Os Estudos de Impacto Ambiental (EIA) foram legalmente institucionalizados no Brasil durante a década de 1980. Estes são balizados a partir do Termo de Referência (TR) que define as diretrizes que o EIAs deverão seguir, mas não determina qual grupo faunístico e metodologias devem ser adotadas, o que fica a critério dos empreendedores e consultores contratados. Visando verificar se esse procedimento resulta ou não em ausência de padronização entre os TRs e os relatórios de EIAs, bem como em outros possíveis desajustes que resultem na menor eficácia dos relatórios de EIA, foram compararados nove relatórios de empreendimentos hidrelétricos das décadas de 1980, 1990 e dos anos 2000. Para tanto, foram utilizadas informações como atendimento às exigências contidas nos TRs e metodologias utilizadas, no que diz respeito aos métodos de coleta, esforço amostral, levantamento de grupos de aves e mamíferos dependentes de hábitats específicos relacionados, solidez das listas de faunas e análise dos dados. Além disso, foi avaliada a aplicabilidade do delineamento RAPELD na avaliação de impacto de empreendimentos hidrelétricos. Os resultados indicaram que há discrepância quanto aos esforços amostrais e às metodologias utilizadas nos estudos, além da ausência de informações requeridas pelos Termos de Referência e a escassez de dados relacionados aos grupos de fauna associada aos ambientes que serão afetados e a aves e mamíferos dependentes de ambientes aluviais. O delineamento RAPELD muitas vezes não é aplicável em regiões com alterações antrogênicas, mas deve-se levar em consideração que a recomendação de sua utilização pelo órgão ambiental para um casos analisados indica uma sutil evolução recente no delineamento amostral. As análises realizadas neste trabalho podem servir como indicadores sobre o estado geral da efetividade dos EIA como ferramentas a serem utilizadas pela sociedade no que se refere às intervenções ambientais. / Environmental Impact Assessment (EIA) studies were legally institutionalised in Brazil in the 1980s, and their elaboration is based on guidelines established by Terms of Reference (TR) which define the main directives to be followed by each project\'s EIA, but often do not determine the faunal groups to include and the methods to be employed choices which are then left at the discretion of the company proposing the project and their hired consultants. In order to analyse whether this procedure does or does not result in an absence of standardisation among Terms of Reference and EIA studies, as well as in other disparities which may impair the effectiveness of EIA reports, this work compared 9 EIA reports for hydro-power projects from the 1980s, 1990s and 2000s. The reports were compared with regard to such information as compliance with the requirements set by the TRs and methodology used (including sampling methods, sampling effort, study of bird and mammal groups dependent on specific habit types, reliability of the fauna lists provided and data analysis). The appropriateness of the RAPELD sampling design for Hydro-power environmental impact assessments was also analysed. The results indicated incongruities as to the sampling effort and the methodologies employed for the studies, as well as an absence of information required according to the Terms of Reference and a paucity of data specifically dealing with fauna groups associated with environments to be directly affected by the projects and with mammals and birds dependent on alluvial environments. The RAPELD sampling design is often considered inappropriate for highly human-modified regions, but it is noted that its recommendation by environmental agencies for some of the cases analysed indicates a recent improvement in sampling designs. This work\'s findings may serve as indicators of the overall state of the effectiveness of EIA studies as tools for the society to assess the effects of interventions in the environment.

The water level at Hjälta power station in Faxälven varies depending on the water flow that passes through the power station. The varying water level causes head losses, lesser energy generation and loss of income. The varying water level is caused by a short but narrow and shallow part of the river, known as Klockarforsen. To increase the water flow and decrease the resulting head losses, it is possible to dredge the stream bed in Klockarforsen in order to achieve a greater depth.  By using a sonar to map the bathymetry in Klockarforsen, it has been possible to create a model of this part of the river. The model has been constructed and processed in ArcGIS and HEC-RAS, in order to examine how a dredging would affect the water level, head losses, energy generation, income and retention water levels.  The results show that a dredging to a depth of four or six meters could raise the water level and the head height at Hjälta power station with an average of 0.32 and 0.41 meters, respectively. During the period between 2014-2019, 1.11-3.84 GWh more energy would have been generated annually if Klockarforsen had been dredged. Which means that the income for the power station would have increased by between MSEK 0.39-1.3 per year. The increased energy generation and income are considerable, but in terms of how much energy and income is generated annually, the figures are more modest. The energy production and income increase by between 0.13-0.3 percent annually.

abstract: Climate change is affecting power generation globally. Increase in the ambient air temperature due to the emission of greenhouse gases, caused mainly by burning of fossil fuels, is the most prominent reason for this effect. This increase in the temperature along with the changing precipitation levels has led to the melting of the snow packs and increase in the evaporation levels, thus affecting hydropower. The hydropower in the United States might increase by 8%-60% due to Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 scenarios respectively by 2050. Wind power generation is mainly affected by the change in the wind speed and solar power generation is mainly affected by the increase in the ambient air temperature, changes in precipitation and solar radiation. Solar power output reduces by approximately a total of 2.5 billion kilowatt- hour (kWh) by 2050 for an increase in ambient air temperature of 1 degree Celsius. Increase in the ambient air and water temperature mainly affect the thermal power generation. An increase in the temperature as per the RCP 4.5 and RCP 8.5 climate change scenarios could decrease the total thermal power generation in the United States by an average of 26 billion kWh and a possible income loss of around 1.5 billion dollars. This thesis discusses the various effects of climate change on each of these four power plant types. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2020

In the last decade, the power generation mix and the energy markets have been affected by the growing development of distributed and renewable energy sources.Nevertheless, a significant drawback of solar and wind energy is their intermittent and weather-dependent production, which often leads to a mismatch between renewable energy production and its use. Thus, the need for energy storage is recently emerging and becoming more relevant in this era of the energy transition. Among several technologies, today, pumped hydro energy storage (PHES) represents the largest share of the energy storage systems in the world. However, possible new investors, who might be attracted by potential profit in PHES, are repelled bythe long payback period and the scarcity of adequate site topology for such power plants. Relevant design decisions can be taken to reduce the costs and improve the performance or to escape the PHES topographical requirements. For this reason, the first part of this PhD thesis reviews and provides potential assessments of some unconventional PHES systems, applied in synergy with existing infrastructures. Such is the standpoint of micro facilities near waterway locks, or underground cavities used as lower reservoirs (UPSH), or the use of pump-turbines at variable geometryto cope with fluctuating loads.Moreover, important information on PHES in micro-scale is largely missing and their potential in distributed energy systems still needs to be unveiled. In the attempt to fill this gap, this thesis provides a techno-economic overview of the design and characterization of a first-of-its-kind PHES micro facility. In micro-scales hydropower projects, the initial capital cost of a conventional hydroelectric unit is hard to be determined and often economically prohibitive. Interestingly, in order to cut the total capital investment, the micro-PHES prototype runs with a single centrifugal pump for both pumping and generating phases and exploits existing stormwater reservoirs. The variable speed regulation is also implemented and it allows the pump to constantly operate at the maximum hydraulic efficiency in order to deal with load variations. In the same way, the pump working in reverse, namely pump as turbine (PaT), runs at the most suitable speed and it keeps a high efficiency over a wide load range. In addition, the analysis of the techno-economic parameters for such a system provides an important dataset for micro-PHES feasibility breakdown.PaTs are a legitimate cost-effective option in micro hydropower but an universal performance prediction does not exist. Their hydraulic efficiency can possibly shift from the higher efficiency of traditional hydraulic turbines. Nowadays, these reasons restrict PaTs exploitation. In this thesis, a multivariate regression method is applied to the CFD results to build a surrogate model of the PaT hydraulic characteristics as a function of the cutwater geometrical modifications. Based on this model, an optimization problem is solved to identify the most advantageous geometrical assetof the PaT cutwater to maximize the hydraulic efficiency. The presented methodology and design optimization of the cutwater in PaTs, which are extremely suited to our current energy generation needs, provides a unique and much-sought guide to its performance, improvements, and adaptation to hydropower. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The aim of this master’s thesis is the optimal design of swirl turbines for small water power plant. It is described a different possibilities of turbine‘s install for locality Vrchlabí. It presents a design of turbines and draft tubes. For the installation of turbines is computed theoretical production of annual electric energy. Furthermore it describes a design of supply channel and intake structure.

Sammanfattning Biflödesområden och sammanflödeszoner spelar en viktig roll, inte minst genom deras förmåga att förändra miljöförhållandena och framkalla ett biologiskt svar i huvudfåran de rinner ut i. Biflödesområden utgör även platser med högt inneboende ekologiskt värde, där särskilda biofysiska processer och ekologiska tjänster ofta är koncentrerade. Syftet med denna studie var att undersöka huruvida biflödesmynningsområden inom Klarälvens avrinningsområde utgjorde hotspots för fisk samt kartlägga eventuella fluviala påverkansfaktorer. Parametrar som studerades var artförekomst och medeltäthet samt omvärldsfaktorerna medeldjup, lokalbredd, bottensubstrat, vattennivå, vattenhastighet och förekomsten av vandringshinder i vattendraget. Flest arter återfanns i Klarälvens huvudfåra, varpå biflödesmynningarna hade näst flest arter och uppströms biflödena lägst antal arter. Medeltäthet av arterna bergsimpa (Cottus poecilopus), elritsa (Phoxinus phoxinus) och lake (Lota lota) var störst i biflödesmynningarna, medan medeltätheten av lax (Salmo salar) och öring (Salmo trutta) var som störst uppströms biflödena. Resultatet visade också att öring, i större utsträckning än lax, förekom högre uppströms i biflödena, ett förhållande som även stödjs av tidigare studier. Gällande omvärldsfaktorerna var vattenhastigheten signifikant högre i biflödemynningarna och uppströms biflödena jämfört med i huvudfåran, samtidigt som det högsta diversitetsvärdet för bottensubstratkompositionen återfanns i huvudfåran. Utifrån dessa resultat var det svårt att dra en slutsats kring om biflödesmynningarna faktiskt utgjorde hotspots för fisk eller inte, då det skiftade beroende på vilka parametrar som studerades. En bedömning gjordes att biflödesmynningsområden inom Klarälvens avrinningsområde inte utgjorde hotspots för fisk. Nyckelord: Biflödesmynning, biflöde, huvudfåra, Klarälven, flottning, vattenkraft / Abstract Tributary areas and confluence zones play an important role, not least through their ability to change environmental conditions and elicit a biological response in the main stream they flow into. Tributary areas also provide sites of high inherent ecological value, where specific biophysical processes and ecological services are often concentrated. The purpose of this study was to investigate whether tributary mouths within the catchment area of Klarälven constituted hotspots for fish and to identify possible environmental factors associated with hotspots. Parameters studied were species composition and mean density, as well as the physical factors such as average depth, local width, bottom substrate, water level, water velocity and the occurrence of migratory obstacles in the watercourse. Most species were found in the mainstream, whereas tributary mouths had the second highest species richness and upstream tributaries had the lowest number of species. The mean density of the alpine bullhead (Cottus poecilopus), eurasian minnow (Phoxinus phoxinus) and burbot (Lota lota) was greatest in the tributary mouths, while the mean density of salmon (Salmo salar) and trout (Salmo trutta) was greatest upstream of the tributaries. The results also showed that trout, to a greater extent than salmon, occurred higher upstream in the tributaries, a relationship that is also supported by previous studies. Regarding the physical factors, water velocity was significantly higher in the tributary mouths and upstream tributaries than in the mainstream, while the highest diversity for bottom substrate composition was found in the mainstream. Based on these results, it was difficult to conclude whether tributary mouths actually constituted hotspots for fish or not, as it varied depending on the parameters studied. Overall tributary mouths within the catchment area of Klarälven did not constitute hotspots for fish. Keywords: Estuary, tributary, mainstream, river, rafting, hydropower

The development of hydroelectric power production and the damming of water courses that ensues causes a threat to the migration patterns of Atlantic salmon (Salmo salar), by altering their habitat and compromising river connectivity. Because the species’ survival heavily depends on the completion of their migration between rivers and oceans, the design of guidance structures that promote successful passages around dams is a critical goal. Physical structures have been used to steer downwards-migrating smolts through safe fishways but they have not always proven effective, both from an ecological and economical perspective. In this study, the potential of bubbles in guiding salmon trajectories around a hydropower dam was tested as an alternative to existing guiding systems. Here the hypotheses were: i) bubbles guide downstream-migrating smolts around dams; ii) the reaction of smolts to a bubble barrier is linked to their individual boldness; iii) bubbles have varying effects on different school sizes. The first and third hypotheses were tested in the field, by recording sonar footage at the entrance of a fishway, downstream of a bubble barrier. The second hypothesis was evaluated by conducting a scototaxis experiment and an assessment of the reaction of young salmon to bubbles in the laboratory. My analysis of the fish abundance data collected in the river confirmed the first and third hypotheses. In the field, the presence of a predator (Esox lucius) was revealed to be a more influential factor than bubbles in regulating the number of smolts steered towards the fishway, indicating that predators generated a larger anxiety-like response in smolts than bubbles. In the controlled laboratory setting, there was no significant correlation between anxiety-like behaviour and reaction to bubbles and the second hypothesis did not appear to be valid. Therefore, the cause of avoidance of the barrier remains unclear, but bubble barriers seem to be an efficient and cost-effective structure for guiding downstream-migrating salmon smolts.

We are currently witnessing a rapid expansion of renewable power production, an increase dominated by wind and solar power. These intermittent energy sources, while having low production costs, increases the uncertainty on the electrical markets. Hydropower is a renewable source of electricity that is capable of controlled production. It is assumed that hydropower will take a more central role in terms of balancing deficiencies caused by intermittent sources. In this thesis, we present a detailed model of a single hydropower plant consisting of 𝑛 turbines. This model is then used as input of solving the optimisation problem of revenue maximisation for the hydro plant owner. The model used takes into account head effects as well as stochastic inflow of water and the stochastic fluctuations of electricity prices.

Aeration issued through a ventilation shaft is an important measure to prevent cavitation and large gauge pressure in flood discharge tunnels. In order to dimension the ventilation shaft appropriately, itis necessary to have a good understanding of the air-water flow in the tunnel. In this study, the multiphase flow through a discharge tunnel was simulated in the computational fluid dynamics (CFD) software ANSYS Fluent. Since the flow was separated, the simulation setup used the volume of fluid (VOF) multiphase model, that could track the water surface. Furthermore, the so called RNG k-epsilon turbulence model was used. The CFD model was validated with measured data provided from two open channel experiments carried out on a scaled model at Sichuan University. To ensure mesh independence, grid convergence index (GCI)studies were performed for the two validating cases. After the validation, a top wall and a ventilation shaft was added to the CFD model. The flow was then simulated for four different shaft designs and four different water inlet velocities. The air demand and air supply for the various scenarios could thereby be calculated. The results of this study were also compared with previous research on multiphase flow through tunnels with similar design. It was concluded that the air flow downstream in the tunnel converged for the two larger designs. It was also concluded that the air demand in the tunnel was satisfied for the larger ventilation shafts. A smaller study on cavitation was made and the risk was considered non-existent for all the simulated cases.

The purpose of this study is to analyse how a battery energy storage system (BESS) can support the frequency and voltage stability for an islanded microgrid containing a hydropower plant. Two different microgrids, both situated in Sweden, are evaluated. Modelling and dynamic simulations are conducted in the PowerFactory tool. The result shows that both the frequency and the voltage control can be improved with the BESS. However, with the allowed limit of ± 1 Hz, not all simulated scenarios including a BESS meets the requirement. A large difference between the BESS and generator capacity might be a possible cause for this. By dividing the larger loads so that smaller loads are attained, the frequency deviation might be reduced. Furthermore, by adjusting the systems PID-parameters according to the island mode operation, faster regulation can be attained. The system operates according to the Master slave control strategy, with the hydropower being the master unit with voltage control and the BESS being a slave unit with PQ control. The ability to operate an islanded microgrid can ensure the supply of electricity to inhabitants and vital functions in society. By utilizing a BESS for increasing electric stability, emission of CO2 is indirectly mitigated. As cost for BESS are expected to decrease rapidly, they will be accessible for utilization all over the world.