Operational flexibility provided by storage in generation expansion planning with high shares of renewables

The integration of variable renewable energy resources result in an increased need for operational flexibility. Energy storage is one of the alternatives to conventional generation technologies to provide this flexibility. A generic model for energy storage is introduced into a generation expansion planning model, considering operational constraints of power plants and system balancing requirements. Different targets for the final renewable electricity generation towards the future are imposed, quantifying the need for electricity storage and the impact on the electricity generation mix. When facing high renewable targets, storage is found to reduce the need for installed generation capacity, both conventional and renewable, and reduce the electricity generation costs.