Exploring the feedback mechanisms between water and energy sectors in hydropower systems

Abstract:

Multi-sector modelling frameworks are a fundamental platform for exploring the effect of climate-induced disruptions on power system operations. Existing frameworks generally rely on the coupling between hydrologic models and power system models representing the broad spectrum of decisions made at the grid scale. Such coupling is typically unidirectional, meaning that it captures the dependence of electricity supply on water availability. But, by doing so, models neglect the feedback mechanisms between power and water systems: failing to do so may add uncertainty to vulnerability assessments and misguide the design of water-energy management strategies. To overcome this problem, we developed a modelling framework hinged on a bidirectional coupling between water and power system models. With this coupling, we simulate the constraints imposed by water availability on grid operations as well as the feedback between the state of the energy and water systems. For example, the framework explicitly accounts for conditions of hydropower oversupply, during which part of the water could be stored in reservoirs or allocated to other sectors. We evaluate the framework on a real-world case study based on the Cambodian grid, which relies on hydro, solar, and thermopower. Our analysis relies on two steps. First, we carry out a vulnerability assessment, with and without feedback mechanism. With this comparison, we show that the feedback mechanism better characterizes system dynamics, pointing to opportunities for improving operations. In the second part of the analysis, we bank on these results to demonstrate that managing hydropower reservoirs with the feedback mechanism in mind allows us to improve system’s performance—evaluated in terms of power production costs and CO₂ emissions. Overall, our work contributes a novel modelling tool for climate-water-energy nexus studies, further bridging the gap between water and energy sectors.