Comparative life cycle assessment of renewable energy storage systems for net-zero buildings with varying self-sufficient ratios

The transition towards zero and net-zero buildings necessitates identifying sustainable and effective renewable energy systems to reduce the impacts of operational energy. This study analyses the environmental impacts of multiple microgrids that consist of a photovoltaic plant and a hybrid hydrogen/battery energy storage system in a grid-connected building. To this end, a three-step simulation process was proposed. The first step involved modelling the energy consumption of the building during operation. Following that, the size of components was optimised. Lastly, a comparative life cycle assessment was conducted to evaluate different self-sufficient ratios (SSR). The results show that as SSR increase, the optimised capacities of all components generally increase, although this relationship is complex, particularly as the system approaches full renewable capacity. The climate change impact initially decreases to its lowest values but then increase again towards achieving full self-sufficiency. Furthermore, the results highlight the importance of considering multiple environmental impact categories when designing renewable energy systems. A sensitivity analysis reveals that countries with carbon-intensive electricity grids can reduce climate change impacts by increasing their renewable energy penetration. However, for countries with a high proportion of renewable energy, a higher SSR may not lead to a lower climate change impact but rather exacerbate it.