Techno-economic optimization of a 100% renewable energy system in 2050 for countries with high shares of hydropower: The case of Portugal

Abstract As energy system will increasingly become renewable, they will face new challenges that mainly arise due to the varying output by many renewable energy technologies. An issue that is especially prominent for countries with high shares of hydropower in their electricity generation is the varying yearly output of these technologies. This work aims to propose a techno-economically optimized energy system for such a country, using Portugal as example. For this purpose the current situation is analyzed and an energy demand model for 2050 created. The energy system is optimized for years with different outputs of hydropower to analyze the system’s behavior using the simulation tool EnergyPLAN. As the tool does not possess inherent optimization capabilities it was coupled with the gray wolf optimization algorithm using Matlab. Subsequently, a system is proposed that is able to cover Portugal’s expected energy demand under all circumstances. The future system will rely strongly on wind and solar power as they are expected to cover around 75% of Portugal’s electricity demand. Furthermore, the analysis showed that Portugal needs to build up electrolyzer capacities of 4.2 GW and SynGas capacities of 2.4 GW as the SynGas will be used to balance supply in demand, especially in years with lower hydropower output. The system’s cost will be between 22 and 35% cheaper than the created reference model. Furthermore, the primary energy demand is expected to decrease from 253 TWh to around 150 TWh while the electricity demand rises from 49 TWh to around 110 TWh.