"Developing a sustainable and smart energy system for Germany" is a comprehensive study that addresses the challenges and opportunities of creating a sustainable and intelligent energy system in Germany. Given the ambitious goals of the German government in energy and climate policy, introduced in 2010 with the Energy Concept, the necessity of smart grids is emphasized to manage the high variability of renewable energy sources. This study utilizes the EnergyPlan model to analyze the various components and design of such a system. Through hourly computer simulations, the structure of a smart grid is developed that can balance energy supply and demand in Germany. The analysis takes into account modern technologies such as electric vehicles, combined heat and power plants, heat pumps, electrolyzers, power-to-gas, and CCS, and examines three different scenarios for the use of renewable energy by the year 2050.