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Hydrostor Wants to Stash Energy in Underwater Bags

Submerged bags of air could turn wind and solar power into round-the-clock resources

4 min read
Hydrostor Wants to Stash Energy in Underwater Bags
In the Bag: Energy bags like this 5-meter-diameter one, from Thin Red Line Aerospace, of Canada, could be used to store electricity underwater as compressed air. Engineers hope the technology could one day smooth out the intermittency of electricity produced by offshore wind farms and other renewable energy sources.
Photo: Keith Thompson/Thin Red Line Aerospace

With the worldwide proliferation of wind- and solar-generated power, the fickleness of these renewable sources is a problem crying out for a good solution. A Canadian start-up called Hydrostor thinks it has an answer: air-filled bags.

In August, the Toronto company plans to sink several large balloonlike bags into Lake Ontario, and then, using electricity from Toronto Hydro’s grid to run a compressor, it will fill the bags with air. Later, when the utility needs electricity, the air will be emptied from the bags and run through a turboexpander, which uses the expanding air to drive a turbine. The result will be the world’s first commercial facility for underwater compressed-air energy storage. This animation from Hydrostor explains how its system works:

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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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