Electric Energy Storage in the Stockholm Royal Seaport

Abstract: Stockholm Royal Seaport is an urban development project for a planned expansion of housing and services that will take place in the district of Hjorthagen in Stockholm. The Stockholm Royal Seaport project aims to develop a smart grid for integration of consumers and producers into the utility electrical grid. The Stockholm Royal Seaport Smart Grid integrates new concepts such as active house, local storage, decentralised renewable production, electric vehicle charging and an electrified harbour into the grid. The aim of this master thesis is to describe and study some of the main aspects and benefits of the implementation of Electrical Energy Storage (EES) systems as one of the solutions to be included in smart grids. The study is focussed in the Stockholm Royal Seaport case. The main EES technologies currently available or under research and development are introduced, studying its specifications, costs, main applications and benefits in distribution grids. EES systems can cover a wide range of applications, but not all of them are equally valuable and not all the technologies are suitable and feasible for the same applications. The regulations that should be modified in order for a utility to get benefits of the different applications that EES offer are identified. Some regulations could prevent the distribution system operator (DSO) to own and operate the EES system and some market rules cannot be fulfilled by certain EES technologies. The main applications in island operation are also described and the benefit for consumers of avoiding outages is estimated for the Stockholm Royal Seaport case. EES systems can replace other equipment and improve operation of certain units in island mode. The benefit of improving reliability and quality of the electricity service greatly varies between different kinds of customers. In the Stockholm Royal Seaport case, residential and commerce consumers has been considered and reliability indexes from Fortum grid in Stockholm have been used.The possibility of renting  some capacity in the EES system to consumer with generation facilities to store its electricity surplus is analyzed to determine its economic benefit. This kind of agreement could be beneficial for the consumer when the prize for selling the electricity surplus is low compared with the prize for buying it according to the electricity contract. The efficiency of the EES system must be high enough and the price for using it is not too high. Finally, the major milestones and key challenges for the implementation of the EES system are introduced. Those milestones cover the selection of the applications that must be carried out and its requirements, the selection of the most suitable and feasible EES technology, the design of the modes of operation and its simulation, and obtaining the right to own and operate the EES system by the DSO.