Life Cycle Analysis of EXASUN Module

Abstract

This thesis deals with the Life Cycle Assessment (LCA) of the manufacture of an EXASUN X-Glass photovoltaic (PV) module to understand its true environmental impact. The methodology and general guidelines for conducting an LCA on a Photovoltaic (PV) system are developed, within the scope of this thesis. The LCA follows a standard framework, proposed by International Organization for Standards (ISO) and International Energy Association (IEA). LCA is a technique used to understand the total environmental impact of all the processes involved in the manufacture of a particular product. It takes into account all production process stages, to check the highest impact involved in production. The results from this LCA study are obtained using the SimaPro software. These results quantify the production impact and aid in understanding where and how to improve the carbon footprint of associated production processes. The environmental impact categories from the ReCiPe 2016 assessment methods were used in this study. All the impact categories such as global warming potential, ozone depletion, photochemical ozone formation, etc. were taken into consideration. This includes all the mid point and end point categories offered by ReCiPe method. Additionally, the cumulative energy demand method was used to calculate the total renewable and non-renewable energies mix, used in the production process. Subsequently, using this information, impact categories such as energy payback time, net energy ratio and GHG emissions rate were obtained. This study is based on the data obtained from Ecoinvent LCA database, accessed through the SimaPro software. This data was then changed according to the inventory update published by IEA PVPS. PV cell data was obtained from literature. However, the remaining materials used in the X-Glass module’s manufacture were noted and their associated data was used to develop an appropriate LCA model. The model incroporated factors including transport, quantity, etc. The functional unit (FU) in this study is 1 m2 of X-Glass production. For better analysis, all the impacts caused by manufacturing 1 X-Glass module were used to compare the results. Results clearly show that the contribution of PV cells production to the environmental impact is high when mono-Si is used by the PV module. The energy requirements and geographical influence of these energy mixes that are involved in the PV cell manufacture are clearly explained. The cells for a typical X-Glass manufacture were modeled with a Chinese energy mix as the cells were produced in China. The energy payback time (EPBT) of X-Glass module installed in the Netherlands are 1.3 years with 73 g CO2/kWh GHG emission rate. The CO2 offset period was found be 3.9 years. These modules were then compared to a similar model developed for an European energy mix. The differences in results, due to the change in energy mix show that he energy payback time for manufacturing the same X-Glass module was found to be 1.3 years, with GHG emission rate of 32 g CO2 eq. The CO2 offset period for these was 1.7 years. The obtained results were cross-validated based on literature, outlining various LCA studies conducted on similar PV technologies. Thus, based on the results, it can be concluded that the environmental performance of X-Glass module was found to improve by 40% when cells from Europe are used as the EPBT of EU based model was found to be 1.3 years with an emission rate of 32 g CO2 eq.