Operational Flexibility of Hydropower Plants for Renewable Integration: Balancing Energy and Capacity Supply with Environmental and Water Use Constraints

The global power sector is undergoing a profound transformation driven by the rapid expansion of variable renewable energy sources, supported by climate commitments and increasingly competitive technologies. This shift heightens the need for operational flexibility. Hydropower plants with storage play a central role in enabling renewable integration and ensuring that the system can balance the supply; however, their flexibility is often limited by environmental constraints and competing water uses. This study assesses strategies to enhance renewable integration through improved operational flexibility in hydropower plants. The analysis combines Stochastic Dual Dynamic Programming (SDDP) with hourly operational simulations to represent system operation under uncertain inflows and variable renewable energy (VRE) in Brazil’s Northeast region—an area marked by a high share of hydropower and VRE. The methodology incorporates critical hydrological conditions and evaluates how relaxing selected operational constraints, commonly imposed for environmental purposes, influences energy and capacity supply. Results show that hydropower can provide substantial generation modulation to offset renewable variability. Enhanced coordination between hydropower and renewables also reduces thermal dispatch, lowering associated emissions and costs. The findings reinforce that hydropower remains essential in low-carbon power systems and suggest that adapting operational rules and regulatory frameworks is necessary to unlock its full flexibility potential while meeting power-system requirements.