Assessing uncertainty space for long-term flexibility needs in future European sector-coupled energy system

Abstract Future energy systems increasingly relying on variable renewable sources will require flexibility, yet the role and competition of different flexibility providers remain uncertain. We use a pan-European sector-coupled energy system model to quantify flexibility needs across sectors, regions, and timescales in a Net-Zero energy system. We explore uncertainty spaces for flexibility portfolios using 33 weather years and Monte Carlo simulations. Sector coupling unlocks flexibility opportunities, through electrified heating, electric vehicles and hydrogen production. Daily and weekly flexibility are provided by electric heating, electric vehicles, transmission and batteries, whereas annual flexibility relies on hydropower, electrolyzers, electricity transmission -nearly doubled by 2050- and peak gas. Peak gas capacity remains necessary as a low-capacity-factor backup, transitioning from natural gas to biomethane, with a 212 GW median capacity. Uncertainty in electric vehicles and hydrogen deployment impacts the flexibility mix. Our study highlights the need for diverse, cross-sectoral flexibility portfolios across regions and timescales.