Water supply energy management system
Over the past few years, requirements for drinking water supply in Germany have become more and more demanding. While the secure supply of high-quality drinking water for the public was the priority during the past decades, rising energy costs and the energy reform being implemented by the German Federal Government now also require that energy is used efficiently. Water suppliers must therefore rise to the challenge of continuing to prioritise a secure supply of high-quality drinking water while coping with the increasing demand for energy efficiency. Therefore, the operation of drinking water supply systems, such as urban water supply networks or long-distance water pipelines, is an extremely complex task which can no longer be carried out without the use of modern tools. Today, such supply systems use state-of-the-art technology and are controlled via central control stations and partly automated function sequences. The operators must ensure a reliable supply of excellent quality drinking water for consumers at a reasonable price.
Fig. 1 Structure of the assistance system
The joint research project EWave aims to develop an innovative energy management system which will be trialled at Rheinisch-Westfälischen Wasserwerksgesellschaft mbH (RWW), a water supplier which has a typical network structure. The objective is to devise energy-optimised operating plans for plants for water collection, treatment and distribution within the supply system. Moreover, the fluctuating energy supply from suppliers' own power plants must be co-ordinated with the energy supplied by one or more external energy suppliers. The scope for optimisation calculation is restricted by technical and operational aspects. Here too, the quality and security of the supply, in particular, must be guaranteed at all times. Water suppliers' electricity consumption is highest for water treatment and water distribution. Therefore, as far as energy optimisation is concerned, the focus must be on both specifying the running times and switching times of the network pumps and distributing the required production output to the available water plants. As conditions on the electricity market are changing, shorter contract terms with differing rates and diverse pricing packages can be expected. This means that, on the one hand, new opportunities for optimisation open up; on the other hand, operating procedures which have been predominately static so far must become more dynamic. That also means that knowledge and experience accumulated over decades by the operating personnel is partly devalued and must be further developed. The research project EWave intends to close this gap.
In the first stage, EWave, the energy management system to be developed, will be used as a strategic planning tool for the plant management. It should be possible to reassess fundamental ideas regarding the plant operation mode, which should also be used to prepare interim operating instructions. In a subsequent stage, EWave is to be used as an operating assistance system (decision support system). Independently of this stage, a semi-automated procedure including the option to subsequently revise the calculation results manually will be developed. In an initial calculation run, an energy-optimised operation is calculated. This energy-optimised operation is passed on to the operator in the form of a suggestion which can either be applied as it is or can be changed very easily. The operator can change the framework conditions according to the specific situation. Once the new framework conditions have been determined, the operation is re‑calculated. It should be possible to transfer the knowledge and experience gained in the context of this research project to drinking water supply plants with a similar structure. Therefore, at the start and throughout the project, workshops for a wide range of water supply companies are to be conducted in order to record the experience individual water suppliers have gained with energy management systems and an energy-efficient plant operation, to pool company-specific requirements and to subsequently include these in a transferable list of requirements. By involving further water suppliers beforehand, early acceptance of the approach should be encouraged, practical requirements should be better reflected in the developments that are planned and the number of potential areas of application for the insights gained during the project should be significantly increased.
Fig. 2: Overview of the EWave cycle: an assistance system for operational optimisation of the overall system and the individual network within the framework conditions of renewable energies
Once the energy management system has been successfully implemented at RWW and the legal requirements have been clarified, the industry partners Siemens, RWW and GreyLogix Aqua GmbH, together with the research institutions providing scientific assistance, intend to develop a joint marketing strategy which will also allow small and medium-sized water suppliers to use the optimization approach which has been developed.