We designed the first Restoration Hydro Turbine (RHT) blade in early 2019 based on the hypothesis that adding a forward tilt to relatively thick leading edges would allow fish to survive after being struck at much higher speeds than the same thicker blades without any forward tilt.
We confirmed that hypothesis in blade strike tests at Alden Research Laboratory (also in 2019) and built and installed several reference turbines with RHT blade designs. Over the past four years we’ve used those turbines to conduct fish passage tests on multiple species including American eel, Rainbow trout, and juvenile alewife — all with perfect or near-perfect survival.
Even as our fish passage studies highlighted the larger potential of RHT designs, we focused on creating a standardized family of FishSafe™ turbines (with capacities less than 3 MW and with runner diameter less than 2.5 m). These turbines were primarily intended for non-powered dam (NPD) retrofits in the small hydro market. Soon, however, it became clear that the demand for FishSafe™ turbines extended far beyond NPD retrofits and that our RHT designs could be applied much more broadly.
Since 2021 we’ve received increasingly-frequent requests to engineer FishSafe™ turbines to rehabilitate existing hydropower plants. In response we’ve created numerous custom designs ranging from horizontal turbines at only a few meters of head to vertical turbines at greater than 30 meters of head, with runner diameters exceeding 4 meters and power in excess of 40 MW. In delivering on these requests, we’ve honed our capabilities to rapidly generate new runner designs optimized for simultaneous satisfaction of multiple goals, including fish survival, hydraulic efficiency, cavitation resistance, low structural stress, and good manufacturability.
Meeting the market need on a timeline that matters
The speed at which we can install FishSafe™ RHTs is important for the climate, for the health of fisheries, for freshwater biodiversity, and for owners working to meet relicensing requirements. To ensure we can install those turbines on a timeline that matters and to maximize benefits to our customers, we've begun collaborating with other turbine manufacturers, allowing our industry-leading knowledge in FishSafe™ runner design to be implemented by familiar and trusted manufacturing organizations.
We’ve also formalized our engineering services for developers and owners. Natel’s industry-leading modeling capabilities are now available to inform decision-making about how best to maintain, retrofit, or upgrade assets. Additionally, we can combine our analysis and modeling tools with scale-model testing at our in-house hydraulic loop to provide a complete picture of hydraulic and environmental performance.
Eel passage at high speed, fish-safe retrofits to transform the hydro fleet, new DOE-funded projects, and the "mussel" behind clean water.
The company will install up to 90 of its Restoration Hydro Turbines at three non-powered dams
ALAMEDA, Calif. — Sept. 28, 2021 — Natel Energy, a supplier of sustainable hydropower solutions, announced today it will develop, finance and construct three non-powered dam sites along Louisiana’s Red River in partnership with Nelson Energy, a Minneapolis-based firm that has successfully developed and licensed over $250 million of hydroelectric projects in the U.S. With Nelson Energy as an advisory partner, Natel will install between 60 and 90 of its flagship product, the Restoration Hydro Turbine (RHT), to retrofit three existing dams and add 80 MW of renewable power to the grid — enough energy to power 35,960 average US homes each year.