Das Projekt "BVG-Battery energy storage in Berlin" wird vom Umweltbundesamt gefördert und von EAB Fernwärme GmbH durchgeführt. Objective: It was planned to set up a battery-storage-system for the underground network of the Berlin public transportation (BVG - Berliner Verkehrsbetriebe). The subway trains work with DC-motors, which are powered via DC-volt-changers by the local utility. The DC-volt-changers are designed to cover the peak load resulting from the simultaneous start-up of several trains. The BVG trains are equipped with break-generators. That means the conversion of kinetic energy to electricity is possible. Through the battery-storage-system this energy becomes utilizable. With the storage two aims are realized: 1. Up to 35 per cent of the break-energy can be transformed to electricity for the use of subway trains. 2. The DC-volt-changers peak capacity can be reduced. The first aim results in an economy of primary energy, so that costs are reduced and emissions avoided. Several advantages are related to the second aim: - The price for the power put to disposal of the BVG is diminished. - New DC-volt-changers can be designed to lower load peaks. - The BVG load peaks, that are simultaneous to those of the local utility can be equalized. General Information: In the framework of an EU-demonstration programme a large storage battery was planned for the Berlin underground network. The following advantages are related to the direct connection of the battery to the DC-grid: - With computer control back-up an equalization of the load-curve is realizable. This results in a reduction of the peak load and thereby in a reduction of the kW price. - Peak loads, due to the simultaneous start-up of several trains, can be supplied by the battery. - With adequately equipped trains the break-energy is more efficiently usable. - The battery ensures emergency supply to the underground network. That means that a failure in the public supply-system can be compensated, so that all trains are able to reach the nearest station. - The DC-volt-changers peak-capacity can be reduced. Theoretically 50 per cent of the input-energy can be recovered by the transformation of break-energy. In practice measurements showed that networks without a storage are only able to recover 15 per cent. For the planned battery-system a recovery rate of 35 per cent is expected. During the preliminary examination of the project a location for the battery was found and the optimum parameters for parts and components were defined together with the manufacturers. The results were that the chosen location required a battery with a characteristic capacity of 3600 Ah. A saving potential of 1200 MWh per year and a peak load reduction of 450 kW were expected according to a battery simulation. To demonstrate the interaction of the different components of the system and to optimize future installations, measurements during the operation-phase were planned. Achievements: Our results of the extensive measurements and computer simulations can be implemented in any other similar project europewide. Tender documents for...