Energy efficiency in a water supply system: Energy consumption and CO2 emission

Environmentally friendly hybrid solutions to improve the energy and hydraulic efficiency in water supply systems

Advanced control of large-scale wind turbines: Structural load reduction and lifetime control

Abstract: ABSTRACT: Objective- To design a simple cost effective and efficient method for a water supply system employing a brushless DC motor, fed with renewable source of energy(solar energy) from solar photovoltaic array and to obtain maximum power output from SPV array using maximum power point tracking(MPPT),employing zeta converter. Design / Methodology/ Approach- Performance evaluation of proposed SPV array-fed BLDC motor-driven water pump employing a zeta converter is carried out using simulated results. The proposed system is designed, modeled, and simulated considering the random and instant variations in solar irradiance level and its suitability is demonstrated by testing the starting, steady state, and dynamic behaviour. Findings- The SPV array-zeta converter-fed VSI–BLDC motor-pump has been proposed and its suitability has been demonstrated through simulated results and experimental validation. Practical implications- We can implement this system in Rural area irrigation & fresh water pumping, Mini pump applications, BLDC application in robotics, Energy efficient mechanical machine operation.

The cost of energy used for pumping water constitutes a large proportion of operational expenditure for a water utility. Energy saving measures in water supply systems can be realized in different ways, by design of the system to be energy efficient, by proper maintenance of equipment especially pumps and by optimal control of the system. The cost of the pumping is a product of energy consumption and an electricity tariff. The energy can be reduced by pumping less water, lowering the head against which the water is pumped and by operating pumps near peak efficiency. The cost can also be reduced by re-scheduling the pumping from expensive to cheap tariff periods. Typically the real time control for time varying tariffs is implemented in a predictive control fashion, in which an optimal time schedule is calculated ahead over 24 hours period by a solver and recalculated at regular intervals e.g. 1 hour. In order to operate the scheme in real time the solver must be sufficiently fast and this may not always be possible for big water supply systems. In this paper a method to synthesize feedback control rules is proposed taking into account a time varying tariff. The rules are calculated off-line and then implemented in local PLCs or in a control room. Once the rules are implemented the response to the changing state of the water system is instantaneous. In this paper the feedback rules are calculated by a genetic algorithm. Each pump station has a rule described by two water levels in a downstream reservoir and two values of pump speed, for each tariff period. The lower and upper water levels of the downstream reservoir correspond to the pump being ON or OFF. The approach has been applied to a large scale water supply system and compared with the traditional time schedule approach. The achieved cost for the feedback control is only slightly higher than that for the time schedule approach. However, the feedback control by its nature is more robust and performs well in the presence of uncertainty in water demands and in inaccuracy of hydraulic models.

Energy efficiency and renewable energy sources have drawn a greater attention by EU, in particular for climate change policies as it can substantially cut down CO2 emissions to meet EU environmental obligations. It is well established that in drinking pipe systems Pressure Reducing Valves (PRV) are used as a mean for excess energy dissipation for the purpose of pressure control. This type of solution can be adopted, as a mitigation method to control the system losses, in particular, the available overload, which must have to be dissipated to avoid leakage or rupture occurrence in the pipe system. The use of micro-hydro systems seems to provide a better approach as a sustainable solution in terms of controlling the system pressure as well as to provide a non-negligible income by producing clean energy. Computational simulations, experimental research and engineering project development are carried out to analyse and compare the hydraulic system behaviour between a PRV and a pump working as a turbine (PT). This research creates an important challenge for seasonal stabilization of the energy supply by using water supply systems, due to the stochastic nature of river-hydro resources.

The reliability of water supply and wastewater disposal systems has a significant impact on the environment: therefore, it is essential to implement new methods and approaches that reduce the risk of emergency situations. Based on the experience in automation, maintenance and modernization of wastewater disposal and water supply systems, the study suggests introducing additional programmable modules into automated control systems that provide control and regulation directly on the actuator. For this purpose, the study involves OWEN Logic programming environment, which manages pumping stations through programmable relays. The paper presents functional diagrams that have been introduced into standard macros to increase the reliability of pumping units. In addition, the paper demonstrates that the implementation of multi-level management facilitates the improvement of existing water supply and wastewater disposal systems, thereby increasing their functional capabilities and ensuring the efficient operation of technological equipment. The conducted analysis shows that the adoption of this method for managing technological processes will enhance the reliability and durability of the equipment, ensuring uninterrupted operation of pumping stations. With a change in the performance of water supply and wastewater disposal systems, the installed devices will allow for modernization with minimal economic costs, and reprogramming the operation of the low-level automation without affecting the performance of other levels.

The energy consumption and greenhouse gas (GHG) emissions associated with urban water systems have come under scrutiny in recent times, as a result of increasing interest in climate change, to which urban water systems are particularly vulnerable. The approach most commonly taken previously to modelling these results has been to consider various urban water system components in great detail, but in isolation from the rest of the system. This piecewise approach is suboptimal, since it systematically fails to reveal the relative importance of the energy consumption and GHG emissions associated with each system component in the context of the entire urban water system. Hence, it was determined that a new approach to modelling the energy consumption and GHG emissions associated with urban water systems was necessary. It was further determined that the value derived from such a model would be greatly enhanced if it could also model the water consumption and wastewater generation associated with each system component, such that integrated policies could be developed, aimed at minimising water consumption, wastewater generation, energy consumption and GHG emissions concurrently. Hence, the following research question was posed: How should the relationships between the water consumption, wastewater generation, energy consumption and GHG emissions associated with the operation of urban water systems be modelled such that the impact of various changes to the system configuration made at different spatial scales can be determined within the context of the entire system? In this research project, life cycle assessment ideas were employed to develop such a new modelling methodology. Initially, the approach was developed at the building-scale, such that the end uses of water present in a selected building and any associated appliances could be modelled, along with the fraction of the citywide water supply and wastewater systems directly associated with providing services to that building. This vast breadth of scope was delivered by considering only the operational life cycle stage of each urban water system component, excluding both the pre- and post-operational life cycle stages of the associated infrastructure. The value of this pilot model was illustrated by several case studies, focused on residential buildings connected to the centralised water supply and wastewater systems in Melbourne, Australia. Later, the approach was extended to the city-scale by using probabilistic distributions of each input parameter, such that all of the end uses of water present in a city, and all of the associated building-scale appliances could be modelled, along with the associated complete water supply and wastewater systems. The value of this city-scale model was illustrated by applying it to model a hypothetical case study city, resembling Melbourne, Australia in many ways. Due to a lack of data, this application was limited to the residential sector of the case study city, along with the fraction of the citywide water supply and wastewater systems directly associated with providing services to that sector. The results generated by the pilot and city-scale models showed that the new modelling methodology could be employed at a wide range of scales to assess the relative importance of each modelled urban water system component in terms of the specified results. Importantly, the high resolution of those results enabled the identification of the underlying causes of the relative importance of each urban water system component, such that efficient and effective approaches to reducing each result for each system component could be developed. Interestingly, for the specific case studies investigated, it was revealed that some commonly neglected system components were actually extremely important, such as domestic hot water services, a trend found to be largely driven by hot water consumption in showers.

Argentina has a big territorial extension. Because of it, Argentina has a variety of climates ranging from subtropical to Antarctic ones. Also it has a variety of orography and soils, from estuaries and humid Pampas to the Andes and the Andean region of the Puna. It also has a hydrographic situation of rivers from mountain ranges and plains (Parana and Uruguay), of diverse flows as well as an extensive Atlantic coast that reaches Antarctic latitudes. This allows to find in Argentina all varieties of renewable energy sources (RES) with relevant resources (hydro, biomass, solar, tidal, wave, marine currents, etc.). Among them, Wind Energy stands out particularly from Andean zone, to Atlantic coast in Patagonia with plant coefficient around 0.45. This chapter does not only refer to Wind Energy but also how it is included in the development of the rest of the RES in Argentina. Also consider the training of HHRR, laws, testing institutes and accumulation of energy and technology. Detailed description of use of Mini wind turbines applied in urban environments is Included. Since 1980s, different private and state companies began to study and install small wind farms with European turbines. These companies obtained more experience in where is the best place of wind resource than in the behavior and maintenance and operation of the turbines. During 1990s, development of investments in wind farms was made by Utility Services Cooperatives. But economic crisis meant that some of them did not continue installation or maintenance or simply was remained as wind project. In 2010, Argentinean government began to have interest in developing renewable energy (wind, PV, biomass, and micro-hydro) because of successive annual energy crises since 2005. The existing laws were modified and GENREN state renewable energy contest was launched with a great deal of wind farm proposals. But tariff conditions meant that only 30% of the projects began to be carried out. On the other hand it allowed local developments of wind turbines (NRG 1.2 MW, IMPSA WIND 2.5 MW). During 2016, the electricity tariff and importation of renewable energy equipment market is flexibilized, continued by the corresponding national and provincial laws. This change permitted editions of the RENOVAR Plans (1, 1.5, 2, 3) that allow the installation of turbines up to 3.5 MW Type II (limited by wind turbulence index in Argentina) to reach 20% of RE insertion in Argentine Electric System by 2025 (7000 MW). These wind energy investments begun to reveal Argentinean wind potential of 200,000 MW at 80 m height. This will permit to export energy in the future to the rest of South America, to at least six countries. A wind map for 80 m of height was made, which is applicable to different wind turbines from1 to 3.5 MW power. Academic specialists since 1990s, carry out mini and micro scale wind energy studies for wind farms in isolated mini-grids, and small wind turbines in urban environments. This development of wind installations is being accompanied by work force training in installation, operation and maintenance to be technicians and postgraduate courses. Since 1996 the impulse of RES and Hydrogen as vector of energy accumulation, permitted to develop the formulation and approval of laws, resolutions, ordinances at national, provincial, and municipal levels, beginning adequacy of regulations for construction of urban, residential, and agricultural buildings to the use of RES (PV and small and medium wind turbines). “In situ” Test Laboratory was implemented and available in the city of Cutral Co (Neuquen Province) to characterize small wind turbines, which has given impetus to local production. Also this laboratory with legal and technical regulations characterized and adjusted the nominal parameters of the small wind turbines of national manufacture. Today, both cases compete with that technology manufactured in Europe, the USA, and Asia. This chapter concludes with Argentinean experience by means of recommendations to politicians, businessmen, and investors of what aspects must be taken into account in renewable energy projects to be successful in an emerging or developing countries.

Water is one of the scarce resources which is very important for the development for humankind hence efficient allocation is needed. The demand for domestic water as elsewhere is increasing as time goes according to records. This study was about the economic efficiency of domestic water allocation in Moshi Rural District, the case of Kirua-Kahe area. There were three specific objectives in this study which are to evaluate the domestic water allocation of Kirua-Kahe Water Project in Moshi Rural District, to determine the domestic water allocation efficiency in Kirua-Kahe Water Project and to examine the effectiveness of Kirua-Kahe domestic water allocation in Moshi Rural District. The findings show that Kirua-Kahe uses Gravity water supply and Pumping system. Gravity water supply system has 8 working intakes, 2 boreholes. The Pumping water Supply system consists of 15 small pumping schemes being pumped from boreholes and 1 spring. From the sampled villages, the findings also show within the family female members were mostly concerned with water usage. Until January 2015, Kirua-Kahe Gravity had a total of 5 403 customer connections and 401 customer connections for Kirua-Kahe Pumping. Customers are Public, Homes, Social Institutions and Commercial connections. Pricing is used for consumers as contribution for the sustainability of the project. The economic efficiency was carried out based on analysis of usage and collection efficiency and all constraints and optimality conditions were satisfied. Further research is needed to design service delivery models, technological innovations and education.

Optimization of operational planning for wind/hydro hybrid water supply systems

Most pumping stations in urban water supply systems in Ukraine are not equipped with adjustable drive, and traditional turning on/off of pumping units and repositioning the adjustable valves are used as an operational control of pumping station modes. Moreover, even in large cities, centralized water supply systems management is carried out manually. With this approach, there are significant energy losses, pumping unit capacity is not used efficiently. The paper proposes a strategy to optimize the operating modes of pumping station with multi-type pumping units based on a stochastic model of quasi-stationary regimes in water supply and distribution systems, taking into account both the stochastic nature тof water consumption processes, and the statistical properties of the model parameters. This strategy is resource-and energy-saving and allows to: • minimize the mathematical expectation of PS energy expenditure on the planning interval (day); • obtain an optimal solution, sustainable to the estimated level of stochastic perturbations by the flow and the head at the PS outlet with a probability not below the given; • minimize the number of PU switching. The problem of planning the pumping station modes with one-day anticipation is formulated and solved. Solving this problem has allowed to find the optimal structure of working pumping units, flow rate for each pumping unit and the position of the adjustable valves for four pumping station modes, planned during the day.

In the water supply system, for stable operation and management, pressure control, and energy consumption are important factors. However, gravity flow water supply systems can cause leaks and pipe damage when high pressure from upstream moves downstream. Therefore, the only popular way to control pressure within an acceptable range is to use a pressure reduction valve to control pressure within an appropriate range. However, using only the pressure reduction valve causes indiscriminate energy waste in operating and managing the water supply system. Accordingly, a micro-hydro turbine was proposed to replace the pressure reduction valve to provide appropriate pressure control and energy recovery. In addition, existing micro-hydro turbine designs were designed with only energy recovery in mind, but for sustainable operation, various design factors must be considered for optimal design. However, in design, EPANET2.2, the model simulation program in this study, does not have a model that can calculate the size of the turbine, so it is replaced with the pressure reduction valve and designed using the corresponding pressure and flow rate. Therefore, in this study, the range that satisfies the appropriate pressure condition is determined by using the pressure reduction valve (if a micro-hydro turbine is used with a surplus pressure head considering appropriate pressure control, the potential energy recovery amount can be determined). Therefore, a multi-objective optimal design technique was proposed that can optimize objective functions such as energy recovery and installation cost. The optimization technique is a multi-objective harmony search, and benchmark networks were applied to verify the proposed methodology. Through this study, it is expected that it can be effectively used in the sustainable operation of the water supply system by considering various design factors through adjustment of the set pressure.

The progressive integration of renewable energy sources such as wind turbines and photovoltaic pannels in the current electrical network, and the rise of the electrical mobility, provoke a change of paradigm in the sector of energy management. The increasing variability of the electricity production and consumption profiles, together with the requirement for a reliable supply of energy, necessitates the implementation of energy storage means of different scales and for a wide range of applications. Redox flow batteries (RFBs) are well adapted for buffering the fluctuations of solar or wind energy production. They present a fast response time, can withstand a large number of charge-discharge cycles and their ouput power is independant of their energy capacity. The main limitation of RFBs resides in their low energy density. The objective of the present work was to test a mean to overcome this low energy density. A new concept was developed, which rests on the addition of a second pathway to discharge the RFB. This pathway allows to generate hydrogen and oxygen, without affecting the functioning of the RFB. This concept was called dual-circuit RFB and was patented. RFBs are based on two liquids electrolytes, each stored in a reservoir, and flowing through an electrochemical cell for their electrochemical conversion. Each electrolyte contains one redox couple and Ce(IV)/Ce(III) and V(III)/V(II) were selected as positive and negative redox couples in the RFB developed here. Charge-discharge curves of a V–Ce RFB were measured for characterisation purposes and for the preparation of the charged electrolytes. The latter ones can be discharged electrochemically in the RFB to generate electricity (electrochemical discharge mode), or they can be directed in a secondary circuit where they are discharged for the production of hydrogen or oxygen (chemical discharge mode). The chemical discharge of the negative electrolyte consists of the reaction of V(II) with protons to produce hydrogen and V(III). Mo2C was selected as heterogenous catalyst for the characterisation of the reaction. A conversion close to 100% suggested no loss of current. A kinetic analysis provided some insights into the catalytic mechanism of this reaction. The chemical discharge of the positive electrolyte aimed at the conversion of Ce(IV) to Ce(III) by the oxidation of water to oxygen and also necessitates a catalyst. Iridium dioxide (IrO2) and ruthenium dioxide (RuO2) were evaluated in terms of conversion and kinetics. The composition of the positive electrolyte was shown to be of importance for this reaction. To show the feasibility of this concept, a larger-scale demonstrator system was designed based on a 10 kW (40kWh) commercially available vanadium RFB. A characterisation of this RFB was first performed. The design a suitable Mo2C catalyst and its corresponding catalytic bed is also discussed. As a conclusion, the concept developed and experimentally tested in the present work leads to a RFB system which is characterised by two discharge modes, increasing its energy storage capacity and energy density. The dual-circuit RFB also represents a crossing between electrical grid and hydrogen mobility as the hydrogen produced by surplus electricity could be delivered to fuel cell cars. The application of this system in a local distribution electrical network, close to a wind or solar source seems a promising approach.

Small-scale hydropower plants (SHP), and in particular the micro-hydropower plants (MHP) and pico-hydropower plants (PHP), are considering as an alternative energy resource based on the hydroelectric potential available in urban water cycle because of the excess of pressure existing in some urban water supply systems (WSS). Nowadays, pressure-reducing valves are necessary to reduce water pressure in WSS, so the use of a pump as turbine (PAT) can be considered as a proper way for reaching both an enough water head reduction and a hydropower generation possibility (self-consumption or energy recovery). MHPs are based on existing hydraulic resources where the PAT location is necessary, especially in those points with an excess of energy, which derives in an extra cost in terms of conservation and maintenance of the infrastructure or lead to the necessary installation of dissipation devices. The locations of these points are strongly influenced by the geographical and hydrological conditions, so a Geographic Information System (GIS) is a very useful tool for implementation of SHP and MHP or PHP projects. This paper describes the assessment and comparison of the methodology followed in the SHP and MHP locations: necessary data, GIS development, hydrologic model and hydropower potential.

Water supply pumping stations are among the main energy-consuming elements in the water supply system. The energy optimization of a pumping station can significantly affect the energy consumption of a water utility. This article deals with the energy optimization of water pumping stations. The work assumes several variants of optimization of water supply pumping stations through changes in the water supply system, pressure changes in the pumping station, and modification of the number of pumps. After analyzing the network, conducting field tests, and creating a model of the water supply network, the network was calibrated in order to reproduce the existing water network as accurately as possible. Then, a variant analysis was performed, and the best optimization method for the pumping station was selected. In two variants, there was a decrease in electricity consumption; in three there, was an increase; in one, there was no change. By connecting the DMA zones and modifying the pressure in the pumping station, the energy consumption of the pumping stations was reduced. On this basis, it was found that it is possible to optimize the water pumping station by modifying the pumping station and work related to the network layout.