North America: Steel in the water

Last September in Baltimore at the AWEA Offshore WINDPOWER conference the buzz words heard over and over again were “we have steel in the water.” This is, of course, a reference to the jacket foundations for the five French built GE Haliade 6MW wind turbines which will be installed on the first North American Offshore Wind Farm site almost 5km South East of Block Island, population 1,051, in the state of Rhode Island, on the North Eastern coast of the United States of America.

This 30MW, $300 million (€275 million), wind farm project was launched in 2008 and has passed all the hurdles and now looks like being completed
in record time. Although not having completely unanimous approval it has been a project that most people really want to see succeed. In the words of
the developer, Deepwater Wind: “… the (Block Island) community effectively chose the spot (which) greatly reduced opposition to the project.”

Boosted support

Local support for the project was endorsed by The Rhode Island groups including the Environmental Council of Rhode Island, Fossil Free Rhode Island, Clean Water Action Rhode Island, The Nature Conservancy, and people of Block Island. Public opinion has also been boosted by the support for renewable energy from the White House.

All that can be seen at the wind farm site today is the 21m high jackets standing on the ocean floor with a few metres of each jacket above the water. Each of the jacket foundations will support one of the wind farm’s five 6MW wind turbines which are 180m high and spaced 600m apart. They are each pinned to the ocean floor by four 60m long, 1.5m diameter piles. These jackets are very similar to the many oil and gas platforms to be found in the Gulf of Mexico, in fact that is where they were constructed by Gulf Island Fabrication in Louisiana. However, in the small North East state of Rhode Island they remain a very strange sight.

Exclusion zone

As with European wind farm construction work special attention has been paid to ensure that the indigenous marine life has not been affected by the
construction. Specifically in this part of the ocean, the North Atlantic right whale and the humpback whale, both considered endangered species, and
other marine species listed as being in a sensitive situation, were not further endangered.

On completion of this construction stage Deepwater Wind management announced complete success and even reported a sighting of whales within the construction zone during this phase. The US Coast Guard has enforced that a 600m exclusion zone around each foundation for all vessels not engaged in construction activities during this work. The whole phase has been a text book operation with only a minor slip when the barge used to ship the jackets from Louisiana broke away and had to be towed back to the work area before beaching.

Offshore work

The offshore work has been carried out by an American built jack-up barge, a lift barge in American terms, the L/B Robert. The 3-legged self-propelled vessel is fitted with four cranes, the largest of which has a maximum 500t lift SWL at 10m radius. The maximum water depth for the vessel is 85m.

Other lifting work was carried out by the floating crane barge Weeks 533, the largest revolving floating crane on the East Coast of the United States. Installation of the nacelles and blades will continue this year as will the cable laying operations which should all result in first electricity being produced in Q4 2016.

Block Island Wind Farm

Block Island Wind Farm will replace the need for operating the diesel generators on the island which are “dirty, noisy, and very expensive”. During the peak summer season, the electricity price increases to 24 cents per kilowatt-hour, well above mainland prices. Block Island’s current peak demand is about 5MW meaning that the wind farm will produce far more than the island can use. Now, for the first time, a new cable from the island to the mainland will be able to export excess electricity generated to the eastern seaboard grid. It is reported that Deepwater Wind has signed a 20-year power purchase agreement with National Grid to sell the power, starting at 24 cents a kilowatt-hour.

This whole project has been seen as a North American demonstrator project, despite its importance to the population of Block Island. There are several projects in the pipeline, including the Cape Wind project but present indications that it maybe some time before these other projects reach maturity. In the meantime, look out for the US Wind project off the coast of Maryland. They plan a met mast installation this year to be built by Louisiana-based Keystone Engineering Inc. The Italian-backed company has won federal leases to develop a large 500MW wind project 15 miles
off Maryland’s coast. Between 85 to 125 turbines will be installed in 20-30m water depth. The $2.5 billion project is currently the largest offshore wind project on the drawing board in North America.

Dick Hill


This article first appeared in the February 2016 edition of the Offshore WIND Magazine

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Posted on July 11, 2016

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