Run-of-River Power

By Charlotte Helston

I. Overview

With the general success of large hydropower as the world's leading source of renewable energy, it is only reasonable that countries consider small hydro - run-of-river - development as well. This is particularly relevant for Canada, a country that has tapped its abundant hydropower resources for more than a century. All of Canada's major hydropower developments are large, and though they already contribute 60% of Canada's electricity (and about 90% of B.C.'s) there remains a growing need for more energy. Large hydro dams are costly to build, and new facilities require extensive timelines for consultation, planning and regulatory requirements, construction, etc. In addition, most of the more favourable hydropower sites in Canada have been developed. These factors have propelled small hydro into the energy scene. An old technology with many recent innovations, small hydro is appealing for its reduced environmental impacts, potentially cheaper development, and plentiful prospective sites.

Public discourse about small hydro often mistakes the reduction of environmental and social impacts for elimination of them. It is important to understand that small hydro inflicts a smaller impact on aquatic ecosystems and local communities, but like all forms of energy cannot completely prevent stresses on plant, animal, and human well-being. Additionally, the negative, cumulative effects of ROR systems operating along the same river network may present further problems, and research in this area is severely lacking.

Although not yet cost comparable to large hydro, small hydro is still capable of yielding lower costs per kWh than some other sources, such as diesel-electric. In Canada, small hydro has found a niche in replacing polluting diesel generators in remote, often First Nations, communities. This development must be undertaken with care, however, as the risk of affecting river ecosystems directly connects to the stability of traditional lifestyles. The linkage between social and environmental concerns is closely bonded in these places.

Long and often confusing permitting processes have slowed the progress of small hydro in Canada, alongside hesitancy created by unaddressed social and environmental concerns. Small hydro is likely to gain a stronger presence in coming years if research and development (R&D) becomes more of a priority. Developments must be made in the technology's overall efficiency, as well as in its environmental status, in order for expansion to truly take hold.

II. How Run-of-River Works

Small hydro, often called run-of-river (ROR), carries many similarities to its parent system, large hydro. Both harness the energy in flowing water to generate electricity. In Canada, small hydro is usually broken down as follows: micro hydro referring to developments with an installed capacity of less than 100 kW, mini hydro between 100 kW-1MW, and small hydro is used to describe projects of between 1 and 50 MW. Some large hydro stations can have outputs of hundreds or even thousands of MegaWatts. On average, small hydro systems in Canada exhibit annual capacity factors in the range of 40-80%.

In ROR systems, running water is diverted from a river and guided down a channel, or penstock, which leads to a generating house. Here, the force of the moving water spins a turbine, which then drives a generator. Used water is fed back into the main river further downstream. The difference between run-of-river and large, conventional storage hydro, is the absence of a dam and reservoir. Run-of-river relies on coursing rivers to generate electricity, as opposed to stored water. Most small hydro facilities do use a dam, or weir, to ensure enough water enters the penstock. Pondage is also used at some facilities to store small amounts of water. Plants with pondage tend to be more reliable, as they assuage the effects of daily and seasonal flow infrequencies.

Run-of-River Diagram
A diagram showing how a small hydro, or run-of-river facility, draws power from a mountain stream.

The absence of a dam has two main implications. The first is that if/when water levels are depleted upstream due to drought conditions or water extraction, the "fuel" for the ROR system is unavailable. Without a dam for storing water, there is no back up.

The second implication is that the elimination of a dam simultaneously reduces the environmental impacts of flooding. In conventional storage hydro, the creation of reservoirs causes once dry land to become inundated, thereby affecting local communities as well as plant and animal wildlife. Additional effects include traumatization of fish, such as salmon, poor water quality, and enhanced release of methane from stagnant waters. Read more about the environmental impacts of large hydro here.

The elimination of a dam, or reduction in scale of one (some sites do use pondage) lessens the impact ROR systems have on the environment. The impacts are not wholly avoided, but they are minimized to what many consider a tolerable amount.

III. Geography of Run-of-River

Where can Run-of-River be developed?

For a run-of-river system to operate, two geographical features are required. One is a substantial flow of water, originating either from rainfall or snowpack melting. The other is a sufficient pitch to enhance the water's energy. The greater the fall of water, the more gravity is able to increase the kinetic energy in it. Small hydro can be installed at existing dams, on their own, or in private systems that power single dwellings. Sometimes, plants are constructed in conjunction with river and lake water-level control and irrigation systems.

The unique location and set of geographical factors associated with small hydro plants means that power output is never identical across sites. Power potential is a direct function of head and water flow.

Ambro Creek
Ambro Creek, a creek typical of the kind where run-of-river facilities are built.

The BC Sustainable Energy Association (BCSEA) offers a calculation for determining approximate power potential based on given geographical factors, by the formula:

P = Q•H x 7.83

Where P is the power produced (in kW)

Q is the water flow in cubic meters/second

H is the hydrostatic head of the water in meters

Although somewhat simple, the above potential power calculation requires thorough fieldwork to gather reliable data. Daily and seasonal fluctuations in flow mean that observations over time are necessary to determine accurate river flow averages. Digital elevation maps can provides an initial estimate of the hydrostatic head, but detailed surveying is eventually required. Because large constructions are kept to a minimum, it is essential to find naturally efficient sites.

IV. Run-of-River Around the World

What countries have developed small hydropower?

China, and Asia in general, are becoming new leaders in all types of hydropower, both large and small, in line with its unparalleled sprint for renewable energy. More than half of the world's small hydro is installed in China. In 2007 alone, China invested $12 billion in renewable energy sources, including small hydro. Many developments in Australia and New Zealand are focusing on small hydropower plants as well.

As small hydro is a relatively new and emerging energy resource, many countries are concentrating efforts on research and development (R&D) to make the technology more cost-effective. The most promising field is that of the turbines, which are considered the most expensive component of the system. Different models are being developed for different types of sites, efficiencies are going up, and costs are being reduced as the technology becomes more widespread. Improvements are also being made in terms of minimizing environmental impacts -- a main barrier in the expansion of this energy resource. It is expected that as R&D continues, small hydro will become more common in Canada, and the rest of the world.

V. Run-of-River in Canada

Parts of Canada are fortunate to possess ideal conditions for hydropower stations. The Pacific coast of Canada is one of several regions to receive rainfall in excess of 2,000 mm per year, alongside places like the Himalayas, Indonesia, and the upper Amazon. The Cascades and Rockies provide mountainous terrain, often topped with snow and glaciers. Together, the rain, slopes, and frozen water make for excellent hydropower, both large and small.

Rocky Mountains
The Rocky Mountains in Banff National Park. The various mountain ranges of Canada, in Quebec, Ontario, Manitoba and British Columbia, make for excellent locations for small hydro operations.

Already, and for the past hundred years, Canada has tapped the renewable resource of large hydro. Small hydro also has a long history in Canada as well, dating back nearly a century. Installed small hydro in Canada presently sits at a capacity of 3,400 MW. At present, 60% of Canada's electricity is accounted for by one form of hydropower or another, and reports state that with expansion and new development, twice the existing capacity could be achieved. Much of this will likely occur with run-of-river projects.

Large scale hydro facilities that use dams and reservoirs cause a host of unfavourable environmental impacts, which has caused a public backlash against any new planned large hydro developments. Run-of-river is much more environmentally benign than large hydro, as it avoids the use of a dam and reservoir. But a relatively clean environmental bill is not enough to get small hydro power stations erected on a large scale across the country.

The higher expense of ROR systems are primarily because of their meager capacity and inability to store energy. Recent improvements in turbine efficiency, and an expectation of continued advancements, have kept hopes high about the future of small hydro.

Over 5,500 potential Canadian sites for run of river turbines have been identified, most located in BC, Newfoundland, Quebec, Ontario, the Northwest Territories, and the Yukon.


VI. Run-of-River in B.C.

There are 32 existing small hydro projects in BC that together put out 3,500 GW hours -- enough to supply electricity to 350,000 homes. The majority of the conveniently located small hydro sites have already been developed. Remaining potential sites are mostly remote, and expensive, areas for development.

Forecasts for small hydro are promising with energy costs and energy demands continuing to climb, and the BC government aiming for electricity self-sufficiency by 2016. Run-of-river can likely play a role in this development.

BC Hydro, the province's chief electrical utility, will only accept new projects that are considered "clean", in accordance with the 2008 Clean Power Call. Run-of-river projects are therefore competing with solar, wave and wind, but due to BC Hydro's bias toward hydropower, they are likely to dominate the clean energy development proposals with their low environmental impact, and low development cost. Furthermore, ROR enjoys the affiliation with large hydro, which BC residents already rely on for about 90% of their electricity.

Lengthy permitting procedures are one of the reasons run-of-river development has not yet begun on a greater scale. Projects must sometimes obtain more than 50 permits, licenses and approvals from approximately 14 regulatory bodies. It bears noting that these facilities will be in place for more than 100 years, making several years of planning a reasonable, and thoughtful step. Growing consideration for collaboration between a variety of social and environmental groups has made permitting slower, but makes for a much sounder outcome. Only if this movement toward comprehensive collaboration continues will hydropower be able to offer positive benefits for all stakeholders, as well as the environment.

VII. Politics of Run-of-River

Through a combination of recent calls for renewable energy RFPs, standard offer programs, and net-metering across Canada, small hydro has captured the country's attention. Historic barriers such as tensions with local First Nations communities, and ecological concerns have only recently been somewhat addressed by the provincial and federal governments.

Canada's constitution separates jurisdiction over energy between the federal and provincial governments. Provincial governments carry responsibility for, as Natural Resources Canada describes, "…Resource management within their borders, which includes the production, transmission, and distribution of electricity." Federal jurisdiction is primarily concerned with "The international movements of energy and energy using equipment, and with works extending beyond a province's borders... [and] leads in areas such as energy science and technology and research".

The responsibility for environmental assessments falls mainly on provincial governments, though some assessments are conducted at the Federal level. Generally, the federal government is only actively involved with fiscal and production incentives, and research and development. NRCan has supported the hydraulic machinery lab at Laval University, the only independent hydro-turbine testing facility in Canada. Further expansion of R&D work is recognized by Natural Resources Canada as an essential part of small hydro development. Not only will R&D improve the economics of the technology, it can also lessen environmental impacts, as was seen in the development of fish friendly turbines.

Conducting environmental assessments, and giving the final authorization for hydroelectric developments is up to the provincial government, unless sites are on federal Crown lands. Current licensing procedures run about 40 months, with the following requirements to be addressed: land access, water rights (including the Fisheries Act and Navigable Waters Protection Act), provincial regulations, and an environmental assessment, including consultations with First Nations. Communication with local First Nations is improving: when a new hydropower project or refurbishment scheme is proposed, public hearings, roundtable discussions, formal and informal meetings, information sessions, and the creation of committees follows to varying degrees.

Run-of-River developers complain of excessive red tape and permitting procedures that have slowed the development of this technology.

Provincial regulations include: water management policies, waterway works, protection of water habitats, flood management, dam safety policies, protection of public rights, specific environmental assessment issues, and electricity market legislation. Small hydro projects may be able to bypass certain fees and even the provincial Environmental Assessment (EA) process, though justification for these types of allowances appear unsupported by any written legislation.

What kind of government incentives support small hydro?

As of 2007, the ecoENERGY for Renewable Power program has offered an incentive of 1 cent per kWh for electricity produced from eligible projects. Small hydro projects are acceptable if they are certified low-impact (typically run-of-river with less than 48 hour storage and minimal environmental impact). The federal government has also engaged in the Purchases of Electricity from Renewable Resources (PERR), which requires the government to purchase 20% of its electricity through the program. Though new agreements are no longer being negotiated under this program, it did briefly provide a first customer to help interested utilities gain experience... achieve emissions reductions in federal operations, and leverage first purchases to create viable green power markets".

CanMet Data
The steps that must be taken before a construction of a hydroelectric project can go ahead.

VIII. Run-of-River Economics

The small hydro industry generates $150 million annually in the Canadian economy through a combination of national and international projects. With an estimated undeveloped potential of 15,000 MW, and a growth rate of 50-150 MW/year, small hydro is expected to contribute more and more, bit by bit, to the Canadian economy.

What does small hydro development cost?

Studies say hydropower, large or small, offers the most valuable form of energy as it provides the greatest amount of energy over its lifetime, compared to the energy required for its manufacture, operation, and disposal (Canmet 2008). The non-monetary values are significant as well; the social and environmental advantages of small hydro leave it less resisted by various types of organizations. Often it is the financial costs, rather than the "true costs" of conventional energy sources that are praised for their low apparent prices. As time goes on, true costs will likely be perceived with greater value.

Social and environmental factors aside, how much does it cost to develop a small hydro facility?

transmission line
Considerable transmission infrastructure is often required to bring power from small hydro projects, often located in remote areas, to consumers. This can raise the price of small hydro power substantially.

Each project is site-specific, with natural factors ultimately determining the end cost. How much work must be done to prepare the site (transmission lines for remote areas, establishment of roads, bridges, etc.) as well as the efficiency of the plant upon completion together influence how much money is required up front, and how much money will be paid back through operation. In general, only about 25% of costs are relatively fixed, with the rest dependent on location and site conditions.

Typically, low-head, high flow sites are more expensive to develop than high-head, low-flow sites. As head increases, the cost of generating equipment generally decreases. The right combination of head and flow is what makes hydro cost-efficient.

While construction costs are minimal as compared to large hydro with their dams and reservoirs, up front costs remain the largest investment in small hydro as well. The average investment cost in 2008 was $2,000 to $5,000 per installed kW, with an overall cost of $0.04 to $0.10 per kW. Rural regions typically require greater investments of around $6000 per kW. The single largest mechanical investment is the turbine, ranging from 20-50% of the total cost of the project. Turbines, as well as most other equipment, have life spans of at least 25 years, and can be refurbished. Expanded Research and Development (R&D) could improve performance and reduce costs of turbines and related mechanical equipment, if it were made a priority by the Canadian government.

What is the cost to B.C. consumers?

BC's predisposition to the use of large hydropower has led to some of the cheapest electricity in the world. The Peace River region, where two major dams put out 3,424 MW, purchases electricity for about 2-3 cents per kWh. Electricity from small hydro continues to be more expensive than that from large hydro. A report by Natural Resources Canada (2010) says small hydro could be developed for 7 cents/kWh, still a reasonable amount compared to 9.39 cents/kWh in Oregon, or 14.83 cents/kWh in California.

How many jobs does the small hydro industry support?

In the 1990s, small hydro contributed about $100 million a year to the Canadian economy, predominantly in manufacturing and services. The hydropower industry, encompassing large hydro, has supported hundreds of thousands of jobs since its inception at the beginning of the 20th century. Employment ranges from engineering jobs, to construction jobs, which often support local community tradesmen and women.

With a century long history with hydropower, Canada has some of the most experienced individuals involved in hydro in the world. However, Canmet has raised concerns about the hydropower industry's aging work force. In reference to a 2007 Natural Resources Canada meeting, they stated there is only about 10 years of expertise left in Canada. A lack of university or college courses on hydro is reportedly to blame. It is of some concern that as small hydro breaks into the mainstream, it will be doing so as the industry's experts leave the scene. It does, on the other hand, demonstrate an area of upcoming job openings for properly trained individuals.

IX. Environmental Impact of Run-of-River

Small hydro is responsible for very few greenhouse gas emissions. The construction, which accounts for the majority of emissions, is balanced out by a practically emissions free operation life. The fuel, water, is one of the most valuable materials on earth, and is the component most affected by development.

In large hydro, manipulation of natural river flows causes an array of environmental impacts. Run-of-river systems minimize these side-effects as they require less infrastructure. The absence of large reservoirs and dams considerably limits the social and environmental impacts, as the river is not transformed into a lake. The need for communities to relocate is avoided, and the effects on riparian and aquatic ecosystems are mitigated.

However, mitigated effects are not to be mistaken as avoided effects. Any diversion of natural river flows causes changes in the workings of the aquatic ecosystem. River continuity is fragile and dependent on the stability of many interrelationships. Generally, the smaller the diversion of water, the gentler the impact. Low head, in which the height difference between the water level upstream and downstream is relatively small, allows for the construction of fish ladders, which provide migration routes for fish. High head sites, where drastic elevation occurs, pose a more challenging location for constructing ladders. This environmental fact is at odds with economic common sense: the greater the head, the more profitable the venture. Developers are thus challenged to find a middle ground, wherein the facility earns a profit, without risking high environmental side-effects.

fish ladder
A fish ladder at John Day Dam in the United States.

By altering the regular flow of water, small hydro plants affect numerous aquatic species. Morphological changes of the river basin and water composition can increase species mortality, disrupt migration, and cause imbalances in biodiversity. Thermal pollution, increased turbidity, and the alteration of nutrients are the main drivers of aquatic ecosystem transformation. These changes also have negative affects on reproduction. Fish eggs are known to be destroyed by strong variations in river flows. Artificial hydropeakings and sedimentation can harm and even devastate habitats, and hamper the establishment of new ones.

Every facility is a unique case, with more or less of an environmental impact. Whether or not the plant utilizes pondage for water storage, as well as the size of the weir, affect the magnitude of environmental impact. Attempts to seamlessly introduce the facility, altering it as little as possible, and providing measures to reduce impacts where they must occur, can lead to a situation where the energy plant and natural ecosystem coexist without severe side-effects.

Is Run-of-River worth the environmental impact?

Discussion has arisen worldwide regarding just how promising the small hydro industry will be in solving "the energy problem". Its recent surge in popularity may be ill considered. It is difficult to evaluate any energy, thus, the following is more so an examination of the environmental and economical factors of small hydro.

The energy output of small hydro facilities is so low that even the small damage inflicted upon the environment by run-of-river construction may outweigh the environmental benefits it has over large hydroelectric dams. The only way for small hydro to make a large contribution to the energy sector is for a lot of facilities to be constructed. The debate over fewer large hydro, compared to many small hydro, is wrought with pros and cons that don't seem to add up decisively. It is true that with careful planning, small hydro can pose very few risks to the environment. So, if it doesn't hurt, do it? While small hydro may not hurt the environment, it will only be able to contribute small amounts of energy, where big amounts are needed if the world is to carry on as is.

Using Run-of-River to replace diesel electric systems for remote communities

Polluting diesel generators can be swapped for run-of-river systems.

Perhaps the most effective possibility of ROR systems in Canada is in remote, off-grid areas. In locations where costly generators are used, the high up front costs of small hydro are offset. Diesel fuel emits substantial amounts of carbon dioxide and other dangerous particulates, and poses the risk of accidental spills. It is also quite costly. Average oil prices in 2011 were around $100 per barrel, and when the expenses of transportation to remote communities is factored in, the overall cost of diesel is much higher than that provided by small hydro.

What role does small hydro have in powering remote First Nation's communities?

Recent examples of First Nations-owned small hydro projects include the Hupacaseth who operate the China Creek project near Port Alberni, BC, and the Taku River Tlingit First Nation owned Pine Creek project near Atlin, BC. For remote First Nation's communities, small hydro offers potential economic independence that cannot be obtained when external fuels, such as diesel, are relied on.

Chief Daryl Peters said of the small hydro project in his community, "[The Douglas First Nation's] intention is to harness the untapped energy of the water in a way that preserves its natural flow and also supports the generation of renewable energy, [allowing] us to preserve the biodiversity of our lands and waters and create new economic opportunities for our people."

Small hydro is not without its own flaws, however. First nation's communities have expressed concern about impacts on streams and fish life. For many communities, livelihoods hinge on the health and resilience of surrounding resource sites, including rivers. Fish, such as salmon, are a staple food in many First Nation's diets. Hydro facilities, large or small, are known to affect fish populations to varying degrees. Fish may be caught and killed in the turbines, disoriented by altered river flows, or affected by modified water composition.

Despite these concerns, many first nations are eager to begin development for the jobs it would create. A general consensus among communities for expanded infrastructure, fed by the economic opportunities small hydro could provide, demonstrates a main priority in generating wealth. Most existing developments in first nations communities boast "fish friendly" designs, and though relative to many other sites they have a minimal environmental impact, it is difficult to measure or predict the future effects of a new technology. The desire for enhanced economic opportunities may jeopardize traditional ways of life. For this reasons, it is imperative that development in first nations communities be conducted with careful planning, consultation, and discussion.

X. Bibliography

To ensure continuity of material, all of the external web pages linked and presented on our site were cached in May 2012. Readers are recommended to explore the current links for any changes.

Government of British Columbia. 'BC Energy Plan.' 2011. Accessed May 30, 2012.

BC Hydro. 'BC Hydro integrated resource plan: First Nations Consultation.'Castlegar. 2011. Accessed May 30, 2012.

Chen, Y., R. Hardman. 'The run of river energy sector.' Cleantech. 2011. Accessed May 30, 2012.

Government of Canada. 'Energy in the Chinese-Canadian bilateral relationship.' 2011. Accessed May 30, 2012.

Environment Canada. 'Environmental Impacts of Hydro Power.' Electricity generation-hydro power. 2010. Accessed May 30, 2012.

The European Small Hydropower Association. 'Environmental Barometer on Small Hydro Power.' Brussels, Belgium. 2009. Accessed May 30, 2012.

Canmet Energy and Natural Resources Canada. 'Emerging hydro power technologies R&D in Canada: A strategy for 2007-2011.' Ontario, Canada. 2011. Accessed May 30, 2012.

Gunter, G. 'Hydropower -- A green energy?' Clean Journal. Vol 37:9. p726-734. 2009. Accessed May 30, 2012.

Natural Resources Canada. 'Low head hydro market assessment. Hatch Energy.' 2008. Vol:1. Main Report. Ontario, Canada.

Centre for Energy. 'Maps: Canada.' British Columbia. 2011. Accessed May 30, 2012.

Western Economic Diversification Canada. 'Rural and First Nation communities focus on community alternative energy development to stimulate local economies.' News Releases. 2004.

Salvador, A. 2005.

Canmet and Natural Resources Canada. 'Small Hydro Power. Renewables.' 2009. Accessed May 30, 2012.

Natural Resources Canada.'Small scale hydro -- Public policy & experience: Country report for Canada.' International Energy Agency. Hydropower Technologies and Programs. 2010. Accessed May 30, 2012.

CanREN. 'Small-scale hydro. Technologies & Applications.' 2002. Accessed May 30, 2012.

U.S. Energy Information Administration. 'U.S. Monthly Electricity Usage.'.2011. Accessed May 30, 2012.

XI. References