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A sustainable pathway for ammonia synthesis by means of the Haber-Bosch process should reduce or zero out the use of fossil fuels, taking advantage of renewable sources. Using renewable energy systems, hydrogen can be obtained from biomass gasification, biogas reforming or electrolysis of water with electricity generated by solar or wind energy. The scale-up of the concept is not an easy issue. From a theoretical point of view there is no limit to multiply single units but on a practical way, chemical companies are hardly reaching the size of 100 kW, due to energy, economic and sustainability problems. Hydrogen, from high-temperature water electrolysis, from biomass gasification and from biogas reforming, has been considered as the most promising solutions for ammonia production plants, based on the Haber-Bosch process. In this study the impact of three different strategies, for renewables integration and scale-up sustainability in the ammonia synthesis process, was investigated using thermochemical simulations. The study is finalized to compare the energy efficiency and sustainability of those three strategies. For a complete evaluation of the benefits of the overall system, the balance of plant, the use of additional units and the equivalent greenhouse gas emissions have been considered

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Nowadays energy storage is strongly needed to allow grid safety and stability due to the wide penetration of renewable plants. Mainly economic and technological issues impede a relevant integration of conventional storage devices in the energy system. In this scenario, the hybridization of different storage technologies can be a techno-economic solution useful to overcome these issues and promote their diffusion. Hybridization allows multi-operation modes of the Energy Storage System (ESS), merging the positive features of base-technologies and extending their application ranges. This paper provides a dynamic analysis of a hybrid energy storage system (H-ESS) consisting of a flywheel and a battery pack coupled to a photovoltaic generation plant and a residential load up to 20 kW. A dynamic model of the overall micro-grid (MG) was developed implementing the H-ESS preliminary sizing and a suitable management algorithm. The instantaneous behavior of each component was evaluated. A brief summary of the MG performance at different weather and load conditions was provided together with a characterization of the impact of power fluctuations on the battery current and on the power exchange with the grid.

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