Selection of electrolytic capacitors is mainly based on their reliability. Beside this property, the evaluation of environmental performances of such devices is crucial due to their wide dissemination and utilization of critical raw materials for their production. Starting from the environmental analysis of the stages of selection and supply of raw materials, it is possible to improve the sustainability of the manufacturing process of a capacitor. In addition, the use stage and end-of-life of the devices can be analyzed to evaluate their entire life cycle. In this study, LCA (Life Cycle Assessment) methodology is applied to perform a comparative analysis between two types of aluminum electrolytic capacitors. These products can be applied in different sectors as industrial, inverter and UPS, solar, medical and tractions systems. The aim of this study is to compare the environmental impact due to the stages of production (from the raw materials supply to the assembly) and end-of-life (recycle or disposal of wastes) of two aluminum electrolytic capacitors, which are characterized by different internal designs but are manufactured by the same producer.
The paper was presented by Chiara Moletti, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Italy at the 3rdPCNS 7-10th September 2021, Milano, Italy as paper No.1.8.
The goal of this study is to assess the environmental performances of two types of aluminum electrolytic capacitors, namely “Type 1” and “Type 2”. The two capacitors differ for the electrolyte source and composition: Type 2 electrolyte is an evolution of Type 1 electrolyte, which is studied and sourced from with a specialty chemicals producer partner. . The study of the environmental impacts may lead to the adoption of virtuous policies that, preserving the device performances, decrease the production footprint on the environment.
Since both capacitors are produced in different sizes, a reference product has been selected for the analysis of the environmental impact to define the functional unit (FU) of the LCA study. Hence, the FU is the capacitor having a mass of 0.06 kg.
The LCA study has been carried out on the basis of the standard EN 50693:2019  which establishes specific requirements for the environmental analysis of electrical products. The study focuses on the manufacturing stage to assess and compare the environmental impact related to the production of the two types of aluminum electrolytic capacitors. According to the standard, the manufacturing stage has been subdivided in the following steps: acquisition of raw materials, transport to manufacturing site, component manufacturing, end-of-life treatment of generated waste. The boundaries of the system are schematized in Figure 2.
LIFE CYCLE INVENTORY
The acquisition of the raw materials includes all the processes related to the extraction and production of such materials. In this case the main raw materials are aluminum, the electrolyte, paper, and the dielectric envelope of the device.
The second process unit is the transport of raw materials to the manufacturing site (e.g. ship or land transport), in this phase the amount of transported material is calculated together with all the data about distances and packaging related to the supply to the production site. The packaging used during transport have been excluded from the model of the system since their impact is negligible with respect to the other contributions, or it is reused as in the case of wooden pallets, and hence it is part of the cut-off of the system according to the EN 50693:2019 .
The input flows in the capacitor manufacturing, assembly and packaging process unit are raw materials, energy (gas and electricity) and water related to the manufacturing operations. The outputs are the product, the scraps of aluminum, paper and plastic materials.
The last step is the evaluation of the end-of-life which includes the management, treatment and disposal of scraps and waste generated during manufacturing; in addition, it includes the transport to the center of waste collection. This stage is crucial because the possibility of recycling or reusing waste materials can be evaluated and accounted into the lifecycle of the product. For example, only a portion of the discarded paper and part of the aluminum scraps can be recycled whilst all materials contaminated by the electrolyte or plastic materials are sent to incineration. Moreover, the washing water are collected and sent to sewage treatment.
The life cycle inventory (LCI) has been realized using primary data for the transport, production and end-of-life stages while raw materials production step has been modelled using Ecoinvent 3.6 database .
Life cycle impact assessment
The quantification of impacts is performed with the software SimaPro®, version 22.214.171.124, and the indicators have been computed according to the indications given by ISO 50639  and ISO 15084  standards. Among the results, the focus has been set on the Global Warming Potential (GWP) which quantifies the impact category of climate change, that, for the purposes of our research, is the most revealing result.