The European Energy system is currently transitioning towards a reduced use of fossil fuels and increasing use of renewable energy. Hydrogen as energy carrier for renewable electricity has a potential to play a significant role in this transition. It can be stored and transported in its gaseous or liquid state, and utilized in industries that require highprocess heat, which makes them difficult to decarbonize. Further, hydrogen storage canbe employed to store over‐produced renewable electricity in large scale and for long periods of time. This research aims to develop a methodology to conduct a layout and dispatch optimization for utilizing locally produced hydrogen. The objective is to find the least cost supply pathway for a defined demand. In this case study, hydrogen is produced by water electrolysis supplied by the local electricity grid and renewable electricity, such as solar PV, onshore and offshore wind turbines. The scope is limited to gaseous hydrogen thereby the distribution is also limited to pipelines or road trucks. The optimized supplychain comprises four main stages: I) electricity generation and storage; II) hydrogen production; III) hydrogen compression and storage; IV) hydrogen transportation to the end consumer. It results in the system's optimum hourly dispatch schedule and a proposed least‐cost layout. The developed methodology is finally applied to an industrial case study in Sweden, for which scenarios with varying boundary conditions are tested. The least cost supply chain for the case study resulted in a system solely supplied with electricity purchased from the grid, a PEM electrolyzer, a hydrogen storage in a Lined Rock Cavern, and hydrogen transport via pipeline. The lowest Levelized Cost of Hydrogen from electricity purchase until delivery is 5.17 EUR/kgH2. The study concludes that there is no one optimum solution for all and the constraints of the optimization problem need to be evaluated case by case.The study further highlights that intermittency and peaks of both electricity availability and hydrogen demand can lead to an increase in system cost owing to the oversizing and storage needs. / Det europeiska energisystemet är för närvarande i en övergångsprocess mot en minskande användning av fossila bränslen och en ökande användning av förnybar energi. Vätgas som energibärare för förnybar el har potential att spela en viktig roll i denna övergång. Vätgas kan lagras och transporteras i gasform eller flytande form, och användas i industrier som kräver hög processvärme vars koldioxidutsläpp därför är svåra att minska. Vidare kan vätgaslagring användas för att lagra överproducerad förnybar el istor skala och under långa perioder. Denna forskning syftar till att utveckla en metod för layout och distributions optimering för utnyttjandet av lokalt producerad vätgas. Målet är att hitta den minst kostsamma försörjningsvägen för en definierad efterfrågan. I den här fallstudien produceras vätgas genom vattenelektrolys som försörjs av det lokala elnätet och förnybar el, t.ex. solceller, vindkraftverk på land och till havs. Omfattningen är begränsad till gasformig vätgas och därmed är distributionen också begränsad till rörledningar eller lastbilar. Den optimerade försörjningskedjan består av fyra huvudsteg: I) elproduktion och lagring, II) vätgasproduktion, III) komprimering och lagring av vätgas, IV) transport av vätgas till slutkonsumenten. Metodens output är systemets optimala timplan och ett förslag till layout med den lägsta kostnaden.  Den utvecklade metoden tillämpas slutligen i en industriell fallstudie i Sverige, för vilken scenarier med varierande randvillkor testas. Den minst kostsamma försörjningskedjan för fallstudien resulterade i ett system som enbart försörjs med el som köps från nätet, en PEM‐elektrolyser, ett magasin för vätgaslagring i ett fodrat bergrum och vätgastransport via en rörledning. Den lägsta Levelized Cost för vätgas från el inköp till leverans är 5,17EUR/ kgH2. I studien dras slutsatsen att det inte finns någon optimal lösning i allmänhet och att begränsningarna i optimeringsproblemet måste utvärderas från fall till fall. Studien belyser vidare att ostadighet och toppar i både eltillgången och efterfrågan på vätgas kan leda till en ökning av systemkostnaderna på grund av överdimensionering och lagringsbehov.

There is a well-established market for hydrogen, mainly for refining purposes, producing chemicals, and producing fertilizers. Today, almost all hydrogen is sourced from fossil fuels, with less than 1% of hydrogen sourced from renewable sources. Alternative solutions for fossil-free hydrogen are necessary to ensure that the demand for hydrogen can be met in a sustainable fashion. The objective of this study is to analyse the feasibility and cost-effectiveness of combining hydrogen production through electrolysis with electricity production from an array of wave energy converters to supply the hydrogen market with fossil-free hydrogen. A techno-economic analysis is performed for 16 cases of offshore hydrogen production and storage in eastern Japan, using three storage mediums; Compressed hydrogen, liquid hydrogen and ammonia. Technical and economical specifications of all components required for the production systems are modelled for each case to find the most beneficial system through the Levelized Cost Of Hydrogen (LCOH), which is compared to other available renewable and fossil hydrogen sources today. The production systems evaluated in this study reach an LCOH of $5.5-7.1 /kgH2 depending on the hydrogen storage medium, where compressed hydrogen is the cheapest. This can be considered competitive with other renewable hydrogen sources, but not with fossil counterparts. / Det finns en väletablerad marknad för vätgas, främst för raffinering och framställning av kemikalier samt gödningsmedel. Idag produceras nästan all vätgas av fossila bränslen, med mindre än 1% från förnybara källor. Alternativa lösningar för förnybar vätgas är nödvändiga för att möta efterfrågan på ett hållbart sätt. Syftet med denna studie är att analysera om det är ekonomiskt försvarbart att producera vätgas offshore genom elektrolys av el från vågkraftverk för att förse vätgasmarknaden med fossilfri vätgas. Detta utförs genom en tekno-ekonomisk analys av 16 fall av havsbaserad vätgasproduktion och lagring i östra Japan. Fallen behandlar tre lagringsmedium; komprimerad vätgas, flytande vätgas och ammoniak. Tekniska och ekonomiska specifikationer för alla komponenter som krävs för produktionssystemet modelleras för varje fall. Det mest fördelaktiga systemet beräknas genom Levelized Cost of Hydrogen (LCOH), som jämförs med andra tillgängliga förnybara och fossila produktionssystem för att avgöra systemets konkurrenskraft på marknaden. Produktionssystemen som utvärderas i denna studie har en LCOH från $5.5-7.1 /kgH2 beroende på lagringsmedium, där komprimerad vätgas är det billigaste. Detta resultat kan betraktas som konkurrenskraftigt med andra förnybara vätgaskällor, men inte med fossila motsvarigheter.

This study develops a novel pyrolysis process combined with in-line catalytic reforming toproduce high purity hydrogen and carbon products from waste plastics. The input resource is waste plastic material in the form of discarded Covid masks. Results show that for the optimized pyrolysis followed by in-line biochar-based catalytic reforming process, the hydrogen yield is 98.2 mg/g-mask (up to 87% purity), and the carbonyield is 642.4 mg/g-mask, with over 70% of the waste plastic being completely cracked to elemental carbon and hydrogen. The overall process has virtually no CO2 emissions. The use of biomass char catalysts has been studied to contribute to increased hydrogen yield. This is because the unique porous structure of the biochar catalyst increases the residence time of the pyrolysis vapor in the catalytic layer, allowing sufficient cracking of the macromolecular vapor, therefore, increasing the hydrogen yield. The process is also facilitated by the cracking temperature, which increases the cracking of the pyrolysis vapor, resulting in an increase in char yield. However, high temperatures may breakdown the structure of the biomass char catalyst, causing more of the pyrolysis vapor to be converted to CH4, reducing the hydrogen yield. The optimum hydrogen yield was obtained at process parameters of a Biochar catalyst-to-Maskratio (C/M ratio) of 2 and a cracking temperature of 900 oC. / Detta examensarbete utvecklar en ny pyrolysprocess kombinerad med en katalytisk reformeringsprocess i följd för att producera högrenade väte- och kolprodukter från plastavfall. Resursen till processen består av avfallsprodukter i form av kasserade munskydd. Resultaten visar att för den optimerade pyrolys- och biokol-katalytiska reformeringsprocessen är vätgasavkastningen 98,2 mg/g plastavfall (upp till 87 % renhet) och kolavkastningen 642,4 mg/g plastavfall, med över 70 % av plastavfallet fullständigt knäckt till enkla kol- och vätemolekyler. Den genomgripande processen har praktiskt taget inga koldioxidutsläpp. Användningen av biokol-katalysatorer av biomassa har studerats för att bidra till ett ökat vätgasutbyte. Detta beror på att biokolkatalysatorns unika porösa struktur ökar uppehållstiden för pyrolysångorna i det katalytiska skiktet, vilket möjliggör tillräcklig krackning av de makromolekylära ångorna och därmed ökar vätgasutbytet. Processen underlättas också av krackningstemperaturen, som ökar krackningen av pyrolysångorna, vilket leder till ökad kolavkastning. Höga temperaturer kan dock bryta ned strukturen hos katalysatorn för biomassakol, vilket gör att en större del av pyrolysångorna omvandlas till CH4, vilket minskar vätgasutbytet. Det optimala vätgasutbytet uppnåddes vid C/M-parameter (katalysator-till-munskydd förhållande) = 2och en krackningstemperatur på 900 0C.

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Society is facing major challenges to reduce the use of fossil sources. Two of the greatest goals are the UN’s Sustainable Development Goals to ensure access to sustainable energy for all by 2030 and the EU’s goal to be climate-neutral by 2050. Big changes need to be done to achieve this, all while the demand for both electricity and hydrogen gas is expected to increase drastically. The Swedish electricity demand is expected to double by 2045 and the hydrogen demand is expected to quadruple by 2030, compared to today’s levels. This paper has examined the optimal way to produce hydrogen gas in Halland, regarding performance, sustainability, and reliability. This was done by evaluating different scenarios for hydrogen production, the possibilities to utilize the waste heat and how the hydrogen gas is to be converted back to electricity. Three methods to produce hydrogen gas has been examined in this paper, AEC-, PEM- and SOE-electrolysis. Through literature studies PEM-electrolysis has been established as the most efficient way to produce renewable hydrogen gas. The method performs better than the other two regarding both mass of hydrogen gas produced per unit of energy used and the possibility to utilize the waste heat in the local district heating network. Five locations in Halland have been examined since they are considered suitable to house hydrogen production, Hyltebruk, Varberg, Falkenberg and in connection with two offshore windfarms. This paper does not take expansion of the existing electricity grid into consideration, which has made the result dependent on the various locations’ existing transmission capacity. This gives every place its unique conditions, creating unique possibilities. The largest and smallest production possible would be located in Varberg respectively Falkenberg, corresponding to nearly 100 % respectively 0.02 % of the expected hydrogen demand in Sweden by 2030. Due to the enormous requirements the expected future demand is putting on the industry, even the smallest contribution should be welcomed. / Samhället står inför stora utmaningar för att minska användandet av fossila källor. Några av de stora målen består av FN:s globala mål om hållbar energi för alla år 2030 och EU:s mål om klimatneutralitet till år 2050. För att nå dit krävs stora förändringar och behovet av både el och vätgas förväntas öka drastiskt. Sveriges elbehov förväntas mer än dubbleras till år 2045 medan vätgasbehovet förväntas fyrdubblas till år 2030, jämfört med dagens nivåer. Det här arbetet har undersökt hur man på bästa sätt relaterat till prestanda, hållbarhet och reliabilitet kan produceras vätgas i Halland. Detta utfördes genom att utvärdera olika scenarier för vätgasproduktion, möjligheterna till att tillvarata restvärme samt hur vätgasen kan konverteras tillbaka till el. De tre metoder för vätgasproduktion som arbetet baserats på är teknikerna AEC-, PEM- och SOE-elektrolys. Genom litteraturstudier har PEM-tekniken fastställts som den effektivaste metoden för förnybar framställning av vätgas. Tekniken presterar bäst både med avseende på massa vätgas producerad per konsumerad enhet energi och på möjligheten att utnyttja restvärmen i fjärrvärmenätet. Fem olika platser i Halland har undersökts då de ansetts lämpliga för vätgasproduktion, Hyltebruk, Varberg och Falkenberg samt i anslutning till två havsbaserade vindkraftsparker. Arbetet har avgränsats till att inte beröra utbyggnad av det befintliga elnätet vilket gjort att resultatet baserats på den befintliga överföringskapaciteten. Detta ger alla platser unika förutsättningar, vilka leder till unika möjligheter. Den största och minsta möjliga produktionen fastlås möjlig i Varberg respektive Falkenberg, motsvarande uppemot 100 % respektive 0,02 % av det förutspådda vätgasbehovet 2030. Även det minsta bidrag ska dock välkommas, i och med de enorma krav framtidens behov ställer på branschen.

Mixed-metal supramolecular complexes containing one or two RuII light absorbing subunits coupled through polyazine bridging ligands to a RhIII reactive metal center were prepared for use as photocatalysts for the production of solar H2 fuel from H2O. The electrochemical, photophysical, and photochemical properties upon variation of the monodentate, labile ligands coordinated to the Rh reactive metal center were investigated. Bimetallic complexes [(Ph2phen)2Ru(dpp)RhX2(Ph2phen)]3+ (Ph2phen = 4,10-diphenyl-1,10-phenanthroline; dpp = 2,3-bis(2-pyridyl)pyrazine; X = Br- or Cl-) were prepared using a building block approach, allowing for selective component choice. The identity of the halide coordinated to Rh did not impact the light absorbing or excited state properties of the structural motif. However, the o-donating ability of the halides modulated the Rh-based cathodic electrochemistry and required the use of multiple pathways to explain the reduction of Rh by two electrons. Regardless of halide identity, the bimetallic complex possessed a Ru-based HOMO (highest occupied molecular orbital) and Rh-based LUMO (lowest unoccupied molecular orbital) important for photoinitiated electron collection at Rh. As a photocatalyst for H2 evolution, the X = Br- complex produced nearly 30% more H2 than the X = Cl- analogue. H2 production experiments with added halide suggested that ion pairing with halides played a major role in catalyst deactivation, which provided evidence for the importance of component selection for photocatalyst design. New trimetallic complex [{(bpy)2Ru(dpp)}2Ru(OH)2](PF6)5 (bpy = 2,2'-bipyridine) was prepared for comparison to halide analogues [{(bpy)2Ru(dpp)}2RhX2](PF6)5 (X = Br- or Cl-). The synthesis of a halide-free supramolecule containing OH- ligands afforded an ideal system to further examine the impact of the ligands at the reactive metal center on H2 photocatalysis. Electrochemistry results revealed that while the identity of the ligands at Rh did modulate the Rh-based reduction potential, all three complexes possessed a Ru-based HOMO and Rh-based LUMO. The light absorbing properties were not impacted by the identity of the monodentate ligands at Rh; however, the excited state properties did vary upon changing the ligands at Rh. The hydroxo trimetallic complex functioned as a photocatalyst for H2 production in organic solvent, producing nearly double the amount of H2 as the highest performing Br-' trimetallic complex in DMF solvent. Interestingly, H2 production studies in high dielectric aqueous solvent revealed no discrepancies in H2 evolution upon variation of the ligands at Rh, which further supported the ion pairing phenomenon realized for the bimetallic motif. Variation of the labile ligands coordinated to the Rh reactive metal center in RuIIRhIII multimetallic supramolecules provided important insight about the large impact of small structural variation on H2 photocatalysis. Electrochemical, photophysical, and photochemical studies of new RuIIRhIII complexes afforded a deeper understanding of the molecular processes important for the design of new complexes applicable to solar fuel production schemes. / Ph. D.

Perfluorosulfonate ionomers, such as Nafion® have been shown to demonstrate a profound affinity for large cationic complexes, and the study of polymer-bound cations may provide insight regarding Nafion® morphology by contrasting molecular size with existing models. The trimetallic complex, [{(bpy)2Ru(dpp)}2RhBr2] 5+, is readily absorbed by ion exchange into Na+ -form Nafion® membranes under ambient conditions. The dimensions of three different isomers of the trimetallic complex are estimated to be: 23.6 Å × 13.3 Å × 10.8 Å, 18.9 Å × 18.0 Å × 13.7 Å, and 23.1 Å × 12.0 Å × 11.4 Å, yielding an average molecular volume of 1.2×103 Å3 . At equilibrium, the partition coefficient for the ion-exchange of the trimetallic complex into Nafion® from a DMF solution is 5.7 × 103 . Furthermore, the total cationic charge of the exchanged trimetallic complexes counterbalances 86 ± 2% of the anionic SO3 − sites in Nafion®. The characteristic dimensions of morphological models for the ionic domains in Nafion® are comparable to the molecular dimensions of the large mixedmetal complexes. Surprisingly, SAXS analysis indicates that the complexes absorb into the ionic domains of Nafion® without significantly changing the ionomer morphology. Given the profound affinity for absorption of these large cationic molecules, a more open-channel model for the morphology of perfluorosulfonate ionomers is more reasonable, in agreement with recent experimental findings. In contrast to smaller monometallic complexes, the time- v dependent uptake of the large trimetallic cations is biexponential. This behavior is attributed to a fast initial ion-exchange process on the surface of the membrane, accompanied by a slower, transport-limited ion-exchange for sites in the interior of the ionomer matrix. The development of Nafion®/[{(bpy)2Ru(dpp)}2RhBr2] 5+ modified electrodes is also described for both FTO electrodes and materials made from electrospun carbon mats. The [{(bpy)2Ru(dpp)}2RhBr2] 5+ complexes behave as photocatalytic hydrogen production catalysts in the Nafion® membrane. Furthermore, a second bulk photoelectrolysis experiment with the Nafion®/[{(bpy)2Ru(dpp)}2RhBr2] 5+/FTO electrodes shows an enhancement of catalytic activity compared to the first photoelectrolysis experiment. This enhancement is attributed to halide loss following the first reduction process. Lastly, electrospun carbon nanofiber mats behave as electron donor materials for [{(bpy)2Ru(dpp)}2RhBr2] 5+/Nafion® membranes. / Ph. D.

The goal of this research is to test the design constraints of active dpp-bridged RuII,RhIII (dpp = 2,3-bis(2-pyridyl)pyrazine)) supramolecular photocatalysts for water reduction to H2 and provide mechanistic insights into the catalytic cycle. Two member of a new RuII,RhIII motifs with only one Rh-'Cl bond, [(bpy)2Ru(dpp)RhCl(tpy)](PF6)4 ( bpy = 2,2'-bipyridine, tpy = 2,2':6,2"-terpyridine) and [(bpy)2Ru(dpp)RhCl(tpm)](PF6)4, (tpm = tris(1-pyrazolyl)methane), and a cis-RhCl2 model system, [(bpy)2Ru(dpp)RhCl2(bpy)](PF6)3, were prepared. This new motif was to test whether two Rh-'Cl bonds on RhIII are required for the photocatalytic water reduction. 1H NMR spectroscopic analysis of complexes prepared using deuterated ligands was used to characterize these three RuII,RhIII supramolecular complexes. Electrochemical studies suggested that replacing bpy with a tridentate ligand on RhIII shifts the RhIII/II and RhII/I reduction couples positively, which can modulate the orbital energetics of the RhIII LUMO (lowest-unoccupied molecular orbital). This substitute also changes the rate of ligand dissociation following the reduction of RhIII. In tpm and bpy systems, RhII intermediate is more stable than that in the tpy system. All three complexes were good light absorbers in the visible region and weak emitters from their emissive Ru(dπ)-'dpp(π*) 3MLCT (metal-to-ligand charge transfer) excited states at room temperature. The population of a low-lying 3MMCT (metal-to-metal charge transfer) ES (excited state) from the 3MLCT ES contributed to the weak emission, indicating an important intramolecular electron transfer process from dpp' to RhIII upon photoexcitation. The lower-lying 3MMCT excited state in the tpm and tpy systems relative to the bpy system result in a higher rate constant (ket = 2.6 x 10^7 vs 1.7 x 10^7 s-1) for intramolecular electron transfer. Spectrophotochemical analysis suggested that all three complexes were photoinitiated electron collectors capable of collecting two electrons on the RhIII center to generate the RuII,RhI species in the presence of DMA (N,N-dimethylaniline). The observed H2 production from water using [(bpy)2Ru(dpp)RhCl(tpm)](PF6)4 and [(bpy)2Ru(dpp)RhCl(tpy)](PF6)4 established that two halides on RhIII are not necessary in the dpp-bridge RuII,RhIII supramolecular photocatalytic-water-reduction system. This new discovery opens a new approach to the design of different RuII,RhIII motifs for photocatalysis. The active species for water reduction is proposed to be [(bpy)2Ru(dpp)RhICl(TL)]3+ from [(bpy)2Ru(dpp)RhCl(TL)](PF6)4 (TL (terminal ligand) = tpy or tpm) and [(bpy)2Ru(dpp)Rh(bpy)]3+ from [(bpy)2Ru(dpp)RhCl2(bpy)](PF6)3 respectively. Included here is the design and study of a RuII,RhI complex, [(bpy)2Ru(dpp)RhCl(COD)](PF6)3 (COD =1,5-cyclooctadiene) to provide more insights into the photophysical and photochemical properties of polypyridyl RuII,RhI species. Electrochemical and photophysical studies revealed a dpp-based LUMO in this RuII,RhI complex, suggesting dpp reduction upon photoexcitation. Photochemical study found that [(bpy)2Ru(dpp)RhCl(COD)](PF6)3 is an active photocatalyst for water reduction and that additional reduction(s) is (are) required after the generation of the RuII,RhI active species in the RuII,RhIII supramolecular photocatalytic H2 production system. This hypothesis was supported by the electrocatalytic behaviors of the RuII,RhIII supramolecular complexes for proton reduction. Cyclic voltammetry results in the presence of an acid suggested that the protonolysis of the RuII,RhIIH and RuII,RhIH species are electrocatalytic H2-evolution pathways. The mechanism is acid-dependent and influenced by terminal ligand. The studies of electrocatalytic proton reduction on these RuII,RhIII complexes suggested several possible intermediates involved in the photocatalytic water reduction cycle. The insights gained from this research can provide guidance in designing new type of RuII,RhIII and RuII,RhI complexes with better photocatalytic and/or electrocatalytic H2 production performance. / Ph. D.