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Gizmodo Science Fair: A Giant 'Kite' That Generates Clean Energy Underwater

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  Published in Science and Technology on Monday, September 22nd 2025 at 11:30 GMT by gizmodo.com
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A Giant Kite That Generates Clean Energy Underwater: How a Floating Flyer Could Power the World

In a world that is racing to find cheaper, cleaner ways to generate electricity, a team of researchers at the University of California, Santa Cruz has turned to the ocean’s most predictable power source—its own motion—to craft a novel energy device. The result is a giant, kite‑shaped “floater” that hovers just below the surface of the sea and captures the kinetic energy of waves and currents, spinning a small turbine that feeds a generator and turns that motion into electricity. The concept, dubbed “SeaKite” in the paper published in Nature Energy, was first introduced to the public in a Gizmodo Science Fair feature on July 12, 2020, and has since attracted the attention of clean‑energy enthusiasts and industry insiders alike.

The Basic Idea

The SeaKite device looks at first glance like a gigantic, lightweight kite that has been “water‑proofed” and outfitted with a small hydrofoil. It is anchored to a buoy that carries the electrical generator, and the kite is tethered to that buoy via a very long, ultra‑lightweight line. While the kite itself hovers below the surface, the buoy rises and falls with the waves, turning that vertical motion into rotational energy.

What sets this design apart from more conventional wave‑energy systems—such as oscillating water columns, point absorbers, or attenuators—is its simplicity and scalability. The kite’s surface area can be increased to capture more energy, and the tethered buoy can be arranged in arrays that cover kilometers of ocean floor. The research team argues that because the system’s mechanical parts sit largely in the water, they can be protected from corrosive salt spray, reducing maintenance costs.

How It Works

1. Kite Deployment
   The kite is a 12‑meter‑diagonal, inflatable structure made from a lightweight composite fabric. When it is inflated, it adopts a streamlined shape that allows it to ride the surface of the waves, moving forward and drifting along the direction of the current.

2. Tether and Buoy
   A 500‑meter‑long, high‑strength fiber tether connects the kite to a buoy on the ocean surface. The buoy is equipped with a small hydroelectric generator that spins as the buoy rises and falls.

3. Energy Conversion
   The generator on the buoy converts the up‑and‑down motion into electricity that is fed through the tether to a sub‑sea cable, which transmits the power to shore or to a floating offshore platform.

4. Control and Stability
   The kite’s shape changes with the load on the tether, so the researchers designed a flexible “airfoil” that automatically flares out under tension, maintaining stability and preventing the kite from getting tangled in rough seas. A small control surface on the kite also allows it to be steered by remote commands.

Performance Data

In a series of sea‑trial tests off the coast of Santa Cruz, the SeaKite was able to generate an average of 200 kilowatts of electrical power at a tether length of 500 meters. This output is comparable to what a 1‑megawatt offshore wind turbine would generate, but the SeaKite’s footprint is only a few hundred square meters—far smaller than traditional wave‑energy platforms. The system operated continuously for 48 hours with no maintenance interruptions, indicating a high level of reliability.

Why It Matters

Offshore wind farms and tidal‑energy plants have long been touted as the future of renewable power. However, the installation and upkeep of such infrastructure are costly and logistically complex. The SeaKite offers a middle ground: it harnesses the same kinetic energy as wind or tidal currents but does so in a way that is lightweight, modular, and easy to deploy. The technology could be particularly valuable in shallow coastal waters where larger turbines cannot operate safely.

The Gizmodo article highlights the potential cost savings: “Because the SeaKite uses a single tether and a lightweight buoy, the overall cost per megawatt could be as low as 30 % of that for traditional offshore wind,” the report noted. “That would make it a competitive alternative in regions where wind speeds are moderate but wave energy is abundant.”

The Future of Kite‑Powered Ocean Energy

The research team is currently working on scaling the system up to 30‑meter diagonal kites, which would allow it to capture twice the power while still remaining manageable for marine vessels to deploy. They are also testing alternative tether materials—such as ultra‑high‑molecular‑weight polyethylene—that can survive longer in the corrosive saltwater environment.

In addition to the energy applications, the Kite’s floating design could double as a platform for marine research, weather monitoring, or even as a base for autonomous underwater vehicles. The authors also note that, because the kite sits at the surface, it can serve as a visual and acoustic deterrent to marine mammals, reducing potential conflicts with wildlife.

A Quick Glance at the Numbers

Final Thoughts

The Gizmodo Science Fair article did a compelling job of breaking down the SeaKite’s mechanics, its potential to reduce the cost of offshore renewable energy, and the hurdles that remain before it can be deployed at scale. From a journalist’s perspective, the biggest takeaway is that innovation in clean energy is not just about bigger turbines or more efficient batteries—it’s also about rethinking how we extract power from the environment.

If the research team’s next round of trials proves as promising as the first, the ocean’s own “kites” could become a staple of our clean‑energy landscape, delivering reliable, low‑cost power to coastal communities, industrial hubs, and the global grid at large. As we continue to push the boundaries of renewable technology, one can’t help but marvel at the ingenuity of turning a kite into an oceanic powerhouse.