Electric power generation via pressure regulation in water distribution systems
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Date
2025-05-07
Authors
Μπιδέρης-Δάβος, Άδμητος
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Abstract
Over the past two decades, the European Union took firm action against climate change, resulting in about 40% drop in greenhouse gas emissions. In order to accomplish the even higher objective of climate-neutrality by the year 2050, not only renewable generation must be further increased, but significant improvements in energy efficiency through multi-sectoral co-operation and co-ordination must be done. To this direction, utilizing existing infrastructure to the fullest and reduction of energy dissipation at its absolute minimum are required.
Currently, though, large amounts of energy are dissipated in Water Distribution Systems (WDSs) during the process of water pressure regulation with the use of passive hydraulic devices, such as Pressure Reduction Valves (PRVs) and Brake-Pressure Tanks (BPTs). At the same time, existing WDSs do not incorporate efficient strategies for achieving water savings through water pressure control. Appropriate methods towards these two still have not been extensively researched.
In this context, the objective of this thesis was to investigate the potential of energy recovery in WDSs, with the employment of micro-turbines that will do not only inject significant amounts of sustainable energy to the Power Distribution System (PDS), but simultaneously perform precise regulation of water pressure. For this purpose, for the first time, a specific methodology was developed for the proper selection, sizing, and design of the turbine, which allowed the replacement of the existing PRVs with micro-turbines that provide equivalent water pressure regulation.
Pressure Regulating Turbines (PRTs) operate as interconnecting links between the two systems allowing their co-optimization for both power generation and accurate pressure regulation. Dimensioning of PRTs is produced in such way, so that they can be directly accommodated in existing WDS infrastructure in order to ensure their practical implementation and the reduction of civil and mechanical work costs. The design process of PRTs has been enhanced so that it also involves basic economic assessment properties during the design point selection process, along the objectives of accurate pressure regulation and maximum energy yield. In the context of the thesis, an innovative extension of the mathematical formulation of Optimal Power Flow (OPF) was developed, so that the impact of PRTs as power generation and pressure regulation devices is considered in the operational objectives and constraints of both the WDS and PDS.
The suggested mathematical approach offers expandability. This has been demonstrated, first, with the incorporation of different voltage control strategies in the optimization process, so that their impact on both systems can been assessed. It was proven that intelligent decentralized control schemes can achieve comparable PRT penetration level to PDSs, without the telecommunication burden and costs of centralized control. Second, a trade-off between precise pressure regulation and increased power generation could be formulated in the form of soft constraints, allowing network operators to increase the amount of renewable power generation by a significant 7% (€2.8K of additional revenue per year) with negligible impact on quality of service.
Application of the co-optimization framework on real-sized simulated WDS and PDS networks indicated that, energy recovery from PRTs is expected to add a significant income to the operator’s budget (approximately €40K), while increasing the share of renewables in the energy mix.
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Διεσπαρμένη παραγωγή ενέργειας, Υδροστρόβιλοι ρύθμισης πίεσης, Υδροπαραγωγή, Σχεδιασμός υδροστροβίλων, Δίκτυο διανομής νερού, Δίκτυο διανομής ηλεκτρικής ενέργειας, Συν-βελτιστοποίηση δικτύων, Οικονομική ανάλυση, Έλεγχος τάσης