Special Issue "Electrical Energy Production in the Water Sector"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Electrical Power and Energy System".

Deadline for manuscript submissions: closed (15 October 2019).

Special Issue Editor

Prof. Dr. Helena M. Ramos
Website
Guest Editor
Civil Engineering, Architecture and Georesources Department, CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, 1049-001, Portugal
Interests: hydropower; hydraulic transients; pumped-storage; water and energy nexus; hydrodynamic
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Special Issue Information

Dear Colleagues,

Water, as the most vital and scarce resource, is seen as an opportunity to invest in growing knowledge and technologies for a sustainable future. From the source until reaching the user’s tap, efficient sustainable water management is regarded as a priority for current mindful societies. Renewable energy solutions have had an exponential growth over the past years, and prospects of increasing. Solar and wind resources have been regarded together to define hybrid solutions, in order to adapt to new systems, promoting more efficient networks. Solar and/or wind pumping are examples of new solutions that are being invested because of their feasibility and environmental impact. Moreover, one of the most reliable alternative energy sources is hydropower. In the scope of small and micro hydropower solutions, and from the point of view of optimizing the water sector systems, the concept of recovering energy that is currently being wasted emerges as an opportunity to not only to attain sustainability, but also capitalization.

Hence, on the one hand, the water sector systems consume high quantities of energy that, in light of a sustainable future, needs to be recovered. The expenses necessary for water pumping are substantial and the need for solutions that can harness some of the system’s energy is perceived as being more and more essential. The excessive water pressure existing in these systems induces significant water and energy losses, needing better water sector systems’ efficiency solutions, and at the same time creating a potential energy that can be harnessed by means of micro hydropower plants (e.g. a pump working as a turbine (PAT) or other energy converters suitable for low powers). On the other hand, the high intermittence of renewable energy sources sets the production of electricity, which remains highly dependent on fossil fuels. As there is complementarity between renewable energy sources, their joint integration will be a good solution to reduce this dependency. Together with this, a pumped-storage system capable of generating hydro reserves can coexist in an optimization way to supply the surplus demand from small to large solutions.

Hydropower is a mature technology, with the possibility of technological improvements and the flexibility to adapt to many new challenges, namely: the water–food–energy–ecosystem nexus, climate change and its impacts on water resources, the storage of electrical energy for other renewable sources integration, pressure control and leakage reduction in water supply systems, and for energy recovery. Hydropower offers a significant potential for carbon emission reductions, and with an annual generation of 4000 TWh, 16% of the world electricity generation, hydropower remains the largest source of renewable energy in the electricity sector. There is a potential to double the global hydropower generation to 8000 TWh or more.

In this Special Issue, the role of hydropower in the improvement of the water sector efficiency and on the reduction of energy dependency are important variables for the near future. In this context, authors are invited to submit papers dealing with new design solutions, hybrid solutions, energy recovery, pumped-storage hydropower and hybrid plants, pump as turbine operation, new energy converter technologies, complementarity between renewable sources, range of hydropower turbines, eco-design and systems for a more flexible operation, and pump and tubine optimization to variable speed.

The scope of this Special Issue is, of course, not limited to the above-mentioned topics. The journal will be pleased to receive papers from the full value-chain of hydropower, including resource-mapping, planning, design, construction, maintenance and operation, interaction and integration with other uses of water and energy, and the effects on the climate change.

Prof. Helena M. Ramos
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Irrigation systems
  • Pump as Turbine (PAT)
  • Water Distribution Networks (WDN)
  • Hydropower solutions
  • Sustainability
  • Operation
  • Eco-design
  • Water–food–energy–ecosystem nexus
  • Renewable energy
  • Hybrid energy solution
  • Pumped-storage

Published Papers (4 papers)

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Research

Open AccessArticle
Micro Axial Turbine Hill Charts: Affinity Laws, Experiments and CFD Simulations for Different Diameters
Energies 2019, 12(15), 2908; https://doi.org/10.3390/en12152908 - 28 Jul 2019
Abstract
Water supply systems are one of the main hydraulic systems with significant potential for the installation of micro-hydropower devices. Although there are already some mini-hydropower applications in water supply systems, it is still a huge potential that continues to be under-exploited. The arrangement [...] Read more.
Water supply systems are one of the main hydraulic systems with significant potential for the installation of micro-hydropower devices. Although there are already some mini-hydropower applications in water supply systems, it is still a huge potential that continues to be under-exploited. The arrangement based on an axial turbine, such as an inline tubular propeller, with different diameters and rotational speeds suitable to exploit the existing potential in the water sector, is fully tested. The turbine with the nominal diameter of 85 mm was analysed through experimental campaigns and numerical models for a large range of heads and flow measurements to access its performance. A good correlation between the physical model and the numerical results were obtained, with mean values of deviation less than 5% regarding flow, mechanical power and efficiency. These results were extrapolated to other similar turbine with 170 mm, using affinity laws to investigate the power extraction performance. Both geometries were also numerically investigated using computational fluid dynamics (CFD) models and comparisons were made between the affinity model and experimental results. The results identified differences when compared with the classical affinity curves. Therefore, new formulations based on affinity equations were proposed for the analyzed axial turbine with different diameters without imposing a constant turbine efficiency since actually it does not keep constant as CFD calibrated model proved. Compared to experimental test efficiencies for different rotational speeds, the new proposed affinity laws provided a maximum error of 12% for both diameters. Full article
(This article belongs to the Special Issue Electrical Energy Production in the Water Sector)
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Open AccessArticle
Flow Conditions for PATs Operating in Parallel: Experimental and Numerical Analyses
Energies 2019, 12(5), 901; https://doi.org/10.3390/en12050901 - 08 Mar 2019
Cited by 1
Abstract
Micro-hydro systems can be used as a promising new source of renewable energy generation, requiring a low investment cost of hydraulic, mechanical, and electrical equipment. The improvement of the water management associated with the use of pumps working as turbines (PATs) is a [...] Read more.
Micro-hydro systems can be used as a promising new source of renewable energy generation, requiring a low investment cost of hydraulic, mechanical, and electrical equipment. The improvement of the water management associated with the use of pumps working as turbines (PATs) is a real advantage when the availability of these machines is considered for a wide range of flow rates and heads. Parallel turbomachines can be used to optimize the flow management of the system. In the present study, experimental tests were performed in two equal PATs working in parallel and in single mode. These results were used to calibrate and validate the numerical simulations. The analysis of pressure variation and head losses was evaluated during steady state conditions using different numerical models (1D and 3D). From the 1D model, the installation curve of the system was able to be defined and used to calculate the operating point of the two PATs running in parallel. As for the computational fluid dynamics (CFD) model, intensive analysis was carried out to predict the PATs′ behavior under different flow conditions and to evaluate the different head losses detected within the impellers. The results show system performance differences between two units running in parallel against a single unit, providing a greater operational flow range. The performance in parallel design conditions show a peak efficiency with less shock losses within the impeller. Furthermore, by combining multiple PATs in parallel arrangement, a site’s efficiency increases, covering a wide range of applications from the minimum to the maximum flow rate. The simulated flow rates were in good agreement with the measured data, presenting an average error of 10%. Full article
(This article belongs to the Special Issue Electrical Energy Production in the Water Sector)
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Open AccessArticle
Numerical Simulation Three-Dimensional Nonlinear Seepage in a Pumped-Storage Power Station: Case Study
Energies 2019, 12(1), 180; https://doi.org/10.3390/en12010180 - 07 Jan 2019
Cited by 1
Abstract
Due to high water pressure in the concrete reinforced hydraulic tunnels, surrounding rocks are confronted with nonlinear seepage problem in the pumped storage power station. In this study, to conduct nonlinear seepage numerical simulation, a nonlinear seepage numerical model combining the Forchheimer nonlinear [...] Read more.
Due to high water pressure in the concrete reinforced hydraulic tunnels, surrounding rocks are confronted with nonlinear seepage problem in the pumped storage power station. In this study, to conduct nonlinear seepage numerical simulation, a nonlinear seepage numerical model combining the Forchheimer nonlinear flow theory, the discrete variational inequality formulation of Signorini’s type and an adaptive penalized Heaviside function is established. This numerical seepage model is employed to the seepage analysis of the hydraulic tunnel surrounding rocks in the Yangjiang pumped-storage power station, which is the highest water pressure tunnel under construction in China. Moreover, the permeability of the surrounding rocks under high water pressure is determined by high pressure packer test and its approximate analytical model. It is shown that the flow in the surrounding rocks is particularly prone to become nonlinear as a result of the high flow velocities and hydraulic gradients in the nearby of the seepage-control measures and the high permeability fault. The nonlinear flow theory generates smaller flow rate than the Darcy flow theory. With the increase of nonlinear flow, this observation would become more remarkable. Full article
(This article belongs to the Special Issue Electrical Energy Production in the Water Sector)
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Open AccessFeature PaperArticle
A Geospatial Assessment of Small-Scale Hydropower Potential in Sub-Saharan Africa
Energies 2018, 11(11), 3100; https://doi.org/10.3390/en11113100 - 09 Nov 2018
Cited by 11
Abstract
Sub-Saharan Africa has been at the epicenter of an ongoing global dialogue around the issue of energy poverty. More than half of the world’s population without access to modern energy services lives there. It also happens to be a sub-continent with plentiful renewable [...] Read more.
Sub-Saharan Africa has been at the epicenter of an ongoing global dialogue around the issue of energy poverty. More than half of the world’s population without access to modern energy services lives there. It also happens to be a sub-continent with plentiful renewable energy resource potential. Hydropower is one of them, and to a large extent it remains untapped. This study focuses on the technical assessment of small-scale hydropower (0.01–10 MW) in Sub-Saharan Africa. The underlying methodology was based on open source geospatial datasets, whose combination allowed a consistent evaluation of 712,615 km of river network spanning over 44 countries. Environmental, topological, and social constraints were included in the form of constraints in the optimization algorithm. The results are presented on a country and power pool basis. Full article
(This article belongs to the Special Issue Electrical Energy Production in the Water Sector)
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