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New types of membranes for electrolyzer hydrogen - oxygen
Hýbl, Jiří ; Sedlaříková, Marie (referee) ; Kunovjánek, Miroslav (advisor)
This work deals with the production of hydrogen and oxygen by electrolysis. Aims of this thesis are to measure different types of membranes and choose the best for use in elektrolyzer for hydrogen and oxygen production. Properties of membranes were tested in the laboratory electrolyzer in the short and long operation. The emerging gases from elektrolyzer were also tested on a gas chromatograph to determine the purity of produced hydrogen. At the same time are also tested different concentrations of KOH elektrolyte and the effect of concentrations on efficiency of electrolyzer.
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Storage systems for renewable energy
Švácha, Filip ; Kracík, Petr (referee) ; Poláčik, Ján (advisor)
The aim of the thesis is to describe the current possibilities of storing electricity from renewable sources focusing on hydrogen technologies. In the first three parts, the question of energy sto-rage from renewable sources, the current energy storage options and the actual energy storage in hydrogen are discussed in the form of research. The last part is practical and its aim is to compare the current possibilities in designing a system that stores energy in hydrogen. Subsequently, the most favorable option is chosen and compared to other energy storage methods.
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Possibilities of using hydrogen in the energy sector
Holík, Michal ; Lisá, Hana (referee) ; Baláš, Marek (advisor)
This bachelor thesis describes hydrogen energy and gives the reader an introductory look into the world of hydrogen technologies. The first part describes the production of hydrogen from fossil and renewable sources. The second part deals with the possibilities of processing and use of hydrogen in energy. The third part represents the specific application of its use.
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Hydrogen vs. electricity - comparison of energy performance of EV powertrains
Šándor, Kristián ; Mišík, Ondrej (referee) ; Fišer, Jan (advisor)
The topic of emission reduction and the increase in the share of energy produced from renewable sources remains actual and highly discussed in 2021. It was the major reason why I chose to compose this bachelor’s thesis, in which I aim to critically evaluate and compare the energy performance of an electrical vehicle and a hydrogen vehicle. The theoretical part of the thesis outlines the aforementioned drivetrains as well as the plug-in hybrid drivetrain. The practical part of the thesis focuses on calculations of the energy performance of the drivetrains for the year 2021 with a rational estimate for 2050. The methods of electricity and hydrogen production are crucial for energy performance evaluation. Data shows that electric cars operated in countries with a high share of energy produced from renewable sources are the least energetically demanding. On the other hand, if the energy production depends predominantly on fossil fuels, it is more efficient to operate a hydrogen vehicle. Calculations show that when considering the indirect emissions during the operation as well as the energy performance, the plug-in hybrid vehicles are the least efficient. The difference in efficiency between electric and hydrogen vehicles varies depending on the mode of energy production of that specific country. The conclusion of this thesis also discusses advantages, disadvantages and technological challenges concerning the aforementioned drivetrains.
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Towards highly-doped Ge and ZnO nanowires: Growth, characterization and doping level analysis
Pejchal, Tomáš ; Mikulík,, Petr (referee) ; Grym,, Jan (referee) ; Kolíbal, Miroslav (advisor)
Vysoce dopovaná polovodičová nanovlákna představují nadějnou třídu nanostruktur pro budoucí aplikace v elektronice, optoelektronice nebo bio-senzorice. Tato práce se zaměřuje na přípravu a charakterizaci nanovláken germania a oxidu zinečnatého s cílem dosáhnout vysoké úrovně dopování. Úvodní část dizertační práce se zabývá přípravou germaniových nanovláken metodou VLS (pára – kapalina – pevná látka). Nejprve jsou popsány faktory ovlivňující růst nanovláken a jejich morfologii – složení katalytické částice, vliv adsorbovaných atomů či molekul a potenciální inkorporace atomů katalyzátoru do objemu nanovláken. Nanovlákna připravená ze zlatých katalytických nanočástic v podmínkách ultravysokého vakua (tzv. MBE metodou) a za přítomnosti atomárního vodíku (proces napodobující podmínky CVD metod) vykazují odlišnou morfologii a směr růstu. Tyto rozdíly odhalují kombinovaný účinek adsorpce atomárního vodíku a šíření zlatého katalyzátoru na stěny nanovláken. Tento efekt je klíčový pro vysvětlení rozdílů ve výsledné morfologii nanovláken připravených MBE a CVD metodami. Další část práce se věnuje přípravě Ge nanovláken z katalyzátorů obsahujících prvky III. skupiny a studiu jejich případné inkorporace, která by mohla vést k dopování nanovláken. Bylo zjištěno, že in-situ připravené směsné Au–Ga nanočástice lze úspěšně využít pro růst germaniových nanovláken, přestože stabilita katalyzátoru je nižší než v případě čistého zlata. I přes vysokou koncentraci gallia v katalytické částici nebyla pozorována inkorporace gallia do objemu nanovlákna. Tato metoda dopování nanovláken se tedy pro uvedenou materiálovou kombinaci ukázala jako nevhodná. Ve třetí části práce jsou popsány výsledky charakterizace ZnO nanodrátů a vývoj metody jejich difuzního dopování galliem. Je prokázán vliv žíhání nanodrátů na koncentraci kyslíkových vakancí (VO) – ve srovnání s žíháním v podmínkách vysokého vakua se koncentrace VO snižuje žíháním v plynném peroxidu vodíku. Dále je zdokumentována inkorporace gallia do ZnO nanodrátů při teplotě nad 350 °C – pozorováno pomocí in-situ SEM. Při teplotě nad 450 °C dochází ke galliem indukované dekompozici ZnO nanodrátů. K určení koncentrace a prostorového rozložení Ga atomů v nanovláknech je využito teoretického difuzního modelu a STEM EDS měření nanovláken. Byla nalezena korelace mezi koncentrací kyslíkových vakancí a inkorporací gallia do objemu ZnO nanovláken. Koncentrace gallia dosahuje řádově 10^21 cm^-3, což dokazuje vhodnost použité metody pro dosažení vysokých úrovní dopování, které jsou potřebné pro budoucí bio-senzorické aplikace v infračervené oblasti.
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Hydrogen quantification by electron spectroscopy
Endstrasser, Zdeněk ; Polčák, Josef (referee) ; Čechal, Jan (advisor)
The absence of hydrogen in the photoelectron spectrum remains one of the greatest limitations of X-ray photoelectron spectroscopy. The main aim of this work is therefore to determine the concentration of hydrogen atoms in the near surface region of a sample. The REELS electron spectroscopic method based on quasi-elastic electron scattering is used for this purpose. The choice of this method was given mainly by the fact that the photoelectron spectrometers has an electron source in the basic equipment, so there is no requirement to purchase additional equipment. In our case, measurements were realized using the AXIS Supra photoelectron spectrometer in CEITEC laboratories. We were primarily focused on the study of polymer samples in this work. The gus cluster ion source was used for sputter cleaning of the sample surface. Then the XPS and REELS measurements were performed on such cleaned samples. The obtained data were subsequently evaluated, and the results discussed. The most important output of this work was to develop the methodology of detection and quantification of hydrogen atoms. However, the theoretical description of the methods used, and the appreciation of critical aspects associated with the use of the REELS method are also embraced. In particular, the effect of sample charging and electron dose on measurement results is discussed.
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Low temperature fuel cell for ultra-light-plane
Hladiš, Lukáš ; Brázdil, Marian (referee) ; Pospíšil, Jiří (advisor)
This thesis deals with the concept of propulsion for ultralight plane with using fuel cells technology. Here are described the individual kinds of fuel cells and possible fuel. Furthermore it is listed the calculation of low-temperature fuel cell H2 - O2 with polymeric membrane (PEM). The thesis includes also a part with the design drawings of the proposed solutions.
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Technologies for use hydrogen from Energiepark Mainz
Florian, Tibor ; Šnajdárek, Ladislav (referee) ; Škorpík, Jiří (advisor)
The goal of this bachelor’s thesis is the description of hydrogen, its production methods, subsequent use and comparison by selected criteria. In the beginning of the thesis, hydrogen is described as an element. The following chapter briefly deals with its history in energy industry and the most commonly used production technologies. The emphasis is on a Power-to-Gas facility, Energiepark Mainz. In the end, hydrogen is compared as a fuel in the automotive industry.
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Hydrogen Production from Biomass
Ožana, Ferdinand ; Beňo, Zdeněk (referee) ; Houdková, Lucie (advisor)
First part of this master´s thesis decribes the basic properties of hydrogen, its utilization in industry and economy. Greater attention is focused on the possibilities of hydrogen produciton. Next part describes anaerobic fermentation and optimum conditions for hydrogen production. The main part of the thesis deals with posibility of hydrogen production in an experimental laboratory unit using brewer´s grains as a primary material. The experiment was aimed to find suitable process conditions for hydrogen production. The quantity of produced gas and his quality depending on the amount of brewer´s grains and frequency of the dosage was observed. Based on the experiment, some recommendations are proposed for further research. An automatic feeding system is the most important of them. It will improve the quality of experimental work. A separate chapter is devoted to the automatic feeding system.
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