The objective of HIGREEW (Affordable High-performance Green REdox floW batteries) is to design, develop and validate and an advanced redox flow battery, based on new water-soluble low-cost organic electrolyte compatible with optimized low resistance membrane and fast electrodes kinetics for a high energy density and long-life service. The battery prototype engineering design will be twofold: affordable balance of plant to optimize performance through advanced control strategy to achieve an LCOS of < 0.10€/kWh/cycle at the end of the project and 0.05€/kWh/cycle by 2030 and designed for recycling, to maximize the recycling of the components. The consortium is formed by 9 partners coordinated by CIC Energigune, Spanish research centre, that will be the focus on electrolyte and algorithm development to maximise the batteries life span and minimise its LCOS. The development of advanced materials will be complemented with the University Autonomous of Madrid to improve membranes performance and the French CNRS research centre to optimize the electrode. The 3 key components will be tested and validated at lab scale and cell level with the collaboration of the University of West Bohemia (CZ). The stack engineering will be developed by C-TECH, UK’s SME specialised in electrochemical and electro-heating process equipment, that will work together with Pinflow to optimize active components at laboratory scale and battery stack design. The system design and scale up to manufacture a battery prototype of 5Kw will be done in collaboration between Heights, UK’s engineering, and Gamesa Electric, Spanish large industry leader in renewables. The battery prototype will be tested and validated in the pilot plant of Siemens Gamesa -third party linked to Gamesa- located in Spain. The testing and validation will be the focus on safety-hazards, LCA and LCOS. The exploitation strategy will be led by Uniresearch, who are highly experienced in EU projects. The project will last 40M with a cost of 3,7M€.