Sprecher
Beschreibung
The increasing dependence of future electricity systems on variable wind and solar generation makes weather variability a critical uncertainty in long-term energy system planning. In particular, prolonged periods of simultaneously low wind and solar generation, known as dunkelflauten, can create substantial requirements for long-duration flexibility. This study investigates how interannual weather variability affects the design of a climate-neutral German electricity system and assesses biomass pyrolysis as an alternative flexibility option combining dispatchable electricity generation with negative emissions.
The analysis is based on the open-source energy system model MyPyPSA-Ger. First, 40 historical weather years are applied to an overnight optimization of the German net-zero electricity system in 2045 to quantify weather-induced variations in technology deployment and system costs and to identify the meteorological characteristics driving these differences. Subsequently, a favorable and a challenging weather year are implemented in a myopic capacity expansion framework from 2020 to 2050, both with and without pyrolysis.
The results reveal a strong dependence of future system design on the selected weather year. Annualized system costs range from €63 billion to €86 billion, while hydrogen storage requirements vary by nearly a factor of three. Among the investigated weather indicators, the duration of dunkelflauten shows the strongest relationship with hydrogen storage deployment, with each additional day increasing storage requirements by approximately 0.5 TWh.
Integrating pyrolysis substantially reduces this weather sensitivity. Negative emissions from biochar enable dispatchable pyrolysis-based generation and temporary operation of gas-fired power plants while maintaining net-zero emissions. In the challenging weather scenario, hydrogen storage requirements decrease by more than 80%. The results demonstrate that combining durable carbon removal with dispatchable generation can diversify the flexibility portfolio and significantly enhance the robustness of future renewable-based electricity systems.
