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Electrical Storage
SmartRegion Pellworm 26.8.2015

Researchers testing the use of efficient storage systems in the SmartRegion Pellworm project.
© Eon

Hybride storage system based on renewables

How electrical storage systems optimally work together with renewable energies is being investigated by researchers of the project “SmartRegion Pellworm”. To this end, they test the use of efficient storage systems. The island Pellworm could reduce the supply of energy from the mainland by up to 90 percent by now.

Project status Construction has been completed
Typical system size / Energy [MWh] 0,56 (li-Ion) + 1,6 (Redox-Flow)
Typical system size / Output [MW] 0,56 (Li-Ion) + 0,2 (Redox-Flow)
Efficiency AC/AC Li-Ion: 95 %; Redox-Flow: 55 bis 65 %
Storage loss [1/d] Li-Ion: 0,1 %; Redox-Flow: ~ 0,0027 % (<1%/Jahr)
Cycle durability (80 % discharge level) Li-Ion: 9200 by 0.5 Imax; Redox-Flow: >20.000
Service life oft he system (1cycle/day) Li-Ion: 20 years; Redox-Flow: 25years
Typical discharge time Li-Ion: 1-2 h; Redox flow: 5-10 h
Response time when preparing the energy Li-Ion: 10 ms; Redox-Flow: 4 ms inkl. Power electronics: 50 ms
Typical period between storage and withdrawal Li-Ion: 0,5-5 h; Redox flow: 2-24 h
Example application areas Li-Ion: Hochleistungsspeicher (Peak Shaving, Primärregelleistung); Redox-Flow: Hochenergie (Load shifting, Energiehandel)
Project duration April 2012 until June 2015

The renewables share of gross electricity consumption in Germany shall be 50% minimum in 2030. An important way to achieve this target includes research and demonstration of smart storage concepts which allow a coordination of different storage technologies zu to increase cost efficiency and stability. The SmartRegion Pellworm project shall test and demonstrate an efficient use of electric storage devices in a system with a high rate of renewables. Major topics are data access, distributed storage, battery systems, modelling, communication systems, energy management systems, business cases and transferability.

  • The picture shows the preparation of the lithium-ion battery on the island Pellworm. &copy; Eon
  • The pictures shows the installation of the power electronics. &copy; Fraunhofer UMSICHT
  • Cooling the power electronics &copy; Fraunhofer AST
  • Filling the redox-flow battery &copy; Eon
  • Researchers testing the use of efficient storage systems in the SmartRegion Pellworm project. &copy; Eon
  • Full view of the store &copy; Eon
  • Work at network station &copy; Eon

The isle of Pellworm is an ideal location for installation and operation of a smart grid as West Coast Universitiy of Applied Sciences and Advanced System Technology (AST) Baranch of Fraunhofer IOSB have proved. There is a hybrid power plant with a 772 kW photovoltaic system and a 300 kW wind power system. Power generation based on renewables is three times higher than the power consumption of the residents of Pellworm. Pellworm already has it´s own hybrid power plant using energy from sun and wind. Acceptance of the residents is high, more than 75 percent of the islanders are open to renewables and power grid extensions.

Combination between renewables and storages

Smart storage concepts are important elements for renewable extensions. The SmartRegion Pellworm project faces these challenges. Scientists research the use of efficient storage systems based on the combination of several technologies. The project shall come up with new information about an optimum cooperation of storage systems and renewables. The use of storage systems is able to reduce Pellworm´s onshore energy supply up to 90 percent.

An integration of central and local electrical battery systems to be installed shall be realized based on communication technologies including the integration of existing electrothermal storage devices. By an additional load profile analysis and a weather based production forecast of the island´s existing hybrid power plant an optimized operation management concept shall be developed to minimize the onshore energy supply and to maximize the production of the power generation units.


Hybrid Storage System
It shall be analysed if the proposed combination of different technologies within a hybrid storage system realizes a sustainable concept and if there is an added value for the region. Therefore the  concept has to be analysed concerning the benefit for different regional stakeholders and possible applications of the storage systems for energy suppliers and grid operators shall be evaluated. From the power economical point of view an evaluation of an aggregator concept in the context of a congested region and in consideration of sales related and regulatory aspects shall be done. The technical cooperation of plant components, information and communication systems, metering systems and the energy management system shall be analysed and evaluated, too.

Direct Marketing Concept of Renewables
In addition to an unbundling compliant management concept a direct supply based on renewables shall be realised and tested. To avoid too high investment costs a virtual balancing zone inside the island and not the island itself as a balancing zone shall be set up. Participation of other interested power plants based on renewables next to the hybrid power plant ist desirable and might be considered as an additional business case. In particular, this includes private photovoltaic systems which play an essential role in the island´s electricity portfolio. The consideration of photovoltaic roof-top-installations makes sense because of the economic and environmental incentives to increase internal conumption of PV electricity.  

Energy Management Systems
An energy management system based on decentralised approaches shall be realized covering the whole range from the distribution network to the low voltage level. Software modules shall be developed to enable an optimum operation of network sections based on global demands and under inclusion of the network status and the storage systems using wind and PV forecasts. In addition to energy management in undisturbed situations an optimum network operation during and after the event of fault (islanding, cold start-up) shall be investigated.

Operational Management and Energy Management
Development and demonstration of a multi functional storage system shall generate benefit for different stakeholders. This includes support of the network operation, reduction of operation materials loads and the participation in different markets as additional application case. Selected singe use operation strategies of the hybrid storage system shall be tested an the benefit for the relevant stakeholder shall be evaluated. Based on tested and attractive single use operation strategies a multi functional strategy shall be realized in order to select the operations strategy depending on the current value of the storage service.

Business Cases
Development of future business cases based on the SmartRegion concept is another important technical project goal. Flexibility and multi functionality of the the hybrid storage system together with other energy systems shall be considered. Following scientific questions shall be answered:

  • What is the commercial potential of a hybrid power plant marketing together?
  • With battery storage systems and decentralized thermal storage systems at spot and balancing markets?
  • Which services can be provided for the local distribution network by the hybrid storage system and Pellworm´s new measurement equipment?
  • Are there cost reductions possible for network operations?
  • How is is possible to provide a local customer portfolio sustainably with the hybrid storage system and local renewalble energy units?
  • What´s the influence on supply costs?

Customer Interaction and Technology Acceptance
Development of a for customers transparent and acceptable approach to direct marketing of renewables is another project goal. At first a suitable and participating customer portfolio (from the energy supplier point of view)with specific composition and amount shall be developed. Based on an attractive and clearly arranged visualisation system the customer shall be able to get information about project activities, his consumption data and the current percentage of renewable energies.

To ensure and investigate transferability of the project concept is a major technical and scientific project goal. It shall be analysed and evaluated how the use of the SmartRegion concept in another region with high percentage of renewables affects on supply systems. Adequate dimensioning and location selection for storage systems in different regions shall be part of the analysis. Representative results for different types of regions in Germany (rural, suburban, urban)shall be achieved.

Information, Communication and Metering Technologies
For incorporation into informations and communications technologies and control of a variety of decentralised units the evaluation of a Pellworm specific informations and communications architecture is a major project goal. Different transmission technologies taking cost efficiency and safety/speed requirements into account shall be considered and tested.

Supported by: The Federal Government on the basis of a decision by the German Bundestag


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