• Energy Research
• 2021-2025close

[EN] The inclusion of new strategies is crucial to achieve the different targets of the sustainable development goals for the guarantee of supply in the different cities and reduction the consumption of non-renewable resources. The development of these strategies implies the improvement of the sustainability indicators and green rating systems of the city. This research proposes a decarbonisation strategy, which includes different optimization procedures based on a self-calibration process according to recorded flow values over time. These stages are integrated into one tool to define the best making decision in the management of the supply system, analysing whether self -consumption of energy is feasible. It was applied on the Bahamas. The application of the strategy enabled the decrease of the annual consumption of energy equal to 32%. The self-consumption could represent 30% of the consumed energy of the pump station. The making decision to define the best operation strategy, establishing a Levelized Cost of Energy around 0.12 euro/kWh when the feasibility of using photovoltaic systems combined with micro hydropower was done. It implies the reduction of 40% of the tCO2 emission, getting a cost of carbon abatement values around 400 euro/tCO2 for different discount rates and scenarios. Fundings Grant PID2020-114781RA-I00 funded by MCIN/AEI/10.13039/501100011033.

In upcoming years, water demand is expected to boost worldwide, and with that, wastewater generation and the required energy for treatment. Provided that efficiency measures should be implemented at first instance, developments of renewable energy technologies are needed to improve sustainability at wastewater treatment plants (WWTPs). Based on theoretical analyses of literature data, this article presents a novel perspective of the role that hydropower could play in that energy framework. This research applied a new approach compared to previous studies, considering the introduction of sustainability aspects in the decision-making process, other than economic feasibility. With that aim, a broad search of real case studies was conducted, and suitable Key Performance Indicators based on the energy self-sufficiency concept were selected and applied to the identified cases. The findings suggest that there is not a rule of thumb to determine feasibility for hydropower installation and this technology might deserve more attention. This new perspective can help to raise awareness among policy makers, decision managers, or plant operators, of the possibilities hydropower could offer to the wastewater industry in the pathway towards more sustainable systems.

<p class="JAREAbstract">The present paper focuses on the selection of parameters that maximize electrical energy production of a horizontal axis wind turbine using Python programming language. The study takes as reference turbines of Villonaco wind field in Ecuador. For this aim, the Blade Element Momentum (BEM) theory was implemented, to define rotor geometry and power curve. Furthermore, wind speeds were analyzed using the Weibull probability distribution and the most probable speed was 10.50 m/s. The results were compared with mean annual energy production of a Villonaco’s wind turbine to validate the model. Turbine height, rated wind speed and rotor radius were the selected parameters to determine the influence in generated energy. Individual increment in rotor radius and rated wind speed cause a significant increase in energy produced. While the increment in turbine’s height reduces energy generated by 0.88%.</p>

The constant growth of the population and the increase in the need for resources create challenges, and it is necessary to seek more sustainable solutions to manage them more adequately and efficiently. In recent years, the use of renewable energy systems has increased, in which water distribution networks are no exception. Pumps operating as turbines (PATs) are an innovative solution with enormous potential to achieve these sustainable development goals. As a means of improving sustainability, in this research, an optimized regulation tool is developed to maximize the recovered energy in the system using PATs in water distribution networks (WDNs). This is possible due to the use of empirical methods for the estimation of the characteristic curves. The tool was developed in Simulink MATLAB, in which the optimization and iterative steps were carried out. It is based on the intended methodology and applied to a real case study. When implementing the tool, the results given are the hydraulic–electrical regulation strategies, where the number of machines working, the frequency inverter setpoint, and the degree of opening of the pressure-reducing valves (PRV) is defined for any given time. After the analysis in the case study, the tool recovered 28% of the supplied energy in the system. This daily recovered energy was above 7160 kWh, and it contributed to an increase in efficiency and sustainability.

[EN] In the current world economic environment where reducing energy costs is a high priority, it is not surprising that sustainable water and energy management are key topics among the water and electric industry. Specifically, water suppliers, pump manufacturers, and operatives of small hydropower systems, all recognize that pumps working as turbines can be an efficient, simple, and economic approach to generating power and recover the excess of energy in water pressurized systems. In both, variable operating flow rate conditions (ex: presence of different water users) impose the need to augment the range of a proper pump as turbine system. One solution is to associate several pumps as turbines in series to increase the recovered energy. In that context, this work assesses their reliability at transient off-grid conditions by two pumps as turbines connected in series. Each one has an identical self-excited induction generator feeding a three-phase and balanced resistive load. Changes (increase/decrease in values) were applied to the resistive loads and the bank of capacitors at one group only, which allowed examining how changes affect the overall two-group system dynamics. Results show that one change in the first pump as turbine group will significantly affect the other group dynamics. For example, a decrease in load of the first group will affect the flow and head of the other system, until reaching a new equilibrium point. However, as both groups are not mechanically connected, they can achieve different equilibrium speeds. Furthermore, the highest impact occurred in the group where no changes were imposed. The first group maintained its global efficiency value, while the second had its efficiency decreased by about 8%. Similarly, an increase in the capacitance value caused a reduction in its efficiency (lesser but around 2%). Finally, a numerical model was developed and validated through experimental tests to be an applicable prediction model This work was supported by FCT, through IDMEC, under LAETA, project UID/EMS/50022/2020 and the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA PROGRAMME 2014-2020 and CERIS (CEHIDRO-IST) , the Hydraulic Laboratory, for experiments on PATs. This research is also supported by the "Program to support the academic career of the faculty of the Universitat Politecnica de Valencia 2019/2020 in the project 'A Step Ahead In Sustainability Of Water Systems For The Energy Transition In Communities' of the Modesto Perez-Sanchez

New technologies for water pressurized systems try to implement the introduction of strategies for the improvement of the sustainable indicators. One of these technologies is the implementation of pumps working as turbines. The use of these recovery machines was proposed some years ago, and the interest in this technology has increased over the last years. The simulation of these machines is necessary when analyzing pressurized water systems, or when optimization procedures are proposed for their management, great care must be taken. In these cases, the knowledge of the operation curves is crucial to reach accurate results. This study proposes different regression expressions to define three operational curves when the machines operate under variable rotational speed. These curves are the best efficiency head, the best power-head and the best power flow. The here proposed methods were compared with other five published methods. The comparison shows the proposed method was the best when it is compared with the rest of the published procedures, reducing the error values between 8 and 20%.

Incorporating energy recovery systems using renewable energies in water distribution systems is being analysed and implemented to improve sustainability, ensuring the SDG-7. Pumps working as turbines are an innovative technology, and a powerful tool to reach this energy improvement. This research develops a methodology that enables the development of an analysis tool for the optimized regulation of an energy recovery system using Simulink MATLAB. The said methodology is capable of processing variable operation systems (VOS), which considers the flow variation through time. Also, it considered the variation of the rotational speed of the machines linked directly to the efficiency aiming to maximize the recovered energy. Finally, the methodology was applied to a real case study defining the signal parameters to the regulation equipment in terms of numbers of pumps working as turbines (PATs) in operation, rotational speed, and the degree of opening of the pressure reducing valves installed. The tool contemplates the energy analysis, which shows the recovery of 60% of the supplied energy in the system. This daily recovered energy was above 1898 kWh, and it contributed to an increase in efficiency and sustainability.