Showing papers on "Hydropower published in 2018"

Governing the commons? : water and power in Pakistan's Indus basin

Abstract: Surface irrigation is a common pool resource characterized by asymmetric appropriation opportunities across upstream and downstream water users. Large canal systems are also predominantly managed by the state. This paper studies water allocation under an irrigation bureaucracy subject to corruption and rent-seeking. Data on the landholdings and political influence of nearly quarter million irrigators in Pakistan’s vast Indus Basin watershed allow the construction of a novel index of lobbying power. Consistent with a model of misgovernance, the decline in water availability and land values from channel head to tail is accentuated along canals having greater lobbying power at the head than at the tail.

Sustainable hydropower in the 21st century

Abstract: Hydropower has been the leading source of renewable energy across the world, accounting for up to 71% of this supply as of 2016. This capacity was built up in North America and Europe between 1920 and 1970 when thousands of dams were built. Big dams stopped being built in developed nations, because the best sites for dams were already developed and environmental and social concerns made the costs unacceptable. Nowadays, more dams are being removed in North America and Europe than are being built. The hydropower industry moved to building dams in the developing world and since the 1970s, began to build even larger hydropower dams along the Mekong River Basin, the Amazon River Basin, and the Congo River Basin. The same problems are being repeated: disrupting river ecology, deforestation, losing aquatic and terrestrial biodiversity, releasing substantial greenhouse gases, displacing thousands of people, and altering people’s livelihoods plus affecting the food systems, water quality, and agriculture near them. This paper studies the proliferation of large dams in developing countries and the importance of incorporating climate change into considerations of whether to build a dam along with some of the governance and compensation challenges. We also examine the overestimation of benefits and underestimation of costs along with changes that are needed to address the legitimate social and environmental concerns of people living in areas where dams are planned. Finally, we propose innovative solutions that can move hydropower toward sustainable practices together with solar, wind, and other renewable sources.

Changes in short term river flow regulation and hydropeaking in Nordic rivers

Abstract: Quantifying short-term changes in river flow is important in understanding the environmental impacts of hydropower generation. Energy markets can change rapidly and energy demand fluctuates at sub-daily scales, which may cause corresponding changes in regulated river flow (hydropeaking). Due to increasing use of renewable energy, in future hydropower will play a greater role as a load balancing power source. This may increase current hydropeaking levels in Nordic river systems, creating challenges in maintaining a healthy ecological status. This study examined driving forces for hydropeaking in Nordic rivers using extensive datasets from 150 sites with hourly time step river discharge data. It also investigated the influence of increased wind power production on hydropeaking. The data revealed that hydropeaking is at high levels in the Nordic rivers and have seen an increase over the last decade and especially over the past few years. These results indicate that increased building for renewable energy may increase hydropeaking in Nordic rivers.

Global proliferation of small hydropower plants – science and policy

Abstract: Large‐scale electricity policies that embrace renewable resources have led to continued investments in hydropower. Despite evolving viewpoints regarding the sustainability of large hydropower installations, there has been a major increase in support for the widespread development of small hydropower plants (SHPs). A global synthesis reveals that 82,891 SHPs are operating or are under construction (11 SHPs for every one large hydropower plant) and that this number is estimated to triple if all potential generation capacity were to be developed. Fueled by considerable political and economic incentives in recent decades, the growth of SHPs has greatly outpaced available ecological science. We provide evidence for not only the lack of scientifically informed oversight of SHP development but also the limitations of the capacity‐based regulations currently in use. The potential indiscriminate expansion of SHPs under the pretense of promoting sustainable energy is concerning, and we identify several important steps to help ensure new scientific advances, effective management, and policy reform in the future.

Hydropower development situation and prospects in China

Abstract: China's economic development faces an energy challenge, and the appropriate solution to this energy bottleneck is the key to a robust, rapid, and sustainable development. Abundant hydropower resources provide unprecedented advantages and opportunities for China's rapid hydropower development over the last five decades. China's hydropower growth contributed greatly to the global output net growth, with the current installed hydropower capacity at 320 GW. This study uses the 13th Five-Year energy plan to summarize the development of China's hydropower sector for the past 50 years and its current progress, recommend the major hydropower bases and its scale, describe the main problems encountered in developing China's hydropower resources and the solutions to these difficulties, and predict China's hydropower development trends and prospects in the future. This study aims to give an overview of the present situation of hydropower in China and its future political, economic and environment perspectives and challenges.

A Review of the Integrated Effects of Changing Climate, Land Use, and Dams on Mekong River Hydrology

Abstract: The ongoing and proposed construction of large-scale hydropower dams in the Mekong river basin is a subject of intense debate and growing international concern due to the unprecedented and potentially irreversible impacts these dams are likely to have on the hydrological, agricultural, and ecological systems across the basin. Studies have shown that some of the dams built in the tributaries and the main stem of the upper Mekong have already caused basin-wide impacts by altering the magnitude and seasonality of flows, blocking sediment transport, affecting fisheries and livelihoods of downstream inhabitants, and changing the flood pulse to the Tonle Sap Lake. There are hundreds of additional dams planned for the near future that would result in further changes, potentially causing permanent damage to the highly productive agricultural systems and fisheries, as well as the riverine and floodplain ecosystems. Several studies have examined the potential impacts of existing and planned dams but the integrated effects of the dams when combined with the adverse hydrologic consequences of climate change remain largely unknown. Here, we provide a detailed review of the existing literature on the changes in climate, land use, and dam construction and the resulting impacts on hydrological, agricultural, and ecological systems across the Mekong. The review provides a basis to better understand the effects of climate change and accelerating human water management activities on the coupled hydrological-agricultural-ecological systems, and identifies existing challenges to study the region’s Water, Energy, and Food (WEF) nexus with emphasis on the influence of future dams and projected climate change. In the last section, we synthesize the results and highlight the urgent need to develop integrated models to holistically study the coupled natural-human systems across the basin that account for the impacts of climate change and water infrastructure development. This review provides a framework for future research in the Mekong, including studies that integrate hydrological, agricultural, and ecological modeling systems.

Improved trade-offs of hydropower and sand connectivity by strategic dam planning in the Mekong

Abstract: Dams in the Mekong Basin are mostly planned project-by-project and without strategic analysis of their cumulative impacts on river processes such as sediment connectivity. We analyse missed and future opportunities for reducing hydropower impacts on sediment connectivity through strategic planning of dams in the Se Kong, Se San and Sre Pok (‘3S’) tributaries of the lower Mekong, which are critically important as a source of sand for the Mekong Delta. With strategic planning, 68% of the hydropower potential of the 3S Basin could have been developed while trapping 21% of the basin’s sand load. The current dam portfolio resulting from project-by-project planning uses 54% of the hydropower potential while trapping 91% of the sand load. Results from the 3S demonstrate that strategic network-scale planning is crucial for developing lower-impact hydropower, a relevant finding given the at least 3,700 major dams that are proposed worldwide. Dams in the Mekong Basin are built without considering impacts on river processes. This study shows that with strategic planning in the lower Mekong, 68% of the basin’s hydropower potential could have been developed while trapping 21% of the basin’s sand load.

Global Water Transfer Megaprojects: A Potential Solution for the Water-Food-Energy Nexus?

Abstract: Globally, freshwater is unevenly distributed, both in space and time. Climate change, land use alteration, and increasing human exploitation will further increase the pressure on water as a resource for human welfare and on inland water ecosystems. Water transfer megaprojects (WTMP) are defined here as large-scale engineering interventions to divert water within and between river basins that meet one of the following criteria: construction costs > USD 1 billion, distance of transfer > 190 km, or volume of water transferred exceeds 0.23 km3 per year. WTMP represent an engineered solution to cope with water scarcity. These projects are most commonly associated with large-scale agricultural and energy development schemes, and many of them serve multiple purposes. Despite numerous case studies that focus on the social, economic and environmental impacts of individual water transfer megaprojects, a global inventory of existing, planned and proposed projects is lacking. We carried out the first comprehensive global inventory of WTMP that are planned, proposed or under construction. We collected key information (e.g. location, distance, volume, costs, purpose) on 34 existing and 76 future (planned, proposed or under construction) WTMP. If realized, the total volume of water transferred by future projects will reach 1,910 km3 per year with a total transfer distance of more than twice the length of the Earth’s equator. The largest future WTMP are located in North America, Asia and Africa and the predicted total investment will exceed 2.7 trillion US$. Among future projects, 42 are for agricultural development, 13 for hydropower development and 10 combine both purposes. Future megaprojects are also planned to support mining, ecosystem restoration and navigation. Our results underscore the extent to which humans have and are planning to re-engineer the global hydrological network and flows through WTMP, creating a network of “artificial rivers”. They emphasize the need to ensure the inclusion of these projects in global and basin hydrological models, and to develop internationally agreed criteria to assess the ecological, social and economic impacts of WTMP.

Burden on hydropower units for short-term balancing of renewable power systems

Abstract: There is a general need to change hydropower operational regimes to balance the growing contribution of variable renewable energy sources in power systems. Quantifying the burden on generation equipment is increasingly uncertain and difficult. Here, we propose a framework combining technical and economic indicators to analyze primary frequency control (PFC) on a timescale of seconds. We develop a model integrating hydraulic, mechanical, and electrical subsystems to characterize efficiency loss, wear and fatigue, regulation mileage, and frequency quality. We evaluate burden relief strategies under three idealized remuneration schemes for PFC, inspired by those used in Sweden, the USA, and China, respectively. We show how burden and compensation vary under future scenarios of renewable power systems. Our framework can be used by producers to develop favorable operation strategies that reduce burden and increase economic value, and by transmission system operators to provide insights on the relation between incentive structures and regulating performance.

A review of the causes, impacts and solutions for electricity supply crises in Brazil

Abstract: From the end of 2013 to the end of 2015, Brazil faced serious challenges to supply its demand for electricity due to a prolonged drought in the Southeast and Northeast regions with the consequent loss of hydroelectric generation. This paper presents an historical analysis of major world energy crises from 1988 to 2015 and in Brazil from 1924 to 2015. Analysing the natural river flow of key Brazilian dams from 1931 until 2017, this paper suggests that hydropower generation in Brazil has a 10–15 years cyclical pattern of hydropower generation. The periods of drought in this cyclical pattern usually coincides with energy crises due to the reduction in hydropower generation. It was found that the drought in 2015 had an impact of 110 TWh in hydropower generation, from which 25 TWh are due to head loss and 70 TWh are from lack of stored hydropower in July of 2014. In addition, 48 TWh were not generated due to delays in the construction of new power plants. Other causes of the Brazilian energy crisis of 2015 are presented and the overall electricity generation impact of these causes are compared. In addition, this paper presents the impacts on the energy, water and food supply sectors in Brazil, and the strategies employed to reduce the impact of the crises. With the intention of preventing future energy crises, the paper then shows the potential alternatives to improve electricity supply security in Brazil, particularly in terms of diversifying and widening the share of renewable sources and increasing the energy storage potential of the country.

State of the art, shortcomings and future challenges for a sustainable sediment management in hydropower: A review

Abstract: It is predicted that 60% of all new energy investments over the next 20 years will be in renewables The estimation for new hydropower production is 25% of all new renewables primarily due to potential in China, Africa, Latin America and South-East Asia Also in Europe a growth of hydropower production is aimed to achieve emission targets within the European Union by 2050 However, one of the main economic, technical and ecological challenges in future are the deposition, the treatment, and the disturbed dynamics of sediments in river catchments, which reduce the future market potential of hydropower substantially Due to a lack in awareness of those sedimentological challenges (eg lack of process understanding), various huge economical, technical and ecological problems emerge with an increasing relevance for hydropower industry, water management authorities and the society in future Based on a substantial literature review, (i) legal frameworks and (ii) reservoir management techniques including (iii) process understanding and numerical modelling are addressed in this article Moreover, the relevant cost-effective aspects of abrasion are worked out for (iv) turbine runners and (v) sediment bypass systems as well as the (vi) the ecological relevance of sediments and possible disturbances are described in this manuscript to open a future discussion on technical opportunities It was concluded, that all these issues should be addressed within the framework of the overall aim to minimize the costs under consideration of ecological requirements and standards by an improved sediment management in terms of hydropower use Moreover, it was stated that trans- and interdisciplinary research is required, to achieve those aims in future

Gravity water wheels as a micro hydropower energy source: A review based on historic data, design methods, efficiencies and modern optimizations

Abstract: Nowadays, due to the need for clean energy and sustainable electricity production, hydropower plays a central role in satisfying the energy demand. Particularly, use of low head micro hydropower plants is spreading worldwide, due to their low payback periods and good environmental sustainability. Gravity water wheels are micro hydropower converters typically used in sites with heads less than 6 m and discharges of a few cubic meters per second. Although water wheels were scientifically investigated as far back as the eighteenth century, they were largely ignored throughout the twentieth century, and only in the last two decades has there been a renewed interest in their use among the scientific community. In this paper a review on gravity water wheels is presented, distinguishing between undershot, breastshot and overshot water wheels. Water wheels technology is discussed focusing on geometric and hydraulic design; data and engineering equations found in historic books of the nineteenth century are also presented. Water wheels' performance is described examining experimental results, and modern theoretical models for efficiency estimation are presented. Finally, results achieved through experiments and numerical simulations were discussed with the aim of optimizing the performance of gravity water wheels. The results showed that maximum efficiency of overshot and undershot water wheels was around 85%, while that of breastshot water wheels ranged from 75% to 80%, depending on inflow configuration. Maximum efficiency of modern water wheels can be maintained at such high values over a wider range of flow rates and hydraulic conditions with respect to older installations. Hence well designed water wheels can be considered as efficient and cost-effective micro hydropower converters.

A review of the potential impacts of climate change on bulk power system planning and operations in the United States

Abstract: Climate change might impact various components of the bulk electric power system, including electricity demand; transmission; and thermal, hydropower, wind, and solar generators. Most research in this area quantifies impacts on one or a few components and does not link these impacts to effects on power system planning and operations. Here, we advance the understanding of how climate change might impact the bulk U.S. power system in three ways. First, we synthesize recent research to capture likely component-level impacts of climate change in the United States. Second, given the interconnected nature of the electric power system, we assess how aggregated component-level impacts might affect power system planning and operations. Third, we outline an agenda for future research on climate change impacts on power system planning and operations. Although component-level impacts vary in their magnitude, collectively they might significantly affect planning and operations. Most notably, increased demand plus reduced firm capacity across generation types might require systems to procure significant additional capacity to maintain planning reserve margins, and regional declines in renewable resources might need to be offset by increasing zero-carbon investment to meet decarbonization targets. Aggregated impacts might also affect operations, e.g., through shifts in dispatching and increased operational reserve requirements. Future research should aggregate component-level impacts at operational timescales, quantify impacts on wind and solar variability, and contextualize climate change impacts within ongoing shifts in the electric power system.

Dams: Ecological Impacts and Management

Abstract: Dam construction goes back in human history for more than 5000 years (e.g., Sadd el-Kafara dam in Egypt for flood protection), but most of the world’s existing dams have been built after the Second World War as consequence or basis of economic development. Today, there are about 6000 existing or planned large hydropower dams (>15 m height) worldwide (Zarfl et al. 2014) and an uncountable number of small dams. For example, with more than 5000 mostly small hydropower plants, Austria is one of the countries with the highest density of hydropower dams (about 6 dams per 100 km2, Wagner et al. 2015). Downstream flows are mainly altered by large dams, e.g., there are 654 reservoirs with storage capacities ≥0.5 km3 (Lehner and Doll 2004). Damming rivers currently stores the equivalent of 15% of global annual river runoff (Likens 2010). As a result, 48% of rivers (expressed as river volume) globally are moderately to severely impacted by either flow regulation, fragmentation, or both.

Tradeoff analysis between electricity generation and ecosystem services in the Lower Mekong Basin

Abstract: The Mekong River is the largest freshwater fishery and the third most bio-diverse river system in the world. Two of 11 planned mainstream hydropower projects, Xayaburi and Don Sahong, are nearly completed and a third project proposal, Pak Beng, has been submitted by the Lao PDR government for consideration. This paper builds on previous studies and examines the tradeoffs (between water use, food security supply and energy production) for the proposed mainstream hydropower projects in the Lower Mekong Basin (LMB). The paper concludes that the forecast loss of capture fisheries, sediment/nutrients and social mitigation costs measured as Net Present Value (NPV at 10% discount rate) are greater than the benefits from electricity generation, improved irrigation and flood control. The paper also forecasts huge negative economic impacts for Cambodia and Vietnam in contrast to previous Mekong River Commission’s (MRC) conclusions that all countries will benefit from hydropower development. The paper recommends reassessing the economic impacts of hydropower development using full environmental cost accounting. It also recommends that a new LMB energy strategy be developed taking into account less hydropower income than previously anticipated, updated forecasts for LMB power demand and anticipated technology developments for improved energy efficiency & renewable energy (especially solar which is now competitive with hydropower).