The Restoration Hydro Turbine (RHT) is a hydroelectric turbine combining high performance, safe fish passage and a short draft tube for simple civil works.
Special fish friendly blades are optimized for low head between 2 m - 10 m (6.5 ft - 33 ft), eliminating the need for fine fish screens thus increasing total plant efficiency while reducing both upfront and operations and maintenance costs.
Single units have capacities from 32 kW to 1,400 kW; with plans to extend to larger units over time. Civil works are simplified due to compactness and availability of configurations such as pit, radial-inflow open-forebay, and spiral case.
Restoration Hydro Turbine
- Fish friendly: >99% safe passage of fish <200 mm at 7 meters head
- Short draft tube: 50% shorter draft tube vs conventional Kaplan turbines
- Very low cavitation risk: allows turbine placement above tailwater
- Compact: delivered as a pre-engineered water to wire solution
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 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 friendliness.
Fish Friendly Operation
Low number of blades reduces likelihood of strike. Large, blunt leading edge creates a pressure wave and local low velocity zone in advance of the runner blade (a fish saving “force field”) , gently decelerating fish which pass gently around the blade. Slanted blade tip reduces relative strike speed, allowing high runner rpm and reducing generator cost. The runner has the same high efficiency as a well-designed conventional propeller blade. Variable speed and variable wicket gates enable double-regulated efficiency curve. The turbine has been designed to enable survival of >99% of fish less than 200 mm in length (such as salmon smolts), despite compact runner diameter of 1m - 3m, enabling simple project logistics .
|RHT||Compact Bulb or Pit Kaplan||Matrix||DIVE||Small Vertical Kaplan||Crossflow||VLH||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|
Form Factor and Applications
Restoration Hydro Turbines can be installed in a range of settings, including retrofit of existing turbines (for low-cost compliance with environmental requirements, or to improve output of old units), existing non-power dams, irrigation canals, and run-of-river new stream reach developments.
Radial Open Flume
Natel’s RHT is available in several different regulation and power takeoff configurations. The correct selection for your project will be driven by flow and head operating characteristics.
The Linear Pelton is a proprietary hydropower turbine designed for high flows at low heads, generating electricity at or less than US $0.05 at projects as small as 1 MW. Civil works and installation are simplified, delivering significant cost savings.
The Linear Pelton excels at low net heads between 7 to 20 m (23 to 65 feet). Single unit capacities range from 25 kW to 1000 kW. Civil works can be greatly simplified over legacy hydro technologies, enabling much more cost-competitive projects from 25 kW to 25 MW or more.
- Civil construction costs are much lower than for Kaplan, Archimedes or bulb turbines.
- No cavitation allows for new flexibility in installation configurations
- High efficiency and flat performance curve, like a conventional Pelton turbine
- Fish-friendly due to order-of-magnitude lower pressure drops and impact velocities
- Quick and inexpensive maintenance
- Units rated to 1 MW, and 7 to 20 m (23 to 65 feet) of net head