1,721,000 research outputs found
Sustainable Energy Production and Consumption. Benefits, Strategies and Environmental Costing.
No full textFuel Cells for Transportation: An Overview
Full text linkFuel cells were invented more than 180 years ago. Intensive development for the space program in the 1960s was followed by even more intensive development in automotive applications since the 1990s. After almost every car manufacturer have had at least one prototype by the turn of the century, currently there are only two fuel cell car models available on the market. Is there a future for fuel cells for transportation? The future of fuel cells, including the fuel cells for transportation, is tightly related to the energy transition that is already taking place. In such a transition, hydrogen produced from renewable energy sources would enable the decarbonization of otherwise hard-to-decarbonize sectors. Fuel cells are the technology that will enable hydrogen’s use in transportation. Technology is ready, and political decisions have been made, so in the next decades, fuel cells will be widely used in transportation—not only in automobiles, but also in delivery vehicles, trucks, buses, coaches, trains, and even ships and airplanes.</p
The influence of operating parameters on the activation of the membrane electrolyzer
No full textU ovom doktorskom radu prikazani su i analizirani rezultati istraživanja kojemu je cilj bio utvrditi utjecaj radnih parametara na aktivaciju membranskog elektrolizatora i vrijeme potrebno da se postignu stabilni radni uvjeti prilikom prvog korištenja membranskoelektrodnog sklopa. Poznato je da pri aktivaciji membransko-elektrodnog sklopa dolazi do formiranja ionskih puteva unutar ionomera i formiranja elektrokemijske aktivne površine, a što za posljedicu ima poboljšanje performansi uređaja. Sve dostupne informacije o aktivaciji membransko-elektrodnog sklopa dolaze iz istraživanja PEM gorivnih članaka, i za sada j aktivacija membranskog elektrolizatora potpuno neistražena, pa ne postoje ni službene preporuke kako obaviti postupak.
Za istraživanje su korišteni komercijalno dostupni membransko-elektrodni sklopovi i jedinični elektrolizator, a utjecaj radnih parametara na aktivaciju membranskog elektrolizatora je istražen testiranjem aktivacijskih postupaka dobivenih kombiniranjem različitih radnih profila i temperatura. Na temelju rezultata j utvrđeno da svi aktivacijski postupci postižu aktivaciju unutar 32 sata, ali da dinamika mjerenih veličina i iznos promjene ovise o korištenom aktivacijskom postupku. Najveć povećanje performansi i stabilnost radnih parametara postignuti su profilima napajanja kraćim zadržavanjem u jednoj radnoj točci, i ovim postupcima aktivacija je postignuta između 10. i 12. sata testiranja. Također je uočeno da viša radna temperatura ubrzava proces aktivacije membransko-elektrodnog sklopa i povećava stabilnost.This study presents the results of a research that aimed to establish the influence of operating parameters on the activation of the membrane electrolyzer and the time required to achieve stable operating conditions during the first use of the membrane electrode assembly.
It is known that there is an increase in performance when the membrane electrode assembly is activated, which is a consequence of the formation of ion channels within the ionomer and the growth of the electrochemically active surface. Activation of the membrane electrolyzer has not been investigated and there is no official recommended activation procedure. In the research, a commercial unit electrolyzer and membrane electrode assemblies were used to test the effects of different power supply profiles and operating temperatures. Research has shown that all activation procedures achieve activation within 32 hours and that the dynamics of the measured quantities and the amount of change depend on the activation procedure used.
Power profiles with shorter periods of operation at a single operating point achieved the greatest increase in performance and stability, and activation was achieved between the 10th and 12th hours of testing, while the same procedures at a higher operating temperature required less time to achieve activation
Application of solid oxide fuel cells in marine energy systems
No full textU ovoj doktorskoj disertaciji istraženo je i analizirano brodsko parnoturbinsko postrojenje s ugrađenim postrojenjem za uplinjavanje na brodu za prijevoz ukapljenog prirodnog plina. Provedena je energijska i eksergijska analiza brodskog parnoturbinskog postrojenja tijekom procesa uplinjavanja na plutajućem plinskom iskrcajnom terminalu. Istraživanje u sklopu doktorske disertacije obavljeno je na nekoliko različitih plutajućih plinskih terminala, a rezultati su praćeni tijekom iskrcaja od početka 2014. do kraja 2020. godine. Kod procesa uplinjavanja, morska, slatka ili destilirana voda koristi se kao izvor topline i prolazi kroz visokotlačni isparivač prirodnog plina, u kojem ukapljeni prirodni plin prelazi u plinovito stanje. Predložen je i proračunan hibridni energijski sustav s gorivnim člankom s krutim oksidom koji se sastoji iz dva dijela. Glavna je komponenta prvog dijela sklop gorivnog članka s krutim oksidom, a glavna komponenta drugog dijela je generator pare. Predloženi hibridni energijski sustav imao bi primjenu u pogledu smanjenja emisije štetnih ispušnih plinova te u pogledu povećanja ekonomičnosti i učinkovitosti. Identificirani su utjecajni parametri na ekonomičnost primjene sustava (promjena cijene goriva, cijena koštanja uređaja, promjena propisa o dozvoljenim emisijama štetnih ispušnih plinova...) i obavljena analiza osjetljivosti na promjene tih ulaznih parametara. Prilikom definiranja i analize sustava gorivnih članka s krutim oksidom, dimenzionirao se sustav koji bi zamijenio tri postojeća turbogeneratora ukupne nominalne snage od 11100 kW. Na temelju dobivenih rezultata provedenih istraživanja zaključeno je pri kojim uvjetima rada novi hibridni sustav povećava učinkovitost za 12 % i smanjuje emisije ispušnih plinova između 72.56 % i 81.64 %, ovisno o iskrcajnim protocima stlačenog prirodnog plina.In this doctoral thesis was researched and analysed a steam turbine propulsion plant with installed re-gasification system on LNG carrier. An energy and exergy analysis of the ship's steam turbine plant during the re-gasification process at the floating gas discharge terminal was carried out. The research as part of the doctoral dissertation was carried out on several different floating gas terminals, and the results were monitored during cargo discharge from the beginning 2014 to the end of 2020. In the re-gasification process, sea, fresh or destillated water is used as a heat source and passes through a high-pressure vaporizer, in which liquid natural gas changes to a gaseous state. A hybrid energy system with a solid oxide fuel cell consisting of two parts is proposed and calculated. The main component of the first part is the solid oxide fuel cell assembly, and the main component of the second part is the steam generator. The proposed hybrid energy system would have applications in terms of reducing the emission of harmful exhaust gases and in terms of increasing economy and efficiency. Influential parameters on the economy of the system's application were identified (change in fuel price, device cost price, change in regulations on permitted emissions of harmful exhaust gases...) and sensitivity analysis to changes in these input parameters was performed. When defining and analyzing the solid oxide fuel cell system, a system was dimensioned that would replace three existing turbogenerators with a total nominal power of 11100 kW. Based on the obtained results of the conducted research, it was concluded under which operating conditions the new hybrid system increases efficiency by 12 % and reduces exhaust gas emissions between 72.56 % and 81.64 % depending on the discharge flow of compressed natural gas
Application of solid oxide fuel cells in marine energy systems
No full textU ovoj doktorskoj disertaciji istraženo je i analizirano brodsko parnoturbinsko postrojenje s ugrađenim postrojenjem za uplinjavanje na brodu za prijevoz ukapljenog prirodnog plina. Provedena je energijska i eksergijska analiza brodskog parnoturbinskog postrojenja tijekom procesa uplinjavanja na plutajućem plinskom iskrcajnom terminalu. Istraživanje u sklopu doktorske disertacije obavljeno je na nekoliko različitih plutajućih plinskih terminala, a rezultati su praćeni tijekom iskrcaja od početka 2014. do kraja 2020. godine. Kod procesa uplinjavanja, morska, slatka ili destilirana voda koristi se kao izvor topline i prolazi kroz visokotlačni isparivač prirodnog plina, u kojem ukapljeni prirodni plin prelazi u plinovito stanje. Predložen je i proračunan hibridni energijski sustav s gorivnim člankom s krutim oksidom koji se sastoji iz dva dijela. Glavna je komponenta prvog dijela sklop gorivnog članka s krutim oksidom, a glavna komponenta drugog dijela je generator pare. Predloženi hibridni energijski sustav imao bi primjenu u pogledu smanjenja emisije štetnih ispušnih plinova te u pogledu povećanja ekonomičnosti i učinkovitosti. Identificirani su utjecajni parametri na ekonomičnost primjene sustava (promjena cijene goriva, cijena koštanja uređaja, promjena propisa o dozvoljenim emisijama štetnih ispušnih plinova...) i obavljena analiza osjetljivosti na promjene tih ulaznih parametara. Prilikom definiranja i analize sustava gorivnih članka s krutim oksidom, dimenzionirao se sustav koji bi zamijenio tri postojeća turbogeneratora ukupne nominalne snage od 11100 kW. Na temelju dobivenih rezultata provedenih istraživanja zaključeno je pri kojim uvjetima rada novi hibridni sustav povećava učinkovitost za 12 % i smanjuje emisije ispušnih plinova između 72.56 % i 81.64 %, ovisno o iskrcajnim protocima stlačenog prirodnog plina.In this doctoral thesis was researched and analysed a steam turbine propulsion plant with installed re-gasification system on LNG carrier. An energy and exergy analysis of the ship's steam turbine plant during the re-gasification process at the floating gas discharge terminal was carried out. The research as part of the doctoral dissertation was carried out on several different floating gas terminals, and the results were monitored during cargo discharge from the beginning 2014 to the end of 2020. In the re-gasification process, sea, fresh or destillated water is used as a heat source and passes through a high-pressure vaporizer, in which liquid natural gas changes to a gaseous state. A hybrid energy system with a solid oxide fuel cell consisting of two parts is proposed and calculated. The main component of the first part is the solid oxide fuel cell assembly, and the main component of the second part is the steam generator. The proposed hybrid energy system would have applications in terms of reducing the emission of harmful exhaust gases and in terms of increasing economy and efficiency. Influential parameters on the economy of the system's application were identified (change in fuel price, device cost price, change in regulations on permitted emissions of harmful exhaust gases...) and sensitivity analysis to changes in these input parameters was performed. When defining and analyzing the solid oxide fuel cell system, a system was dimensioned that would replace three existing turbogenerators with a total nominal power of 11100 kW. Based on the obtained results of the conducted research, it was concluded under which operating conditions the new hybrid system increases efficiency by 12 % and reduces exhaust gas emissions between 72.56 % and 81.64 % depending on the discharge flow of compressed natural gas
The influence of operating parameters on the activation of the membrane electrolyzer
No full textU ovom doktorskom radu prikazani su i analizirani rezultati istraživanja kojemu je cilj bio utvrditi utjecaj radnih parametara na aktivaciju membranskog elektrolizatora i vrijeme potrebno da se postignu stabilni radni uvjeti prilikom prvog korištenja membranskoelektrodnog sklopa. Poznato je da pri aktivaciji membransko-elektrodnog sklopa dolazi do formiranja ionskih puteva unutar ionomera i formiranja elektrokemijske aktivne površine, a što za posljedicu ima poboljšanje performansi uređaja. Sve dostupne informacije o aktivaciji membransko-elektrodnog sklopa dolaze iz istraživanja PEM gorivnih članaka, i za sada j aktivacija membranskog elektrolizatora potpuno neistražena, pa ne postoje ni službene preporuke kako obaviti postupak.
Za istraživanje su korišteni komercijalno dostupni membransko-elektrodni sklopovi i jedinični elektrolizator, a utjecaj radnih parametara na aktivaciju membranskog elektrolizatora je istražen testiranjem aktivacijskih postupaka dobivenih kombiniranjem različitih radnih profila i temperatura. Na temelju rezultata j utvrđeno da svi aktivacijski postupci postižu aktivaciju unutar 32 sata, ali da dinamika mjerenih veličina i iznos promjene ovise o korištenom aktivacijskom postupku. Najveć povećanje performansi i stabilnost radnih parametara postignuti su profilima napajanja kraćim zadržavanjem u jednoj radnoj točci, i ovim postupcima aktivacija je postignuta između 10. i 12. sata testiranja. Također je uočeno da viša radna temperatura ubrzava proces aktivacije membransko-elektrodnog sklopa i povećava stabilnost.This study presents the results of a research that aimed to establish the influence of operating parameters on the activation of the membrane electrolyzer and the time required to achieve stable operating conditions during the first use of the membrane electrode assembly.
It is known that there is an increase in performance when the membrane electrode assembly is activated, which is a consequence of the formation of ion channels within the ionomer and the growth of the electrochemically active surface. Activation of the membrane electrolyzer has not been investigated and there is no official recommended activation procedure. In the research, a commercial unit electrolyzer and membrane electrode assemblies were used to test the effects of different power supply profiles and operating temperatures. Research has shown that all activation procedures achieve activation within 32 hours and that the dynamics of the measured quantities and the amount of change depend on the activation procedure used.
Power profiles with shorter periods of operation at a single operating point achieved the greatest increase in performance and stability, and activation was achieved between the 10th and 12th hours of testing, while the same procedures at a higher operating temperature required less time to achieve activation
Techno-economic analysis of the use of fuel cells and hydrogen in the railway environment
No full textU ovome će radu biti predočeno trenutačno stanje („state of the art“) tehnologije,
ekonomska opravdanost i tržišni potencijal za FCH („Fuel Cell Hydrogen“) tehnologiju u
željezničkom sektoru. Pokazano je da se FCH tehnologija može nositi sa željezničkim
prijevozom. Nakon pregleda stručne literature napravljena je tehno-ekonomska analiza
trase Split-Trogir. Korištenjem simulacija jednog vlaka (STS) dobiven je energetski profil
trase. Metodom ekvivalentnog godišnjeg troška (EAC) uspoređene su tri tehnološke
varijante vlakova (dizel, FCH i OLE). Dobiveni rezultati, za navedene pretpostavke i
tehno-ekonomske parametre, za trasu Split-Trogir daju prednost elektrifikaciji nadzemnim
vodom (OLE). FCH tehnologija također ima povoljniji EAC od dizel tehnologije koja se
pokazala kao najlošija opcija.This thesis will present the current state, economic viability and market potential for FCH
(Fuel Cell Hydrogen) technology in the railway sector. It has been shown that FCH
technology can handle rail transport. After reviewing of the literature, a techno-economic
analysis of the Split-Trogir route was made. Using single train simulations (STS), the
energy profile of the route was obtained. The equivalent annual cost (EAC) method
compared three train technology variants (diesel, FCH and OLE). The obtained results, for
the stated assumptions and techno-economic parameters, for the Split-Trogir route gave
advantage to catenary electrification (OLE). FCH technology also has a more favorable
EAC than diesel technology which has proven to be the worst option
The energy potential of micro-cogeneration systems with membrane fuel cells coupled with renewable energy sources
No full textModeliran je mikro-kogeneracijski sustav s vodikovim podsustavom (gorivni članak, elektrolizator i spremnik vodika) u sprezi s obnovljivim izvorima energije, odnosno podsustavom s vjetroturbinom i fotonaponskim panelom, te dizalicom topline, takav da poslužuje električnom energijom, grijanjem i hlađenjem samostalno kućanstvo u mediteranskoj klimi. Satni model koristio se za simulaciju njegovog rada tijekom cijele godine. Primijenjena je jedinstvena strategija upravljanja energijom kako bi se postigla konfiguracija s minimalnom veličinom komponenti bez manjka ili viška proizvedene energije. Kombinacijom rada gorivnih članaka s dizalicom topline prati se električni i toplinski (topla voda, grijanje i hlađenje prostora) profil kućanstva. Analizirana su tri režima rada hibridnog sustava za posluživanje AC profila potrošnje električne energije s različitim vršnim opterećenjima (pojedinačno ili više uređaja istovremeno kroz poslijepodne ili noću/ujutro), ali s jednakom ukupnom godišnjom potražnjom. Provedenom analizom odabran je hibridni sustav s najprikladnijim posluživanjem AC profila za mediteransku klimu, te je uspoređen s najčešće korištenim sustavom sa samo baterijskom pohranom. Pokazalo se da je za pohranu energije u vodik dovoljno samo 10% više energije iz obnovljivih izvora, pri čemu je tada potrebna baterija manja za čak pet puta.A micro-cogeneration system with a hydrogen subsystem (fuel cell, electrolyzer, and hydrogen tank) was modeled in conjunction with renewable energy sources, that is, a subsystem with a wind turbine and photovoltaic panel, and a heat pump, such that it serves an independent household in a Mediterranean climate with electricity, heating, and cooling. The hourly model was used to simulate its operation throughout the year. A unique energy management strategy was applied to achieve a configuration with a minimum size of components without a shortage or excess of produced energy. The household's electrical and thermal (hot water, space heating, and cooling) load profile is followed by combining the fuel cell with the heat pump. Three hybrid system operation modes were analyzed to serve the AC profile of electricity consumption with different peak loads (individual or multiple devices simultaneously through the afternoon or night/morning) but with the same total annual demand. Through the analysis, a hybrid system was selected with the most suitable serving AC profile for the Mediterranean climate, and it was compared with the most commonly used system with only battery storage. It has been shown that only 10% more energy from renewable sources is enough to store energy in hydrogen, and the battery required is as much as five times smaller
The energy potential of micro-cogeneration systems with membrane fuel cells coupled with renewable energy sources
No full textModeliran je mikro-kogeneracijski sustav s vodikovim podsustavom (gorivni članak, elektrolizator i spremnik vodika) u sprezi s obnovljivim izvorima energije, odnosno podsustavom s vjetroturbinom i fotonaponskim panelom, te dizalicom topline, takav da poslužuje električnom energijom, grijanjem i hlađenjem samostalno kućanstvo u mediteranskoj klimi. Satni model koristio se za simulaciju njegovog rada tijekom cijele godine. Primijenjena je jedinstvena strategija upravljanja energijom kako bi se postigla konfiguracija s minimalnom veličinom komponenti bez manjka ili viška proizvedene energije. Kombinacijom rada gorivnih članaka s dizalicom topline prati se električni i toplinski (topla voda, grijanje i hlađenje prostora) profil kućanstva. Analizirana su tri režima rada hibridnog sustava za posluživanje AC profila potrošnje električne energije s različitim vršnim opterećenjima (pojedinačno ili više uređaja istovremeno kroz poslijepodne ili noću/ujutro), ali s jednakom ukupnom godišnjom potražnjom. Provedenom analizom odabran je hibridni sustav s najprikladnijim posluživanjem AC profila za mediteransku klimu, te je uspoređen s najčešće korištenim sustavom sa samo baterijskom pohranom. Pokazalo se da je za pohranu energije u vodik dovoljno samo 10% više energije iz obnovljivih izvora, pri čemu je tada potrebna baterija manja za čak pet puta.A micro-cogeneration system with a hydrogen subsystem (fuel cell, electrolyzer, and hydrogen tank) was modeled in conjunction with renewable energy sources, that is, a subsystem with a wind turbine and photovoltaic panel, and a heat pump, such that it serves an independent household in a Mediterranean climate with electricity, heating, and cooling. The hourly model was used to simulate its operation throughout the year. A unique energy management strategy was applied to achieve a configuration with a minimum size of components without a shortage or excess of produced energy. The household's electrical and thermal (hot water, space heating, and cooling) load profile is followed by combining the fuel cell with the heat pump. Three hybrid system operation modes were analyzed to serve the AC profile of electricity consumption with different peak loads (individual or multiple devices simultaneously through the afternoon or night/morning) but with the same total annual demand. Through the analysis, a hybrid system was selected with the most suitable serving AC profile for the Mediterranean climate, and it was compared with the most commonly used system with only battery storage. It has been shown that only 10% more energy from renewable sources is enough to store energy in hydrogen, and the battery required is as much as five times smaller
Application of electrochemical impedance spectroscopy in catalyst layer degradation diagnostics of proton exchange membrane fuel cells
No full textU ovoj doktorskoj disertaciji, pisanoj prema tzv. skandinavskom modelu, odnosno u obliku skupa tri objavljena znanstvena rada s preglednim poglavljem, pokazano je da je primjenom elektrokemijske impedancijske spektroskopije moguće dijagnosticirati degradaciju katalitičkog sloja membranskog gorivnog članka, uzrokovanu smanjenjem elektrokemijske aktivne površine, na osnovu usporedbe impedancijskih odzivnih spektara izmjerenih u odreĎenim vremenskim intervalima tijekom njegovog rada. U tu svrhu, razvijen je i novi nadomjesni impedancijski model u obliku električnog ekvivalentnog kruga s 11 elemenata i dvije tzv. rezonantne petlje, sastavljene od paralelno vezanih otpornika, kondenzatora i zavojnice, a koji je primijenjen tijekom ubrzanog degradacijskog testa s cikliranjem katodnog napona. TakoĎer, u području niskih frekvencija impedancijskog odzivnog spektra evidentna je prisutnost induktivne značajke, čiji su mogući uzroci iz literature načelno poopćeni i po prvi puta svrstani u tri grupe mogućih uzroka, i to: popratne kemijske reakcije s meĎuspojevima, utjecaj koncentracije ugljikovog monoksida (ukoliko se ne koriste izrazito čisti reaktanti) i transport vode. Predloţeni model je eksperimentalno verificiran u različitim radnim uvjetima, a obuhvaća i procese odgovorne za induktivnu značajku na niskim frekvencijama, te daje novi doprinos boljem razumijevanju ove pojave, koja je eksperimentalno po prvi put potvrĎena u ovako širokom rasponu gustoća struja, temperatura, tlakova, vlaţnosti i protoka reaktanata.In this doctoral thesis, written in the so-called Scandinavian model as a set of three published scientific papers with an overview chapter, it has been shown that catalyst layer degradation of proton exchange membrane fuel cell, caused by the loss of electrochemical active surface area, is possible to diagnose with electrochemical impedance spectroscopy at certain time steps during the operation. Hence, a novel impedance equivalent circuit model with 11 elements and two so-called resonant loops, comprising of a resistance, capacitance and inductance in parallel, was developed and applied during an accelerated degradation test with cathode voltage cycling. Furthermore, there is an evident presence of the low-frequency inductive phenomenon in Nyquist plot, so three generalized explanations from literature with their variations have been imposed as plausible causes, here for the first time: side reactions with intermediate species, carbon monoxide poisoning (when reactant gases are not used rated ultrapure) and water transport. The proposed model, experimentally verified in various operating conditions, includes the processes responsible for this inductive phenomenon, which was experimentally confirmed for the first time in such a wide range of current densities, temperatures, backpressures, humidities and reactants flows, and gives a new contribution to better understanding of this phenomenon
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