Deepwater installs experimental data collecting buoy off west side

Thu, 03/31/2011 - 10:00pm
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With a demonstration wind farm proposed for three miles southeast of Block Island, island residents are curious about how a man-made turbine will affect the horizon. During the next six to eight weeks they will get a preview of what a structure anchored off the island’s shores will look like. Granted, this one is far shorter than the turbines proposed for the wind farm.

Two weeks ago, on March 19, Deepwater Wind installed the Sea ZephIR — a type of spar buoy — half a mile due west of the Coast Guard station.

The buoy uses infrared sensors to measure wind speed, direction and sheer, as well as wave height and frequency and collect data on bird and bat activity in the area. Eventually the Sea ZephIR will also include a system to detect the migration of marine mammals.

It will be redeployed, after its sensors are fine tuned, to a site 20 miles off the coast of New Jersey, where it will collect data for a proposed wind farm there. Garden State Offshore Energy — a partnership between Deepwater Wind and Public Service Electric and Gas (PSE&G), New Jersey’s largest publicly owned utility — is developing the project.

The buoy, the delicate sensors of which will be tuned in the coming weeks, is a narrow column rising about 40 feet above the water, much less than the proposed Block Island wind farm turbine height of over 500 feet.

The other 60 feet of its total 100-foot length is hidden beneath the water, which is 88 feet deep at that location. It is anchored by a tether to a 110-ton concrete weight, which keeps it from swaying in the waves.

The electronic equipment is powered by three small wind turbines attached to the top of the tower, which charge a battery that can power the buoy for more than two weeks without needing to recharge.

The unit, which Deepwater Wind island liaison Bryan Wilson said cost in the millions-of-dollars range, will solve a number of problems with the European method of using met towers on top of pilings driven into the seabed to support them on a site.

Those types of pilings are cost prohibitive at the depths Deepwater is proposing for its turbines and are also not reusable. The Sea ZephIR will be able to be redeployed to multiple sites after it is finished collecting its data and can be installed in water more than 100 feet deep.

Spar buoys have been used for years as aids to navigation; however, this is the first buoy of its kind that will be used to collect wind data. It is still experimental and was placed in the waters near the Coast Guard station so it could be compared with data coming from the met tower stationed there on land.

Wilson with the help of consultant Rob Gilpin have been monitoring the buoy and troubleshooting any problems that arise. After installing the sensor equipment on March 22, they returned a week later to work on an issue with the unit’s radio communication capabilities. Wilson also noted that the buoy has developed a slight list, which the engineers are reviewing.

Once the spar buoy is redeployed a second one will be commissioned, which will again be brought west of the Coast Guard station for testing. After another six to eight week period it will be moved to the site of the proposed Block Island demonstration project three miles off the southeastern side of the island.

Wilson said that the second buoy is still in the design phase and will most likely be deployed after the summer season.