Mapping renewable energy futures in the Cologne planning region: Land-use constraints and landscape impacts.

Germany aims to become climate-neutral by 2045, which necessitates a far-reaching transformation of its energy system. Central to this shift is the ongoing expansion of renewable energy sources, particularly wind power and photovoltaics. This study seeks to model the growth of renewable energy systems in the Cologne planning region in western Germany in a way that is consistent with national and international climate targets. For this purpose, we employ a Geographic Information System (GIS)-based methodology combined with a siting algorithm. This allows us to apply land-use regulation scenarios to simulate various regulatory pathways and evaluate their effects on the resulting energy landscapes. The modeling period spans 2023-2045, and population data, CO₂ budgets, and electricity demand are derived for this timeframe. The findings indicate that climate-neutral electricity production in the region cannot be achieved under the current planning framework due to a lack of sufficient land for renewable energy installations. Even in scenarios with more flexible planning rules and higher-efficiency wind turbines, available land remains scarce. Only a substantial reduction in energy demand, modeled in this study at 50%, would make the targets attainable. Regardless, the energy transition would profoundly reshape the landscape, as land requirements are substantial in every scenario. Nonetheless, the region could still markedly increase the share of renewable electricity production through targeted measures. The study confirms that combining a GIS-based approach with a siting algorithm is a robust method for exploring alternative energy pathways.