Background and objectives
Technical systems of water supply are primarily designed and operated for providing secure water. Approaches for saving and recovery of used energy are not pursued systematically and widely so far. The project ENERWA pursued new approaches to develop energy potentials in water supply systems in the entire process chain, on the level of technical components as well as in the control concepts. Previous approaches mainly focus on components and energy analyses of single process stages without considering the potentials of an overall work management and system structure. In the context of the recent energy policy changes, additional energy storage potentials of water management facilities are investigated. Previously unused potential of energy saving, recovering and storage should be identified and evaluated in the entire process chain.
Therefore, the research objectives of ENERWA are:
(1) systematic development of energy optimization potentials and the application at all levels (components, process stages, structure, network);
(2) investigation of ecological, social, legal, economic and hygienic limits with the implementation of energy efficiency potentials and preparation of solutions for removal of existing barriers and
(3) generalization and preparation of the generated results to make them publicly available in numerous ways.
Fig. 1: ENERWA: Energy potentials of water supply considering dynamic conditions
The project ENERWA tackles the energy optimization of extraction and treatment plants with the help of a diversified consortium of research institutions, engineering companies and end users. It analyses the optimization of energy use of water catchment and treatment plants as well as regulation concepts for an efficient water distribution and estimates the limits of recovery and temporary storage of energy in drinking water reservoirs and transportation-storage-distribution systems.
The investigations focus exemplary on four low mountain regions with a high energy potential where the single steps of the process chain are carried out by different companies. The participating ENERWA partners run representative typical German supply systems (water catchment and treatment of surface and ground water, transportation and distribution networks in low mountain regions and lowlands).
In the analysis of the technically feasible energy potential, economic and other relevant conditions are detected (from the rainfall-runoff dynamics in the catchment area to the dynamics of drinking water use). In this study, the focus goes beyond the company level by exploring the potential of optimization of the whole water supply system and the exploration of options of a consumption control or the limits of energy storage in reservoirs.
ENERWA uses different, problem-specific methods of investigation: processing of the technical-legal-economic backgrounds, technical measure analysis programs and pilot stages of innovations for energy-saving and thermal energy use in water works, model-based simulations, ecological field studies on domestic water reservoirs about the limits in the operation of drinking water reservoirs, moderated acceptance studies of the users concerned and economic optimization models including energy-economic funding pursuant the Renewable Energies Act (EEG).
In the Aachen city region, the (i) drinking-water treatment by WAG Nordeifel is investigated regarding energy and resource consumption as well as the (ii) water distribution by the company enwor. WAG uses a large pilot plant and a conventional reference system. For the water distribution, enwor strives to produce electricity for the region by using the slope in the water distribution system.
In the area Rheinisch-Bergischer Kreis, the Wupperverband runs a multifunctional system of twelve reservoirs for flood protection, raise of low water levels and the provision of raw water for the drinking water supply. For an energetic use, the flexibility and availability of runoffs, the raw water quality and the ecological requirements of flowing waters have to be considered. The water provider Rhein-Wupper provides a waterworks with ozonation for the study.
The Aggerverband from the area Bergisches Land provides two waterworks as well as the distribution system for this study. 217 km long distance water pipelines and 45 overhead tanks between 240 müNN and 515 müNN are additionally available. The special challenge in using the energy potential in this region is the hydrological variability while maintaining the safety and quality of the supply at the same time.
In the Ruhr-region the Ruhrverband runs a system with eight reservoirs with a special focus on energy industry. The Ruhrverband carries out the ENERWA investigations regarding the effects of a changed reservoir management. The focus lies on monitoring the reservoir water and its underflow regarding a dynamic operation of the reservoir. Study object for surface water treatment at the river Ruhr is going to be a waterworks of RWW Rheinisch-Westfälische Wasserwerksgesellschaft. It has a very large storage volume for seepage of treated water, which is suitable for the dynamization of the operation. An additional mobile container pilot plant is going to be built, in order to optimize the control of a dynamic management.
The planned work programme is divided into the project management and the work areas A to E with 8 work packages each (see figure). The research approach ranges from the details of energetic optimization of single system components in AP B up to an overall approach of the whole process chain in AP C. The solutions are assessed keeping in mind the ecological, societal (consumption pattern of customers, acceptance), legal and economic conditions. The project aims to make the results transferable, widely distributed and ready for further use.
Based on the exemplary results gained in the pilot plants, criteria and recommendations for the transferability of the results are deduced. Building on this, standardized energy efficiency questions are developed, which allow an interested user the application of the developed methods and implemented solutions over a web service. ENERWA is making important contributions to the distribution and the acceptance of energy efficiency solutions: For scientific and economic distribution, the results are summarized into a recommendation concept for energy efficient and sustainable, resource-saving water supply (manual, analysis tool, best practice). They also will be analysed regarding the social and political acceptance. A study about the increase in efficiency and marketing explores national and international market perspectives for the German water management.
Fig. 2: ENERWA-Project structure with the work packages A-E