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    A parametric investigation of hydrogen energy potential based on H2S in Black Sea deep waters
    (PERGAMON-ELSEVIER SCIENCE LTD, 2007) Midilli, Adnan; Ay, Murat; Kale, Ayfer; Veziroglu, T. Nejat
    In this study, a parametric investigation is carried out to estimate the hydrogen energy potential depending on the quantities of H2S in Black Sea deep waters. The required data for H2S in Black Sea deep waters are taken from the literature. For this investigation, the H2S concentration and water layer depth are taken into account, and 100% of conversion efficiency is assumed. Consequently, it is estimated that total hydrogen energy potential is approximately 270 million tons produced from 4.587 billion tons of H2S in Black Sea deep waters. Using this amount of hydrogen, it will be possible to produce 38.3 million TJ of thermal energy or 8.97 million GWh of electricity energy. Moreover, it is determined that total hydrogen potential in Black Sea deep waters is almost equal to 808 million tons of gasoline or 766 million tons of NG (natural gas) or 841 million tons of fuel oil or 851 million tons of natural petroleum. These values show that the hydrogen potential from hydrogen sulphur in Black Sea deep water will play an important role to supply energy demands of the regional countries. Thus, it can be said that hydrogen energy reserve in Black Sea is an important candidate for the future hydrogen energy systems. (c) 2006 International Association for Hydrogen Energy.
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    Green energy strategies for sustainable development
    (ELSEVIER SCI LTD, 2006) Midilli, Adnan; Dincer, Ibrahim; Ay, Murat
    In this study we propose some green energy strategies for sustainable development. In this regard, seven green energy strategies are taken into consideration to determine the sectoral, technological, and application impact ratios. Based on these ratios, we derive a new parameter as the green energy impact ratio. In addition, the green energy-based sustainability ratio is obtained by depending upon the green energy impact ratio, and the green energy utilization ratio that is calculated using actual energy data taken from literature. In order to verify these parameters, three cases are considered. Consequently, it can be considered that the sectoral impact ratio is more important and should be kept constant as much as possible in a green energy policy implementation. Moreover, the green energy-based sustainability ratio increases with an increase of technological, sectoral, and application impact ratios. This means that all negative effects on the industrial, technological, sectoral and social developments partially and/or completely decrease throughout the transition and utilization to and of green energy and technologies when possible sustainable energy strategies are preferred and applied. Thus., the sustainable energy strategies can make an important contribution to the economies of the countries where green energy (e.g., wind, solar, tidal, biomass) is abundantly produced. Therefore, the investment in green energy supply and progress should be encouraged by governments and other authorities for a green energy replacement of fossil fuels for more environmentally benign and sustainable future. (c) 2005 Elsevier Ltd. All rights reserved.
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    Investigation of hydrogen production from boron compounds for PEM fuel cells
    (ELSEVIER SCIENCE BV, 2006) Ay, Murat; Midilli, Adnan; Dincer, Ibrahim
    This paper presents a comprehensive study of hydrogen production from sodium borohydride (NaBH4), which is synthesized from sodium tetraborate (Na2B4O7) decomposition, for proton exchange membrane (PEM) fuel cells. For this purpose, Na2B4O7 decomposition reaction at 450-500 degrees C under hydrogen atmosphere and NaBH4 decomposition reaction at 25-40 degrees C under atmospheric pressure are selected as a common temperature range in practice, and the inlet molar quantities of Na2B4O7 are chosen from 1 to 6 mol with 0.5 mol interval as well. In order to form NaBH4 solution with 7.5 wt.% NaBH4, 1 wt.% NaOH, 91.5 wt.% H2O, the molar quantities of NaBH4 are determined. For a PEM fuel cell operation, the required hydrogen production rates are estimated depending on 60, 65, 70 and 75 g of catalyst used in the NaBH4 solution at 25, 32.5 and 40 degrees C, respectively. It is concluded that the highest rate of hydrogen production per unit area from NaBH4 solution at 40 degrees C is found to be 3.834 x 10(-5) g H-2 s(-1) cm(-2) for 75 g catalyst. Utilizing 80% of this hydrogen production, the maximum amounts of power generation from a PEM fuel cell per unit area at 80 degrees C under 5 atm are estimated as 1.121 W cm(-2) for 0.016 cm by utilizing hydrogen from 75 g catalyst assisted NaBH4 solution at 40 degrees C. (c) 2005 Elsevier B.V. All rights reserved.
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    Yakıt pili yardımıyla bor bileşiklerinden güç üretiminin parametrik araştırılması ve termodinamik analizi
    (Niğde Üniversitesi, 2005) Ay, Murat; Midilli, Adnan
    ÖZET YAKIT PİLİ YARDIMIYLA BOR BİLEŞİKLERİNDEN GÜÇ ÜRETİMİNİN PARAMETRİK ARAŞTIRILMASI VE TERMODİNAMİK ANALİZİ AY, Murat Niğde Üniversitesi Fen Bilimleri Enstitüsü Makina Mühendisliği Ana Bilim Dalı Danışman: Doç. Dr. Adnan MİDİLLİ Temmuz 2005, 48 sayfa Bu tez çalışmasında, bor bileşiklerinden hidrojen üretiminin parametrik araştırılması ve PEM yakıt pili yardımıyla güç üretiminin termodinamik analizi çalışılmıştır. Bu amaçla, sodyum tetraborat {NCİ2B4O7) bozunum reaksiyonundan sentezlenen sodyum borhidritin (NaBH4) kullanılmasıyla hidrojen üretimi parametrik olarak çalışılmış, elde edilen bu hidrojenin PEM yakıt pilinde kullanılmasıyla güç üretimi incelenmiş ve PEM yakıt pilinin enerji ve ekserji analizleri yapılmıştır. Bu kapsamda, 450-500 °C'de hidrojen atmosferinde gerçekleşen N0.2B4O7 bozunum reaksiyonu ile 25-40 °C ve İ atm'de gerçekleşen NaBHj bozunum reaksiyonu dikkate alınmıştır. Bunun yanında, PEM yakıt pili çalışma sıcaklığı, basıncı ve membran kalınlığı farklı değer aralıklarında seçilmiştir. Sonuç olarak; hidrojen üretim hızının, NC1BH4 bozunum reaksiyonu sıcaklığı ve katalizör miktarının artması ile arttığı parametrik olarak belirlenmiştir. Ayrıca, yakıt pili sıcaklığı ve basıncının atması ve membran kalınlığının daha düşük olması durumunda PEM yakıt pilinin performansının arttığı görülmüştür. Anahtar kelimeler: Sodyum Tetraborat, Sodyum Borhidrit, Hidrojen, PEM Yakıt Pili, Termodinamik Analiz, Enerji Analizi, Ekserji Analizi. III