Starting on January 1, 2018, Next Kraftwerke will provide the Lake Constance Water Supply Association (Zweckverband Bodensee-Wasserversorgung) with the flexible energy tariff package “Best of 96”. The six water pumps at the Süßenmühle pumping station on the banks of Lake Constance will soon play a significant role in supplying the German energy grid with around 32 MW of flexibility by joining Next Kraftwerke’s Virtual Power Plant Next Pool. By introducing flexible operating times to the pumps - which boast a total capacity of 55 MW - and the water treatment plant 300 meters above, fluctuations on the energy market can be reduced.
Every hour, Next Kraftwerke supplies the pumps’ central control system with energy prices for the following 96 fifteen-minute intervals. This occurs automatically via a REST API. Using this M2M communication process, the Lake Constance Water Supply Association can optimize the use of its pumps and water reservoirs. It means that untreated water for around four million customers in southern Baden-Württemberg will only be pumped to the treatment plant when the energy price on the intraday or day-ahead energy market is low. This factors in operational restrictions, such as the minimum fill limits of the water reservoirs located above the lake on Sipplinger Berg, anticipated water delivery, and the maximum output at peak times for network fee optimization. After successfully delivering the optimized operational timetable, energy traders from Next Kraftwerke acquire the necessary energy on the spot market, EPEX SPOT. Finally, Next Kraftwerke calculates the energy delivered in strict fifteen-minute cycles. This is controlled by an upper price limit, known as a cap, which is set at the beginning of the contract.
Christoph Drusenbaum, a production and treatment engineer at the Lake Constance Water Supply Association, praised the pioneering element of the association’s new flexibility. “Our decision to go with a flexible power tariff is the result of a research project funded by the German Federal Ministry for Education and Research (BMBF) called ‘enWasser.’ Since May 2014, the study has analyzed how energy used in water supply systems can be covered by cost-efficient renewable energies. With an estimated total consumption of around 155 GWh in 2018, energy costs represent a disproportionate amount of our total costs, and we see serious potential for savings. In our simulations as part of ‘enWasser,’ we have also seen that using conventional day/night tariffs provides much lower potential for cost savings when compared to a variable price calculated every fifteen minutes. We therefore hope that our collaboration with Next Kraftwerke will result in a significant reduction of our costs.”
Felix Jedamzik, Key Account Manager at Next Kraftwerke, adds: “Our variable energy tariffs are particularly suited for power consumption processes with a certain buffer zone. In this case, pumping and distributing water at the five reservoirs on Sipplinger Berg no longer needs to occur simultaneously. This gives our energy traders the flexibility they need to link low energy prices with price-optimized consumption. Since energy prices on the intraday market usually correlate with surplus situations created by weather-dependent renewable energy production, we add relief to the German grid by managing the loads of the water pumps. To put it simply, the project is ‘half’ of a pumped-storage power plant.”
Next Kraftwerke won the bid as a power provider after a public call to tender by the Lake Constance Water Supply Association. The most cost-effective bid was considered against the background of Germany’s energy transition and additional services such as load management.