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Are Floating Wind Turbines The Next Best Thing?

by Stanford Magnets

With all of Japan's fifty nuclear reactors offline and expensive gas imports striking a blow to the economy, the government has begun tapping renewable energy to resolve the country's energy problem. One option being looked at is wind energy, given the country's long coastline, particularly the newly built floating windmills which started operating at the end of 2013. But are they really a viable alternative?

Offshore windmills are not new, but they typically stand on towers that have to be driven deep into the ocean floor. This causes restrictions to how far a wind turbine can be placed offshore. Thus these new floating wind turbines have been highly welcomed as they not only overcome these restrictions but are also a clean, sustainable and safer alternative to nuclear energy. Another advantage of using floating platforms is that the windmills could be moved around. If a company with 400 wind turbines in Boston for example needs more power in New York City, it can unhook some of their windmills and tow them south.

Locating wind farms out at sea can reduce visual and noise pollution whilst providing better accommodation for fishing and shipping lanes. In addition, the wind is typically more consistent and stronger over the sea, therefore floating windmills could also generate more energy-5.0 megawatts (MW), compared to 1.5 MW for onshore units and 3.5 MW for conventional offshore setups.

However Paul J. Scalise, a research fellow at the Institute of Social Science, at the University of Tokyo, said it was far too early to place such big hopes on offshore wind power. Mr. Ishihara's forecasts, he said, needed to be adjusted for load factors, disruptions to sea lanes and fishing zones, as well as possible "not in my backyard" protests by fishermen and other local residents. With those restrictions, he estimates Japan's offshore wind generation potential far lower, from a third to three-fifths of Japan's current electric power supply.

"We shouldn't forget the obvious reality check. The farther from the coast they place these floating wind farms, the more expensive it becomes to build them and transmit the power back to Japan," he said. "It becomes a cost-plus benefit analysis in which you weigh the benefits of the electricity versus the cost to build and maintain the infrastructure."

The financial cost also needs to be considered. Building the first three turbines off Fukushima - each with a different design - comes to about 2 million yen, or about $20,000 a kilowatt, about eight times as much as the cost of building a wind turbine on land. With increasing economies of scale and design improvements, the consortium says it hopes to bring that cost down to about twice the cost of land-based turbines.

Durability is the third large question mark. Shimizu, the construction company, says the turbine's blades have been designed to last at least two decades, and to withstand the biggest typhoons to have hit the region over the last half-century. But Mr. Imamura at Shimizu acknowledges that no one is certain how long, or how well, the turbines will hold up.

Norway and Portugal are also experimenting with small-scale, floating wind farms, but Japan's project is set to be the largest and among the earliest to commercialize the technology.

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