SDG&E energizes 117 mile, 500,000 volt transmission line

San Diego, June 18, 2012 — San Diego Gas & Electric put into service the Sunrise Powerlink, a 500,000-volt transmission line linking San Diego to the Imperial Valley, one of the most renewable-rich regions in California.

The completion of the nearly $1.9 billion project culminates a rigorous, 5-year-long environmental review and permitting process and 18 months of construction that encompassed both overhead and underground technology as well as different climates and rough, remote terrain.

The Sunrise Powerlink 438 transmission structures contain 13,200 tons of steel. By comparison, the Hoover Dam contains 44,000 tons of steel.

The project was the subject of an extensive regulatory review — a collaborative effort involving SDG&E and a number of state and federal agencies — considered to be the most comprehensive study of a proposed transmission power line in state history.

Capable of bringing initially up to 800 MW of additional imported power into San Diego, the Sunrise Powerlink will play an especially important role this summer, as the line was originally designed to do. The transmission line will eventually carry 1,000 MW of power, or enough energy to serve 650,000 homes.

SDG&E and the California Independent System Operator Corporation (ISO), the agency that manages most of the statewide grid, consider the Sunrise Powerlink one of the important mitigation measures that will help maintain electric reliability during heat waves without power from the San Onofre Nuclear Generating Station.

The Sunrise Powerlink consists of more than 110 miles of overhead 500kV and 230kV transmission towers and conductor, 6.2 miles of underground 230kV cable and a 40-acre, 500kV transmission substation, which reduces the voltage for use by homes and businesses.

More than 4.7 million work hours were required to complete the project — the equivalent of 2,260 people working 40 hours per week for a year. Because nearly 75 percent of the tower locations required helicopters to set the tower structures for environmental reasons, it took more than 28,000 flight hours to complete the aerial construction.

In the near future, the Sunrise Powerlink will deliver a significant amount of wind and solar power to San Diego. Over the past three years, SDG&E has signed eight renewable agreements for more than 1,000 MW of solar and wind power from projects in Imperial County; that green energy will be transmitted across the Sunrise Powerlink.

By 2020, 33 percent of SDG&E's power will be derived from renewable resources. In 2011, more than 20 percent of SDG&E's electricity was obtained from renewable energy.

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