Optimization of a decentralized energy system by implementing three different storage solutions for a small residential district in Ludvika, Sweden

Abstract: The acceleration towards achieving a low carbon society has raised many challenges in the energy sector. The existing systems, highly dependent on fossil fuels, are not sustainable and recommendations are made to accelerate the transition by using more renewable and low-carbon sources of energy. By being responsible for over 70 % of the greenhouse gas emissions, cities or districts have a major role to play in this transition and present a large potential for implementation of renewable energy systems. The optimization of those systems and a better use of energy are crucial to reduce emissions and reach carbon neutrality. This study evaluates the potential of the implementation of three storage solutions for a decentralized energy system in a residential cluster in Ludvika, Sweden, equipped with photovoltaics panels. The first solution includes stationary batteries, the second includes a hydrogen storage solution and the third offers a hybrid solution from the two previous storages. Simulations were conducted using two numerical tools with an hourly resolution.The first scenario was conducted using Spine modelling tools, and the other simulations, including the cost analysis, were conducted on Excel with the support of Visual Basic for Applications. The comparison between the three solutions showed that the stationary batteries, blessed with a higher efficiency, offers the best results. The autonomy of the site, initially at 19.1 %, was raised to 22.8 % due to the batteries, and the system allowed to save up to 9.6 MW∙h per year. The investment price of the battery system was the highest of the three solutions. However, the payback period is reached in 20 years, within the average lifespan of the batteries and 10 years shorter than with the other solutions. The results also showed that the benefits of implementing a hydrogen storage solution were not visible as the excess in the photovoltaic production was not enough to cover the energy demand in a long-term period.