Hydropower Schemes Research Articles

Ruin-of-the-rivers? A global review of run-of-the-river dams.

The classification of a hydropower scheme as run-of-the-river (or run-of-river; ROR) evokes an image of a low-impact installation; however, examination of eight case studies worldwide shows that substantial negative societal and ecological impacts are tied to them, albeit in somewhat different ways. We conclude that ROR dams not only potentially displace communities, disrupt livelihoods, and degrade environments in surrounding areas, but they also divert water from areas of need, impact aquatic ecology through habitat destruction and disruption of fish migrations, emit non-trivial amounts of greenhouse gases over the lifespan of the project, and disrupt streamflow in downstream river sections. While these negative impacts vary on a case-by-case basis, medium and large ROR dams consistently have multiple and cumulative impacts, even when not having appreciable reservoirs. We contend that many impactful dams do not qualify as low-impact ROR projects, despite being defined as such. Such mislabeling is facilitated in part by the ambiguous definition of the term, which risks the ROR concept being used by proponents of impactful structures to downplay their negative effects and thus mislead the public or gain status, including within the Clean Development Mechanism in relation to mitigating climate change.

Downstream Migration Success of Atlantic Salmon Smolts in a River Catchment Highly Fragmented by Hydroelectric Impoundments

ABSTRACTRiverine habitat fragmentation by barriers, including impoundments, is common and their effects on obligate aquatic organisms are manifold. Organisms, such as Atlantic salmon (Salmo salar), that make extensive river migrations are particularly vulnerable to the effects of impoundments. In this study, we use acoustic telemetry to examine the migratory behaviour of Atlantic salmon, as they migrate to sea for the first time as juvenile ‘smolts’, in a river with a series of dams that form a complex hydropower scheme. We demonstrate that overall migration success in the River Dee catchment and particularly through standing waters was remarkably high. We speculate that high migration success in standing waters could be due to relative current speeds providing good quality directional cues to migrants. Migration success past the two dams in this study, was relatively high, although the number of unsuccessful passage attempts before a successful passage was also very high. The vast majority of smolts passed the dams when the turbines were operational. At one dam, smolts did not use an available fish pass but migrated through the generating turbines. These findings provide several routes through which generation could be managed to enhance the success of downstream smolt migration in rivers where there are similar patterns of hydrogeneration in place.

Consideration of climate change impacts on a hydropower scheme in Iran

Consideration of climate change impacts on a hydropower scheme in Iran

Shaping changes in the ecological status of watercourses within barrages with hydropower schemes – literature review

Shaping changes in the ecological status of watercourses within barrages with hydropower schemes – literature review

High-resolution mapping of land use changes in Norwegian hydropower systems

The Transition towards sustainable energy systems requires phasing out fossil fuels. Hydropower is a key source of renewable energy and can contribute to reaching a 100 % low carbon-based energy system. Uncertainty remains about land cover changes due to hydropower deployment with a widespread perception of major losses in the land from inundation and associated habitat loss in the surrounding areas due to improved access and recreational use. Norway has a dominant share of hydropower generation in Europe with knowledge gaps in the associated land cover changes. We conducted one of the first retrospective analyses of land use change associated with hydropower development in Norway during the last 80 years. Using remote sensing data, we performed object-based analysis on sets of aerial images representing land systems before and after hydropower construction. We quantified the change in the land due to development of 40 hydropower schemes representing 24 % of the total Norwegian installed capacity. Our analysis revealed that 88 % of analyzed reservoirs were developed by regulating or expanding natural lakes. Vegetation growth was observed in the surrounding regions of 22 of 40 schemes, while urbanization was limited to only 0.9 % of the total surrounding area, primarily located within 400 m from reservoir's borders. Our findings provide insights into interaction between land use change and hydropower development in Norway. Our work provides a basis for further assessment of relevant environmental impacts and can be used to quantify expected land changes due to an increase in Norway's hydropower with integration into the European energy market.

Assessing small hydropower sites in Nigeria for sustainable development using ArcGIS

This paper focuses on the prospects of small hydropower plants (SHP) in Nigeria and utilizes ArcGIS software for analyzing the country’s hydropower energy potential. The analysis conducted using ArcGIS reveals the significant SHP potential in various states across Nigeria. By overlaying water areas and waterline data on maps, potential sites for SHP are identified, particularly in states such as Borno, Niger, Edo, Anambra, and Jigawa. Further analysis was done using data for water lines in Nigeria converted into shaped files for the six geopolitical zones of Nigeria, with the various states and local government areas, to provide expanded views for different possible schemes for SHP. Data set were built up for the different geopolitical zones and statistical analyses were done for SHP potentials. Interpolations were performed using Inverse Distance Weighting (IDW) tool on ArcGIS to show areas ideally suitable to site dam schemes for hydropower production and other schemes that require less water storage for small hydropower production. The strengths of each state in the various zones with regard to water inlands and lands subject to inundation were also identified. Some major challenges and opportunities in using ArcGIS in assessing small hydropower schemes in Nigeria, were also highlighted.

An assessment of the economic feasibility of the floating PV technology in Aotearoa–New Zealand

Electricity generation from utility-scale solar facilities is projected to grow to between 5 and 16 TWh by 2050 in Aotearoa–New Zealand. The floating photovoltaic (FPV) technology is considered a viable option for the country, because of the good solar resource at existing hydropower schemes. This paper aims to inform the understanding of the economic feasibility of FPV systems through the analysis of specific cases – Maraetai Dam and Lake Tekapo. To do so, the solar resource and FPV outputs are obtained through the modelling of Solargis and using industry standard technical specification. As well as the normal uncertainties associated with (potential) FPV performance evaluations, the influence of water temperature is also considered. The overall FPV output is estimated to be between 1,115 and 1,497 kWh/kWp. Using available Engineering, Procurement and Construction (EPC) costs, the levelized cost of energy (LCOE) metric, for a 10 MW installation, is determined to be between NZ$176 and NZ$237 per MWh, with total electricity generation over 25 years between 263 and 353 GWh. In order to reach the required LCOE value of less than NZ$100/MWh for utility scale generation, the EPC costs will have to be reduced by a factor of 2 to around NZ$1,500/kWp.

Impact of climate change on hydropower potential in the UK and Ireland

Despite making up a small proportion of total electricity generation in the UK and Ireland, hydropower has an important role in providing resilience to the energy network and contributing to governmental net-zero emissions targets. Run-of-river hydropower schemes are popular in both countries, but are vulnerable to changes in streamflow patterns. In this study, we examine how climate change induced streamflow alterations will affect hydropower in the UK and Ireland. We use EXP-HYDRO hydrological model to simulate future streamflow in 585 catchments under worst-case future climate change (Representative Concentration Pathway 8.5). Within 178 catchments we identify 531 run-of-river hydropower abstractions and analyze the impact of modelled streamflows on hydropower water abstraction characteristics. Results show that by 2080 there will be a reduction in annual hydropower water abstraction in Wales (−2.1%) and Northern Ireland (−1.9%), increased abstraction in England (+3.0%) and Scotland (+12.9%), and no changes in Ireland. For annual average power generation, a 6.2% increase is projected for Great Britain by the 2080s, and a 1.4% decrease for the island of Ireland. Our results suggest that the ability of hydropower schemes to make optimal use of future flows will depend on abstraction license conditions, with implications for overall power grid resilience.

Modelling and simulation of a hydropower system using wastewater discharged from Marine outfalls

Municipal or industrial wastewater from the treatment plant is discharge by marine outfalls through the use of a pressurized pipeline scheme. The wastewater is discharged deep under the sea surface at a distance from the coast. During discharging of the wastewater, the excess pressure is applied to push the wastewater deep under the sea. The operation of allowing the wastewater to be discharge far away from the coast, takes the environmental perspective into consideration. However, from engineering perspective, significant amount of energy is wasted during discharging of wastewater and can be recovered. Hence, the aim of this paper is to model and simulate an energy recovery system able recover some of the energy wasted, using a hydro-turbine and generator in a hydropower scheme. The simulation results, for the South African Green Point outfall, have demonstrated that the marine outfalls have the potential to generate electrical energy during discharging of the wastewater. Using a 16-kW permanent magnet synchronous generator, the load demand of a 16 kW resistive load was met at a nominal voltage of 313 Vrms. Given the constant discharge flowrate of 28.4 × 106 litres of wastewater per day at Green Point outfall site, a significant amount of electrical energy can be generated.

Investigation into cavitation damage potentiality using pressure pulsation phenomena in a low head Francis turbine for small hydropower schemes

This study investigated unsteady pressure pulsations in a low-head Francis turbine under the effects of strong cavitation for different plant discharge factors and submergence levels of the draft tube at normal water temperature. The effect of the submergence water level of the draft tube at a dominating frequency was found to be negligible underrated-load and upper-part-load plant-operating conditions. However, the amplitude increased as the submergence of the head of the draft tube increased. At a high plant discharge coefficient, i.e., under overload conditions, the maximum amplitude was found at the blade-passing frequency. Additionally, a cavitation region was observed in the vicinity of the blades of the Francis runner, indicating the start of cavitation damage. Moreover, the results revealed the characteristics of low-frequency high amplitudes, which were predominant in the draft tube for the lower-part-load condition. According to the relevant literature, such amplitudes can cause instability in the hydraulic system of a powerplant, potentially resulting in fatigue-related damage to the turbine during operation. This study's predicted numerical results indicated the potentiality of cavitation damage in low-head Francis runners for different plant-operating conditions.

Estimating Energy Efficient Design Parameters for Trash Racks at Low Head Hydropower Stations

Trash racks are usually composed of an array of bars installed in a hydropower scheme to safeguard the turbines by collecting water-borne detritus. However, current design approaches for the design of trash racks focus on structural criteria. A little attention renders the proper evaluation of hydraulic criteria, which causes a significant hydraulic head loss in low head hydropower schemes with an integral intake. This study investigates the head loss through trash racks by employing computational fluid dynamics (CFD) for several design combinations. A three-dimensional model of trash racks using fractional area/volume obstacle representation (FAVOR) method in FLOW-3D is set up to define the effects of the meshing on the geometry and several simulations are carried out considering various approach velocities and different bar spacings, inclination angles, and blockage ratios. The results indicate that head loss increases with an increase in approach velocity, the inclination angle of the rack with channel bed, and blockage ratio. It is noticed that a clear spacing between vertical bars greater than or equal to 0.075 m has a minimum head loss before it becomes significantly high for lower spacing. In addition, the head loss coefficient increases for screen angles greater than 60°, which can be considered as an optimal parameter for design purpose.

The Assessment of Environmental and Socio Economic Benefits of River Siti Hydropower Scheme in Mount Elgon Biosphere Reserve, Uganda

The study was carried out to assess the perceptions and responses of targeted beneficiaries of Siti Hydropower on the impact and benefits of the renewable energy scheme. Households in proximity to the power supply line were purposefully selected as a sample population. A semi-structured questionnaire was administered to 38 randomly selected household heads living on both sides of the power supply line. Face to face interviews with staff working with hydropower project and Mt. Elgon National Park (Biosphere Reserve) as well as the District Natural Resource Managers were conducted. In addition, nine focused group discussions involving 72 people, (eighteen of whom were women) were held. The results show that 78.9% of the respondents were of the view that the hydropower project had caused significant environmental problems and 21.1 % of the respondents did not think that the project had any significant negative impact on the environment. About 47.4% of the respondents associated the project with soil erosion along the water channel as the most negative environmental impact of the project, while 21.4% of the respondents highlighted the disruption of the water flow of R. Siti and R. Nyalit and 13.2% of the respondents identified deforestation especially inside Mt. Elgon National Park where the weir (intake) of the power station was located. However, 18.4% of the respondents did not believe that the project caused any negative environmental problem. Regarding the anticipated benefits, 42.1% of the respondents associated the project with social economic improvement of residents, 36.8% reduction on the reliance on fuel wood energy and 21.1% protection of R. Siti and R. Nyalit banks.

DOES MICRO HYDROPOWER IMPROVE PRODUCTIVITY OF MAIZE CROP? A CASE OF RURAL KHYBER PAKHTUNKHWA

Micro hydropower (MHP) schemes play an important role in socio-economic development of an area. This study attempts to identify the effects of MHP schemes on productivity of maize crop in three selected tehsils namely Alpuri, Besham and Puran of district Shangla, Khyber Pakhtunkhwa, Pakistan. A total of 220 households were randomly selected from the selected tehsils. Primary data were collected through a questionnaire-based survey. Binary logit model was used to find out the effects of MHP scheme on productivity of maize crop in the research area. The results of the estimated model confirm that MHP scheme has a positively significant effect on productivity of maize crop and thereby, income of people in the study area, as shown by the p-value less than 0.05. The overall model was highly significant which confirms that MHP positively affects productivity of maize crop and income of the farmers. The study concludes that electricity produced from MHP schemes has an important role in socio-economic and sustainable agricultural development in the research area in specific and rural areas in general.

Operational hydrometeorological forecasting on the Rhône River in France: moving toward a seamless probabilistic approach

Compagnie Nationale du Rhône (CNR) has operated the Rhône River since 1934 according to three core missions – hydropower generation, inland navigation and irrigation – using 19 run of-river multi-purpose hydropower schemes. To ensure hydraulic safety and optimise hydro power production and commercialisation, CNR developed a range of hydrometeorological forecasting tools, currently run every day in real time by CNR forecasters. The first is an hourly deterministic tool, giving forecasts up to the next 4 days. This tool does not allow quantification of uncertainties, which is a key issue to improve forecasts and take better operational decisions. At the same time, national meteorological centres provide ensemble meteorological forecasts, and thus information about uncertainty. Therefore, CNR is developing a chain of ensemble forecasting tools based on ensemble meteorological forecasts and various post-processing methods. These tools provide hourly/daily hydrological forecasts up to the next 4/12 days. The operational use of such a probabilistic forecasting chain is intended to facilitate decision-making processes. All these tools have been designed to leave large room for human expertise. This paper presents the tools described above, but also their interaction with human forecasters as well as the first attempts to link them together to add consistency between the different forecast types.

Creep of concrete during Alkali-Aggregates Reaction

The sustainability of operating hydropower schemes is an important issue in the context of ecologic-transition. However, some concrete dams are affected by Alkali-Aggregates Reaction (AAR), which can be a major concern for their safety. In the case of arch dams, where the overall stability is based on the transmission of stresses from the structure to the foundation, the swelling induced by the reaction can generate additional stresses. As concrete creeps under mechanical loading, a competition occurs between stress rising due to swelling and stress release due to creep. To capture this competition, the creep test must be led after a significant level of swelling and not before its initiation as often observed in lab tests. So, a new testing program has been developed to capture interactions between compressive creep and swelling induced by ongoing AAR. It was applied on two similar concretes differing one-another only by the reactivity of their aggregates. After one month of autogenous curing, concrete samples were immersed in sodium-hydroxide solution to accelerate the AAR. Once a significant part of the maximal free swelling is reached, they were sealed to keep the ongoing reaction, and a part of them were loaded uniaxially, while the others remained free of stress. The results show that 40% of the swelling occurring before the loading was rapidly erased in the compressed direction. Afterwards, similar creep evolutions were observed for reactive and non-reactive concretes, without any report of the swelling in the free directions for the reactive one, despite the ongoing of AAR.

Potential of a Nonperennial Tributary Integrated with Solar Energy for Rural Electrification: A Case Study of Ikukwa Village in Tanzania

This study evaluates the hydropower potential in the design of a micro-hydro/solar photovoltaic hybrid system with battery energy storage for increasing the access to electricity in Ikukwa Village in Mbeya Region of Tanzania. Usually, hybridized hydropower schemes are designed from perennial streams for the provision of electricity. This study incorporates the run-of-the river (COE) power scheme, which originates from the untapped potential of nonperennial hydro-energy source and the use of traditional approach of data measurements for Ikata tributary to design hybrid system. The system is optimized by the minimization of the total net present cost (NPC) and cost of energy (COE) using the soft computing method of Hybrid Optimization of Multiple Energy Resources (HOMER) software and artificial intelligent (AI) techniques. AI optimization techniques such as particle swarm optimization (PSO), grey wolf optimization (GWO), and GWO-PSO hybrid (GWO-PSOHD) algorithms have been employed for further optimal results. The data for solar radiation and the tributary have been obtained from the National Aeronautics and Space Administration (NASA) and traditional methods of measurements, respectively. The estimated maximum water flow rate and head are 2.943 m3/s and 13 m, respectively. In the same period, the approximated theoretical power potential of the tributary is found to be 375 kW. Total NPCs obtained from HOMER, PSO, GWO, and GWO-PSOHD methods are $ 141, 397.76, $ 95 167.21, $ 92 472.82, and $ 91,854.10, respectively. Similarly, the optimal results of COE from HOMER, PSO, GWO, and GWO-PSOHD approaches are $ 0.1818/kWh, $ 0.1185/kWh, $ 0.1182/kWh, and $ 0.1181/kWh, respectively. Comparatively, PSO implementation has indicated the greatest energy cost, while the cost acquired by GWO-PSOHD is the lowest for all aforementioned AI optimization techniques. The tributary under study has a high potential of diversification of energy sources for rural electrification in the area of study and other parts of the world with comparable conditions.

Design of Desanding Facilities for Hydropower Schemes Based on Trapping Efficiency

Turbine wear caused by hydro-abrasion due to suspended sediment in the turbine water has a negative impact on the power production and revenue of hydropower schemes. Efficiency of desanding facilities that reduce suspended sediment load ahead of turbines is key to limiting hydro-abrasion. Existing facilities built according to common design approaches often show lack of performance, in particular under non-ideal site-specific inlet and outlet conditions. Consequently, a new design concept that allows for the optimized design of desanding facilities at hydropower schemes has been developed based on prototype field measurements and CFD modeling. The effects of facility layout and components, such as tranquilizing racks, transition zone and outflow weir and related design parameters on the flow field and involved particle settling have been investigated in a comprehensive numerical model study. Hence, length adjustment terms were deduced from resulting changes in trapping efficiency, which allow for the estimation of the required basin length and an optimized facility layout. Compared to design approaches considering linear settling trajectories of sediment particles, the proposed procedure leads to longer settling basins in general and thus to increased trapping efficiencies of desanding facilities. Furthermore, the findings about the effect of specific facility components may allow for the optimisation of existing desanding facilities in an economical way.

Counter-reporting sustainability from the bottom up: the case of the construction company WeBuild and dam-related conflicts

Controversies around large-scale development projects offer many cases and insights which may be analyzed through the lenses of corporate social (ir)responsibility (CSIR) and business ethics studies. In this paper, we confront the CSR narratives and strategies of WeBuild (formerly known as Salini Impregilo), an Italian transnational construction company. Starting from the Global Atlas of Environmental Justice (EJAtlas), we collect evidence from NGOs, environmental justice organizations, journalists, scholars, and community leaders on socio-environmental injustices and controversies surrounding 38 large hydropower schemes built by the corporation throughout the last century. As a counter-reporting exercise, we code (un)sustainability discourses from a plurality of sources, looking at their discrepancy under the critical lenses of post-normal science and political ecology, with environmental justice as a normative framework. Our results show how the mismatch of narratives can be interpreted by considering the voluntary, self-reporting, non-binding nature of CSR accounting performed by a corporation wishing to grow in a global competitive market. Contributing to critical perspectives on political CS(I)R, we question the reliability of current CSR mechanisms and instruments, calling for the inclusion of complexity dimensions in and a re-politicization of CS(I)R accounting and ethics. We argue that the fields of post-normal science and political ecology can contribute to these goals.

Multiyear rainfall variability in the Mono river basin and its impacts on Nangbeto hydropower scheme

Abstract. Hydropower energy, the main renewable energy source in West Africa, contributes to more than half of the Togo and Benin National electrification. This resource highly depends on water availability in rivers or reservoirs. The water availability heavily relies on climate patterns of the area. In the climate change context, the sustainability of hydropower plants is at risk. This work aims to assess the sensitivity of the Nangbeto hydropower plant to multiyear climate variability using statistical analysis. The results show that energy generation at Nangbeto hydropower is more modulated by four main variables namely inflow to reservoir, water level, rainfall of the actual and the previous year. The energy generation is found to be strongly and significantly correlated to inflow to reservoir, water level, and rainfall. Overall, the Nangbeto hydropower generation is more sensitive to inflow which is controlled by climate variables (rainfall, temperature) and land use/cover change. Therefore, the probable future change in these variables is suggested to be deeply investigated.

Hydraulic Design Challenges of High Head 880 MW Gouvães Pumped-Storage Power Plant

The 880 MW pumped-storage power plant of Gouvães, which is part of the Alto Tâmega hydro power scheme from Iberdrola is currently under construction in the north of Portugal. The power plant is equipped with 4 reversible Francis pump-turbines with a gross head of 660 m. The power plant features several challenges with respect to the hydraulic design such as: i) ultra-high-head single stage reversible Francis pump-turbine of very low specific speed leading to severe hydraulic transients, ii) a long high-pressure penstock, iii) an headrace differential surge tank linked to a 4700 meters long headrace tunnel and iv) a complex tailrace differential surge tank linked to a 700 meters long tailrace tunnel. To perform the hydraulic design of the pumped-storage power plant, a stepwise approach presented in the paper was undertaken by Iberdrola. A detailed 1D hydraulic transient analysis was performed to optimize the headrace and tailrace surge tank dimensions. Then a combined CFD and reduced scale physical transient tests of both surge tanks was conducted. This enabled to address the complex 3D flow physics that develop in surge tanks but are not captured by 1D transient simulations such as free surface, upsurges against walls, verification of throttle singular head losses and effects not captured by 3D CFD such as air-water mixture and detection of air entrainment risk.