Trans Bay Cable, LLC has awarded Siemens Power Transmission & Distribution, Inc. a contract worth more than US$150 million to construct a 53-mile undersea high voltage direct current (HVDC) transmission link between San Francisco’s City Center electrical power grid and a Pacific Gas & Electric substation near Pittsburg, California. The HVDC PLUS system will transmit up to 400 MW at a direct current (DC) voltage of 200 kV and is the first order for Siemens using its HVDC PLUS technology. The main advantages of the new HVDC PLUS link are the increased network security and reliability due to network upgrades and reduced system losses.

A wholly owned subsidiary of Babcock & Brown LP, Trans Bay Cable LLC, the project developer, will make the electrical connection available to supply electrical energy from Pittsburg to increase reliability and cover increasing demands for power in San Francisco. The project will be implemented by a consortium of Siemens and Milan-based Prysmian Energy Cables and Systems. As consortium leader, Siemens was awarded a turnkey contract that comprises the converter stations for the HVDC PLUS system, including engineering, design, manufacturing, installation and commissioning of the HVDC transmission system. The company will deliver all high-voltage components including transformers, converter submodules, converter reactors and breakers and is responsible for the control and protection, civil works and building systems, including the special requirements for electrical components and buildings in a highly seismic zone like San Francisco. The HVDC PLUS solution for Trans Bay Cable uses a minimum amount of space – crucial for converter sites in urban areas – and minimizes environmental impact such as visual implication, audible noise and transport during construction. Prysmian will provide the submarine power cables that will be installed in the San Francisco Bay.

Construction will begin in the third quarter of 2007 and the system will begin operation in 2010.

“As demonstrated in California in past weeks, soaring energy demands require that we develop new technologies to provide more flexibility in the transmission and distribution of our nation’s power supply. This system will provide the reliable, consistent and safe transmission of power from the City of Pittsburg to San Francisco,” said Dave Pacyna, president and CEO of Siemens Power Transmission & Distribution. “Babcock & Brown and Siemens have been working together with federal, state and local political and regulatory leaders whose support and vision have been vital to ensuring the success of this project. Siemens is pleased to put our advanced technologies to work to improve our country’s energy infrastructure.”

“Trans Bay Cable’s mission is to provide a commercially viable energy solution for greater San Francisco. As energy demand increases worldwide, high voltage direct current transmission plays an increasingly important role, particularly in megacities like San Francisco, especially as it becomes necessary to tap energy reserves far away from the point of consumption,” said David Parquet, Trans Bay Cable vice president.