EarthTalk: What’s the latest in tidal energy?

—Mary W., New York, NY

July 3. Tidal energy—generated from the natural rise and fall of ocean tides—is one of the most predictable forms of renewable energy. Unlike wind or solar, which fluctuate based on weather, tides follow gravitational cycles that are easy to forecast. Despite this reliability and growing interest in clean energy, tidal power still accounts for only a small share of global electricity production.

There are three main ways to capture tidal energy: tidal barrages (low dams that trap water), tidal stream turbines (underwater turbines placed in fast-moving currents), and dynamic tidal power systems (which use coastal water pressure differences).

Tidal ups and downs

One of the most recent breakthroughs happened in early 2025, when Proteus Marine Renewables installed Japan’s first commercial-scale tidal turbine off the coast of Goto City. The 1.1 megawatt (MW) device, anchored to the seabed, shows how far the technology has come. “This milestone demonstrates that tidal energy is ready for prime time in Asia and beyond,” said Proteus CEO Andrew Clark.

Tidal energy offers several key advantages. It has high energy density, doesn’t depend on weather or sunlight, and has less impact on land and views than wind or solar farms. As Inc. Magazine’s Chris Stokel-Walker put it, “Tidal power is more reliable than solar. Why aren’t we using it?”

The answer largely concerns cost and location. Tidal systems are expensive to build and maintain, especially when placed offshore. They also only work well in coastal areas with strong, steady tides — limiting where projects can go. Additionally, there are environmental concerns about how turbines might affect marine life and sediment flow. In the U.S., permitting and regulatory processes can be slow and confusing, making it difficult to get new projects started. Local opposition from fishing communities and unclear jurisdiction over coastal waters have also slowed progress in key regions like the Pacific Northwest and parts of New England.

Groundswell

Still, momentum is building. Scotland, France and Canada have invested in pilot projects, and the U.S. Department of Energy is researching opportunities along American coastlines. New modular turbine designs are helping lower costs and speed up installation, an important factor to the continued development of tidal energy. As Professor Brian Polagye says, “The fundamental question is one of economics”—tidal power is still expensive and often built on a case-by-case basis, so growth will depend on more standardized designs, better supply chains, and steady long-term investment.

If tidal energy is to grow, it will need more research, better policies and stronger public support. Advocates can push for clean energy plans that include marine renewables and support companies working to improve the technology. Tidal power won’t replace solar and wind, but it could become an important part of a cleaner, more reliable energy mix if given the chance.

CONTACTS: Evaluating the Present and Future Potential of Tidal Power in the U.S., altenergymag.com/article/2024/10/evaluating-the-present-and-future-potential-of-tidal-power-in-the-us/43464; Tidal stream power can significantly enhance energy security,

plymouth.ac.uk/news/tidal-stream-power-can-significantly-enhance-energy-security.

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