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

Natel FishSafe™ RHT Designs

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

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

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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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Broad Product Range

FishSafe™  RHT runners can be designed for most turbine configurations operating at head up to 40 m (130 ft), without limits on turbine diameter.

Typical turbine configurations include vertical or horizontal axis, axial or radial inflow, and straight or elbow draft tubes.

RHT runners can be coupled to any common power takeoff including direct drive synchronous or permanent magnet generators with fixed or variable speed operation.

Turbine selection chart comparing RHT designs to Francis and Kaplan designs
Illustration showing some of the variety of turbine configuration options that are possible for the RHT.

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 fish passage testing, why fish-safe is different from fish-friendly, and why fish-safe turbines matter.

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 world-class 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.

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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Turbine install
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