| Solar energy is an inexhaustible clean energy, and photovoltaic (PV) technology is booming nowadays, since the problem of energy shortage and environmental pollution is serous. However, PV technology is not always clean during its whole life cycle, it consumed energy and discharged pollutants to the environment. There’s no systematic research so far about it in China. Thence, in the study, we quantitatively assess the life-cycle energy consumption and environmental impacts of PV systems in China.Based on the data collected from Chinese PV companies by the methods of field investigation and expert advice, as well as literature research, we build the life cycle assessment model of PV system with the software GaBi4, and the databases of PE and Ecoinvent. The system boundary includes upstream process starting from silica extraction to the solar grade multi-crystalline silicon production, midstream process involving ingots growing and wafer slicing, downstream process consisting of cells fabrication and modules assembly. The CML method is used to evaluate the Primary Energy Demand (PED), Acidification Potential (AP), Eutrophication Potential (EP), Global Warming Potential (GWP), Human Toxicity Potential (HTP), Ozone Layer Depletion Potential (ODP), Photochemical Ozone Creation Potential (POCP) and Energy Payback Time (EPBT) of the PV system. In addition, the PED and environmental impacts of PV technology and other power generation systems in China are compared. Transportation and location effects are also discussed.The results show that the PED of multi-Si PV system in China is12.61MJ/Wp, EPBT is in the range of2.1-5.7years. AP is1.04×10-2kg SO2-eq/Wp, EP is1.03×10-3kg PO34-eq/Wp, GWP is1.24kg CO2-eq/Wp, HTP is0.43kg DCB-eq/Wp, ODP is7.35×10-8kg R11-eq/Wp and POCP is6.55×10-4kg ethane-eq/Wp. The most critical phase is the solar grade silicon production which is characterised by great electricity consumption, while Chinese electricity is mainly produced by coal-fired power plants. Therefore, it’s important to reduce the energy consumption of this stage, and apply the more advanced, efficient and environmental friendly technology to produce the PV systems. Compared with other power generation systems in China, PV technology is more greener since it has lower PED and environmental impacts. If the coal-fired power plants were completely replaced by PV systems, the reduced PED would be3.98×1013MJ. Given the impact of distance, the environmental impacts caused by transportation of PV modules is negligible compared to that of the whole PV system. However, the results show that installation location is important, and it’s appropriate to install PV systems in areas with high solar radiation, such as Tibet Autonomous Region, northeastern Qinghai and western borders of Gansu. |
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