Hydraulic modelling helps water utility achieve energy savings and reduce carbon footprint

In light of the changing energy market, the public utility company ‘Waterworks and Sewerage’ Novi Sad in Serbia needed to improve its water supply system. Together with the Regional Centre for Energy Policy Research (REKK), DHI’s engineers used hydraulic modelling to identify energy saving interventions, forecast energy use and provide a cost-benefit analysis to determine the best operational scenarios. The partnership delivered a much-needed solution for the water utility, which has not yet developed a hydraulic model for Srem area—the most complex part of the water system—to date.

*This project has been co-financed by the Western Balkan Green Center of the Ministry of Innovation and Technology of Hungary.

Challenge

In the project area, water supply primarily relies on pumping, with approximately 45 pumps in operation, leading to substantial energy demands and associated costs for the water utility. A calibrated hydraulic model would be most effective in identifying methods to reduce energy consumption of the pumps. Additionally, the model's results would be used to calculate strategies for reducing CO2 emissions. However, the complex nature of the water system has prevented the development of such a hydraulic model until now.

Solution

DHI developed a hydraulic sub-model of the Novi Sad water network consisting of 210 km of pipelines of diameter 100-900 mm (excluding service pipes), primarily made of AC, PE, PVC, and Cl/CLS. The Srem area water network consists of over 15 pressure zones, a high number of pumping stations (about 45 pumps) and 14 storage tanks.

The model represented about 25% of the water system involving 8,800 customer connections. It was carefully modelled to ensure a good match between simulated and observed data; calibration plots were developed for 54 comparison points, 21 flows and 33 pressures or water levels. Energy optimisation measures included a pump operations efficiency review and system-wide energy audit.

DHI's solution aimed to:

• Create a calibrated hydraulic model of the highly complex water system
• Link the hydraulic model to the energy market forecast model
• Provide cost-benefit analysis and suggestions for better operations
• Analyse potential CO2 savings to support climate change mitigation

Electricity price forecast and cost calculations

Using the European Power Market Model that provides wholesale electricity prices for each hour and each country, DHI’s partner REKK helped ViKNS calculate average energy prices to estimate retail price points. REKK derived these conclusions:

• Energy prices are increasing yearly
• Daytime prices are now higher than night time because of electricity demand
• When more and more solar energy is used during the day (8am-8pm), daytime prices will become cheaper. This is particularly true during summer months, thus price differences between winter and summer increases further.

Results

• The hydraulic model accurately captures the complexities of the water system, improving planning and operational decision-making
• By linking the hydraulic model with an energy market forecast model, pricing estimates are now more accurate, leading to informed financial decisions and cost savings
• Through rigorous scenario analysis, valuable energy savings measures have been identified, optimising operations and reducing overall energy consumption