What Type Of Hydropower Plant Does Not Use A Dam?

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Introducing Run-of-River Hydropower

Run-of-river hydropower is a type of hydroelectric power generation that harnesses the natural flow of rivers and streams to produce electricity without the need for dams. Unlike conventional hydropower that stores water in reservoirs behind dams, run-of-river systems divert a portion of a river’s flow through a canal or penstock to spin turbines and generate power.

Run-of-river facilities use the kinetic energy of flowing water to generate electricity in real time, meaning the water is not stored but passes through the facility and back into the river. This allows run-of-river projects to generate power with little or no impact on the natural flow and level of the river (International Hydropower Association).

Compared to dam-based hydropower, run-of-river systems are generally considered more environmentally friendly as they do not require large dams and reservoirs that can disrupt ecosystems. Run-of-river projects also have a smaller footprint and faster project development times. However, they provide less flexibility than reservoirs to store water and generate electricity on demand. The amount of power generated depends on seasonal water volumes in the river (Clean Energy BC).

Overall, run-of-river hydropower provides a renewable energy source that can utilize the natural flow of rivers with minimal disruption. It serves as an alternative to dam projects in areas where diverting some flow is feasible but damming the entire river is undesirable.

How Run-of-River Hydropower Works

Run-of-river hydropower utilizes the natural flow of rivers to generate electricity, without the need for dams or water storage reservoirs. Water is diverted from the river into an intake channel, where it flows downhill through a penstock pipe to a turbine inside the hydropower plant. The force of the flowing water spins the turbine, which turns a generator to produce electricity. The water exits the plant through a tailrace channel back into the river downstream.

Unlike conventional hydropower dams that store large reservoirs of water, run-of-river systems allow the river to flow through the plant in a near-natural state. The water intake and flow through the plant is continuous, with little or no manipulation of the river’s flow and volume. This allows run-of-river projects to harness electricity from rivers not suitable for dams while minimizing the environmental impact on the surrounding ecosystem.

According to Wikipedia, “Run-of-the-river 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 and intake structure is built to create a headpond ensuring that there is enough water entering the penstock pipes leading to the turbines which powers the generator.” (https://en.wikipedia.org/wiki/Run-of-the-river_hydroelectricity)

Benefits of Run-of-River

Run-of-river hydropower offers several key advantages compared to traditional dam-based hydropower projects. One major benefit is that run-of-river is much more environmentally friendly and has less impact on wildlife and habitat. Since run-of-river projects do not require large reservoirs, they avoid flooding extensive areas upstream. This prevents the destruction of forests and wildlife habitats that often occurs with dam construction. Run-of-river allows fish migration to continue naturally along the river, rather than getting blocked by dams.

Additionally, the smaller scale of run-of-river systems means the costs are significantly lower compared to massive hydropower dams. The infrastructure is relatively simple, involving a diversion structure, penstock pipes, and a powerhouse. With lower costs, the payback period is faster and there is less financial risk. This also makes the permitting process much easier than large dam projects, which often get held up for years in environmental impact reviews and regulatory approvals.

Since run-of-river relies on the natural flow of the river, it causes less disruption of the river’s ecosystem and natural water flows downstream. The river continues to function normally, rather than being controlled by dam operators. This avoids many of the ecological damages that can occur when dam reservoirs drastically alter water levels.

Overall, the lower environmental impacts, lower costs, faster permitting, and less disruption make run-of-river an appealing renewable energy solution in many cases. It provides a sustainable hydropower alternative that is both economically and ecologically viable.

Downsides of Run-of-River

One of the main disadvantages of run-of-river hydropower is that it has less energy storage and more variability compared to conventional reservoir-based hydropower dams. Since run-of-river systems do not have large reservoirs for storing water, their power output fluctuates depending on the natural flow of the river [1]. This makes run-of-river “unfirm” power that cannot always meet peak electricity demands.

Run-of-river projects require proper geographical site conditions in order to work well, like adequate water flow in the river and proper elevation drop. Many rivers simply do not have the ideal topography or hydrology to support run-of-river, limiting available sites. Compared to damming a wide valley, which creates a large reservoir, run-of-river is restricted to certain high-grade sites [2].

Overall, the “unfirm” and variable nature of run-of-river power, coupled with specific site requirements, are some of the main downsides limiting wider adoption. Run-of-river projects require careful planning and site selection to succeed.

Best Geographical Locations

The best geographical locations for run-of-river hydro projects are areas with fast-flowing rivers that originate from mountainous regions and maintain a consistent flow rate year-round. Rivers that descend rapidly from high elevations provide the elevation drop that allows run-of-river systems to generate electricity without the need for a large dam and reservoir.

Ideal rivers for run-of-river have high flow rates, especially during drier seasons. Rivers sourced from mountain snowpack and glacial melt tend to meet this requirement as they are fed consistently from snow and ice reservoirs. Areas with high annual precipitation also provide rivers with steady flow rates necessary for run-of-river hydro.

Locations should be selected to minimize environmental impacts. Rivers that are free-flowing and undisturbed make the best candidates. Rivers with minimal aquatic life, lower biodiversity, and devoid of sensitive species habitats and migration routes are preferable. Remote and difficult to access rivers in mountainous areas often match these criteria.

Prime examples are the hill and mountain areas of India, Nepal, Latin America and Canada which possess the ideal geography and hydrology for run-of-river projects [1].

Notable Run-of-River Projects

Some of the largest run-of-river hydropower projects in the world showcase the scale and capacity that this technology can achieve.

The 1,020 MW Khimti Khola project in Nepal utilizes a 335 meter drop to generate electricity, avoiding the need for a large dam or reservoir [1]. It is one of the largest run-of-river projects in South Asia.

Canada’s 195 MW Brilliant Expansion plant in British Columbia operates by diverting water from the Kootenay River through an underground penstock. It generates enough power for over 160,000 homes [2].

China’s Jin’anqiao Hydropower Station has a massive 12,600 MW capacity generated from 36 turbines along the Jinsha River. It is currently the largest run-of-river facility in the world [3].

These projects demonstrate the ability of run-of-river designs to provide renewable power at a large scale while minimizing environmental impacts.

Economic Viability of Run-of-River Hydropower

Run-of-river hydropower can provide affordable, reliable electricity, but the upfront capital costs are high compared to other renewable energy sources. According to a report by IRENA, the average investment cost for run-of-river hydropower projects under 10 MW capacity is around $2,500 per kW installed.[1] This is 2-3 times higher than wind or solar photovoltaics.

However, hydropower has a long lifespan and low operating costs. Estimates range from $0.02 – $0.10 per kWh for operating costs.[2] With no fuel costs, projects can generate electricity for decades. Run-of-river projects also qualify for production tax credits and other incentives in many jurisdictions.

Globally, hydropower capacity and investment grew steadily in the past decade. But in North America, growth has stagnated recently due to permitting challenges, high upfront costs, and increasing investment in other renewables. Policies that account for the benefits of low-carbon baseload power from hydropower could spur further development.

Environmental Considerations

Run-of-river hydropower can impact the natural environment, especially river ecosystems and wildlife. One major concern is the impact on fish migration and populations. Building small dams and diversion structures can impede the ability of fish to migrate upstream to spawn. According to the U.S. Energy Information Administration, fish ladders and elevators can sometimes be installed to help mitigate this, but their effectiveness varies.

The periodic diversion of water can also degrade fish habitat in the depleted sections of river. Studies have shown run-of-river projects reduce habitat connectivity and availability for native fish species (Kuriqi et al., 2021). Environmental flows need to be carefully studied to prevent population declines.

In addition to fish, other wildlife that rely on the riparian areas along rivers can be impacted by changes in water levels and flow. Animals like amphibians and waterfowl depend on wetland areas that can be disrupted by diversions. Terrestrial species may also be affected if their habitat is flooded by expanded reservoirs.

Proper siting, design adjustments, and environmental flow standards can help mitigate some of these impacts. But in general, run-of-river projects still alter natural hydrology and habitat, so environmental effects need to be closely monitored and managed.

Comparison to Dams

Unlike a traditional dammed hydropower project, run-of-river hydroelectricity does not utilize an impoundment or large man-made reservoir to collect and store water. Instead, a run-of-river project diverts the natural flow of a river through a penstock or canal to generate electricity without the need for dams. This helps minimize the environmental and social disruptions caused by traditional reservoir systems [1].

Some key differences between run-of-river and dam projects:

Dams store large reservoirs of water, while run-of-river draws from the natural flow of the river. This results in less flooding and disruption of ecosystems from run-of-river.

Run-of-river generates less energy overall than dams due to the lack of large reservoirs, but generally has lower project costs.
Dams provide storage and flood control, while run-of-river is dependent on seasonal river flows for generation.
Run-of-river is considered more environmentally friendly, with lower impacts to fish migration and wildlife habitats.

In summary, run-of-river provides a more sustainable hydropower alternative that harnesses energy from rivers while minimizing ecosystem damage. However, dams offer greater energy storage capabilities through reservoirs [2].

Future Outlook

The future outlook for run-of-river hydropower is generally positive, with predictions of continued growth and improvements in technology to overcome current limitations.

According to a 2023 study published in ScienceDirect, run-of-river electricity production in the Alps is predicted to increase over the next century due to climate change leading to increased winter precipitation and glacier melt. The increases are expected to be most pronounced in fall and early winter. https://www.sciencedirect.com/science/article/pii/S004896972302555X

Run-of-river hydropower also has strong potential for providing clean, renewable electricity to rural and remote areas currently lacking access to electricity. Organizations like Energy5 are exploring innovative run-of-river projects to provide decentralized, small-scale hydropower to remote communities and displace fossil fuel use. https://energy5.com/the-potential-of-run-of-river-hydropower-for-rural-electrification

Advancements in turbine technology, power electronics, remote monitoring and control systems may help make run-of-river projects more efficient and cost-effective. There is also research into new turbine designs better suited for low-head sites. Overall, the technology improvements and increasing demand for clean energy should drive continued growth in run-of-river hydropower, especially in areas with ideal topographical conditions.