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Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amount of storage, in which case the storage reservoir is referred to as
pondage Pondage usually refers to the comparably small water storage behind the weir of a run-of-the-river hydroelectric power plant. Such a power plant has considerably less storage than the reservoirs of large dams and conventional hydroelectric stations ...
. A plant without pondage is subject to seasonal river flows, thus the plant will operate as an
intermittent energy source Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable ener ...
. Conventional hydro uses
reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...
s, which regulate water for
flood control Flood control methods are used to reduce or prevent the detrimental effects of flood waters."Flood Control", MSN Encarta, 2008 (see below: Further reading). Flood relief methods are used to reduce the effects of flood waters or high water level ...
, dispatchable electrical power, and the provision of
fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
for
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...
.


Concept

Run-of-the-river, or ROR, hydroelectricity is considered ideal for streams or rivers that can sustain a minimum flow or those regulated by a lake or reservoir upstream. A small dam is usually built to create a headpond ensuring that there is enough water entering the
penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills. H ...
pipes that lead to the
turbines A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful Work (physics), work. The work produced by a turbine can be used ...
, which are at a lower elevation. Projects with pondage, as opposed to those without pondage, can store water for daily load demands. In general, projects divert some or most of a river's flow (up to 95% of mean annual discharge)Knight Piesold Consulting
Plutonic Hydro Inc. Bute Inlet Project. Summary of Project Intake and Turbine Parameters
Knight Piesold Consulting.
through a pipe and/or tunnel leading to electricity-generating turbines, then return the water back to the river downstream.Douglas T, Broomhall P, Orr C. (2007)
Run-of-the-River Hydropower in BC: A Citizen's Guide to Understanding Approvals, Impacts and Sustainability of Independent Power Projects
/ref> Run-of-the-river projects are dramatically different in design and appearance from conventional hydroelectric projects. Traditional hydroelectric dams store enormous quantities of water in
reservoirs A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...
, sometimes flooding large tracts of land. In contrast, run-of-river projects do not have the disadvantages associated with reservoirs and so cause fewer environmental impacts.Hydromax Energy Limited
Hydromax Energy Limited website
/ref> The use of the term "run-of-the-river" for power projects varies around the world. Some may consider a project run-of-the-river if power is produced with no water storage, but limited storage is considered run-of-the-river by others. Developers may mislabel a project run-of-the-river to soothe public perception about its environmental or social effects. The
European Network of Transmission System Operators for Electricity ENTSO-E, the European Network of Transmission System Operators, represents 39 electricity transmission system operators (TSOs) from 35 countries across Europe, thus extending beyond EU borders. ENTSO-E was established and given legal mandates by ...
distinguishes ''run-of-the-river and pondage hydropower'' plants, which can hold enough water to allow generation for up to 24 hours (reservoir capacity / generating capacity ≤ 24 hours), from ''reservoir hydropower'' plants, which hold far more than 24 hours of generation without pumps. The
Bureau of Indian Standards The Bureau of Indian Standards (BIS) is the National Standards Body of India under Department of Consumer affairs, Ministry of Consumer Affairs, Food & Public Distribution, Government of India. It is established by the Bureau of Indian Standar ...
describes run-of-the-river hydroelectricity as:
A power station utilizing the run of the river flows for generation of power with sufficient pondage for supplying water for meeting diurnal or weekly fluctuations of demand. In such stations, the normal course of the river is not materially altered.
Many of the larger run-of-the-river projects have been designed to a scale and generating capacity rivaling some traditional hydroelectric dams.Plutonic Power (2008)
Revised Project Description for Bute Inlet Hydroelectric Project Requirements. P1
Plutonic Power.
For example, the
Beauharnois Hydroelectric Generating Station The Beauharnois generating station is a run-of-the-river hydroelectric power station along the Saint Lawrence Seaway on the Saint Lawrence River, in Quebec, Canada. The station was built in three phases, and comprises 36 turbines, capable of gene ...
in Quebec is rated at 1,853 MW. Some run-of-the-river projects are downstream of other dams and reservoirs. The reservoir was not built by the project but takes advantage of the water supplied by it. An example would be the 1995 1,436 MW
La Grande-1 generating station The La Grande-1 (LG-1) is a hydroelectric power station on the La Grande River that is part of Hydro-Québec's James Bay Project. The station can generate 1,436 MW and was commissioned in 1994–1995. A run of the river generating station, ...
. Previous upstream dams and reservoirs were part of the 1980s
James Bay Project The James Bay Project (french: projet de la Baie-James) refers to the construction of a series of hydroelectric power stations on the La Grande River in northwestern Quebec, Canada by state-owned utility Hydro-Québec, and the diversion of neigh ...
. There are also small and somewhat-mobile forms of a run-of-the-river power plants. One example is the so-called ''electricity buoy'', a small floating
hydroelectric power plant Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
. Like most buoys, it is anchored to the ground, in this case in a river. The energy within the moving water propels a
power generator Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery ( transmission, distribution, etc.) to end users or its sto ...
and thereby creates electricity. Prototypes by commercial producers are generating power on the
Middle Rhine Between Bingen and Bonn, Germany, the river Rhine flows as the Middle Rhine (german: Mittelrhein) through the Rhine Gorge, a formation created by erosion, which happened at about the same rate as an uplift in the region, leaving the river a ...
river in Germany and on the
Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , pa ...
river in Austria.


Advantages

When developed with care to footprint size and location, run-of-the-river hydro projects can create sustainable energy minimizing impacts to the surrounding environment and nearby communities. Advantages include:


Cleaner power and fewer greenhouse gases

Like all hydro-electric power, run-of-the-river harnesses the natural potential energy of water by eliminating the need to burn coal or
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
to generate the electricity needed by consumers and industry. Moreover, run-of-the-river hydroelectric plants do not have reservoirs, thus eliminating the methane and carbon dioxide emissions caused by the decomposition of organic matter in the reservoir of a conventional hydroelectric dam. That is a particular advantage in tropical countries, where methane generation can be a problem.


Less flooding

Without a reservoir, flooding of the upper part of the river does not take place. As a result, people remain living at or near the river and existing habitats are not flooded. Any pre-existing pattern of flooding will continue unaltered, which presents a flood risk to the facility and downstream areas.


Disadvantages


"Unfirm" power

Run-of-the-River power is considered an "unfirm" source of power: a run-of-the-river project has little or no capacity for energy storageDouglas, T. (2007)
"Green" Hydro Power: Understanding Impacts, Approvals, and Sustainability of Run-of River Independent Power Projects in British Columbia
Watershed Watch.
and so cannot co-ordinate the output of electricity generation to match consumer demand. It thus generates much more power when seasonal river flows are high (spring
freshet The term ''freshet'' is most commonly used to describe a spring thaw resulting from snow and ice melt in rivers located in upper North America. A spring freshet can sometimes last several weeks on large river systems, resulting in significant in ...
),Wilderness Committee
Wilderness Committee Comments on the Draft Terms of Reference, Bute Inlet Hydroelectric Private Power Project. Letter to Kathy Eichenberger, Project Assistant Director. P1
Wilderness Committee.
and depending on location, much less during drier summer months or frozen winter months. The plant will probably have a lower head of water than from a dam, and will thus generate less power.


Availability of sites

The potential power at a site is a result of the
head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...
and flow of water. By damming a river, the head is available to generate power at the face of the dam. A dam may create a reservoir hundreds of kilometres long, but in run-of-the-river the head is usually delivered by a canal, pipe or tunnel constructed upstream of the power house. The cost of upstream construction makes a steep drop desirable, such as falls or rapids.


Environmental impacts

Small, well-sited run-of-the-river projects can be developed with minimal environmental impacts. Larger projects have more environmental concerns. For fish-bearing rivers, a ladder may be required, and dissolved gases downstream may affect fish. In
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, the mountainous terrain and wealth of big rivers have made it a global testing ground for 10–50 MW run-of-river technology. As of March 2010, there were 628 applications pending for new water licences solely for power generation, representing more than 750 potential points of river diversion.IPPwatch.com website
IPPwatch.com
.


Concerns

* Diverting large amounts of river water reduces river flows, affecting water velocity and depth, reducing habitat quality for fish and aquatic organisms; reduced flows can lead to excessively warm water for salmon and other fish in summer. * In undeveloped areas, new access roads and transmission lines can cause
habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...
, allowing the introduction of invasive species. * The lack of reservoir storage may result in intermittent operation, reducing the project's viability.


Major examples

*
Jirau Dam The Jirau Dam is a rock-fill dam with an asphalt-concrete core, currently under construction on the Madeira River in the state of Rondônia, Brazil. The dam's hydroelectric power stations will have 50 turbines each 75 MW resulting total installed ...
,
Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
(under construction) *
Santo Antônio Dam The Santo Antônio Dam is a hydroelectric dam on the Madeira River southwest of Porto Velho in the state of Rondônia, Brazil. The dam's run-of-the-river hydroelectric power station have 50 turbines each rated at 71.6 MW resulting in a total inst ...
,
Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
(under construction) *
Chief Joseph Dam The Chief Joseph Dam is a concrete gravity dam on the Columbia River, upriver from Bridgeport, Washington. The dam is upriver from the mouth of the Columbia at Astoria, Oregon. It is operated by the USACE Chief Joseph Dam Project Office and the ...
,
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
*
John Day Dam The John Day Dam is a concrete gravity run-of-the-river dam spanning the Columbia River in the northwestern United States. The dam features a navigation lock plus fish ladders on both sides. The John Day Lock has the highest lift (at ) of any U.S ...
,
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
/Washington,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
*
Beauharnois Hydroelectric Power Station The Beauharnois generating station is a run-of-the-river hydroelectric power station along the Saint Lawrence Seaway on the Saint Lawrence River, in Quebec, Canada. The station was built in three phases, and comprises 36 turbines, capable of gene ...
,
Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...
,
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, *
The Dalles Dam The Dalles Dam is a concrete-gravity run-of-the-river dam spanning the Columbia River, two miles (3 km) east of the city of The Dalles, Oregon, United States. It joins Wasco County, Oregon with Klickitat County, Washington, 300 miles (309&nbs ...
, Oregon/Washington, United States *
Teles Pires Dam The Teles Pires Dam is a Run-of-the-river hydroelectricity, run-of-the-river hydroelectric dam on the Teles Pires, Teles Pires River, upstream of the confluence with the Tapajós river, on the border of the Brazilian states of Mato Grosso and Par ...
, Brazil *
Inga Dams The Inga Dams are two hydroelectric dams connected to one of the largest waterfalls in the world, Inga Falls. They are located in the western Democratic Republic of the Congo and 140 miles southwest of Kinshasa. Inga Falls on the Congo Ri ...
,
Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
* Satluj Jal Vidyut Nigam Ltd,
Satluj River The Sutlej or Satluj River () is the longest of the five rivers that flow through the historic crossroads region of Punjab in northern India and Pakistan. The Sutlej River is also known as ''Satadru''. It is the easternmost tributary of the In ...
,
Shimla Shimla (; ; also known as Simla, List of renamed Indian cities and states#Himachal Pradesh, the official name until 1972) is the capital and the largest city of the States and union territories of India, northern Indian state of Himachal Prade ...
,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
, *
Ghazi-Barotha Hydropower Project Ghazi-Barotha Hydropower Project ( ur, غازى بروتھا) is a 1,450 MW run-of-the-river hydropower connected to the Indus River about west of Attock in Punjab and east of Haripur in Khyber Pakhtunkhwa, Pakistan. Construction of the ...
,
Khyber Pakhtunkhwa Khyber Pakhtunkhwa (; ps, خېبر پښتونخوا; Urdu, Hindko: خیبر پختونخوا) commonly abbreviated as KP or KPK, is one of the Administrative units of Pakistan, four provinces of Pakistan. Located in the Geography of Pakistan, ...
,
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
*
Gezhouba Dam The Gezhouba Dam or Gezhouba Water Control Project () on the Yangtze River is located in the western suburbs of Yichang, in central China's Hubei province. One of the largest run-of-the-river dams, it sits several kilometers upstream from downto ...
,
Yichang Yichang (), alternatively romanized as Ichang, is a prefecture-level city located in western Hubei province, China. It is the third largest city in the province after the capital, Wuhan and the prefecture-level city Xiangyang, by urban populati ...
,
Hubei Hubei (; ; alternately Hupeh) is a landlocked province of the People's Republic of China, and is part of the Central China region. The name of the province means "north of the lake", referring to its position north of Dongting Lake. The prov ...
, China


See also

*
Environmental impact of electricity generation Electric power systems consist of generation plants of different energy sources, transmission networks, and distribution lines. Each of these components can have environmental impacts at multiple stages of their development and use including in ...
*
Environmental impacts of reservoirs The environmental impact of reservoirs comes under ever-increasing scrutiny as the global demand for water and energy increases and the number and size of reservoirs increases. Dams and reservoirs can be used to supply drinking water, generate hy ...
*
Hydropower Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to Electricity generation, produce electricity or to power machines. This is achieved by energy transformation, converting the Pot ...
*
Small hydro Small hydro is the development of hydroelectric power on a scale suitable for local community and industry, or to contribute to distributed generation in a regional electricity grid. Exact definitions vary, but a "small hydro" project is less ...
*
Micro hydro Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro. These installations can provide power to an i ...
*
Pico hydro Pico hydro is a term used for hydroelectric power generation of under 5 kW. These generators have proven to be useful in small, remote communities that require only a small amount of electricity for example, to power one or two fluorescent ...
*
Gravitation water vortex power plant The gravitation water vortex power plant is a type of micro hydro vortex turbine system which is capable of converting energy in a moving fluid to rotational energy using a low hydraulic head of . The technology is based on a round basin with a c ...


Notes


References

* Freedman, B., 2007, Environmental Science: a Canadian Perspective; 4th edition, Pearson Education Canada, Toronto, pp 226,394. {{DEFAULTSORT:Run-Of-The-River Hydroelectricity Hydroelectricity