The traditional approach to use a radial connection line to the mainland grid from an offshore site becomes problematic as project sizes get larger, Deepwater Wind CEO William Moore told TransmissionHub Oct. 13.
“You have a single point of failure as you get to larger project sizes,” he said while attending the American Wind Energy Association Offshore Windpower 2011 Conference & Exhibition in Baltimore, Md. “You have the difficulty of finding interconnection points where you can inject a lot of energy into the grid at a single point and so coming up with network alternatives makes a whole lot of sense.”
With its Rhode Island Sound and New York area projects, Deepwater Wind is attempting to construct an arrangement that will allow the company to introduce a second business function in the form of merchant transmission to, for example, help pay for a good part of the electrical infrastructure needed to interconnect the projects, he said.
Deepwater Wind is working on the Submarine Regional Transmission Line, a high-voltage transmission system connecting a planned offshore wind farm to New York and northern New Jersey. It is also working on the regional offshore transmission network, the New England-Long Island Interconnector, which will connect the company’s proposed Deepwater Wind Energy Center to southern New England and eastern Long Island, N.Y.
“We have interconnection requests in place for all the key interconnect points,” Moore said.
The company said Oct. 11 that it has signed an agreement with Siemens Energy to buy five 6.0-MW direct drive offshore wind turbines for Deepwater Wind’s proposed Block Island Wind Farm offshore Rhode Island.
That 30-MW offshore wind farm will be located in state waters three miles southeast of Block Island, R.I., and includes a transmission cable connecting the island to the mainland grid. National Grid plc subsidiary National Grid USA has agreed to buy all of the output from the project under a 20-year power purchase agreement, Deepwater Wind added.
The project is scheduled to be in the construction phase in 2013 or 2014.
“We’re moving right along with development … and a fair amount of the data we collect for the transmission system as well as the offshore wind farm for Block Island will help us with the bigger project out in Rhode Island Sound,” he said, referencing the company’s separate proposal for a 1,000-MW offshore wind farm.
Transmission is “right up there” among the key challenges for offshore wind development, he said.
“I think it brings its own set of risks and challenges,” Moore said. “We keep hearing that the real bottleneck in this business will be in cable and … not all wind development companies are also good at transmission, so we’re learning fast.”