Second life employment of a traction battery for load match optimisation of a residential building: Life cycle and operation applications

The increasing use of renewable energy technologies for the electricity generation in buildings will require a growing number of energy storage systems (ESSs) in the next years in order to reduce the mismatch between the highly variable on-site electricity generation and the building load. Retired electric vehicle batteries (EVBs), before recycling, can be used for this purpose, considering that they have about 80% of the original energy capacity. In this context, the study aims at examining an ESS made by retired EVBs, in order to identify its optimal size for reducing the mismatch in a net zero energy building equipped with a photovoltaic plant and to assess the life cycle energy and environmental impacts/benefits of the energy system. The case study is represented by a real building for which monitored data on load and on-site generation are available. The functional unit (FU) of the analysis is the electrical energy required by the building in a time scale of 12 years (98,823 kWh). The main outcomes of the study are: the determination of the storage size realized with retired EVBs for the load match optimization in the analysed building, and the eco-profile of the energy system that deliver the performance described by the FU. The study represents an original environmental sustainability analysis, combining the load match analysis and the life cycle approach, of the synergy, inspired to the principles of the circular economy, between the building and the automotive sector.