Turbines

High-performing, reliable fish-safe solutions

The Restoration Hydro Turbine (RHT) is a compact hydroelectric turbine that couples high performance with safe through-turbine fish passage.

Uniquely thick fish-safe blades optimized for low head (2m-20m) applications eliminate the need for fine fish screens, reducing O&M and CAPEX costs while also increasing plant efficiency.

Radial and axial turbine inflow configurations with turbine capacities ranging from 30 kW to 3 MW enable compact, simplified civil works, and can be integrated into matrix designs for larger scale deployments of up to 30 MW.

Natel Energy’s quality and environmental management practices are ISO 9001:2015 and 14001:2015 certified.

Restoration Hydro Turbine

Fish-safe: Demonstrated >99% fish passage survival with proprietary blade design
High performance: Demonstrated efficiency >90%
Compact: Delivered as a pre-engineered water-to-wire solution
Cost-saving: Reduces excavation & concrete usage, reduces/eliminates fish exclusion

Configurations

For dry turbine rooms

Submersible units

MS = Medium Speed, HS = High Speed. Dimension “A” ranges from 1.6-2.2 x runner diameter, and dimension “B” ranges from 3.6-8.5 x runner diameter.

Product Range

The fish-safe Restoration Hydro Turbine is available in multiple configurations with runner diameters measuring from 0.5 m to 2.5 m and greater, and generating capacities from 30 kW to over 3 MW. Direct drive generation, shortened draft tubes, and submersible housings simplify plant design and minimize installation costs.

Fish Safe Runner Retrofits

The Restoration Hydro Turbine is also offered as a runner retrofit, allowing existing hydropower installations to significantly improve their environmental performance without major changes to the existing power plant infrastructure. The most appropriate candidates for RHT retrofit are high-speed, low-head Francis and Kaplan turbines, which will have a similar specific speed and thus similar runner diameter and draft tube requirement to the RHT. Many of these units are very old, and retrofit with the RHT runner could boost efficiency and energy output as well as fish safety.

Safe Fish Passage

A low number of blades reduces likelihood of strike. Blunt, slanted leading edges deflect the fish away from the blades, reducing the likelihood of a direct impact. Slanted blade tips reduce the severity of strike, allowing for high runner rpm and reduced generator cost. The compact runner has the same high efficiency as a well-designed conventional propeller blade. Variable speed and variable wicket gates enable a double-regulated efficiency curve.

Early design stage strike testing validated the benefits of the RHT blade shape on fish survival. Subsequent turbine passage studies have shown >99% survival rates across key migratory fish species passing through the RHT.

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Competitive Advantages

	RHT	Compact Bulb or Pit Kaplan	Matrix	Small Vertical Kaplan	Crossflow	Archimedes Screw
Fish safe - no fish screen
Short draft tube
Low part count
High efficiency (>88%)
Turbine setting over tailwater
Low cost power takeoff
Available in vertical or horizontal axis; pit/scroll/open-flume intakes

Envelope

Performance

Hydraulic Performance

Natel rigorously tests turbine performance at an in-house facility located at our Alameda headquarters. The facility enables scale model turbine testing of net heads up to 10 meters and flow rates up to 1 cms. The test stand utilizes world-class instrumentation for measurement of flow, pressure, torque, and speed to achieve PTC standard compatibility.

In June 2019, a D55 (0.55m diameter runner) RHT prototype unit was tested by Jim Walsh of Rennasonic Inc., chair of IEC TC-4 and PTC-18. Key results from the test are summarized below. The full report is available by request.