Twirling for Power: New Offshore Turbine Design Can Store Energy

SeaTwirl prototype has been tested off the Swedish coast, could scale up dramatically

2 min read
Twirling for Power: New Offshore Turbine Design Can Store Energy

Though there are some alternative wind turbine designs out there, generally speaking, the windmill is a relatively mature technology. In other words, most turbines built will look largely the same. An idea currently being tested in Sweden, though, is about as novel a turbine design as you can get.

The SeaTwirl...well, maybe the Web site can explain what it is and how it works:

SeaTwirl uses a vertical axis wind turbine to absorb the wind energy and a torus ring to store this energy. SeaTwirl uses the physical law for conservation of momentum to enable the storage capacity. When energy should be stored SeaTwirl transports fluids from a less rotationally centered position to a more rotationally centered position to rotate faster, as a skater doing a pirouette. In this way it can store large amounts of energy at low speed and tap it at higher rotational velocity when the demand for energy rises.

It basically functions as a flywheel does. If you want a more thorough explanation, here's a video made by the company:

Some of the info on SeaTwirl's site is a bit sketchy, so I emailed the company's owner/inventor, Daniel Ehrnberg, for some clarifications. He said that the ability to scale up to a massive turbine—listed as a 10-megawatt rating capable of storing 25 000 kWh—is still actually a ways off (four to six years, according to Erhnberg). The biggest prototype made so far was at 1:50 scale, but he told me he is "convinced that the larger SeaTwirl units will have a much better cost-effectiveness than today's technology." He said it is "hard to say" what a full-scale device will actually cost to build.

Ehrnberg also said SeaTwirl plans to use undersea cables that are already in place to bring the power back to shore, at least for the early prototypes. The big advantage to something like this lies in the storage capability: by sending the stored power to the grid only at times of higher demand or lower wind speeds, the technology averts one of the most common renewable energy pitfalls—or at least diminishes it. As offshore wind continues to ramp up in Europe and we get closer to the first turbines in U.S. waters, this is something to keep an eye on.

(Image and video via SeaTwirl/Daniel Ehrnberg)

The Conversation (0)
This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

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