The use of clean and renewable energy systems is still associated with many hurdles for companies – especially with regard to the optimization of costs and of a reliable and efficient energy supply in line with consumption. The example of Westerwälder Holzpellets GmbH, based in Langenbach, Germany, illustrates how this can be achieved. The producer of sawn timber and wood pellets already has photovoltaic systems with 750 KW of production power in its area grid, as well as a biomass heating plant with 685 KW. The electricity produced there is used to supply the factory. From summer 2021, electricity from five wind turbine generators with a total output of currently 2,000 KW will also feed into this grid. The 20-year EEG subsidy for these turbines expired on December 31, 2020.
The disadvantage of renewable energies, however, is that seasonal and weather-related fluctuations influence their availability. Since the aim is to achieve a high level of self consumption, active load management is already being used today for chippers, mills or presses.
Grid fluctuations and short interruptions in the public grid regularly cause difficulties for the sensitive production processes. For this reason, the company was looking for a suitable energy storage system as a complete solution and found it with us: At the end of last year, we delivered a stationary high-performance battery storage system as well as the precisely fitting MSC hybrid converter with a rated power of 1.5 MW. The storage system from our Cooperation partner Mercedes-Benz Energy consists of 112 lithium-ion automotive batteries with a total capacity of 1.4 MWh.
All preparatory work for the commissioning in spring is still in full progress at Westerwälder Holzpellets GmbH. Then the large-scale battery system will start operation and provide a reliable power supply. It will be integrated into the so-called peak shaving in such a way that peaks are cushioned downwards and upwards. Furthermore, the storage solution will provide primary control power to stabilize the power grid.
The next step is to create a mircro grid solution so that Westerwälder Holzpellets can operate independently of the public power grid when needed. In case of a grid failure, the battery storage system is able to maintain production operations. In grid forming operation, the battery provides a micro grid with which other energy producers and -consumers can synchronize. When the public grid is available again, the power converter switches to grid following mode.