Towards Forecast-Informed Sustainable Hydropower Operations

Abstract

To reduce the dependence on fossil fuels, the world needs to mainstream the use of clean and renewable energy sources. Hydropower remains the key renewable source to provide baseload power due to its relatively stable generation and high capacity-factor. However, hydropower operations have historically proven unsustainable due to the impact of dams on the nature and ecosystem. We address the issue of sustainability by proposing a dam operation strategy that is efficient on three fronts: (i) maximizing energy generation while satisfying competing objectives, (ii) feasibility and transferability of dam operation framework, and (iii) environmental and eco-system sustainability. First, we demonstrate the value of short-term weather forecasts to maximize hydropower benefits by optimizing dam release decisions. By coupling the forecast information with a multi-objective optimization framework, optimal release decisions were derived that raised total energy generation by 5.6% year-round for the Detroit dam in Oregon. Next, to ensure the concept is feasible for application in resource-constrained settings, we developed a fast, skillful, and transferable approach to forecast reservoir inflow. To consider the long-term benefits of dam operations in addition to hydropower generation, we developed a nested optimization technique leveraging both short- and long-term forecasts (termed as co-optimization). The co-optimization, when implemented over a network of dams operated in the Upper Colorado Basin, generated 28% higher hydropower annually while satisfying other constraints and competing objectives. The third aspect to safeguard environmental and ecosystem sustainability was addressed by modeling thermal change in downstream rivers as a function of dam operations. Multi-objective optimization with ecosystem-driven constraints helped realize ecosystem-safe hydropower operations by limiting river temperature alteration within safe bounds. Benefits to hydropower faced tradeoffs under more stringent temperature constraints. To extend our concept over future hydropower dams, we proposed a framework to predict the thermal impact of 216 planned dams worldwide. A general homogenized trend of lower highs (reduced river temperatures during summers) and higher lows (warmer temperatures during winters), potentially harmful to native fish species, was predicted across the planned sites. This elucidates the need to incorporate thermal pollution within the dam planning to ensure sustainable hydropower expansion. A decision support system was also developed to facilitate real-world engagement with dam-operating agencies and bridge the gap between research and application domains. It is imperative to mainstream sustainable hydropower operations as an operating standard for existing and future dams, and foster the goal of clean energy without sacrificing the societal and ecosystem benefits.