Deutsche Version  ACT
Overarching Themes
Simulation and planning tool 9.1.2017

The cloud shows the concept behind the Energy Storage Cloud.
© green2store

Bundling storage in the cloud

Scientists did research how battery storage systems can be optimally

operated and the supply network supported as part of the green2store

project. The aim is to bundle decentralised storage systems in a virtual

cloud and make them accessible to various players.

Project status Project completed
Typical system size Energy 0.01 to 0.50 MWh
Typical system size Output 0.01 to 0.50 MW
Project duration November 2012 until December 2016

The goal of the green2store project is to ensure that a greater proportion of renewable energy generation can be integrated into the distribution networks. The project therefore aims to develop a local storage system that contributes to increasing network intake capacity for renewable energies. As there have been great obstacles up to now in relation to investing in storage technologies, the project’s primary goal is to enable non-discriminatory access to all storage units from a technical point of view, and thereby to achieve more intensive use and greater economic efficiency. As part of this project and in view of these specifications, a cluster is being designed, developed and researched that combines a local network storage unit, an area storage unit, a campus storage unit and ten household storage units into one overarching storage system with enhanced capabilities (energy storage cloud). This is being tested and demonstrated in a field trial and is being made available not just to the owner, but also to any other players (multipurpose).

  • View inside local grid station: EWE wants to install a storage system here that can be accessed from the Energy Storage Cloud. © EWE, Ralf Conrads
  • The cloud shows the concept behind the Energy Storage Cloud. © green2store
  • These are the possible players in the Energy Storage Cloud © green2store
  • The map of Germany shows the structure of the field trial. © green2store
  • Division of labour: The partners are responsible for different aspects in the green2store project © green2store

The project aims to answer the central research question of how the integrative usage of local storage units by various players in the energy industry can both technically, and in terms of the energy industry, enable the intake of further renewable electricity generation by the distribution network without increased development and thereby ensure a sustainable conservation of resources.

Economic feasibility through many players

For an individual player in the energy supply system, the investment in an energy storage unit is not economically viable according to the current state of the art. The reason for this is the high acquisition costs, the low efficiency coefficient for individual use, as experience has shown, and the short useful life. A further complicating factor in integrating storage units into network operations is that their deployment is not recognised in the regulation and as a result also may not be allocated to network use charges. This means that, in all probability, investment is flowing into network expansion, which is a safe bet from a regulatory perspective. Furthermore, unbundling prohibits common usage of a storage unit. Integrative storage unit usage could contribute to increased economic efficiency and in this way justify storage unit investment. Such ‘multi-use’ is defined here as storage usage that simultaneously serves several intended uses.

Phases of the project

The green2store project is divided into three phases, each building on one another. The first phase focuses on analyses of technical and economic potential. These evaluate the processes for the integrative usage of storage capacity as regards its cost and benefit. In order to test and demonstrate the concept in the field, technical work is undertaken to prepare an energy storage cloud to connect various storage units into one large unit. This preparation, namely the deployment of this technology in the field, marks the conclusion of the first project phase. As part of the second phase, the energy storage cloud and various operating scenarios are then field-tested. The findings from the field test are evaluated in the final project phase and business models, on the basis of the market model, as well as legal concepts and an eco-audit for battery storage units are drawn up. This evaluation provides key data on the technical, economic, legal and ecological issues and completes the project. 

Provision of storage clouds

The proportion of renewable energies and, as a result, the level of generation fluctuation continues to rise. This trend is increasing the utilisation level of the energy distribution networks. Local battery storage units are seen as an option for relieving the networks, but it has not yet been possible to show how to operate them efficiently using current approaches.

The green2store project aims to combine local storage units into a single energy storage cloud and to make it simultaneously available to different players in the energy industry. This should evaluate the contribution to network support and the economic efficiency of multi-use storage units. The legal and regulatory framework conditions needed for this are derived from this evaluation.