A thick, slanted Restoration Hydro Turbine runner is shown installed in a runner housing.

FishSafe™️ engineering by Natel, manufacturing by trusted industry partners.

FishSafe™ RHT Designs

Restoration Hydro Turbine (RHT) runners can be applied to large and small hydropower plants up to 40 m (130 ft) hydraulic head, with no limit on runner diameter. Available for custom retrofits or new build, RHT designs improve environmental outcomes and reduce costs.

Natel's FishSafe™ Design

Thick, slanted runner blades reduce the likelihood and severity of a strike during fish passage. RHT runner designs span a broad operating range, making them suitable upgrades for many aging propeller or Kaplan turbines in the existing hydropower fleet. Learn more about our highly-regarded turbine manufacturing partners.

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FishSafe™

Demonstrated 98-100% safe fish passage with proprietary blade design.

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High Performance

Demonstrated hydraulic efficiency >90%.

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Retrofit Ready

Modern, FishSafe™ runner replacements for sites up to 40 m (130 ft) in head.

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RHTs combine best-in-class performance — high efficiency and resistance to cavitation — with a revolutionary FishSafe™ design.

Natel FishSafe RHT runners are suitable for in-place replacements in plant upgrades.

FishSafe™ Runner Retrofits

Natel FishSafe™ RHTs can be designed as runner-only or turbine-only replacements for equipment at sites with up to 40 m (130 ft) head, allowing plant owners and operators to modernize their equipment without significant civil cost.

  • Comparable energy production: A FishSafe™ RHT provides efficient energy production, comparable to conventional solutions.
  • Comparable cavitation margin: A FishSafe™ RHT can operate at the same elevation as a conventional runner.
  • Flexible form factor: A FishSafe™ RHT can replace a conventional turbine runner without significant civil cost, by utilizing existing components, including wicket gates, casing/discharge ring, draft tube, and generator.
  • Widely applicable range: There is no limit on RHT diameter, and FishSafe™ RHTs are available with both fixed and adjustable blades, making them suitable replacements for existing propeller and Kaplan-style runners at a variety of sites with up to 40 m (130 ft) of head.

Hydraulic Performance

Natel rigorously tests RHT performance at our in-house closed-loop hydraulic test facility. We use high-quality instrumentation to measure flow, pressure, torque, and speed in scale model turbine tests. Performance tests are conducted to the American Society of Mechanical Engineers PTC-18 standard.

Turbine selection chart comparing RHT designs to Francis and Kaplan designs
A thick, Restoration Hydro Turbine-style blade is shown in contrast to a thin propeller-style sample blade.

Abrasion Resistance

The same principles that guide the fish safety of RHT designs also reduce blade erosion. Tests following the IEC Standard 62364 showed that the unique blade shape that characterizes RHT designs demonstrated high resistance to abrasion. The testing found that the thickness of RHT blades produced a stagnation effect on sediment slurry while the blade sweep also decreased the contact velocity of sediment impacting the runner. The outcome of these effects resulted in six times less material loss on an RHT-style blade sample as compared to a conventional propeller blade.

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