As countries strive to enhance energy security, meet emission reduction goals, and capitalize on cost-effective electricity sources, renewable energy is experiencing rapid growth in global electricity systems. The successful utilization of flexibility resources, such as robust grids, interconnections, demand-side measures, affordable storage, and dispatchable power supply, has enabled many countries to effectively and securely integrate significant shares of variable renewables (VRE) into their power generation. However, as wind and solar power continue to expand their contribution, seasonal variations in system-level surpluses and lower generation will extend beyond daily or hourly fluctuations.

To address the seasonal variability of renewables, flexibility resources will be essential throughout the year, even on a week-to-week or month-to-month basis. This study coordinated by the International Energy Agency (IEA), examines the integration of VRE beyond a 70% share of annual generation in future power systems, focusing on four distinct climatic regions: temperate with hot summers, tropical, cold arid, and continental with warm summers. The study affirms that a diverse mix of flexibility resources is required to manage variability across all timescales and seasons. Specifically, systems with a high proportion of VRE necessitate seasonal flexibility services, which can be supplied by existing thermal power capacities and hydropower plants. Ultimately, as energy systems transition toward achieving net-zero emissions, all flexibility services will need to be fully decarbonized.

• • • Download the complete report on the IEA website.