Cable Laying Ops Begin on Trans Bay Cable Project

Oct 08, 2009, 11:16AM EST
Cable Laying Ops Begin on Trans Bay Cable Project
Cable laying operation in California.

Trans Bay Cable (TBC) is an energy transmission infrastructure project designed to provide additional energy to the City of San Francisco. TBC consists of an approximately 53 mile long transmission line buried under San Francisco Bay to transfer already existing energy from an electric transmission system substation in Pittsburg to San Francisco. This energy transmission project will transport approximately 400 megawatts of hydropower, geothermal, and wind power.
The cable will run along a shallow trench on the San Francisco Bay floor. Dug using a hydro-plow to blast and remove silt, the process will be challenging as the topography of the floor possesses several obstructions. The cable will be installed under the bay floor using the underwater hydro-plow operated by Prysmian Cables and Systems from the world's largest cable ship, the Giulio Verne. A barge will be used in selected areas where the minimum water depth for a ship is not feasible. According to environmental experts, the cable laying activity will have less impact on the bay than a winter storm or tidal action.
This particular cable laying operation is made possible with an advanced subsea hydro-plow telemetry system consisting of a communication and control system designed to support cable burial operations. Electrical power, communication, and control of the telemetry system are provided via umbilical cable. System controls are provided for a Water Depth Sensor, Jetting Water Pressure Sensor, Trencher Attitude (Pitch, Roll, and Heading) Sensor, Stinger Attitude Sensor (Pitch), Video Camera with Pan and Tilt Assembly, Video Camera (Fixed), Water Intrusion Sensor (Leak Detection), Lights (Video Illumination), and Sonar Systems.
Cable laying operations should conclude in early 2010 with commercial operation beginning shortly thereafter. Updates to follow as more information is released.
Filed under: cable, subsea, system, telemetry
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Chuck Bunton
Trans Bay Cable will power San Francisco

By: John Upton

Examiner Staff Writer

November 18, 2009 SAN FRANCISCO — A new electrical cable will soon be able to pump an entire power plant’s worth of electricity into San Francisco.

The half-billion dollar Trans Bay Cable will connect San Francisco’s electrical grid with power plants and other power sources in Pittsburg.

The cable took six weeks to be laid from a ship that reached PG&E’s switch yard at Potrero Hill last week, according to Trans Bay Cable LLC spokesman P.J. Johnston.

Power that could be carried by the cables after installation is complete could provide 40 percent of San Francisco’s power needs, Johnston said. Installation is expected to finish by March.

The project is being rolled out by a joint venture that includes Pittsburg, which operates the Pittsburg Power Co., and private companies and investors.

Approval of the project was instrumental in shutting down an aging PG&E power plant at Hunters View in 2006.

San Francisco officials have said they hope it will eventually help them shutter a 360-megawatt Potrero Hill power plant owned by Mirant Corp.

“The energy that the Trans Bay Cable will bring into San Francisco is integral to our efforts to close the Potrero Hill plant,” San Francisco Public Utilities Commission spokesman Tony Winnicker said.

Activists, city officials and PG&E, which competes with Mirant, have argued to state regulators that the Potrero Hill power plant could be shut down once the cable is operational.

But the California Independent System Operator has ruled that would leave San Francisco vulnerable during blackouts because there is no major source of generators in The City.

In a settlement agreement, City Attorney Dennis Herrera agreed to drop city lawsuits against Mirant in exchange for an agreement that it would shutter the plant and redevelop the site once the ISO rules that it is no longer needed to protect against blackouts.

It’s electric
53 miles: Length of Trans Bay Cable
10 inches: Width of cable
2: Electrical transmission lines in cable
1: Fiber optic communications line in cable
4: Months before cable is operational
400: Megawatts of power that can be transmitted
$505 million: Project cost
40 percent: San Francisco’s power needs that could be transmitted

Source: Trans Bay Cable LLC
11/19/2009 2:33:52 PM

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