Hydro turbines are a clean source of electricity, but their spinning blades can kill larger fish that pass through them. There are already relatively safe hydroelectric turbines for fish. However, they are usually large enough to accommodate their proportionally larger and more widely spaced blades. This means that they are not only more expensive than other models, but they are also more difficult to install into smaller dams.
To prevent this from happening, a new turbine has been developed – safer and more compact. Built by California-based Natel Energy, the Restoration Hydro Turbine (RHT) provides cost-effective energy production with low environmental impact.
Natel Energy claims the RHT is a unique and innovative turbine that combines superior performance with industry-leading fish safety and an extremely compact design. It can reduce installation costs by more than 20% compared to conventional low-pressure hydropower plants.
The Restoration Hydro Turbine (RHT) has an inner diameter of just 1 to 3 meters, depending on the model, and incorporates blades with a blunt, slanting leading edge. Blunt, slanted leading edge deflects the fish away from the blade, reducing the likelihood of a direct impact. Besides, the slanted blade tip reduces the severity of the strike, allowing high runner rpm and reduced generator cost. In addition, no flow-impeding fish-proof screens are required.
The company announced the successful completion of the Monroe Hydro Project with the installation of its 1 MW class D190 Restoration Hydro Turbine (RHT) and 100% safe fish passage test results from the Pacific Northwest National Laboratory (PNNL). The Monroe Hydro Project in Madras, Oregon, is a first-of-its-kind design making use of an existing irrigation canal and a new fish safe turbine technology to generate reliable, renewable energy.
In September 2020, PNNL conducted turbine passage tests that revealed a 100% survival rate for rainbow trout up to 400 mm (15 inches) long, passing downstream through the 1.9-meter diameter D190 RHT. The gross head at the site was approximately 5.2 meters, and the turbine produced approximately 300 kW electrical output.
PNNL engineers used Sensor Fish, RFID tag, radio tag, and balloon tag technologies to assess physical turbine stressors and enable the recovery of all fish after their passage through the turbine. Each fish was carefully inspected after passing through the turbine, and no evidence of passage related injuries was observed. This is a surprisingly good performance given the compactness of the turbine relative to the large size of fish tested.