Environmental impact assessment of energy storage technologies in photovoltaic systems

This thesis addresses the issue of the environmental impact assessment of residential energy systems named Solar Home Systems and Renewable Energy Communities that produce electricity using photovoltaic modules and store it in energy storage systems. These installations are playing a key role in the energy transition and decarbonization because they do not imply direct emissions to the environment and do not directly consume fossil fuels. Nevertheless, these technologies have some environmental impacts during their life cycle. For instance, several rare critical raw materials are necessary for their manufacturing and greenhouse gases are emitted during their production and end of life. Life Cycle Assessment represents the most suitable methodology to evaluate environmental indicators like the natural resources’ depletion. In order to replace traditional power plants, renewable energy and storage technologies should become competitive from the techno-economic point of view. For such reason, it is fundamental to integrate Life Cycle Assessment with auxiliary methodologies like mathematical modelling, optimization tools and Life Cycle Costing. The results of this thesis are collected in five papers where an integrated Life Cycle Assessment approach, combining environmental and techno-economic analyses, is performed. The goal of these works is the evaluation of the most sustainable Solar Home Systems and Renewable Energy Communities configurations. The combination of different methodologies allows to consider all the variables of the problem, such as the spatial and temporal variability of solar radiation and the techno-economic properties and maturity of different energy storage technologies. Among the mature technologies, nickel cobalt manganese and nickel cobalt aluminium lithium-ion batteries are assessed as the most sustainable solutions in all the considered European installation sites (Denmark, France, Spain, Italy, Portugal, Romania, Hungary, and Greece). Nevertheless, an environmental and economic cross evaluation highlights the importance of reducing their costs. Some innovative batteries like solid state lithium-ion batteries, sodium-ion batteries, and vanadium redox flow batteries, already show a great potential being competitive with mature technologies, although some characteristics still need to be improved. Finally, system-level results show that Solar Home Systems and Renewable Energy Communities can provide relevant advantages to the national energy systems, especially when they are connected to the grid and specific economic incentives for their members are considered.