Contents lists available at ScienceDirect Environmental Nanotechnology, Monitoring & Management journal homepage: www.elsevier.com/locate/enmm Investigation of life cycle CO 2 emissions of the polycrystalline and cadmium telluride PV panels Gökhan Yıldız a , Büşra Çalış b , Ali Etem Gürel c,d, *, İlhan Ceylan b a Düzce University, Graduate School of Natural and Applied Sciences, Department of Mechanical Engineering, Konuralp, Düzce, 81620, Turkey b Karabük University, Technology Faculty, Department of Energy Systems Engineering 100.Yıl, 78050, Karabük, Turkey c Düzce University, Technology Faculty, Department of Mechanical Engineering, Konuralp, 81620, Düzce, Turkey d Düzce University, Vocational School, Department of Electricity and Energy, 81010, Düzce, Turkey ARTICLE INFO Keywords: Polycrystalline Cadmium telluride (CdTe) Emission Energy payback time Life cycle ABSTRACT 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 m 2 polycrystalline and CdTe PV panel throughout the life cycle was determined to be 201.4 and 115.04 kg-CO 2 , 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 CO 2 emissions compared to the thermal power plant, and so PV panels appear to be 9.52 times more environmentally friendly. 1. Introduction In recent years, due to the growing population and rapidly devel- oping technology, global energy consumption and energy demand have led to large increases. For example, the world’s primary energy con- sumption has increased by an average of 1.7 % annually in the last 10 years. Today, fossil fuels are used as the most dominant energy source in approximately 85 % (Gürel et al., 2020a, b). Fossil fuels are an im- portant player in air pollution (Ceylan et al., 2020). Although it is not possible to completely remove fossil-fueled systems from our lives to prevent air pollution, it is possible to increase renewable energy sources. Solar energy is the most popular energy source because it has infinite energy source among renewable energy sources. Solar energy was first used in hot water production and space heating. Then, elec- tricity was started to be produced with the aid of PV cells (Yu et al., 2017). Rapidly developing photovoltaic panel technology in recent years is one of the sectors that has one of the biggest market shares in the world and is of global importance. The fact that the sector is so popular today creates competition in the international market, leading to some in- novations by accelerating the technological developments in this competition (Dubey et al., 2013; Gerbinet et al., 2014). The photo- voltaic panel sector, which progresses by updating itself along with different innovations, is presented to the market by improving its https://doi.org/10.1016/j.enmm.2020.100343 Received 6 June 2020; Received in revised form 22 June 2020; Accepted 3 July 2020 Abbreviations: CdTe, cadmium telluride; E PV , electricity generation from PV; CdCl 2 , cadmium chloride; E recy , energy consumption in panel recycling; CdS, cadmium sulfide; GHG, Greenhouse Gas; CH 4 , Methane; HFCs, hydrofluoric carbons; CO 2 , carbon dioxide; NO x , nitrogen oxide; CIGS, copper indium gallium diselenide; N 2 O, dinitrogen monoxide; CIS, copper indium diselenide; PFCs, perfluoro carbons; EF, emission factor; PV, photovoltaic; EGV, electricity generation value; SF 6 , sulfur hexafluoride; EPBT, energy payback time; SiO 2 , silicon dioxide; E cons , energy consumption; SO 2 , sulfur dioxide; E prod , energy consumption in panel production stages; TGGE, total greenhouse gas emission ⁎ Corresponding author. E-mail address: alietemgurel@duzce.edu.tr (A.E. Gürel). Environmental Nanotechnology, Monitoring & Management 14 (2020) 100343 2215-1532/ © 2020 Elsevier B.V. All rights reserved. T