Insights from modeling renewable electricity systems and developing hydropower models

Abstract: One strategy for reaching a carbon-neutral electricity system is a large-scale deployment of wind and solar power. However, electricity systems with high shares of wind and solar power rely on other technologies, e.g., transmission and hydropower, to ensure that demand can be met at all times despite weather-dependent wind and solar power production. Moreover, the deployment of some technologies may be limited by public concern and land availability, which could increase the cost of decarbonizing electricity systems. To analyze designs and costs for future electricity systems with high shares of renewables, energy system models are crucial. In such models, the representation of hydropower is often significantly simplified, overestimating how flexibly hydropower can operate and, thereby, the hydropower’s ability to complement wind and solar power production. This thesis has two overarching aims addressed separately in the two appended papers. First, to explore how deployment limits on wind and solar power, transmission, and nuclear power each affect the cost of future carbon-neutral electricity and how it differs between the Middle East and North Africa region (MENA) and Europe (Paper A). Second, to investigate the accuracy of the hydropower representations used in energy system models and to develop a method for a more accurate hydropower representation (Paper B). In Paper A, we use an energy system model to show that the cost of a carbon-neutral electricity system is considerably lower in MENA than in Europe, which we link to MENA’s better wind and solar resource potential. Also, limiting the deployment of wind and solar power, transmission, or nuclear power can significantly affect system costs. However, the effect is markedly different in the two regions. Paper B examines how realistic different hydropower representations are by developing hydropower optimization models with different levels of detail and comparing them. We find that simple hydropower representations, such as those often used in energy system models, result in unrealistic production profiles and exaggerate the flexibility that hydropower can provide. In addition, we contribute a novel computationally efficient hydropower model that entails a more realistic hydropower production.