Evaluation of multipurpose reservoir operating policies at basin and electric power system scales
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Date
2024
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Abstract
Climatic phenomena, particularly hydrological droughts, have led to significant changes in reservoir operation strategies. Multi-purpose reservoir operations are essential for effectively managing stored water resources for various activities like electricity generation andagricultural irrigation. Despite considerable efforts to support decision making for each economic activity, there remains a weak integrationacross these sectors in joint analyses. To address this, an integrated approach combining a model of a large power system and a model at the basinscale is proposed to analyze the operation of both power and agricultural systems. This approach allows evaluation of the operating policies of amultipurpose reservoir and its performance at both the local and regional scales under different hydrological scenarios. A modification is imple-mented whereby the priority of water extraction to agricultural users is increased. Its effects are assessed for different hydrological trajectories ina case study in the Laja Lake basin in southern Chile, the biggest Chilean basin with a capacity of up to5,500Hm3. The Laja Lake, a multi-purpose reservoir with substantial hydroelectric generation capacity and extensive agricultural areas plays a crucial role in the operation of thenational power system. Based on an analysis of 2025, it is demonstrated that hydrological changes directly impact electrical and agriculturalperformance. Drought conditions increase thermal generation, costs, emission intensity, and water deficits. Furthermore, the policy modificationreveals tradeoffs between the power sector’s emissions and agricultural water deficits. For drier scenarios, increasing agricultural extractionpriority results in low additional operational costs and emissions from the power system, which supports adopting a policy aligned with netzero objectives.