Michael Lippert, of Saft Energy Storage Systems, explains how the SmartRegion Pellworm project will enable an island off the North Sea coast of Germany to increase self-consumption of its own renewable energy
Pellworm Island presents a vision of the renewable energy mix of the future – its current share of renewables already corresponds to Germany's target for 2050. The annual energy production of around 21 GWh from wind energy turbines, photovoltaic (PV) power plants and biogas plants is around three times the annual consumer load of 7 GWh. There is also a remarkably high level of night storage heaters and heat pumps.
Yet, even with this large excess of local production over local consumption, the community of 1,200 people on the island still rely on their connection with the mainland grid, via two 20 kV subsea cables, both for balancing local surpluses or for importing energy at peak periods when demand exceeds supply.
An E.ON pilot project, running from 2012 to 2015, is now implementing a smart grid for Pellworm, based on a combination of intelligent control technology, flexible load management and central energy storage including a containerized Saft Li-ion battery system. One of the main aims of the project is to increase the island's self-consumption of its own renewable energy generation and to transmit less energy to the mainland.
Feasibility study
A feasibility study carried out by E.ON, Schleswig-Holstein Netz AG, Westcoast University of Applied Sciences and Fraunhofer Anwendungszentrum Systemtechnik showed Pellworm Island would be the ideal location for a smart grid project to show how the energy world of the future can be realized on a small, manageable scale. This was based both on the technical suitability of the Island, including its power requirements and generation resources, as well as the willingness of the population to cooperate and the availability of suitable technology. The key findings of the survey were:
• The availability of well established renewable energy resources - E.ON's Hybrid Power Plant, now comprising 300 kW wind and 780 kWp photovoltaics (PV), was first established in 1983.
• With an installed capacity of around 9 MW, Pellworm produces almost three times as much electricity a year as the local consumers need.
• The high proportion of electric heating, which corresponds to approximately 10% of Pellworm's annual energy consumption, is appropriate for use as a flexible load in DSM (Demand Side Management).
• Over 75% of the population showed an open-minded attitude towards the idea of renewable energy and the expansion of the electricity grid.
• The development of the infrastructure (information and communication technologies used in home, as well as the automation of over 50 local 20 kV/ 400 V distribution substations) is mandatory for the implementation of a smart grid.
• A smart grid could relive the pressure on Pellworm's network infrastructure and the upstream electricity grid.
Developing an energy storage blueprint
The major goal of the Pellworm smart grid project is to achieve the maximum usage of regionally based renewable resources, with an optimal utilisation of the existing grid infrastructure to ensure more efficient integration into a congested distribution grid. This requires an intelligent balance of production, consumption and storage as well as recognition of the important role of consumer interaction, technology acceptance and community collaboration.
The main elements in the Pellworm smart grid are:
•Installation and operation of different complementary decentralized storage technologies with a focus on innovative batteries
• Integration of flexible loads at the household level
• Central optimisation of the storage system by an energy management system
• Automatic local substations
• Smart meters with advanced meter management and integrated load control functionality, particularly for the usage of decentralised controllable loads in the low voltage grid
Overall, E.ON's aim is to develop a storage blueprint for a future decentralised energy system.
The decentralized hybrid storage system
Different storage technologies are being implemented on Pellworm to cover the range of needs to store and deliver energy over time-scales ranging from 'minutes-to-hours' and 'hours to days'. A combination of commercially available storage systems within an over-arching hybrid storage system concept has enabled a reduction in investment costs. Retrofitting thermal loads with the potential for flexibility also reduces the system cost for the integration of renewable energy sources.
The 'hours to days' storage is provided by a 200 kW, 1.6 MWh Vanadium Redox-Flow battery.
Load flexibility in terms of 'hours' storage is provided by a combination of night storage heaters and heat pumps, with an average energy capacity per household of 135 kWh and an average power of 17 kW.
The 'minutes to hours' storage is provided by a Saft Intensium Max 20 Lithium-ion (Li-ion) battery system providing 560 kWh of energy storage and 1 MW power. The Intensium Max concept has been developed specifically by Saft as a ready-to-install, megawatt scale, fully integrated containerized solution, to improve the network compatibility of medium to large renewable generation plant. It is designed to smooth intermittent generation and reduce ramp rates, as well as helping to manage power flows within medium voltage grids, making wind and solar energy a predictable and manageable contribution to the energy mix.
Delivered in a standardized 20-foot container for ease of transportation and installation, the Intensium Max integrates the communications interface, battery management and cooling and fire prevention systems. Saft's well proven Li-ion technology will ensure long calendar and cycle life for the system, with an expected operating life of at least 15 years.
SmartRegion Pellworm project – technical and financial objectives
Bartholomäus Wasowicz, responsible for E.ON's scientific support of the projectproject leader for the Pellworm smart grid outlines the technical and financial objectives for the project: "Our main technical aim for the SmartRegion Pellworm project is to collect real-world experience with innovative battery technologies. We are particularly interested to see how Saft's Li-ion technology and the Vanadium Redox-Flow battery complement each other. We are also examining closely how all the various elements, such as thermal storage, come together within the hybrid storage system to provide an holistic approach to the Island's energy storage needs.
"The system will also play an important role in enabling us to evaluate various business models to establish how existing energy storage technology might be used to address the grid challenges created by the increasing grid-penetration of renewable energy sources. For example, we will investigate how energy storage can increase local self-consumption.
"This is essentially a research and development project and the real technical challenges will probably emerge during the commissioning and operational phases. The key challenge so far has been organizational, in the coordination of a large consortium representing disparate interests – equipment suppliers, energy companies, local authorities and the local community – to bring them together within a coherent team.
"Creation of this smart grid will also have a major impact on the local community, which relies greatly on tourism, by boosting Pellworm's green credentials. 30 years ago, people were taking the ferry to the island to see renewable energy in action. In the future, we anticipate that they will be making the same trip to see smart grid and energy storage technology in action.
"The project is scheduled for completion in 2015. However, our hope is that the results will prove so compelling that it will continue beyond then.
"Pellworm Island is ideally suited to this pioneering project because it has the perfect combination of a high level of renewable energy and a very well defined interface with the mainland grid via just two subsea cables. This will enable us to see very clearly the effect of energy storage on the grid's operation. In this case we are dealing with a physical island, but the same principles could be applied in many other situations where grid connections are weak and a large amount of renewable energy is connecting to the network."
Pellworm Island smart grid – operational strategies
The operational strategies for the Pellworm smart grid will comprise market, grid and local supply oriented storage and RES (Renewable Energy Sources) operation including:
• Direct marketing of renewables
• Joint operation of fluctuating renewables and storage systems to address different markets for RES and VPP (Virtual Power Plant) operators
• Day-ahead and Intraday market
• Reserve power markets
Local grid services
For the DSO (Distribution Service Operator)
• Primary goal is the grid integration of renewables and to support the distribution grid operation
• Prevention of curtailment, voltage support and loss reduction are also considered as applications
Sustainable regional supply
For power company sales as well as RES and VPP operators
• Direct supply of local customers with energy from regional renewable generation units
• Storage systems operated to balance generation and local demand
Multifunctional operation
For power company sales as well as RES and VPP operators
• Combination of direct regional supply and market transactions
• Operation is also grid compatible with the aim of reducing curtailment
Energy storage – making smart grids smarter
Dr. Klaus Peter Röttgen, head of E.ON Innovation Center Energy Storage, explains why E.ON believes energy storage will play a vital role in smart grids:
"E.ON regards energy storage as a key innovation that will help improve the grid performance and especially the integration of renewable energy, and Li-ion batteries are one of the most interesting and important technologies in this sector. Pellworm Island is therefore a crucial lighthouse project that will enable us to evaluate how Li-ion technology can operate in a real-world situation to help make smart grids even smarter."
"Further detailed analysis will be required to determine how much energy storage capacity is required, but the initial suggestions are that for Europe it will be in the order of Gigawatts. The horizon for implementation at this scale is very closely tied to the penetration of renewables, since the more renewables that are connected onto the grid then the greater the need for storage to address the volatility and grid compatibility issues.
"For E.ON, the most important barriers to the introduction of energy storage are not technical, so much as legal and administrative. Key questions need to be answered such as:- how will energy storage systems be financed? How will the services they provide be paid for? How can we provide potential investors with the security they need in planning their investments? We are in fact very proud to see how the many government, manufacturing and research partners involved have come together so effectively to get the Pellworm project off the ground.
"Overall, the prospects for energy storage being accepted are good, especially with compact solutions such as Li-ion technology that are easy to install within a restricted footprint. The main measures for the success of this particular project will be that the system works as promised, that there are no HSE (health, safety and environmental) concerns and that the costs are acceptable for future commercial installations. But it is equally important politicians and the general public they serve are happy with this solution.
"Energy storage offers the potential to make smart grids even smarter, and by making grids smarter at a local level we will then be able to optimize the operation of higher level grids."
SmartRegion Pellworm project partners
The SmartRegion Pellworm project is one of the first projects being backed by the German Federal Ministry of the Environment, Nature Conservation and Reactor Safety on the basis of a parliamentary resolution as part of the energy storage support initiative. The project partners include: E.ON (Schleswig-Holstein Netz AG and E.ON Hanse AG), Fachhochschule Westküste, Fraunhofer-Anwendungszentrum Systemtechnik, Gustav Klein GmbH, RWTH Aachen, Saft.
