Conventional Hydropower Research Articles

Assessing hydrokinetic energy conversion for rivers across the world

Energy extraction opportunities may exist at locations undesirable for conventional hydropower plants.

Deep Learning for Forecasting Electricity Demand in Taiwan

According to the World Energy Investment 2018 report, the global annual investment in renewable energy exceeded USD 200 billion for eight consecutive years until 2017. In this paper, a deep-learning-based time-series prediction method, namely a gated recurrent unit (GRU)-based prediction method, is proposed to predict energy generation in Taiwan. Data on thermal power (coal, oil, and gas power), renewable energy (conventional hydropower, solar power, and wind power), pumped hydropower, and nuclear power generation for 1991 to 2020 were obtained from the Bureau of Energy, Ministry of Economic Affairs, Taiwan, and the Taiwan Power Company. The proposed GRU-based method was compared with six common forecasting methods: autoregressive integrated moving average, exponential smoothing (ETS), Holt–Winters ETS, support vector regression (SVR), whale-optimization-algorithm-based SVR, and long short-term memory. Among the methods compared, the proposed method had the lowest mean absolute percentage error and root mean square error and thus the highest accuracy. Government agencies and power companies in Taiwan can use the predictions of accurate energy forecasting models as references to formulate energy policies and design plans for the development of alternative energy sources.

Capacity optimization of pumped storage hydropower and its impact on an integrated conventional hydropower plant operation

The energy sector contributes to around 60% of total greenhouse gas emissions. To limit climate change, the world is going through an energy transition to clean and affordable energy, therefore the share of variable renewable energy is increasing day by day. Power systems require significant flexibility to operate reliably. Pumped storage hydropower allows load balancing and stable integration of intermittent renewable energy in the electrical grid. All energy storage technologies, including pumped storage hydropower, are considered a net negative contributor to the grid since they draw more energy than they deliver. This paper uniquely investigates the true potential of pumped storage hydropower and its optimum operation along with existing conventional hydropower. It considers power, energy production, and utilization for both installations to determine an equilibrium condition for a net positive energy balance. The case study of the 300 MW Balakot conventional hydropower plant in Khyber Pakhtunkhwa, Pakistan indicates that the pumped storage hydropower sites, where additional water streams reach the upper storage reservoir, can reduce pumping energy consumption by up to 166 GWh/year. Accordingly, a pumped storage hydropower facility is proposed at Paras, Pakistan, modeled, and optimized in an integrated manner with the Balakot conventional hydropower plant for a net positive annual energy generation and profitability. The integrated power and energy modeling and capacity optimization of the hydropower complex highlight the importance of suitable site selection for pumped storage hydropower near existing conventional hydropower reservoirs. Value-added contribution of this configuration is that it can enhance annual energy generation from integrated conventional hydropower, reduce the upfront capital cost of the project by 10–15%, squeeze the project implementation schedule and result in a smaller carbon footprint to meet the ultimate objective of limiting climate change. Additionally, it unlocks huge untapped pumped storage hydropower potential besides existing conventional hydropower. Furthermore, the study guides the scientific and engineering organizations on optimum capacity utilization without impeding energy generation from conventional hydropower facilities.

Experimental Study on Enclosed Gravitational Water Vortex Turbine (GWVT) Producing Optimum Power Output for Energy Production

Gravitational Water Vortex Turbine (GWVT) is an emerging concept and showing its future possibility in power production by utilizing the vortex produced in its casing. GWVT performance showed comparable power efficiency and yield with conventional hydropower turbine, thus it is applicable in rural area due to its portability. This study aimed to evaluate the performance of actual physical experiment of enclosed GWVT via horizontal orientation. Conical GWVT was designed in fully enclosed system with conical turbine basin. Different flow rates (5.33 L/s, 6.01 L/s, 6.3 L/s and 6.45 L/s) were manipulated by controlling the mechanical valves and loads with 1 kg increment until the turbine was forced to stop. The optimum rpm and torque were then identified for energy production. The experimental results showed that the enclosed GWVT turbine produced at the best operating condition under flow rate of 6.3L/s with torque produced at 5.47 Nm., shaft angular velocity of 12.71 rad/s, actual power produced of 69.39W and efficiency of 16.06%. Power efficiency found in this study was comparable with the conventional GWVT turbine studies. Thus, it is feasible to operate GWVT in an enclosed casing. The result explained that the turbine worked the best at 6.3 L/s flow rate for the vortex formation to be more stable, thus harnessing more power. The results are useful as a pilot scale design prior to the actual turbine implementation in rural areas.

Hydrokinetic energy conversion: A global riverine perspective

Free-flowing rivers have been impacted by anthropogenic activity and extensive hydropower development. Despite this, many opportunities exist for context-specific energy extraction, at locations deemed undesirable for conventional hydropower plants, in ways that reduce the scale of operation and impact. Hydrokinetic energy conversion is a renewable energy technology that requires accurate resource assessment to support deployment in rivers. We use global-scale modeled river discharge data, combined with a high-resolution vectorized representation of river networks, to estimate channel form, flow velocities, and, hence, global hydrokinetic potential. Our approach is based directly on the transfer of kinetic energy through the river network, rather than conventional, yet less realistic, assessments that are based on conversion from gravitational potential energy. We show that this new approach provides a more accurate global distribution of the hydrokinetic resource, highlighting the importance of the lower-courses of major rivers. The resource is shown to have great potential on the continents of South America, Asia, and Africa. We calculate that the mean hydrokinetic energy of global rivers (excluding Greenland and Antarctica) is 5.911 ± 0.009 PJ (1.642 ± 0.003 TWh).

Experimental comparison of fish mortality and injuries at innovative and conventional small hydropower plants

Abstract Resolving the controversy about hydropower is only possible based on reliable data on its ecological effects, particularly fish welfare. Herein, we propose a comprehensive assessment of conventional and innovative hydropower using a dataset of 52,250 fish. The effects of hydropower on fish were most harmful at sites with Kaplan turbines, showing ≤83% mortality. Innovative hydropower, often termed ‘fish‐friendly’, caused ≤64% mortality. Our findings suggested that the runner peripheral speed, number of turbine blades and turbulence at turbine outlets were the most important factors. Synthesis and applications. To reduce the impact of hydropower on fish, site‐specific characteristics such as head drop, bypass options and river‐specific species composition need to be more intensively considered in optimal turbine technologies and operation modes.

Pumped Storage Hydropower for Sustainable and Low-Carbon Electricity Grids in Pacific Rim Economies

Because generating electricity significantly contributes to global greenhouse gas emissions, meeting the 2015 Paris Agreement and 2021 Glasgow Climate Pact requires rapidly transitioning to zero or low-emissions electricity grids. Though the installation of renewables-based generators—predominantly wind and solar-based systems—is accelerating worldwide, electrical energy storage systems, such as pumped storage hydropower, are needed to balance their weather-dependent output. The authors of this paper are the first to examine the status and potential for pumped storage hydropower development in 24 Pacific Rim economies (the 21 member economies of the Asia Pacific Economic Cooperation plus Cambodia, Lao PDR, and Myanmar). We show that there is 195 times the pumped storage hydropower potential in the 24 target economies as would be required to support 100% renewables-based electricity grids. Further to the electrical energy storage potential, we show that pumped storage hydropower is a low-cost, low-greenhouse-gas-emitting electrical energy storage technology that can be sited and designed to have minimal negative (or in some cases positive) social impacts (e.g., requirements for re-settlement as well as impacts on farming and livelihood practices) and environmental impacts (e.g., impacts on water quality and biodiversity). Because of the high potential for pumped storage hydropower-based electrical energy storage, only sites with low negative (or positive) social and environmental impacts such as brownfield sites and closed-loop PSH developments (where water is moved back and forth between two reservoirs, thus minimally disturbing natural hydrology) need be developed to support the transition to zero or low-carbon electricity grids. In this way, the advantages of well-designed and -sited pumped storage hydropower can effectively address ongoing conflict around the social and environmental impacts of conventional hydropower developments. Noting the International Hydropower Association advocacy for pumped storage hydropower, we make recommendations for how pumped storage hydropower can sustainably reduce electricity-sector greenhouse gas emissions, including through market reforms to encourage investment and the application of standards to avoid and mitigate environmental and social impacts.

Operational benefit of transforming cascade hydropower stations into pumped hydro energy storage systems

This study evaluates the potential benefit of retrofitting existing conventional cascade hydropower stations (CCHSs) with reversible turbines so as to operate them as pumped hydro energy storage (PHES) systems. We examine the energy generation and storage problem for a CCHS with two connected reservoirs that can be transformed into a PHES system in a market setting where the electricity price can be negative. We formulate this problem as a stochastic dynamic program (SDP) under uncertainty in the streamflow rate and electricity price. We analytically derive an upper bound on the profit improvement that can be obtained from the PHES transformation. We conduct numerical experiments with data-calibrated time series models and observe that the PHES system provides a greater benefit under more limited streamflow conditions or more frequently observed negative prices.

Electric Truck Hydropower, a flexible solution to hydropower in mountainous regions

The world is undergoing a transition to a more sustainable energy sector dominated by renewable energy sources. This paper proposes an innovative solution that consists of catching water from streams at high altitudes to fill storage containers and transport them down a mountain, converting the potential energy of water into electricity with the regenerative braking systems of electric trucks and storing it in the truck's battery. The energy stored in the electric truck can be sold to the grid or used by the truck to transport other goods. Results show that the levelized cost of the electricity truck hydropower is 30–100 USD/MWh, which is cheap when compared with conventional hydropower 50–200 USD/MWh. The electricity generation world potential for the technology is estimated to be 1.2 PWh per year, which is equivalent to around 4% of the global energy consumption in 2019. Apart from being a low cost and impact electricity generation technology, electric truck hydropower can operate in combination with solar and wind resources and provide energy storage services to the grid.

Revenue prediction for integrated renewable energy and energy storage system using machine learning techniques

Revenue estimation for integrated renewable energy and energy storage systems is important to support plant owners or operators’ decisions in battery sizing selection that leads to maximized financial performances. A common approach to optimizing revenues of a hybrid hydro and energy storage system is using mixed-integer linear programming (MILP). Although MILP models can provide accurate production cost estimations, they are typically very computationally expensive. To provide a fast yet accurate first-step information to hydropower plant owners or operators who consider integrating energy storage systems, we propose an innovative approach to predicting optimal revenues of an integrated energy generation and storage system. In this study, we examined the performance of two prediction techniques: Generalized Additive Models (GAMs) and machine learning (ML) models developed based on artificial neural networks (ANN). Predictive equations and models are generated based on optimized solutions from a market participation optimization model, the Conventional Hydropower Energy and Environmental Resource System (CHEERS) model. The two predicting techniques reduce the computational time to evaluate annual revenue for one set of battery configurations from 3 h to 1 to 4 min per run while also being implementable with significantly less data. The model validation prediction errors of developed GAMs and ML models are generally below 5%; for model testing predictions, the ML models consistently outperform the regression equations in terms of root mean square errors. This new approach allows plant owners, operators, or potential investors to quickly access multiple battery configurations under different energy generation and market scenarios. This new revenue prediction method will therefore help reduce the barriers, and thereby promoting the deployment of battery hybridization with existing renewable energy sources.

Hydrokinetic Turbine Technology and Its Prospect in Bangladesh: A Review

As a sustainable alternative to fossil fuel, hydropower is becoming increasingly popular since the concern over global warming is growing worldwide. Conventional hydropower technology involves the use of hydraulic turbines, which require a large static head of water created by constructing a dam across the river. This technology, though widely used, has a negative impact on river hydrology and aquatic lives. Hydrokinetic turbine, on the other hand, having a working principle similar to wind turbine doesn’t require a dam or barrier and has negligible impact on the aquatic environment. Bangladesh being the land of rivers can effectively implement hydrokinetic turbine-based technology for supplying electricity in off-grid remote areas. In this article, a review of hydrokinetic turbine technology for extracting the kinetic energy of rivers and oceans has been conducted. The status, merits, and applications of this technology have been briefly discussed. Finally, the prospect of this technology in Bangladesh has been assessed.

Survival estimates across five life stages of redfin (Perca fluviatilis) exposed to simulated pumped-storage hydropower stressors.

The global prevalence of pumped-storage hydropower (PSH) is expected to grow exponentially as countries transition to renewable energy sources. Compared to conventional hydropower, little is currently known regarding PSH impacts on aquatic biota. This study estimated the survival of five life stages (egg, two larval stages, juvenile and adult) of redfin (European) perch (Perca fluviatilis) following passage through a PSH facility during the pumping phase. This was achieved by simulating the individual stressors expected to occur during passage through a 2000-MW PSH facility using laboratory-simulated (shear strain and extreme compression) and modelling (blade strike, BS) approaches. Our results indicate that redfin could survive the shear, pressure and BS stressors expected within the PSH facility, but impacts varied among life stages. Juvenile survival was >70% across all shear strain rates, while the survival of eggs and larvae declined markedly as strain rate increased. All life stages had high survival when exposed to rapid compression and BS. The high survival of redfin to the stressors tested suggests the PSH facility could facilitate the passage of redfin during the pumping phase from the lower to the higher elevation reservoir. This outcome would be welcomed in situations where the species is native, but could have adverse implications for the conservation of native biota where the species is considered a pest.

Day-ahead optimal dispatching of multi-source power system

In this paper, the day-ahead optimal dispatching model of power system that is combined by wind-photovoltaic-hydropower-thermal-pumped storage is established. Firstly, according to the characteristics of the short-term hydropower system dispatching problem, a new mathematical model of the cascade hydropower group system with pumped storage power stations is proposed. The coordinated optimized dispatching model of the hydropower group system formed by the cascading of pumped storage power plants and conventional hydropower in the power system is studied. Secondly, the opportunity constraint programming model of forecast error reserve is used to deal with the output uncertainty of wind power and photovoltaic. The randomness and intermittency of renewable energy on the stability of the power system are overcame by the combination of wind-photovoltaic-pumped storage. Thirdly, the model for the joint optimal dispatch of short-term wind, photovoltaic, hydropower and thermal power systems with pumped storage is developed with system economics as the goal. Fourthly, the operation volatility coefficient of thermal power units is proposed to study the impact of renewable energy on the operation of thermal power. Finally, an example system is used to verify the correctness of the proposed dispatching optimal scheduling model, and the results prove that the daily dispatch optimization model proposed in this paper can increase the economic efficiency of the power system by 5%, reduce the start-stop times of thermal power units by 36.55%, and reduce the fluctuation coefficient of the unit by 2.8.

Putting oceans to work: tidal energy in the USA and the USSR, 1930–1970

ABSTRACT Aspirations to convert the movement of ebb and flow into electricity have a long and checkered history. Proposals for tidal power plants at Passamaquoddy Bay (Maine/New Brunswick) and in the Soviet Murmansk region emerged in the 1920s and were discussed well into the 1960s. Considering that tidal power had to compete with established energy sources like coal, oil, and conventional hydropower, the longevity of discussions about the two tidal power projects is surprising. Their proponents tapped into questions of energy independence, economic progress, and international cooperation to keep the technology in the race. However, the decade-long negotiations did not result in the construction of major tidal power plants. The technology’s geographical immobility (the plants needed to be constructed where high tides coincided with a suitable coastline) and doubts about economic rationality halted tidal dreams both in the USA and in the USSR.

Exploration on the development of conventional and energy-storage hybrid hydropower resources for the mainstream of Manas River in Xinjiang

Exploration on the development of conventional and energy-storage hybrid hydropower resources for the mainstream of Manas River in Xinjiang

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Hydropower and seasonal pumped hydropower storage in the Indus basin:pros and cons

The Indus basin has a large hydropower untapped potential for electricity generation and to regulate the Indus river flow, which could reduce flooding events and provide water supply during drought periods. In this paper, a computational module is developed to localize potential sites for hydropower generation and seasonal pumped hydropower storage (SPHS). The levelized costs for hydropower generation in the basin with conventional dams are as low as 12 USD/MWh, the cost of energy storage is 1 USD/MWh. In case of SPHS plants, the cost of energy storage is 2 USD/MWh. It can be concluded that the conventional hydropower potential is, for the moment, less expensive than SPHS, but its potential in the Indus basin is limited to 26 GW with hydropower costs below 50 USD/MWh and its reservoirs have a short lifetime due to the high sedimentation rates of the basin. SPHS would be an interesting alternative to complement the hydropower potential adding long-term water and energy storage with fewer sediments, social and environmental impacts. Given that the region has the highest potential and lowest costs for SPHS in the world, it could become a major player on seasonal and pluri-annual energy storage in Asia and globally.

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Pump-Turbines in Conventional Hydropower Plants

This paper proposes an innovative approach to retrofit existing hydropower plants with suitable upper and lower reservoirs into pumped storage. The conventional methods are both comprehensive and expensive, mainly due to the increased risk of cavitation during pumping operation. In an existing facility, the installed runner is already sufficiently submerged to avoid unfortunate cavitation, but replacing the runner with a reversible pump-turbine demands an even further increase of the static pressure at the low-pressure side of the turbine. An alternative to the traditional method is discussed in this research by introducing the concept of a booster pump installed in the draft tube. Increasing the pressure at the inlet of the pump-turbine during pumping could eliminate the risk of cavitation and enable operation of a pumped storage plant without submerging the runner further. This conceptual paper discusses the motive for developing pumped storage and presents two uses for the proposed booster pump; eliminating cavitation and correcting for some of the necessary lifting head of the pump-turbine. The project is a part of the Norwegian Research Centre for Hydropower Technology, HydroCen.

Low-head hydropower as a reserve power source: A case study of Northeastern Illinois

Wind power generation faces intermittency challenges, typically requiring reserve power sources to maintain reliability of the electricity grid. This study proposes that hydropower turbines installed at low-head dams can provide reserve power generation to support wind power, avoiding the externalities associated with fossil-fuel plants and conventional hydropower. Low-head dams in the United States are used for flood control, securing municipal water supplies, and providing reservoir pools for recreation. As a case study, we estimated hydropower potential at 12 low-head dams along a 150-km reach of the Fox River (Northeastern Illinois, USA) using a calibrated river flow model. We analyzed the model's output to assess power generation capacity and reliability as a source of baseload power and as a component in a coupled wind-hydropower system. The modeled system performed reliably over a five-year time period despite significant long-term fluctuations in streamflow, offsetting the short-term variability of wind power. However, combining the low-head hydropower system with wind power limited the output of the system to the minimum generated by the low-head hydropower. The low-head hydropower system's small capacity and high break-even price suggest that it is better suited for local applications rather than grid-scale operations, especially if permitting regulations are considered.