Environment

Blunt-bladed hydro turbine packs fish-friendliness into a small unit

Blunt-bladed hydro turbine pac...
The RHT turbine is designed to be built into new hydroelectric projects, or retrofitted into existing ones
The RHT turbine is designed to be built into new hydroelectric projects, or retrofitted into existing ones
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The RHT turbine is designed to be built into new hydroelectric projects, or retrofitted into existing ones
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The RHT turbine is designed to be built into new hydroelectric projects, or retrofitted into existing ones
One of the recovered rainbow trout
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One of the recovered rainbow trout

Hydroelectric turbines may indeed be a non-polluting source of electricity, but their spinning blades can nonetheless kill larger fish that are passing through. A new type is designed not to do so, while maintaining a compact form factor.

First of all, there are already relatively fish-safe hydroelectric turbines. They're typically pretty big, however, to accommodate their proportionally larger, wider-spaced blades. This means that not only are they often more expensive than other models, but they're also more difficult to incorporate into smaller dams.

That's where the Restoration Hydro Turbine (RHT) is designed to come in. Manufactured by California-based Natel Energy, it has an inner diameter of just 1 to 3 meters (3.3 to 9.8 ft) – depending on the model – while also incorporating blades with a blunt, slanting leading edge.

This design reportedly deflects fish away from the blades, significantly reducing the likelihood of direct contact. That said, the blades are claimed to be just as efficient as their conventional counterparts when it comes to spinning up in the flowing current. Additionally, no flow-impeding fish-proof screens are required.

In a study conducted this September, scientists from Washington state's Pacific Northwest National Laboratory (PNNL) assessed the fish-friendliness of a 1-megawatt RHT, that is part of the just-completed Monroe Hydro Project – it's located on a canal in the city of Madras, Oregon. A total of 60 tagged rainbow trout were released through the 1.9-m (6.2-ft)-diameter turbine, each fish up to 15 inches (381 mm) in length.

One of the recovered rainbow trout
One of the recovered rainbow trout

A PNNL-designed device known as the Sensor Fish was also sent through, which is a sensor-equipped gadget that measures the stress that would be placed on a fish in the same situation.

When the trout were recaptured downstream from the RHT, it was found that all of them had made it through alive and uninjured. According to Natel Energy, "This is surprisingly good performance given the compactness of the turbine relative to the large size of fish tested."

Source: Natel Energy

4 comments
4 comments
bwana4swahili
Put them to work on a bird friendly wind turbine!
buzzclick
Sure don't look like claims made are believable. Those spinning rotors look deadly. Maybe they tested them when they were turning slower to get the desired outcome. In so doing, they can't be accused of lying.
Nelson Hyde Chick
bwana4swahili, to prevent bird strikes all that needs to be done is pain one of the blades a contrasting color. https://bgr.com/2020/08/26/wind-turbine-birds-death/
ljaques
Bwana, =buildings= kill 988 million birds per year. Wind turbines kill 2.92-7.82 birds per windmill. Fewer raptors are killed nowadays because of the taller turbines. Check the sound levels these water turbines put out. In the tidal turbine styles, they're 130-160dB. That's downright unfriendly. // I can't imagine how unsightly a single black-bladed turbine would look in the sky. Talk about catching the eye. Horrible!