Power on Sail

As offshore wind power gains momentum, researchers have been struggling with how to wring power out of the ocean’s strongest winds—which flow hundreds of miles offshore in waters too deep to support traditional wind turbines. A newly proposed technology could solve that problem by using an intriguing mix of ships, generators, and “sails” the size of baseball stadiums.

The ships would operate in wind hotspots such as the north-central Pacific and the southern oceans surrounding Antarctica, where winds blow full-circle around the globe without land to break their momentum. There, the ships would unfurl gigantic sail-like parafoils and let them rise about a mile above sea level, where winds are up to four times as fast as those at the ocean’s surface. The parafoils would tow the ships and, in the process, churn water through turbines on the ships’ hulls.

Which raises a question: how do you transport the resultant electricity back to land? The answer: use it to hydrolyze seawater, then combine the hydrogen with carbon dioxide to produce methanol, which could easily be stored on board the ships. One ship design, published in the journal Energy, could produce 100,000 tons of methanol every month. This could be transported on tankers for use in heaters, factories, or fuel cells.

It wouldn’t be the first time that kites flown from ships were used to produce or conserve energy. SkySails, a company based in Hamburg, Germany, sells parafoils which can be used to partially power ordinary cargo ships, reducing fuel consumption by up to 35 percent. To evaluate the new wind-power proposal, it’s important to factor in the cost of designing, building, and operating ships that are completely devoted to wind power, says SkySails engineer and co-founder Stephan Wrage. “Such a project has to be calculated very carefully,” he says, “and compared to other renewable energy sources regarding the cost per kilowatt hour.” ❧

 

Photo: MV Beaufort 3 ©SkySails

—Douglas Fox

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2 Comments

  • K Ver September 24, 2010 at 10:48 pm

    This is awesome.
    Back in 2000 I presented an idea on BBC Radio 4 about using ships (ex-supertankers turned into huge batteries) with wind turbines sailing out to sea. Once on station the ship would charge the batteries using wind power. The ship would then transfer the power back to shore using microwaves once it was ready. Problem was a lead-acid battery the size of supertanker cargo hold was 1/2 billion British Pounds (1 billion USD) Wish I had thought of the liquid methanol as the medium to store the energy!
    This article’s idea seems much better.

    Reply

  • Scott Campbell November 4, 2010 at 7:05 pm

    Just a few questions.

    How environmentally sound is it to use wind energy, to artificially produce hydrocarbon gas, which then would presumably later be burned in these fuels cells? Surely this is not solving an environmental problem, but creating an extra source of emissions in the long run?

    Maybe not? Is the CO2 used to produce the methanol taken from the atmosphere? In that case, the emissions from burning would only be carbon neutral. Perhaps this is a better method of carbon sequestration than it is a fuel source?

    As a merchant sailor myself, I would love the opportunity to use the wind in merchant navigation again. However, sailors would have to be trained extensively to use this method. Also, Using the old trade routes of sailing vessels would mean a drastic re-shaping of the type of traffic in cross ocean shipping lanes. Consideration should be given to vessel maneouvreability, as a lot of small and vulnerable sailing vessels using the trade winds and so on would be seriously impaired by large merchant traffic.

    Reply

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