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    9.08 - Environmental Issues With Hydrogen Production
    (Elsevier, 2022) Baykara, Sema Z.; Figen, Halit Eren; Karaismailoglu, Meltem
    Hydrogen, its sources, production methods and use as fuel are covered in view of its “critical role” pertaining to global warming, climate change and other possible environmental impacts. Mostly, reviews are used as references to provide a wide source of information.; Environmental impact of hydrogen production is not only considered in terms of GHGs and their long-term global warming potential, but also in terms of the wider immediate environmental impact related to accession of sources of hydrogen and processes involved. Ubiquitous nature of hydrogen generation is emphasized as an advantage for securing and sustaining climate, development, eco-health and peace globally. © 2022 Elsevier Ltd. All rights reserved.
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    9.11 - Environmental Issues and Social Issues With Renewable Energy
    (Elsevier, 2022) Baykara, Sema Z.; Figen, Halit Eren; Karaismailoglu, Meltem
    A brief account of possible environmental and social impacts of mature renewable energy technologies is presented in terms of benefits and disadvantages/intrusive effects, keeping in perspective the greater environmental impact of the present fossil-based energy system and the potential further impact of climate change.; The technologies covered include solar energy (thermal and photovoltaic) and its derivatives (bioenergy, hydropower, wind and wave energies) and the others (tidal energy and geothermal energy). They are mostly considered from the point of view of electricity generation in anticipation of transmission opportunity via grid connections, producing a “mix,” and powering the existing stock of electrical appliances, machinery, and transportation vehicles. © 2022 Elsevier Ltd. All rights reserved.
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    Methane decomposition over Fe-based catalysts
    (Elsevier Ltd, 2020) Karaismailoğlu, Meltem; Figen, Halit Eren; Baykara, Sema Z.
    Catalytic approach for methane decomposition can be seriously considered as a promising process for COx free hydrogen generation. In this study, catalytic methane decomposition was performed using Fe-based catalysts, and catalytic performance tests were carried out in a CH4:N2 flow at 750 and 800 °C. The analyses of reaction products were carried out by a mass spectrometer. For the preparation of Fe-based catalysts, sol-gel method was utilized. Yttria (Y2O3) and alumina (Al2O3) were used as support materials. Theoretical molar ratios (Fe2O3/Y2O3/Al2O3) of the samples C1–C5 were 1:0:0, 1:1:0, 1:1:5, 2:1:4 and 3:1:6, respectively. The characterization analyses of fresh and spent catalysts were performed with XRD, SEM, TPR, TG-FTIR and BET surface analysis techniques. Surface basicity of catalysts was determined via CO2-TPD measurements. In the presence of Fe2O3/Y2O3 and Fe2O3/Y2O3/Al2O3 catalysts, methane conversions of 29% and 4% were achieved at 750 °C. Adding alumina into Fe2O3/Y2O3 catalyst leads to the formation of garnet type crystal structure which reduces catalytic activity. © 2020 Hydrogen Energy Publications LLC