Natel Awarded DOE Funding to Expand Scientific Understanding of FishSafe Turbine Design

September 19, 2023
Eel and sturgeon passage tests will help establish new fish safety benchmarks for utility-scale hydro turbines

ALAMEDA, Calif, United States – September 19, 2023 – Natel’s FishSafeTM Restoration Hydro Turbine (RHT) designs are at the core of two research and development projects that have been recommended for funding by the U.S. Department of Energy (DOE) to advance the scientific knowledge required to engineer hydropower turbines that are safe for fish to pass through. 

Hydropower is a critical carbon-free energy source, providing essential grid reliability services that balance intermittent renewable energy sources like wind and solar. But, hydropower plants can reduce river connectivity and harm both migratory and resident fish. The need to address this challenge is pressing: over half of the existing North American and European hydro fleets are more than fifty years old and as result a total of 37 GW across both continents will require upgrades for fish passage, reliability, and efficiency within the next decade. At the same time, the International Energy Agency calls for an additional 50 GW of hydro to be added annually through 2030 to limit warming to 1.5 degrees Celsius. To help meet this demand while preserving aquatic biodiversity, Natel is designing turbines that enable safe downstream passage for fish.

“Natel RHTs use safe fish passage as a design constraint alongside efficient power production. Turbines that allow fish to safely pass through enable fish to travel directly downstream with the bulk of a river’s flow — eliminating the need for fine fish exclusion screens and bypasses that drive up project cost and reduce efficiency,” said Abe Schneider, co-founder and Chief Technology Officer of Natel. “Since 2019 we’ve conducted studies to better understand factors affecting fish survival as they pass through hydropower turbines, and multiple turbines following the RHT design approach have been installed both in the USA and in Europe. These new DOE-funded projects will enhance our ability to create effective utility-scale FishSafe turbine designs.”

Kate Deters, a scientist at Pacific Northwest National Laboratory, measures an American eel as a part of a 2021 study with Natel on passage of American eels through a small-scale FishSafe™️RHT.

A first look at eel passage through utility-scale FishSafe turbines

The first of the two projects, “Hydropower Turbines as Safe Downstream Fish Passage,” will be led by Natel in partnership with environmental consulting firm Normandeau Associates, researchers from Pacific Northwest National Laboratory, the United States Geological Survey's Eastern Ecological Science Center, and hydro plant owner, Great River Hydro. Together the partners will conduct the first field passage test of large American eels through a utility-scale FishSafeTM RHT, with the objective of demonstrating greater than 98% passage survival and monitoring post-passage behavior. To facilitate this study, Natel and a manufacturing partner will install the first utility-scale RHT on the east coast, adding new generation capacity to one of Great River Hydro’s existing hydropower facilities. In addition to the utility-scale field passage test, a laboratory component of the project seeks to address knowledge gaps in factors affecting strike survival of American eel passing through turbines operating at speeds typical of the US hydroelectric fleet.

As Ted Castro-Santos, a Research Ecologist at the Eastern Ecological Science Center, describes, “Eels are particularly vulnerable to injury during downstream passage at dams. Their large size means they are more likely to be struck by conventional turbine blades than smaller-bodied fish. Moreover, owing to their unique biology, individuals most at risk of turbine passage tend to be large females that may be over 20 years old. Development of turbines that can pass eels safely holds substantial promise for promoting their conservation, particularly in those areas where they are most vulnerable.”  

In the U.S. alone, more than 939 hydropower plants (producing 32 GW of power) operate within the population range of American eels, Natel’s innovations in turbine design can allow for these plants to continue generating reliable, renewable power while dramatically improving passage survival for endangered American eels. Protecting eels, which hold significant cultural, economic, and ecological importance, ensures they can continue to provide vital ecosystem services including serving as host fish for freshwater mussels — critical organisms for maintaining clean water.

A White sturgeon is photographed in a clear tube where its condition is inspected prior to passage through a small-scale FishSafe™️ RHT as a part of a preliminary study conducted by Natel in 2021.

Illuminating how sturgeon pass through FishSafe turbines and measuring stress response

The second project, “Effects of White Sturgeon Passage Through a Novel Hydropower Turbine,” will be led by the Fish Conservation Physiology Lab at University of California, Davis. Turbine passage tests conducted at Natel’s hydraulic laboratory in Alameda will allow the team to investigate the stress response of RHT passage on juvenile white sturgeon, helping understand the potential of RHTs to provide safe downstream passage for sturgeon at hydropower facilities throughout the world.

Dr. Ken Zillig, one of the UC Davis scientists leading the project, highlighted the unique focus of the study on fishes’ stress response: “the effects of turbine passage on fish physiology is often limited to measures of survival. This study is novel in its investigation of the sub-lethal impacts of dam passage on sturgeon.” The stress response data will paint a broader picture of how fish experience turbine passage, which can then be taken into account in the turbine design process.

Sturgeon are a group of threatened and endangered long-lived migratory fishes found throughout rivers globally. Like American eels, one consistent threat to sturgeon is the fragmentation of their natural habitat by dangerous or impassable dams and hydropower infrastructure. Developing safe options for fish passage through hydropower turbines is an essential component of restoring sturgeon populations throughout North America.

Hydro plants share habitat with eel, sturgeon, and other resident and migratory fishes. FishSafe turbines are one solution to help protect biodiversity and generate clean power.

Why fish passage studies matter

Conducting original fish passage science is foundational to Natel’s development of FishSafeTM RHTs. Prior scientific studies performed by Natel and third-party scientific partners (Kleinschmidt Associates, the Pacific Northwest National Laboratory and Alden Laboratory) have affirmed 98-100% safe passage through Natel RHTs for various species, sizes, and life stages of fish, including juvenile alewife, American eel, and rainbow trout.

The DOE-funded projects will result in a new body of scientific knowledge that builds upon Natel’s previous research to enhance data-informed engineering of FishSafe turbines. Data from the studies will also give stakeholders information they need to make informed decisions about where and when to apply FishSafe turbines as solutions to improve river connectivity at a wide range of hydropower sites — keeping the existing hydropower fleet online, increasing clean energy generation, and supporting biodiversity and clean water.  

For more on Natel’s effort to advance the science behind FishSafe turbine design, contact

About Natel Energy 

Natel Energy is working to support healthy rivers, promote biodiversity and decarbonize the grid through FishSafeTM hydropower. Natel delivers high-performance FishSafe turbine and plant designs and engineering services informed by industry-leading CFD modeling and analysis and an in-house hydraulic test lab. In partnership with turbine manufacturers, Natel designs solutions to upgrade existing hydropower plants and develop new, sustainable projects worldwide, mitigating climate change and curbing biodiversity loss. Natel’s patented FishSafe™ designs can be applied to sites from 2-40 meters of head with no upper limit on turbine diameter, and with increasingly high rotational speeds — making it possible to design turbines up to 50 MW in capacity and supporting retrofits for 50% of the aging U.S. hydro fleet. Natel is a privately held company located in Alameda, California in the United States. Visit for more information.

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