From “Science Enthusiast”

France has taken a major step in renewable energy by activating what is being hailed as the world’s first commercial-scale tidal lagoon power plant. Located along the Brittany coast south of Saint-Malo, the facility features a massive 12-kilometer curved seawall enclosing approximately 3,400 hectares of coastal waters, creating an artificial lagoon that harnesses the predictable power of Atlantic tides.

Unlike traditional tidal stream devices with rotors placed directly in open sea currents, this design keeps all generating machinery integrated within the seawall structure itself. It uses 90 bidirectional turbines embedded in the barrage. As tides rise, seawater flows into the lagoon through the turbines, spinning them to produce electricity. During ebb tides, water flows outward, generating power in both directions across the four daily tidal cycles. This setup avoids placing moving parts in the open ocean, reducing marine life disruption, corrosion, and maintenance challenges.

The plant is reported to deliver reliable, weather-independent clean energy—potentially around 270 MW—powering tens of thousands of homes. It showcases tidal range technology’s advantages: high predictability and long operational life compared to wind or solar. While building on France’s pioneering legacy with the 1966 Rance Tidal Power Station, this lagoon approach aims for lower environmental impact and greater scalability. It marks an exciting advancement in blue energy, offering a sustainable path to decarbonization by tapping into the ocean’s immense, constant power.

I hope the story above is true.  If it is, it provides hope that at least one flavor of hydrokinetics (tidal) still remains potentially feasible.

What seemed to have killed hydrokinetics isn’t that it’s theoretically impossible; rather, that its levelized cost of energy (LCOE), largely due to high maintenance costs, couldn’t compete with the solar and wind as their LCOE plummeted over the past decade.

Tidal Energy