Optimal Operation of an Energy Storage System based on Gravitational Energy using a Dedicated Railway System

Within an optimization framework, we model the mechanical and electrical components of a novel energy storage system. The system is based on the possibility of storing large amounts of energy in the form of gravitational potential energy if large masses are elevated to a higher altitude through any efficient method, specifically, through a dedicated railway system; later, this energy can be retrieved using regenerative braking in the dedicated railway system. In order to obtain a more general model, we have included in the system a renewable energy plant located nearby, and a conventional railway line that is able to exchange energy with the storage system; the operation of all these facilities together is beneficial for all the agents involved. Moreover, we have also included a connection to an electrical network, thus allowing for exchanges among all the elements in the system. In this setup, we try to determine the optimal operation in order to maximize the profit obtained by the owner of the systems.