Na-seawater battery technology integration with renewable energies: The case study of Sardinia Island

Europe has committed to net zero carbon dioxide emissions by 2050 to boost the clean energy transition. Renewable electricity will be the key energy medium for decarbonization and a huge increase in renewable energy sources (RES) exploitation is expected. Due to RES stochastic character, an extensive energy storage integration in the energy system is needed to avoid the mismatch between generation and demand profiles. Reactive metals are promising energy carriers and storage media characterized by high volumetric energy densities and circularity, due to ease of storage and transportation, material availability and low cost. Among them, sodium is a largely available element since it can be extracted from seawater and exploited through the innovative sodium-seawater battery (SWB). Sodium cations are transferred from SWB’s open cathode to the anode side during charging. Upon discharge, Na metal is oxidized to Na+ ions, which are discarded in seawater. This study assesses the impact of SWB technology focusing on Sardinia Island as a case study. For short-term application, SWB integration to wave energy converters allows a potential reduction of greater than 85% of generated power fluctuations, largely improving the quality of power injected into the grid. Regarding the long-term scenario, SWBs implementation in the energy system allows coverage of the Sardinia annual energy demand thanks to the integration of ~340,000 cubic meter of Na metal, corresponding to a 12-meter height Na reservoir under 4 soccer fields. SWB application to Sardinia also produces CO2 sequestration while covering ~29% of desalinated water requirements for the Sardinian population.