Research

13 pages, 3324 KiB

Open AccessFeature PaperArticle

Increasing Energy Efficiency in Water Collection Systems by Submersible PMSM Well Pumps

by Marcus Beck, Alexander Sperlich, Ricardo Blank, Eckehard Meyer, Ralf Binz and Mathias Ernst

Water 2018, 10(10), 1310; https://doi.org/10.3390/w10101310 - 22 Sep 2018

Cited by 7 | Viewed by 4857

Water collection based on groundwater abstraction has a high energy consumption that depends primarily on the operation and performance of submersible well pumps. The fact of the matter is that these machines still work with a global energy efficiency of less than 50%, [...] Read more.

Water collection based on groundwater abstraction has a high energy consumption that depends primarily on the operation and performance of submersible well pumps. The fact of the matter is that these machines still work with a global energy efficiency of less than 50%, and further investigations of the energy aspects in well pumps are needed. The present study introduces measures to increase the global efficiency of submersible well pumps linked to electrical energy savings. Common submersible pumps with asynchronous motors (ASMs) were compared with innovative permanent magnet synchronous motor (PMSM) technology in real well fields in Berlin and Hamburg waterworks. This study confirms that PMSM pumps showed a 6.8%-points higher global efficiency compared to ASM pumps at optimal working points. The investigation of the impact of well field operation on local pump efficiency offers an additional increase in the global efficiency. In this context, the influence of variable speed control on the global efficiency and the energy consumption was analyzed. Global efficiencies of over 70%, and potential energy savings of up to 20%, were determined for the speed-controlled PMSM pump. This offers water suppliers new incentives to optimize their water collection systems for less energy consumption. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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13 pages, 3253 KiB

Open AccessArticle

Energy Efficient Operation of Variable Speed Submersible Pumps: Simulation of a Ground Water Well Field

by Alexander Sperlich, Dino Pfeiffer, Jens Burgschweiger, Enrique Campbell, Marcus Beck, Regina Gnirss and Mathias Ernst

Water 2018, 10(9), 1255; https://doi.org/10.3390/w10091255 - 15 Sep 2018

Cited by 16 | Viewed by 4248

Abstract

Due to their lower energy consumption, permanent magnet synchronous motor (PMSM) submersible pumps have been introduced in ground water well field operation. Besides direct savings of energy, the introduction of PMSM pumps together with the required variable frequency converters offers new operational scenarios [...] Read more.

Due to their lower energy consumption, permanent magnet synchronous motor (PMSM) submersible pumps have been introduced in ground water well field operation. Besides direct savings of energy, the introduction of PMSM pumps together with the required variable frequency converters offers new operational scenarios to meet the seasonally varying water demand. In this work, potential energy savings of variable speed submersible pumps were investigated. A ground water well field consisting of 13 wells and their transport pipes was modeled in the hydraulic modeling software EPANET 2.0. Using MS visual basic for applications, EPANET was coupled with MS Excel and a genetic algorithm to identify the most energy efficient combination of pump speeds. For the simulated well field, the total specific energy demand required for pumping was significantly lower in partial load operation as compared to nominal pump speed operation. For low and moderate flow scenarios, energy savings in the range of 20% compared to nominal speed operation can be achieved. These findings were confirmed by a monitoring campaign in the well field. Combining hydraulic simulation and optimization using genetic algorithms, the best efficiency scenario for operation of ground water well fields can be found. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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24 pages, 2095 KiB

Open AccessArticle

Evaluating Energy and Cost Requirements for Different Configurations of Off-Grid Rainwater Harvesting Systems

by Heather S. Rose, Charles R. Upshaw and Michael E. Webber

Water 2018, 10(8), 1024; https://doi.org/10.3390/w10081024 - 02 Aug 2018

Cited by 2 | Viewed by 6423

Abstract

The goal of this analysis was to evaluate energy and cost requirements for different configurations of a rainwater harvesting (RWH) system in conjunction with a solar PV and energy storage system for an off-grid house. Using models in fluid mechanics, we evaluated energy [...] Read more.

The goal of this analysis was to evaluate energy and cost requirements for different configurations of a rainwater harvesting (RWH) system in conjunction with a solar PV and energy storage system for an off-grid house. Using models in fluid mechanics, we evaluated energy and power requirements for four different system configurations: 1. An On-Demand System containing a single speed pump (OD-SS), 2. An On-Demand System containing a variable speed pump (OD-VS), 3. A Pressurized Storage System where water is pumped once during the day into a large pressurized tank for later consumption and treated on demand via UV light (PS-AOT), and 4. A Pressurized Storage System where water is treated once per day via UV light and then stored for later consumption (PS-TO). Our analysis showed that the OD-SS system model requires 2.63 kWh per day, the OD-VS system model requires a total energy of 1.65 kWh per day, and the PS-AOT requires 1.67–1.69 kWh per day depending on the pump size, and the PS-TO system requires 0.19–0.36 kWh per day depending on the pump size. When comparing estimated cost between systems, we found the OD-SS system to be the most expensive. With the OD-SS system as a base for system costs, we found the OD-VS system to be 39% less expensive, the PS-AOT system to be 21% less expensive, and the PS-TO system to be 60% less expensive than the base OD-SS system. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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16 pages, 2163 KiB

Open AccessArticle

Labeling Water Transport Efficiencies

by Elena Gómez, Roberto Del Teso, Enrique Cabrera, Enrique Cabrera, Jr. and Javier Soriano

Water 2018, 10(7), 935; https://doi.org/10.3390/w10070935 - 13 Jul 2018

Cited by 7 | Viewed by 3345

Abstract

Pressurized Water Transport Systems (PWTSs) are responsible for a large percentage of the electricity consumption around the world, and current trends suggest that this proportion will continue to increase in the future. Controlling PWTS is therefore fundamental, including improving efficiency when necessary or [...] Read more.

Pressurized Water Transport Systems (PWTSs) are responsible for a large percentage of the electricity consumption around the world, and current trends suggest that this proportion will continue to increase in the future. Controlling PWTS is therefore fundamental, including improving efficiency when necessary or compulsory. To achieve this, metrics to objectively assess the efficiency of the different losses and of the whole system are needed. These metrics, based on economic criteria, will be stricter if environmental costs are added to current water and energy costs. To assess different improvement strategies, some relative metrics, applied to both operational and structural losses, are considered. At the end, taking into account their relevance, these metrics are combined in a global energy score (IS), this being the main contribution of this paper. Finally, to focus on the concepts and methodology, a simple case study is presented. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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14 pages, 2389 KiB

Open AccessArticle

Cost-Optimal Flexibilization of Drinking Water Pumping and Treatment Plants

by Britta Zimmermann, Hedda Gardian and Kurt Rohrig

Water 2018, 10(7), 857; https://doi.org/10.3390/w10070857 - 28 Jun 2018

Cited by 7 | Viewed by 4689

Abstract

This paper examines potential cost savings attained through the flexible operation of water treatment plants and drinking water pumping and the benefits gained by investing in extended water storage capacities that enhance flexibility. An existing plant in South Germany serves as an example. [...] Read more.

This paper examines potential cost savings attained through the flexible operation of water treatment plants and drinking water pumping and the benefits gained by investing in extended water storage capacities that enhance flexibility. An existing plant in South Germany serves as an example. Mixed-integer linear programming is used to model the plant and the electricity procurement on the German spot market while ensuring the security of supply. Cost optimization considering the different cost components reveals potential cost savings through flexible operation. The paper evaluates the benefits of building additional water reservoirs and rates the financial effects of the measures used to enhance the flexibility of water pumping and treatment plants. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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10 pages, 2834 KiB

Open AccessArticle

Improved Assessment of Energy Recovery Potential in Water Supply Systems with High Demand Variation

by Laura Monteiro, João Delgado and Dídia I. C. Covas

Water 2018, 10(6), 773; https://doi.org/10.3390/w10060773 - 13 Jun 2018

Cited by 15 | Viewed by 3458

Abstract

Enhancing energy efficiency of water supply systems by recovering part of the excessive pressure is currently an issue of growing interest for water companies. The installation of micro hydro plants for energy recovery can be profitable in sites with excessive pressure, though requiring [...] Read more.

Enhancing energy efficiency of water supply systems by recovering part of the excessive pressure is currently an issue of growing interest for water companies. The installation of micro hydro plants for energy recovery can be profitable in sites with excessive pressure, though requiring proper technical and economical evaluation. This paper presents a methodology for assessing the energy recovery potential in water supply systems under high seasonal demand variation. The methodology is based on the calculation of head and flow rate conditions that maximize energy production for a specific energy recovery technology, given available head and flow rate ranges. The methodology is applied to the inlet of a storage tank of a water transmission system using hourly collected data over one year. Results show that, in systems of high variability of flow rate, the installation of turbomachines in parallel is necessary for maximizing energy recovery and that the developed methodology returns lower, but more realistic, energy production estimates than other approaches based on average head and flow rate data. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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21 pages, 4157 KiB

Open AccessFeature PaperArticle

Calculating the Economic Level of Friction in Pressurized Water Systems

by Enrique Cabrera, Elena Gómez, Enrique Cabrera, Jr. and Javier Soriano

Water 2018, 10(6), 763; https://doi.org/10.3390/w10060763 - 11 Jun 2018

Cited by 11 | Viewed by 4851

Abstract

In this paper, an algebraic expression is presented to determine the optimum hydraulic gradient (J₀) in a pressurized water system. J₀ represents the economic level of friction losses (ELF), which is dependent on the network’s behavior as well as [...] Read more.

In this paper, an algebraic expression is presented to determine the optimum hydraulic gradient (J₀) in a pressurized water system. J₀ represents the economic level of friction losses (ELF), which is dependent on the network’s behavior as well as other parameters, including energy and the pipe costs. As these have prices changed over time, so has the value of J₀. The network-related parameter was obtained from the total costs function and the sum of the operational and capital expenditures. Because these costs exhibited an opposite trend from J, a minimum total cost exists, specifically, J₀. The algebraic expression, which was derived from the mathematical model of the network, was first calculated for the network’s steady state flow and was later generalized for application to a dynamic one. For a network operating in a given context, J₀ was fairly stable in terms of dynamic flow variations, providing valuable information. The first piece of information was the ELF itself, which indicated the energy efficiency of the system from the perspective of friction loss. The second indicated which pipes required renewal from a similar perspective. Thirdly, it provided a simple criterion to calculate the diameter of new pipes. Finally, as J₀ can be easily updated, when predictions are performed at the network’s designed time fail (e.g., growing urban trends, demand evolution, etc.), decisions can also be updated. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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15 pages, 531 KiB

Open AccessArticle

Decision Support for the Design and Operation of Variable Speed Pumps in Water Supply Systems

by Dimitri Nowak, Helene Krieg, Michael Bortz, Christian Geil, Axel Knapp, Harald Roclawski and Martin Böhle

Water 2018, 10(6), 734; https://doi.org/10.3390/w10060734 - 05 Jun 2018

Cited by 16 | Viewed by 3967

Abstract

The design and operation of water supply systems is a multicriteria task; the energy efficiency should be minimized while, at the same time, respecting technical requirements, such as the balanced operation of available pumps. On one hand, the overall system can be improved [...] Read more.

The design and operation of water supply systems is a multicriteria task; the energy efficiency should be minimized while, at the same time, respecting technical requirements, such as the balanced operation of available pumps. On one hand, the overall system can be improved by the use of variable speed pumps. They increase the number of operating options. On the other hand, they add more complexity to the operation problem. In this paper, we discuss the difficulties associated with speed control and propose a decision support system to overcome them. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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14 pages, 1890 KiB

Open AccessArticle

Top-Down and Bottom-Up Approaches for Water-Energy Balance in Portuguese Supply Systems

by Aisha Mamade, Dália Loureiro, Helena Alegre and Dídia Covas

Water 2018, 10(5), 577; https://doi.org/10.3390/w10050577 - 28 Apr 2018

Cited by 22 | Viewed by 5791

Abstract

Water losses are responsible for increased energy consumption in water supply systems (WSS). The energy associated with water losses (EWL) is typically considered to be proportional to the water loss percentage obtained in water balances. However, this hypothesis is yet to be proved [...] Read more.

Water losses are responsible for increased energy consumption in water supply systems (WSS). The energy associated with water losses (EWL) is typically considered to be proportional to the water loss percentage obtained in water balances. However, this hypothesis is yet to be proved since flow does not vary linearly with headlosses in WSS. The aim of this paper is to validate the hypothesis, present real-life values for water-energy balance (WEB) components, and reference values for the key performance indicator that represents the ratio of total energy in excess (E3). This validation is achieved through the application of two approaches—top-down and bottom-up. The first approach requires minimum data, gives an overview of the main WEB components, and provides an effective diagnosis of energy inefficiencies through the calculation of E3 related to pumps, water losses, and networks. The second approach requires calibrated hydraulic models and provides a detailed assessment of the WEB components. Results allow the validation of the stated hypothesis as well as show that the most significant energy inefficiencies are associated with surplus energy, pumping, and water losses, each reaching up to 40% of total input energy. Less significant components are pipe friction and valve headlosses, each reaching up to 15% of total input energy. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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10 pages, 2773 KiB

Open AccessArticle

Groundwater Abstraction through Siphon Wells—Hydraulic Design and Energy Savings

by Rico Bartak and Thomas Grischek

Water 2018, 10(5), 570; https://doi.org/10.3390/w10050570 - 27 Apr 2018

Cited by 3 | Viewed by 7823

Abstract

Siphon pipes were used for groundwater abstraction from wells before the development of submersible pumps. Many of the existing and operational systems were built before the 1950s and require rehabilitation. Siphon wells are difficult to design and, therefore, are often equipped with submersible [...] Read more.

Siphon pipes were used for groundwater abstraction from wells before the development of submersible pumps. Many of the existing and operational systems were built before the 1950s and require rehabilitation. Siphon wells are difficult to design and, therefore, are often equipped with submersible pumps when the system is rehabilitated or renewed. This study presents a novel calculation tool for siphon wells and investigates the energy savings of such system in comparison to an alternative equipment with submersible pumps. A theoretical energy savings of 38% was first estimated compared to individually-operated wells (IOW) for a fictional design example just based on the calculated water levels and abstraction rates. Real energy data from two riverbank filtration (RBF) sites, which operate both siphon and IOW, were investigated in the second part of the study. The analysis of measured data revealed energy savings of 36–69%, confirming the theoretical estimation. Full article

(This article belongs to the Special Issue Energy Efficient Management of Water Collection, Treatment, Storage and Distribution)

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