As the world increasingly shifts towards renewable energy, hydropower remains a leading source of electricity. In 2022, hydropower produced more power than all other renewables combined.
However, traditional hydropower systems pose significant risks to aquatic life, particularly migratory species like the American Eel. Fortunately, innovations in turbine design are emerging as promising solutions to make hydropower more fish-friendly.
The Challenge of Fish Mortality in Hydropower
Dams can significantly disrupt the natural migration patterns of fish. American Eel are a prime example; their populations in Lake Ontario and the Ottawa River have experienced a staggering 99 per cent decline primarily due to these barriers. The absence of fishways at most dams, which would allow young eels to move upstream, coupled with the lethal impact of dam turbines on out-migrating adults that do make it upstream, are key factors in this crisis. With significant renovations planned for various dams, there is a vital opportunity to integrate new technologies that enhance fish survival while still maintaining energy generation. The approaches and companies discussed here represent just a subset of the many available options aimed at addressing these challenges.
Three Approaches to Fish-Friendly Turbine Design
- Modified Conventional Turbines
Modified Conventional Turbines, such as those developed by Andritz, DIVE, and Alden, are designed to minimize fish injury during passage. These technologies often feature modified blade designs that reduce turbulence and injury risk, making them valuable options for new facilities or refurbishments. DIVE turbines, for example, represent an innovative approach, suitable for smaller applications with a maximum capacity of 4 MW per turbine. This provides a unique solution for sites with smaller power-generating potential, providing an effective way to address fish mortality at new facilities or during certain rebuilds. Their design focuses on minimizing fish injury during passage, making them a valuable option; however, challenges such as cost-effectiveness and the need for infrastructure changes can limit the implementation of modified conventional turbines in certain contexts.
- Low Head Turbines
Low-head turbines are specifically designed for sites with low water drop heights and can be effective in low-flow conditions. Notable examples include the Monsin HPP Eco-Sustainable Turbine, which prioritizes environmental protection while generating renewable energy; and the Eddersheim HPP, which effectively harnesses energy with minimal impact on local fish populations. Studies indicate that low-head turbines have negligible effects on fish entrainment, making them suitable for low-head dam sites with minimal risk to aquatic life, though they are not suitable replacements for turbines at typical hydropower facilities with high head.
- Fish-friendly Runners
Natel Energy has pioneered the development of fish-friendly runners aimed at reducing the lethal risks posed by conventional turbines. Traditional turbine runners (the propellor component) have sharp edges similar to boat propellors, creating dangerous conditions for passing fish. Natel’s designs feature thicker, curved blades that create a “stagnation zone” or an “airbag for fish,” drastically reducing fatal encounters. In tests, over 98 per cent of American Eel survived passage through Natel’s turbines, a significant improvement over the 50 to 80 per cent survival rates of conventional designs. Furthermore, Natel designed modified runners to fit within existing turbines with no further changes to infrastructure. This minimizes costs and creates opportunities to apply fish-friendly technologies to even the largest hydroelectric facilities.
| TURBINE CATEGORY | Pros | Cons |
|---|---|---|
| Modified Conventional Turbines | Enhanced fish survival | Cost-effectiveness issues; limited sites with suitability |
| Low Head Turbines | Suitable for low-head conditions; minimal risk to fish | Limited application in broader hydropower landscape |
| Fish-Friendly Runners | High fish survival rates; significant generating capacity, works within existing systems | Need to wait for scheduled refurbishments to retrofit existing facilities |
Eliminating tradeoffs
Alternate designs for fish-friendly turbines were proposed in previous decades. Though potentially safer for fish, these technologies were not adopted for a number of cost and efficiency reasons. They were less efficient than existing turbines and would have required significant construction to reconfigure hydropower facilities.
Hydropower industry standards for equipment maintenance include the replacement of runners every 30 years. These routine refurbishments create opportunities to make turbines fish friendly by replacing traditional runners with innovative fish-friendly designs. These technologies could potentially be incorporated into much of the existing hydropower fleet, providing a broader solution to the fish mortality and environmental compliance challenges faced by aging hydropower plants.
Though fish-safe turbines primarily address downstream migration, additional solutions are needed for upstream passage, such as natural bypasses or ramps. These complementary approaches can work together to restore fish populations decimated by various hydropower facilities.
A Future of Sustainable Coexistence
The ongoing renovations of dams present crucial opportunities to incorporate these fish-friendly technologies, promoting a future where both hydropower and aquatic life can thrive. By investing in turbine designs that enhance fish safety, the hydropower industry can mitigate ecological impacts while maintaining energy generation.
The advancements in fish-friendly turbine technology highlight the importance of adapting renewable energy systems to protect vulnerable species like the American Eel. As climate change threatens ecosystems, finding ways to harmonize energy generation and conservation is vital. New approaches to fish-friendly turbines not only contribute to river ecosystem health, but also ensure that hydropower remains a viable component of the renewable energy mix.
The integration of fish-friendly turbines into hydropower infrastructure presents an important opportunity for both energy production and ecological preservation. By embracing these innovations, we can work towards a sustainable future where hydropower and aquatic life can coexist in better harmony.
Sarah Sra
Sarah Sra is a Vancouver-based conservation planner with CWF. Her work in B.C. involves managing partnerships with local stakeholders and rightsholders as part of the BC Fish Passage Restoration Initiative.
