Siemens is to deliver a Siestorage energy storage system to Süwag Energie AG for grid stabilization and temporary storage of the volatile power fed into the distribution grid from wind and solar plants. The custom-made storage system is based on lithium-ion batteries and has a capacity of 135 kilowatt hours (kWh) in this version. Süwag Energie AG will use the storage system in conjunction with other distributed storage systems as part of the “green2store” research project. The storage system is to be installed in the low voltage distribution grid in the district of Flein, south of Heilbronn.
For the Süwag Energie AG order, Siemens will first connect three battery cabinets made by South Korean battery manufacturer LG Chem in parallel and then connect them to the 4Q-IGBT converter specially optimized for energy storage applications on the DC side. Parallel connection of additional battery cabinets is already planned. The suitable C-rate for every application can be implemented in a range from c > 0.5 to c < 3 with the Siestorage modular energy storage system based on lithium ion batteries. The C-rate describes the quotient of current divided by capacitance and hence the maximum current of the battery in relation to its capacitance. This gives the reciprocal of the time for which a lithium-ion battery of the stated capacitance can be discharged at the maximum discharge current.
Süwag Energie AG, which is headquartered in Frankfurt am Main, is permanently engaged in further development of alternative energy concepts. With the battery storage system from Siemens, the company is participating in the “green2store” project of the “Energy storage” initiative funded by the German federal government With “green2store,” a consortium from the energy, IT and communications technology sectors is researching into how distributed storage systems can be operated in order to increase the capability of the grid to absorb renewable energy sources. Technical, economic, legal and ecological aspects are being studied. The research project, which has a run time of four years, has a total budget volume or more than €9 million. It is part of the “Batteries in distribution grids” project of the Energy storage initiative and is funded by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). The goal of this joint initiative is to guarantee consistently high supply security in Germany by 2050.
The consortium wants to develop an “Energy Storage Cloud” and apply it in a supraregional field trial. The “Energy Storage Cloud” transfers the cloud solutions familiar from information and communications technology to the energy business. Bundling a number of distributed storage systems together to create a large virtual storage system in the cloud allows storage capacities to be used far more effectively and by various participants simultaneously, independent of the individual storage locations. The research project will also undertake an economic assessment of the integrative utilization of distributed storage systems and will discuss the general regulatory framework. By researching new approaches to using distributed storage systems, “green2store” is contributing to the further integration of renewable energy forms in the electrical distribution network.
The Siestorage storage system will be one of the largest storage elements in this virtual storage network, with a battery capacity of about 135 kWh. Süwag Energie AG will connect the Siestorage controller to a central control system for networked operation. The storage battery will be available via these interfaces for higher-level dynamic storage applications in a network with several distributed storage systems, based on the idea of “cloud computing.”