Evaluation of flexibility provided by cascading hydroelectric assets for variable renewable energy integration

The integration of a significant VRE capacity into Canada's electricity system is a crucial step toward decarbonization. Cascading hydro assets have been found to bolster the generation fleet with the flexibility necessary to mitigate VRE uncertainty and variability. The integration of British Columbia's cascading hydro-dominated system, known for its high flexibility, with Alberta's considerable wind and solar potential can create a hybrid hydro-VRE system with sufficient flexibility for aggressive VRE integration in Alberta. A flexibility metric is introduced into a unit commitment model to quantitatively assess network flexibility while accounting for pertinent operational and technical constraints to examine this proposition. This study also analyzes changes to the effectiveness of cascading hydro assets for network flexibility and VRE integration under distinct climate change scenarios. Results indicate that the integration of the British Columbian and Albertan networks improves the flexibility index approximately two-fold, allowing a 13% increase in VRE penetration in Alberta. However, the study also highlights the significant impact climate change may have on cascading hydro operation and associated network flexibility, which could potentially challenge the capacity of these assets to provide the flexibility required for VRE integration.