Posted: February 18th 2016

Custom transmission for sea2shore

Nearly five million-pound cable is about to set sail from South Korea

Transmission cable

In early April, a nearly five million-pound, 20-mile long, 34.5kV submarine cable will be arriving by barge into Quonset Point in Rhode Island. This custom-designed transmission cable will interconnect to the nation’s first-ever offshore wind farm and will transport clean, renewable energy from Block Island to Narragansett. The cable will also allow the customers of Block Island Power Company to gain access to the wholesale power market. National Grid’s part of the project, known as sea2shore, involves creating the infrastructure to transmit this new source of renewable energy.

“We are so proud to be part of the nation’s first offshore wind farm,” said Tim Horan, president, National Grid, Rhode Island. “This project is an illustration of our commitment to our Connect21 initiative of building future energy networks that leverage the power of renewables.”

National Grid’s Dave Campilii, consulting engineer in Transmission Asset Management, recently went to South Korea to inspect the cable and oversee the final factory acceptance tests. The cable was developed by LS Cable & System Ltd., a South Korea-based global corporation. The company was selected following a worldwide search and an in-depth bidding and qualification process.

LS Cable made the cable to National Grid specifications that were based on industry standards, but also custom-designed specifically to the requirements of the Block Island Sound installation. Deepwater Wind, the developer of the Block Island offshore wind farm, also contracted with LS Cable to build a similar cable that will extend from Block Island to the offshore wind turbines. These five wind turbines will generate approximately six megawatts each for a total of 30 megawatts of clean energy. “Block Island uses about four megawatts of electricity during its peak usage in the summer months, and less than one megawatt in the winter,” said Dave, adding that most of the renewable energy will be transmitted back to the mainland of Rhode Island.

During his eight-day journey in South Korea in mid-January, Dave oversaw the final testing of National Grid’s submarine cable. The testing can take a couple of months, according to Dave, who witnessed the final phases of it. “They build a piece of cable, roughly 100 feet long, and conduct many different tests on it to simulate the conditions the cable might encounter and need to withstand during its delivery and installation.”

Some of the testing involves:

  • Bending and twisting the cable to make sure it will hold up during winding and unwinding from factory to barge, as well as the twisting and turning that may occur during installation under the ocean bed
  • Heating up the cable to emergency operating temperature levels
  • Simulating the effect of multiple lightning strikes on the cable
  • Putting 2 ½ times the normal operating voltage on the cable

The short test length of cable passed all of the tests, as did the 20-mile cable, which is now on its way to Rhode Island for arrival in early April.

Once the cable arrives, the work of burying it begins. A jet plow will bury the cable at a target depth of six feet under the sea bed, putting it out of the reach of anchors and commercial fishing equipment.

Cable transmission

(The diagram shows how the cable will be installed in Block Island Sound.)

The cable comes equipped with steel wire armour to give it protection from its ocean environment. The cable also includes fiber optics for communication between the new substations that will be built on Block Island and Narragansett. Alarms and status information will be transmitted through the fiber optic cable, and on to our System Control Center.

Additionally, the fiber optics will be available for lease to third parties for high-speed Internet access to local residents on Block Island. This will be the first time Block Islanders will have access to high-speed Internet and the first time they will have an electricity supply connected to the mainland.

While Dave shared experiences on his trip and is a lead engineer on the project, there is an extensive multi-disciplinary team of people supporting the sea2shore project, from the Rhode Island and FERC jurisdictions, Engineering, Legal, Licensing and Environmental, Communications and Stakeholder Relations, and many other areas.

“The development of the first offshore wind farm is a major achievement in our nation’s and Rhode Island’s commitment to renewable energy,” said Rudy Wynter, National Grid president, FERC Jurisdiction. “Our sea2shore project is an important component of Deepwater Wind’s success and reflects our Connect21 goal to develop the future grid to be able to accommodate distributed and renewable generation.”

As for Dave, he’s found the project to be very interesting. Asked how he will feel 20 years from now when looking back on the project, Dave said, “It’s a landmark project in my career. I’m very proud to be working on it.”

Time will tell…but perhaps this is the beginning of a new, vibrant offshore wind farm business in the United States harnessing a new source of clean, renewable energy.  For now, we should all be proud of National Grid’s leading role in its development.

Here are some details on how construction kicked off on the sea2shore project

Construction on the approximately $110 million sea2shore project started in January of this year. National Grid’s portion of the project includes:

Block Island

  • New 34.5kV substation on existing Block Island Company (BIPCo) property.
  • Approximately 0.8 miles of underground cable from Block Island Town Beach to the BIPCo property.
  • 2 miles of overhead line on BIPCo property.

Ocean

  • Approximately 20 miles of 34.5kV submarine cable from Block Island town beach (Crescent Beach) to Scarborough State Beach (Narragansett).

Narragansett / South Kingstown

  • New 34.5kV substation at the existing Rhode Island Department of Transportation (RIDOT) maintenance facility.
  • Approximately 3.5 miles of underground cable from Scarborough to the new substation.
  • Additional 0.75 miles of underground cable
  • Upgrades to existing Wakefield substation and West Kingston substation.

For more information on the project go to:

Comments

  1. Jane Degnan

    Will you be repaving Pt. Judith Road once cables and boxes are in place?

    Thank you

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“The development of the first offshore wind farm is a major achievement in our nation’s and Rhode Island’s commitment to renewable energy.”

Rudy Wynter, National Grid president, FERC Jurisdiction