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    Investigation of life cycle CO2 emissions of the polycrystalline and cadmium telluride PV panels
    (Elsevier B.V., 2020) Yildiz, G.; Çalis, B.; Gürel, A.E.; Ceylan, I.
    The importance of energy increases in human life with the development of technology. However, most of the world's energy needs are still met by fossil fuels. The interest in renewable energy is increasing due to the increase in demand for fossil fuels, their limitedness, and environmental damage. Solar energy, which is an unlimited and clean energy source, is among the most popular renewable energy sources. Solar energy is used by processes such as heating and electricity generation. In this study, the emission amount of polycrystalline and cadmium telluride (CdTe) photovoltaic (PV) panels to the environment during the life cycle were compared. During the life cycle, the amount of emission released to the environment during the production, recycling, and electricity generation of the panel was determined. In addition, energy payback times of these two PV types were calculated. The emission amount for both of 1 m2 polycrystalline and CdTe PV panel throughout the life cycle was determined to be 201.4 and 115.04 kg?CO2, respectively. Besides, the average energy payback period of the polycrystalline panel is 0.92 years, while it is 0.57 years for the CdTe panel. In addition, the emission amount of the solar panel and the natural gas-powered thermal power plant known as a clean energy source were compared. As a result, a huge difference was observed between the emission amount released by the PV panel to the environment and the emission released as a result of the energy produced by the thermal power plant under the same conditions during its 17-year lifetime. PV panel saves 1.72 tons of CO2 emissions compared to the thermal power plant, and so PV panels appear to be 9.52 times more environmentally friendly. © 2020 Elsevier B.V.
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    Performance, exergy, and environmental analysis of blast furnace top pressure turbine in an iron-steel factory
    (International University of Sarajevo, 2023) Albayrak, F.I.; Ergün, A.; Yildiz, G.
    The iron-steel industry, which has a large part of its energy consumption, strives to stay at the targeted level in the competition race and to hold on in the field in which it operates. For this purpose, production capacity turned to different energy saving methods due to the effort to reach the relevant standards and high quality low cost strategies. But, energy prices are constantly variable and energy costs are high. In this study, the Blast Furnace Top Pressure Turbine system (TRT), which is one of the important energy saving methods of the iron and steel industry, was examined. Considering the importance of the TRT system, operating conditions, operating parameters, and factors affecting energy recovery, the effect of various operating parameters on the operation of the TRT system was evaluated. Considering the annual operating time of 8000 hours, the annual production amount is 42400000 kWh, the value in terms of tons of oil equivalent is 3640 toe, the investment cost of the plant in 2018 is $400000 and the annual savings amount is $2755900. The amount of carbon emission reduction due to this production amount was calculated as 10888 kgCO2/h on average, and this amount of carbon emission was prevented every year with the commissioning of the facility. When the cost and energy calculations related to the system are examined, the payback period of the project is calculated as approximately 0.15 years. The obtained data showed that the TRT system is a suitable method for energy saving in the iron and steel industry. © The Author 2023. This work is licensed under a Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) that allows others to share and adapt the material for any purpose (even commercially), in any medium with an acknowledgement of the work's authorship and initial publication in this journal.
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    Solar panel cooling using hybrid cooling systems
    (Elsevier, 2023) Yildiz, G.; Karaagaç, M.O.; Ergün, A.; Kayfeci, M.
    Photovoltaic (PV) panels are systems that convert the energy from the sun into electrical energy. A large part of the energy coming to the PV panel is converted into heat, causing the panel temperature to increase and the electrical efficiency to decrease. There are many benefits of cooling the panel to increase the performance and PV panel’s controllability. By removing the heat from the panel, the efficiency of the panel rises and the heat received is used as useful heat. In addition, the cooling of the panels also extends the panel life. The heat produced by the PV panels can cause an increase in the cell temperature above 50°C, and this situation causes a decrease in electrical efficiency (0.4% per 1°C for monocrystalline). Photovoltaic thermal (PVT) panels have been developed to cool the PV panels, and cooling process is carried out by passing water or air behind the panel. This section focuses on the different hybrid cooling techniques used in PVT panels and the effects of these techniques on performance. © 2023 Elsevier Inc. All rights reserved.