge, experience, and skills in a way that complements the technical knowledge gained in the classroom. Finding ways to provide these experiences to more undergraduate students, either outside or within existing core courses, has the potential to enhance the value of program graduates.
7

Μετρήσεις σε πειραματική διάταξη κυψέλης υδρογόνου (fuel cell) τεχνολογίας πολυμερικού ηλεκτρολύτη χαμηλής θερμοκρασίας (PEM)

Καραβότας, Κωνσταντίνος 11 January 2010 (has links)
Στην παρούσα διπλωματική παρουσιάστηκαν όλα τα θεωρητικά και τεχνικά στοιχεία των κελιών καυσίμου. Επίσης, έγινε ανάλυση των διαθέσιμων τεχνολογιών των κελιών καυσίμου, καθώς και μια ιστορική αναδρομή. Τα κελιά καυσίμου και ειδικότερα το υδρογόνο σαν καύσιμο αναμένεται να διαδραματίσει τον σημαντικότερο ρόλο τις επόμενες δεκαετίες. Η τεχνολογία των κελιών καυσίμου συνεχώς βελτιώνεται. Τα κελιά καυσίμου βρίσκουν ολοένα και μεγαλύτερο εύρος εφαρμογών, καθώς είναι ιδιαίτερα φιλικά προς το περιβάλλον. Η αρχή λειτουργίας τους είναι από πολύ παλιά γνωστή, στους επιστημονικούς κύκλους. Το πρόβλημα ήταν ανέκαθεν η βελτιστοποίηση των συστημάτων, ώστε να γίνουν οικονομικότερα και πιο αποδοτικά. Η τεχνολογία της κυψέλης καυσίμου και της μετατροπής του υδρογόνου σε ηλεκτρικό ρεύμα είναι ακόμα σε πρώιμο στάδιο, και έχει αρκετά υψηλό κόστος, αλλά βελτιώνεται με ιδιαίτερα ταχείς ρυθμούς. Τα κελία καυσίμου στο παρελθόν αποτελούσαν λύσεις για παραγωγή ηλεκτρικής ενέργειας, σε πολύ εξειδικευμένες κατασκευές όπως είναι οι διαστημοσυσκευές. Στις προηγούμενες δεκαετίες η τεχνολογία των κελιών καυσίμου ήταν οικονομικά ασύμφορη και όχι και τόσο αποδοτική. Γίνεται ανάλυση των επιμέρους δυσκολιών για την βελτιστοποίηση των συστημάτων τεχνολογίας κελιών καυσίμου και οι τρόποι επίλυσης τους που έχουν προταθεί. Το θεωρητικό μέρος της διπλωματικής συμπληρώνεται από την πειραματική μελέτη, που πραγματοποιήθηκε σε μία εμπορική εφαρμογή. Επίσης, με την βοήθεια ηλεκτρονικού υπολογιστή έγιναν προσομοιώσεις όλων των θεωρητικών μοντέλων που έχουν προταθεί από διάφορους επιστήμονες, πρωτοπόρους στην τεχνολογία των κελιών καυσίμου. Η εμπορική εφαρμογή που χρησιμοποιήθηκε για την εξακρίβωση των θεωρητικών παρατηρήσεων, καλύπτει μόνο ένα μέρος της τεχνολογίας των κελιών καυσίμου, καθώς ήταν μια στοίβα κελιών καυσίμου τεχνολογίας PEM. Τα κελιά καυσίμου τεχνολογίας PEM είναι τα πιο απλά στην κατασκευή και την χρήση, και είναι μια εφαρμοσμένη τεχνολογία εδώ και δεκαετίες. Οι υπόλοιπες τεχνολογίες απαιτούν διαφορετικές συνθήκες λειτουργίας και πολλές από αυτές βρίσκονται σε πειραματικό στάδιο. Τα κελία καυσίμου υψηλών θερμοκρασιών είναι ένα σημαντικό τεχνολογικό επίτευγμα που υπόσχεται πολλά. Η παρούσα διπλωματική αποτελεί ένα πολύ χρήσιμο εργαλείο για την κατανόηση της λειτουργίας ενός κελιού καυσίμου, καθώς και την κατανόηση των διαφόρων θερμοδυναμικών και ηλεκτροχημικών φαινομένων τα οποία συμβαίνουν μέσα στο κελί καυσίμου και είναι υπεύθυνα για την παραγωγή της ηλεκτρικής ενέργειας. Εκθέτονται όλοι οι λόγοι που οδηγούν στην ανάγκη μοντελοποίησης της λειτουργίας των κελιών καυσίμου. Παρουσιάζονται όλα τα μοντέλα τα οποία έχουν προταθεί κατά καιρούς και βοηθούν στην βαθύτερη κατανόηση της λειτουργίας ενός κελιού καυσίμου. 4 Επίσης, γίνεται σύγκριση των υπαρχόντων μοντέλων με την βοήθεια πειραματικής διάταξης, όπου συγκρίνονται τα πειραματικά αποτελέσματα με τα θεωρητικά. Το καύσιμο του μέλλοντος είναι το υδρογόνο και αυτό δύσκολα μπορεί κανείς να το αμφισβητήσει. Υπάρχουν εδώ και μια δεκαετία εφαρμοσμένες λύσεις σε αυτόνομα και διασυνδεδεμένα συστήματα, τα οποία λειτουργούν εξ’ ολοκλήρου με κελιά καυσίμου. Η μελλοντική ανάπτυξη τέτοιων συστημάτων αναμένεται μεγάλη δεδομένου των ενεργειακών προβλημάτων που αντιμετωπίζει η παγκόσμια κοινότητα σήμερα. Πρόκειται για συστήματα τα οποία μπορούν να δώσουν ανεξαρτησία και φιλική προς το περιβάλλον ενέργεια. Οι εναλλακτικές μορφές ενέργειας αποτελούν σημαντική λύση στη δραματική μείωση των ορυκτών πόρων και πρέπει η έρευνα και η αγορά να στραφούν προς την εκμετάλλευσή τους. / This Essay presents all the theoretical and technical attributes of the Fuel Cell technology. There is a thorough analysis of the available fuel cell technologies and also a historic review. Fuel cells, and specially Hydrogen as fuel, will play a significant role during the next decades. This technology develops at an escalated rate. Fuel Cells have a wide range of applications, due to their environmental friendly operation. The working principal of fuel cells is known for many years, the problem is the efficiency improvement of these systems. The transformation of Hydrogen to electricity has a significant cost today, but is estimated to be decreased as the rate of fuel cell usage is increased. Global warming due to carbon dioxide emissions lead to the need of a more efficient and clean fuel. The high rate of development of Hydrogen fuel cell technology means that fuel cell systems will have many more applications than they had in the past. Fuel cell technology was only applied as a power source for very special applications such as space shuttles and generally space devices. The main difficulties for fuel cell operation optimization are discussed here, so as the ways to solve these problems. The theoretical part of this essay is completed with the experimental study made on a commercial application. Moreover, with computer aided simulations, all the theoretical data was compared with the experimental. Theoretical electrical models that had been proposed by many scientists are presented and the results were also compared to the experimental data. This comparison covers only a certain part of the fuel cell technology, that of low temperature proton exchange membrane fuel cells. PEM fuel cells are much easier to construct and operate. This technology is well known for many years, as it has been applied by NASA for over 50 years. The rest of fuel cell types require special working conditions and many of them are in an experimental stage. For example, the much promising technology of high temperature PEM fuel cells. This essay is of great importance for scientist to understand the working principals of fuel cells and the various thermodynamic and electrochemical phenomena taking place inside the fuel cell. These phenomena are responsible for the production of the electrical energy. The need for theoretical modelling of fuel cells is also discussed and analysed. A review of the proposed pem fuel cell models is also made. The fuel of the future is definitely hydrogen and that’s a fact not easily questioned. The future development of hydrogen fuel cell systems for autonomous and interconnected electric power production is expected very high. These systems can produce clean and environmentally friendly energy. Renewable power sources are the most important solution to the global warming problem.
8

Low Platinum Content Thin Film Catalysts for Hydrogen Proton Exchange Membrane Fuel Cells / Low Platinum Content Thin Film Catalysts for Hydrogen Proton Exchange Membrane Fuel Cells

Václavů, Michal January 2016 (has links)
Novel type of catalyst for proton exchange membrane fuel cells anode is demonstrated. It is based on magnetron sputtered Pt-CeO2 a Pt-Sn-CeO2 mixed oxides. It is shown, that these materials allow to significantly decrease amount of platinum in the anode catalyst. The preparation method yields high amount of platinum in ionized form, especially Pt2+ , which is related to the high activity. Stability of these catalytic layers were investigated under conditions similar to fuel cell anode (humidified hydrogen at elevated temperature). Also interaction of hydrogen a water under UHV conditions were studied, demonstrating high stability of the Pt2+ species. In the last part of the work sputtered Pt-Co mixed catalyst were investigated to be used in the PEMFC cathode. It is demonstrated that at right conditions, the sputtered alloy catalyst improves mass activity on cathode by factor more than two.
9

Hydrogen Fuel in Sweden, a Comparative Study of Five Countries

Fereidounizadeh, Neda January 2021 (has links)
Under the shadow of the climate change dilemma and its consequence for the human’s future, the need for secured and stable energy sources is vital. Academia, political leaders, and influential business actors play a key role to introduce schemes to facilitate the adaptation of new technologies and energy systems improvement. Hydrogen as an energy carrier is one of the solutions to tackle environmental concerns in recent decades. However, hydrogen technology needs constant development to reduce its cost and to find production methods by which fossil fuels can be replaced by clean hydrogen. In this study, five different countries in terms of hydrogen technology introduction, their National Strategy on Hydrogen, influential variables on hydrogen application have been investigated. Along with a comparison between five countries, the differences in policies and political incentives and their effect on hydrogen applications have been studied. Policy incentives work differently according to the various cultural norms. In some countries such as Japan financial incentives work better but in some such as Sweden non-financial incentives work well. Along with policy introduction, collaboration between policy, industry, and academia contribute to the successful introduction, diffusion, and application of new technologies. Regarding hydrogen technology in Sweden, introduction of National Strategy on Hydrogen, a shift from hydrogen application in industry to transport section, and giving less priority to biogas and more to hydrogen fuel, applying suitable policy incentives can be helpful for Sweden to act faster and benefit more from hydrogen.
10

Thesis: A SPECTROSCOPIC STUDY OF POLYMER ELECTROLYTE MEMBRANES / A SPECTROSCOPIC STUDY OF STRUCTURE AND DYNAMICS IN PROTON-CONDUCTING POLYMERS FOR HYDROGEN FUEL CELLS

Yan, Zhejia Blossom January 2018 (has links)
This thesis focuses on the state-of-the-art spectroscopic approaches in studying polymer electrolytes for proton exchange membrane fuel cells. With the aim to optimize architectural and chemical design of hydrogen fuel cells, a variety of perfluorosulfonic acid (PFSA) membranes were explored to establish characteristics that ultimately improve PFSA electrolyte performance. The results of the detailed spectroscopic analyses helped to unveil a structure performance relationship. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy was used to distinguish F and C environments, while scanning transmission X-ray microscopy coupled with X-ray absorption spectroscopy provided complementary chemical structural information with direct access to S and O environments. The combination of these two techniques provided advantages in identifying subtle chemical alterations in PFSAs. Furthermore, a novel ssNMR technique was developed with the purpose of probing local dynamics from the polymer perspective. This ¬¬19F dipolar recoupling ssNMR approach was validated and applied to PFSA membranes by monitoring the normalized double quantum build-up curves as a function of relative humidity (%RH) and temperature, and the polymer side chain showed higher local motion as response to temperature and %RH elevation compared to the backbone. The effective dipolar coupling constant was extracted to represent local dynamics and compared amongst tested PFSAs. A standardized metric, the dynamic order parameter, was also introduced and applied to the materials to quantitatively compare them within the same class. This new method provided an alternative way to extract site-specific local dynamics profile for materials with multiple resonances. Additionally, the combination of in situ fuel cell performance evaluation and ex situ ssNMR characterization created a connection between fundamental chemistry and bulk electrochemical measurements. As the first study to correlate these physicochemical properties to material performances, this work parameterized the structural impact at a molecular level and provided insight into improving polymer electrolyte materials. / Thesis / Doctor of Philosophy (PhD) / Proton exchange membrane fuel cells, which help to reduce the reliance on fossil fuels by locally producing only water and heat, have received a significant amount of research attention as an alternative power generator for vehicular and stand-alone energy applications. Perfluorosulfonic acid (PFSA) membranes, the most common commercial polymer electrolyte materials, have been investigated using modern analytical spectroscopies. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy and synchrotron-based scanning transmission X-ray microscopy were used in elucidating material compositions with complementary information. Moreover, an advanced ssNMR method was developed and applied to a variety of PFSAs. Polymer backbones and side chains were separated spectroscopically, and were distinguished based on different local dynamics profiles extracted from the ssNMR experiments. Additionally, bulk material performance evaluations from electrochemical analyses were correlated to PFSA side chain local dynamics profiles. The integrated spectroscopic study illustrated in this thesis provided insight into understanding the structure-performance relationship of PFSA electrolytes.

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