TransnetBW: Adequacy 2025 - Security of supply in the power system
This study examines long‑term security of supply in a climate‑neutral European energy system, focusing on Germany’s 2045 target and the robustness of NEP23 planning assumptions. The study evaluates how weather variability, flexibility availability, hydrogen system development and cross‑border integration affect system adequacy across Germany and Europe
The modelling links a sector‑coupled energy system model, the BID3 electricity market model witha commercial grid model to replicate NEP23 Scenario B and explore deviations from its assumptions. BID3 provides plant‑level dispatch, ENS calculations and cross‑border flow analysis, enabling a fine‑grained view of adequacy under different scenario clusters, including extreme meteorological years, reduced decentral flexibility, hydrogen power plant variations and differing levels of energy sovereignty.
A key finding is that average weather‑based planning underestimates system needs. Renewable output varies sharply year‑to‑year, increasing ENS and raising system stress in adverse years. The study shows that:
- Wind generation can fluctuate by ±15% and solar by ±5% annually.
- Extreme weather years can double average electricity prices.
- Low renewable yield scenarios require significantly higher hydrogen imports and additional long‑duration flexibility.
- These weather‑driven impacts substantially increase reliance on backup assets, imports and seasonal balancing incorporate meteorological uncertainty.
Prosumer behaviour is another decisive adequacy factor. When only half of households and services respond to market signals, the system becomes more vulnerable in stressed conditions. The study finds that:
- Reduced prosumer participation raises ENS and critical peak hours.
- It increases the need for central flexibility, including hydrogen power plants and large‑scale storage.
- Fully market‑oriented prosumers can lower peak prices and ease system balancing through demand shifting.
- This underscores the importance of smart‑meter rollout, dynamic tariffs and targeted flexibility‑enabling regulation
European interconnectivity emerges as a cornerstone of system resilience. Allowing interconnector expansion beyond NEP23 can reduce system costs by up to €18 billion per year and mitigate national adequacy risks. Optimal pathways frequently involve higher NTC levels—76–81 GW for Germany—enabling countries to share diverse weather conditions and reduce the burden on national backup capacity. Overall, the study shows that a secure climate‑neutral energy system requires diversified flexibility, strong cross‑border integration and planning approaches that explicitly incorporate meteorological uncertainty.
>> Link to TransnetBW Adequacy 2050 webpage - external link External link, opens in new window.
>> Download full study report [PDF] - external link External link, opens in new window.
>> Download executive summary [PDF] - external link External link, opens in new window.
>> Download study launch slides [PDF] - external link External link.
>> Download full report [PDF] - internal link pdf, 7.8 MB.
>> Download executive summary [PDF] - internal link pdf, 149.8 kB.
>> Download study launch slides [PDF] - internal link pdf, 625 kB.
