Optimizing Hydropower Operations While Sustaining Ecosystem Functions in a Changing Climate

California's long-term energy plans depend on a science-based understanding of the impact of climate change on renewable energy systems, especially hydropower resources and urban, agricultural, environmental, and recreational water users. Climate change is expected to exacerbate the state’s already high hydroclimatic variability, creating new challenges for management of hydropower and ecosystems, including increased uncertainty and potential increased frequency of system failure. Water system simulation models can help understand and overcome these challenges through climate impact and management scenario analyses.

This Project developed CenSierraPywr, a hydropower optimization modeling framework to consider institutional and physical constraints placed on hydropower operations. This framework – which integrates models, modules, routines, algorithms, wholesale electricity prices and data – has the capability of running various climate change scenarios. The model focused on four major San Joaquin River subbasins: Stanislaus, Tuolumne, Merced, and Upper San Joaquin. Ten climate models at two projected intensities for greenhouse gas emissions were used to generate hydrological conditions that assessed potential impacts on system operations and behavior under future conditions (2031-2060). In addition to global circulation model-centric analyses, the CenSierraPywr model investigated more ecologically supportive flow releases (“functional flows”) from the basin outlets. Although alternative flow management for environmental objectives does not have a large impact on hydropower, there may be tradeoffs with water supply and timing. The scenarios provide insights into management-relevant decision making and trade-offs with hydropower generation in the study area.