The dramatic effects of the climate crisis are calling for a change in the electrical grid paradigm. The market of Energy Storage Systems is now undertaking continuous growth, boosted by the relentless penetration of renewables. In this context, state of the art ESSs still have several limitations mainly due to technological constraints. Technology-dependent reaction times and rigid coupling between energy and power capacity, makes the choice of a specific ESS for different use cases very cumbersome and seldom optimal from both the technical and economic point of view.

SMHYLES project proposes novel sustainable Hybrid Energy Storage Systems (HESSs) based on the combination of two low-CRM storage technologies, one with long duration capacity and one with very highpower density, providing ultra-fast ancillary services, managed in a combined control by smart EMSs. The projects comprehend the design, construction, deployment and demonstration of an Aqueous-based HESS (AHESS) and a Salt-based HESS (SHESS) as well as a storage duration expansion.

Three demo sites in Portugal and Germany cover islanded grid, industrial microgrid, provision of grid services and EV charging use cases. Novel solutions for electrolyte recycling are also scaled up to industrially relevant size. The project will finalize techno-economic analyses to evaluate market segments for HESSs commercialization and deal with life cycle assessment along the whole design process. Digital twins are developed to support the optimal design of HESSs components and systems, define the strategies for HESSs real time management, investigate the business potential of SMHYLES solutions for specific use cases and countries, and support and test the energy management systems of the developed hybrid storage technologies. With high technological and economical advancements, SMHYLES will unlock novel flexible and multi-purpose energy storage solutions and ensure a remarkable impact on the European energy market.

Each storage technology has technical and economic characteristics that are ideally suited for a specific application. These characteristics include, for example, energy and power density, reaction time, environmental sustainability, and safety. Redox flow and salt batteries have a large storage capacity but can only be charged and discharged slowly. A supercapacitor, on the other hand, has fast charging times but cannot store large energy quantities over a long period of time. Only the efficient combination of both functionalities provides the necessary performance and flexibility in use.

“Modern energy storage systems need to guarantee security of supply, performance and safety, have flexible management software and be manufactured and operated in the most sustainable and environmentally friendly way possible”, explains SMHYLES coordinator Edoardo G. Macchi, Head of Battery and Electrification Technologies Unit at the Fondazione Bruno Kessler in Trento, Italy.

Combining sustainable batteries with other storage systems

The central goal of the SMHYLES project is to develop and demonstrate such innovative, safe, and sustainable hybrid energy storage systems on an industrial scale. In SMHYLES, a water-based supercapacitor and either a redox flow battery or a salt battery are to be combined to create innovative hybrid energy storage systems.

The novel hybrid storage systems developed in SMHYLES should be able to store energy over a medium to long period of time and release it very quickly. At the same time, they will reduce the use of critical raw materials, be safe to use (as they are not easily flammable), cost-effective and recyclable. Compared to conventional solutions, these new storage systems are expected to have a 40 per cent lower carbon footprint, also thanks to novel recycling solutions, and a 20 per cent higher reliability and availability, which should make our renewables-based power grids more resilient.