Dynamic simulation and comparison of different configurations for a coupled energy system with 100% renewables

Abstract For the successful transition to a renewable energy source powered society, coupling of different energy sectors is inevitable. The extreme case of a future German energy system consisting of power, heat and gas consumers supplied with 100 % renewables is analyzed here. To find the most cost-effective system configuration, different combinations of storage and conversion technologies are compared by performing dynamic simulations and evaluating the average costs over the period of one year. Renewable power production is modeled by using actual power-generation curves and extrapolating the installed power for each technology according to the German energy system framework. Final energy curves for power, heat and gas demand are created as a result of the study. The gas demand only arises from industries using hydrocarbons as a product in processes and for high temperature process heat. The components of the energy system, e.g. storage and conversion technologies are modeled using the equation-based open-source TransiEnt Library based on Modelica®. To obtain the boundaries of the solution scope, the comparison is started by analyzing homogeneous scenarios, e.g. All-Electric or All-Gas with Power-to-Gas with reconversion to power and heat. To find the optimal configuration within this scope, different combinations of power (adiabatic compressed air energy storage (A-CAES), lithium-ion battery, pumped hydro storage), heat storage (hot water storage) and gas storage (underground storage) technologies as well as conversion technologies, i.e. Power-to-Gas (electrolyzer with methanation), Power-to-Heat (electric heat pump, electric boiler), Gas-to-Heat (gas boiler, gas heat pump), and Gas-to-Power (gas turbine, combined cycle gas turbine) are simulated. The results show that a homogeneous energy system configuration where all services are supplied by either power or gas are technically possible but not economic. Due to the limited technical potential of renewables, ecological feasibility of All-Gas systems is limited. A combination of Power-to-Gas with combined cycle gas turbines, electric heat pumps, a lithium-ion battery and pumped hydro storage is the option with the lowest cost. Using an A-CAES instead of the battery or adding an A-CAES to the battery does not lower the cost.