Tidal Energy Is the Clean Power Source Nobody Is Talking About — Yet

The sun doesn't always shine. The wind doesn't always blow. But the tides? The tides are never late.

Tidal energy — electricity generated from the movement of ocean water driven by the gravitational pull of the moon and sun — is one of the most reliable energy sources on earth. We can predict tidal patterns centuries in advance with near-perfect accuracy. That predictability is, in the world of renewable energy, almost miraculous.

How It Works

There are two main approaches. Tidal barrages work like underwater dams, capturing the potential energy of rising and falling water levels. Tidal stream generators work more like underwater wind turbines, harnessing the kinetic energy of fast-moving tidal currents. The latter has attracted the most investment in recent years — it's less disruptive to marine ecosystems and more scalable.

The world's most powerful tidal stream turbine, deployed off the coast of Scotland, can generate enough electricity to power roughly 2,000 homes from a single device. Arrays of these turbines, placed in high-current channels, could power entire coastal cities.

Why You Haven't Heard More About It

Cost, mostly. Saltwater is brutally corrosive. Underwater installation and maintenance is expensive. And the best tidal resources are concentrated in specific geographies — the UK, Canada, France, South Korea, Australia — rather than distributed globally like solar and wind.

But costs are falling fast. The UK's tidal energy sector has seen costs drop 40% in the last five years, and the government has committed to 1 gigawatt of tidal stream capacity by 2035. That's enough to power roughly 1 million homes.

The Bigger Picture

Tidal energy won't power the whole grid. But it doesn't need to. In a clean energy system, diversity is resilience. Solar peaks at midday. Wind peaks in storms. Tidal peaks twice a day, every day, forever — filling the gaps that other renewables leave behind.

The ocean has been storing energy since before life existed on this planet. We're just now learning to ask it politely.