Demonstration of solutions based on renewable sources that provide flexibility to the energy system Proposals will address one of the following sub-topics: Intermediate bioenergy carriers: Focus will be on the demonstration of the most cost-efficient intermediate bioenergy carrier pathways for energy and transport, which improve the economic viability of the subsequent energy production by addressing solid, liquid and gaseous intermediate bioenergy carriers from biogenic residues and wastes with increased energy density, storage and trade characteristics where relevant. Reduced conversion costs and improved energy efficiency and GHG performance of the intermediate bioenergy carrier pathway will be demonstrated. Production at a scale of up to 5000 tons and process feasibility through applications to fuel production including for the heavy duty, maritime and aviation sectors, as well as to combined heat and power generation, are to be included. Hydropower: Focus will be on the improvement of the average annual overall efficiency of hydroelectric machinery. Projects are expected to provide high availability of hydropower plants and to maximise performance of hydropower plants of all sizes. The aim is adapting to variable speed generation the hydropower plants (new, refurbished and uprated and especially existing ones); it is important that by optimising maintenance intervals for all hydro plants (especially those delivering balancing power because of the related dynamic operation, dynamic loads and increased wear and tear) the outage time will be minimised. Digitalisation measures to increase the potential of hydropower in providing flexibility to the energy system can be included. Thermal energy storage in Concentrated Solar Power (CSP) plants: The focus will be on the demonstration of innovative storage systems for CSP plants. The thermal energy storage solutions proposed will have to achieve much higher storage densities than current mainstream solutions (i.e. at least two times higher) while guaranteeing similar performance in terms of cycles. Proposals are expected to bring the technology from TRL 5 to TRL 7 (please see part G of the General Annexes).The Commission considers that proposals requesting a contribution from the EU of between EUR 12 to 15 million would allow this challenge to be addressed appropriately. Nonetheless, this does not preclude submission and selection of proposals requesting other amounts. : Supporting the power grid balancing and increasing the flexibility of the energy system is possible by means of dispatchable renewable energy sources. The specific challenge is to increase the potential of renewable dispatchable technologies in providing flexibility to the energy system. Different technologies are suitable to address this challenge. The developed technologies will allow plant and system operators to operate successfully in the modern power markets and to make a significant contribution to European renewable energy objectives and policies.