What Is A Sustainable Alternative To Dams?

Dams are constructed barriers across rivers designed to control and manage water resources for various human needs. They provide benefits like flood protection, irrigation, drinking water storage, and hydroelectric power generation. While advantageous, dams fundamentally change rivers and the surrounding environment. Large dams in particular have been criticized for their negative impacts, including:

– Habitat destruction – Dams block fish migration and alter natural water flows, severely damaging riparian and aquatic ecosystems (source).

– Displacement of people – Dams can force the relocation of communities living in the flooded areas behind the dam (source).

– Disruption of river ecosystem – Dams disrupt the natural connectivity of river systems, alter sediment transport, and change river chemistry (source).

These significant sustainability issues have led to a search for more balanced alternatives to large dams that provide needed water resources while minimizing environmental and social disruption.

Run-of-River Hydropower

Run-of-river hydropower plants use the natural flow of a river to generate electricity, without the need for large reservoirs or dams. Water is diverted from the river into a channel or pipeline that feeds into a turbine. After passing through the turbine, the water is discharged back into the river downstream.

Compared to conventional hydropower dams, run-of-river has much less environmental impact as it does not require building large dams or flooding land for reservoirs. The natural flow of the river is maintained, which is better for downstream ecosystems and habitats. According to Kuriqi et al. (2021), run-of-river hydropower “induces lower ecological impacts” compared to dams and reservoirs.

Run-of-river also provides a more consistent source of renewable power compared to dams, as it relies on the river’s natural flow rather than stored water. During periods of drought when reservoir levels are low, run-of-river can still generate electricity. This makes it a more sustainable and reliable source of renewable energy.

However, run-of-river projects still can impact local ecosystems through flow diversion. As Sasthav (2022) discusses, careful environmental design is needed to minimize disruptions to wildlife, sediment transport, and water quality downstream. Overall though, run-of-river provides a lower-impact alternative to meet renewable energy needs compared to large hydropower dams.

Pumped Storage

Pumped storage plants work by pumping water from a lower reservoir to an upper reservoir when electricity demand is low. The water is then released from the upper reservoir to the lower reservoir to generate electricity when demand is high. This allows renewable energy sources like wind and solar to be stored in the form of potential energy in the upper reservoir. Pumped storage is more sustainable than dams because it does not require building new dams or reservoirs. It can use abandoned quarries or mines for the lower reservoir, and just an upper reservoir needs to be built.

Pumped storage has significant advantages over conventional dams. It allows renewable energy to be stored and dispatched when needed. Since no natural river flow is required, pumped storage can be sited almost anywhere. Pumped storage is also very efficient, with around 80% of the energy used to pump the water able to be regained when released to generate electricity (Source). Overall, pumped storage provides large-scale, long-duration energy storage critical for increasing renewable energy on the grid, with much less environmental impact than building new dams.

Small-Scale Hydropower

Small-scale hydropower utilizes smaller rivers and streams to generate electricity with a much reduced impact compared to large hydroelectric dams. Small-scale hydropower systems divert a portion of a river’s flow through a pipe or channel to turn turbines that generate electricity. The water is then returned to the river downstream. Small-scale projects typically have capacities up to 30 MW, whereas large-scale hydro projects can generate hundreds or thousands of megawatts.

The most common type of small-scale hydropower systems are run-of-river. These operate without impoundments or dams, so there is minimal disruption to the natural flow of the river. Run-of-river projects produce a more steady supply of electricity compared to facilities that use stored water. Small-scale systems have a lower impact on fish migration and habitat compared to major dams. There is less flooding of land and disruption of ecosystems when building a small facility versus a large reservoir. Small-scale hydropower can provide clean, renewable energy to rural communities near suitable rivers and streams (Azimov, 2022).

However, small-scale hydropower is site specific and depends on sufficient flow within a stream. The generating potential at any given location is limited compared to a major dam. Smaller facilities may not generate enough electricity for large urban areas with substantial demand. But they can provide local renewable power in an environmentally responsible manner compared to reliance on fossil fuels. Overall, small-scale hydropower is a more sustainable alternative that reduces many of the disruptive effects caused by large hydroelectric dams.

Renewable Energy Alternatives

There are several renewable energy sources that can provide sustainable alternatives to hydroelectric dams, including solar, wind, and geothermal. According to the U.S. Department of Energy, the amount of electricity generated from renewable sources has doubled since 2008, and could potentially replace up to 80% of the nation’s electricity generation by 2050.

Solar and wind energy have grown rapidly in recent years as costs have declined dramatically. The solar industry expanded by over 40% in 2019 alone. Wind power capacity has more than doubled over the past decade. While the output of solar and wind varies based on weather conditions, combining these technologies along with geothermal and existing hydropower can create a more reliable renewable energy mix.

In terms of sustainability, renewable sources like solar and wind are preferable to large hydroelectric dams, which often disrupt river ecosystems, harm fish populations through turbines, and emit greenhouse gases from decomposing vegetation and sediments. Solar and wind farms can be built quickly, scaled to need, and have minimal environmental impact. Geothermal plants use underground reservoirs of steam or hot water and have a small surface footprint.

For example, the Hoover Dam produces an average of 4 billion kWh per year. Generating the same amount of electricity from a combination of solar, wind and geothermal plants would require around 3,000 megawatts of total capacity. While a portfolio of renewable sources may require more land than a single dam, it provides clean energy without interfering with river flows or habitats.

Improving Existing Dams

There are various ways to improve the environmental sustainability of existing dams. One method is installing fish ladders, which allow migratory fish to bypass the dam and access upstream habitat. Proper fish ladder design that considers factors like water flow and fish jumping ability can effectively facilitate fish passage (Developing Better Dams | WWF).

Sediment management techniques can also enhance dam sustainability. Allowing some sediment to pass through the dam, instead of accumulating in the reservoir, helps maintain downstream habitat and replenish beaches and deltas. Selectively lowering dams to flush out excess sediment is another strategy (Improve or remove: Funding for U.S. dams | Stanford News).

Mimicking natural flow regimes below dams can support aquatic ecosystems. This involves coordinating dam operations to vary discharge rates at different times of year, creating flow pulses like those that would occur naturally (Dam Renovation to Prolong Reservoir Life and Mitigate …).

Dam Removal

Decommissioning and removing outdated and unsafe dams can provide significant environmental and social benefits. Dams built decades ago may no longer serve their intended purposes and can pose safety risks if not properly maintained. Removing dams helps restore a river’s natural flow and ecosystem.

According to American Rivers, dam removal “revitalizes river ecology and reconnects habitats for the benefit of fish, wildlife and people.” Removing barriers helps restore habitat connectivity and allows fish migration and healthier fisheries. One study found fish populations increased by 80% after a dam was removed from the Penobscot River in Maine (The Nature Conservancy).

There are also benefits for public safety. Older dams have a higher risk of failure which can cause downstream flooding. Decommissioning removes this threat. Dam removal also eliminates drowning hazards and creates new recreational opportunities on rivers.

Projects like the Elwha River restoration demonstrate the positive ecological impacts of dam removal. After two dams were removed, salmon populations rebounded, sediment flow increased, and new habitat emerged (Snyder Associates). Though not appropriate in all cases, dam removal is an important sustainable alternative to outdated infrastructure.

Watershed Management

Better land use practices can reduce the need for dams for flood control. For example, restoring wetlands and forests helps absorb and slow down flood waters before they reach populated areas. Wetland restoration also helps recharge groundwater supplies, reducing the need for dams and reservoirs for water storage.

Sustainable agriculture techniques like cover crops, no-till farming, and terracing fields prevent soil erosion and runoff after rains. Urban areas can implement green infrastructure like rain gardens, green roofs, and permeable pavements to allow stormwater infiltration rather than runoff.

Watershed management aims to work with natural systems to regulate water flow and quality. This involves understanding the hydrology of a region and implementing integrated land and water management practices. With better watershed management, dams are often unnecessary for flood control and water supply.

Water Conservation

One sustainable alternative to building new dams is reducing water demand through water conservation methods. By improving water use efficiency, overall demand can be lowered, reducing the perceived need for new dams and reservoirs. There are several ways regions can improve water conservation:

Water recycling systems can capture wastewater, stormwater or graywater and treat it for reuse for irrigation or industrial purposes. This reduces the amount of freshwater supply needed from dams and rivers. According to the LA Times, commitments are being made to guarantee water for ecosystems and to tear down dams that damage rivers and kill fish. The largest dam removal in U.S. history is slated to occur over the next several years on the Klamath River along the Oregon-California border.

Installing low-flow water fixtures such as faucets, showerheads and toilets in homes and businesses reduces water waste. Irrigation methods like drip irrigation deliver water directly to plant roots efficiently. Drought-tolerant landscaping also reduces outdoor water demand. Public education campaigns can encourage responsible daily water usage and conservation habits among consumers.

Reducing leakage in existing water infrastructure through pipeline replacement and maintenance also ensures water is used more efficiently. Monitoring tools help detect leaks early. Overall, regions emphasizing water conservation principles use less water compared to their historical levels, reducing the need for new dams.

Conclusion

In summary, the most viable sustainable alternatives to dams identified in this article are run-of-river hydropower, pumped storage hydropower, small-scale hydropower, renewable energy sources like solar and wind power, improving existing dams to be more efficient and environmentally friendly, and dam removal or decommissioning.

More research is needed to expand the adoption of these alternatives, especially on topics like:

• Improving technologies and reducing costs for run-of-river, pumped storage, and small-scale hydropower
• Evaluating the best locations to implement run-of-river and pumped storage projects
• Developing small-scale, modular hydropower systems for remote areas
• Integrating renewable energy sources like solar and wind power into existing grids and dams
• Assessing environmental and social impacts of dam removal projects
• Studying watershed management and water conservation programs to reduce need for dams

With further research and pilot projects, sustainable hydropower and renewable energy alternatives can gain wider adoption around the world as viable substitutes for conventional dam projects.