How optimal pressure management led to energy savings of 43% and reduced water losses

The situation

Goleniów Water and Sewage Utility (GWiK), is a pioneering company widely recognised in the region for its commitment to innovation across various sectors. Sustainability  stands as a cornerstone in GWiK's strategic approach, evident through the implementation of cuttingedge solutions. GWiK's dedication to sustainability is exemplified through strategic investments in renewable energy sources and electromobility.

Additionally, the utilisation of solid sludge from the wastewater treatment process to create natural plant fertiliser showcases their proactive measures in reducing  environmental impact. With operations spanning across nine water treatment plants, GWiK efficiently caters to the needs of over 30,000 inhabitants in the Goleniów county, as well as industrial plants and public facilities.

The largest station in Goleniów, responsible for supplying over 85% of consumers' demand for fresh drinking water, used a system comprising four horizontal, singlestage pumps, each with a power of 37 kW, alongside a proportional pressure control system. GWiK remains at the forefront of efficiency by consistently analysing nonrevenue water.

In 2019, their commitment to optimisation resulted in a commendable nonrevenue water level of 12.54%. The control system at the pumping station managed water pressure pumped into the network proportionally to the current flow, but with a constant, fixed characteristic. In 2017, Grundfos proposed a DDD Audit to GWiK Goleniów to assess the system's condition and identify potential areas of improvement.

Installation of five new highly efficient Grundfos CR 125-2-1 vertical pumps with dedicated Variable Frequency Drives (VFDs)

In 2013, during a prior refurbishment, we installed pumps from a different supplier. However, energy consumption wasn't a primary focus for the new system at that time; it was more of a 1-to-1 replacement. The booster set was controlled using a single frequency converter, which, upon one pump reaching 100% speed, activated another at minimal speed. This setup posed challenges, leading to operational instability during transitional moments. The pump would alternately switch on and off for up to an hour. Even back then, we recognised the need to address this issue.
Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility

The solution

To determine the optimal solution for the customer's requirements, Grundfos conducted a comprehensive DDD Audit, including an analysis of the water supply network at the Goleniów Water Treatment Plant. The study revealed that the existing system operated with an average efficiency of less than 45%, accompanied by relatively high specific energy reaching 0.243 kWh/m3. Furthermore, an examination of specific points in the water supply network highlighted noticeable pressure fluctuations corresponding to varying demands.

The detailed audit report recommended the implementation of a new pressure booster featuring five highly efficient CR 125-2-1 pumps and dedicated frequency converters. This upgrade is anticipated to elevate the average efficiency to 65% and reduce overall energy consumption. Additionally, the proposed system will give a maximum flow rate of 580 m3/h. Moreover, the incorporation of the DDD control system will facilitate dynamic pressure control at strategically placed measuring points in the network, effectively optimising pressure adjustments according to fluctuating demand.

We recognised that the inefficiency extended beyond just the pumps; the control system was also suboptimal. When a portion of the pumps operated at 100% speed, and only one was under the control of the frequency drive, the overall system efficiency considerably decreased.
Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility

The project adopted a design-and-implement approach, including the replacement of four existing vertical pumps, 37 kW each. This was accomplished by installing a booster set, featuring five new CR 125-2-1 pumps, 18,5 kW each. Additionally, the project involved the installation of a new DDD control cabinet, data loggers, sensors for collecting pressure data from the water supply network, delivery of MODBUS communication modules for SCADA system integration and the replacement of piping and manifolds. Importantly, the entire undertaking was executed on the live system, ensuring uninterrupted water supply to end-users.

(Left) 2017 booster with 4 horizontal pumps, (Right) 2022 new system featuring 5 vertical CR-125-2-1 pumps

Being unfamiliar with the DDD control system, I never imagined we could achieve such remarkable outcomes. Upon reviewing the audit results, we came to realise its potential
Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility

The outcomes were significant, as evidenced by the reduction in the average specific energy of the pumping system from 0.243 kWh/m3 to 0.138 kWh/m3. Within just one year of implementation, GWiK achieved a remarkable 43% reduction in energy consumption, translating to annual savings of over 194,000 kWh for the upgraded set. However, the benefits extended beyond energy savings.

Dariusz Kozak (Technical Director, GWiK Sp. z o.o.) and Robert Góra (Senior Sales Engineer, Grundfos).

The outcome

The head of the pump system significantly influences energy consumption. Initially, with the proportional control system at the Goleniów water treatment plant, the pressure at the pump station output fluctuated between 4.2 and 4.4 bar. However, following the implementation and adaptation of the Grundfos DDD system, the system actively and dynamically generated an optimal control curve, resulting in a reduced outlet pressure at the station ranging from 3.3 to 4.1 bar. At the same time, the system stabilised pressure on the end-users' side, ensuring consistent comfort of use regardless of current demand, time of day or season.

We believed we had already achieved optimal control of pressure versus flow. However, it became evident that there are solutions capable of dynamically adapting to changing demands even more effectively. Furthermore, we observed that with DDD control, we could sustain end-user comfort while reducing pressure in the network. This, in turn, resulted in lower energy consumption and reduced water losses.
Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility

Given the constant evolution of the water supply network, the DDD control system utilises daily collected data to fine-tune control for optimal efficiency

As the user, I simply set the desired pressure at critical points in the network, and the DDD controller autonomously analyses the data to adjust the control curve. Automatically, day after day, consistently.
Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility

Reducing pipeline pressure contributes to fewer underground leaks, resulting in decreased water loss through network optimisation. Prior to the refurbishment, the utility recorded non-revenue water (NRW) at 12.5%. Following the implementation of Grundfos DDD, NRW decreased to 9.3%, marking a substantial reduction of 3.2 percentage points. Consequently, the utility prevented the loss of nearly 60,000 m3 fresh, treated water annualy. Considering the significant cost associated with producing each m3 of drinking water, not to mention the imperative of sustainable use of natural resources, these outcomes are noteworthy.

Furthermore, with Grundfos DDD, the system boosts pressure only during periods of high demand to ensure end-user comfort. During low-demand periods, the discharge pressure is substantially decreased. This smooth control minimises stress on pipelines, leading to fewer network failures, reduced repair costs and the secure delivery of water.

Grundfos embraced the challenge of addressing our issues and achieving a specific end result. In doing so, they have demonstrated not only their role as a hardware supplier but also as a genuine partner in the optimisation process..
Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility

Dariusz Kozak, Technical Director at Goleniów Waterworks and Sewage Utility