Autumn 2017 EN

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English Issue Biogas Journal | Autumn_2017 Hall with battery storage unit inside, by WEMAG in Schwerin. Photos: Thomas Gau A typical battery stack, which fills an entire hall in Schwerin. are particularly high, however: The power demanded must be supplied within 30 seconds. But that’s not a problem for the battery storage unit. The first large battery storage unit has also been participating in the market for balancing power since September 2014. In a building similar to a gymnasium at the edge of the old town of Schwerin, a total of 25,600 lithium-manganese oxide cells store electricity in milliseconds. At the end of 2016, WEMAG, the operator, decided to expand the battery unit by mid-2017. With the expansion, the battery park’s power will double from 5 to 10 MW and the capacity will nearly triple from 5 to 14.5 MWh. After participating in the market for balancing power, there is a plan to be able to provide reactive power. Alternative to expanding networks at the local level In the course of its research project “Smart Power Flow”, the Reiner Lemoine Institute (RLI) demonstrated that large storage units are a real economic alternative to expanding the grid at the local level. The inverters and control systemy of the vanadium redox flow battery were independent developments by SMA and Younicos. “From our perspective, increasing network expansion does not make sense from an economic point of view because the grids are designed for a load that is only achieved on a few days per year – that is unnecessarily expensive and complex”, explains project manager Jochen Bühler, a research associate in the area of transformation of energy systems at the RLI, regarding the current situation. The researchers tested alternatives, he said. Large batteries proved to be an economic alternative to local gried expansion, he continued. In the project, the RLI researchers used a prototype of a vanadium redox flow battery, for which they had developed an inverter and control system especially for this project. It was integrated into the electricity network of LEW Verteilnetz GmbH (LVN) in Bavarian Swabia and was checked in a one-year test phase. The scientists noted that its operation is both cost-effective and provides support for the grid. An RLI analysis of the business models for large-scale batteries indicated that under the current, relevant conditions in Germany, using batteries on the balancing power market is by far the most lucrative application area. For this reason, the scientists had also focused the project on this business model, he continued. However, when providing the balancing power, the batteries’ behaviour was initially not conducive to the distributor grid. The grid frequency determined the charging and discharging of the storage unit. For this reason, the RLI developed an intelligent battery control system that regulates the voltage in the local grid and, as a result, increases the ability for renewable energies to be incorporated. “The critical and new thing about our approach is the combination of a battery application at the distributor grid level that is market driven and, at the same time, can service the grid”, continues Bühler. From his perspective, the use of large-scale batteries is worthwhile in many cases for local grid operators as well. The prerequisite here is that the storage units are established by external investors based on sustainable business models and that the batteries be equipped with a control system that allows them to service the grid. Then it is even more economical than expanding the grid for local network operators, even after making any compensation payments for using large-scale batteries. At the same time, this could reduce electricity costs and advance the energy transition more quickly, according to comments on the results. A second life for automobile batteries In Hanover, the local energy provider enercity has also started building a large battery storage unit. The spe- 10
Biogas Journal | Autumn_2017 English Issue cial feature here is that it is a spare parts storage for battery systems for electric cars: About 3,000 of the battery modules reserved for the current smart electric drive vehicle fleet will be brought together in a stationary storage system; according to enercity, this system has a total storage capacity of 17.5 megawatt hours, making it one of the largest facilities in Europe. By marketing the stored capacity on the German market for balancing power, the business model should make an important contribution to stabilizing the electricity grid and to the economic viability of electromobility. According to enercity, such storage units compensate for energy fluctuations with hardly any loss – a task that is currently carried out for the most part by the quickly rotating turbines in fossil fuel power plants. After commissioning, the 15 megawatt battery storage unit is supposed to work continuously, coupled to the grid. Enercity will take over the marketing of the stored capacity on the balancing power market. In order to remain operational in case of replacement, a battery requires regular cyclization during the period of storage – targeted, careful charging and discharging. Otherwise a deep discharge can occur, which can cause the battery to become defective. In addition to the storage costs, the classic and the potentially long-term replacement battery storage would mean high operating costs. The partner companies avoid these costs with the storage application: The grid’s fluctuating demand for balancing power automatically ensures the required cyclization of the batteries. Battery researcher Dirk-Uwe Sauer, however, believes that the “second life” of the batteries as a stationary storage unit is a myth: “The automobile manufacturers who could save disposal costs would benefit”. However, the batteries could not be used in the stationary market in an economical manner, Sauer emphasizes. In addition, “one vehicle frees up batteries for five households”. He thinks that using the batteries in the same way in vehicles makes more sense. The energy transition requires more than changing electricity itself. Additionally, the interaction among the electricity, heat and transport sector must continue to increase. In this respect and in dealing with supply peaks, large-scale battery storage can help. The storage systems required for this need market conditions that make integration easier. This means that clear definitions and strategies are needed – as well as an amended legal context, particularly for storage, in order to meet climate protection targets. Based on the assessment of those involved, what is missing are the necessary guidelines, especially at the federal level, and in particular, strategies for market introduction and research. Author Thomas Gaul Freelance journalist Im Wehrfeld 19a · 30989 Gehrden, Germany Mobile phone: 00 49 172 512 71 71 e-mail: gaul-gehrden@t-online.de Don’t waste the waste! Evonik makes it possible to turn organic waste into green energy. Using its innovative membrane technology, biogas which is released during the wastewater treatment process or the anaerobic digestion process of household waste for example can be upgraded simply and efficiently to pure biomethane and fed directly into the natural gas grid or used as biofuel. www.sepuran.com 11
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