Anticipating more unevenness in its electricity mix in meeting California’s 33% renewable goal by 2020, Sempra Energy’s San Diego Gas and Electric Co. (SDG&E) filed Monday for state regulatory approval of three new power purchase contracts covering up to nearly 450 MW collectively from separate natural gas-fired peaking projects.

With the gas-fired sources, SDG&E said it has supplies it can call on that reach full capacity in 10 to 15 minutes when there is an immediate need for the power.

The projects include the three-unit, 300 MW Pio Pico Energy Center LLC project by the Apex Power Group; the 100 MW Quail Brush Generation Project by Cogentrix Energy LLC; and the 45 MW Escondido Energy Center LLC by Wellhead.

“SDG&E continues to sign contracts for as much renewable power as we can get to meet the state’s 33% mandate, but we also need resources that can be brought online quickly to provide power when other sources, such as wind or solar plants, are not available,” said James Avery, SDG&E’s senior vice president for power supply.

Increased renewables pose an increasing challenge for utility power system operators, Avery said. They literally have to balance supply and demand every few seconds to maintain regional system reliability. In addition to helping balance the load, the peaking generation will be called on during peak demand periods, too, he said.

Located on 10 acres near the existing Otay Mesa baseload generation plant, Pio Pico Energy will include three 100 MW units that are twice the size of typical peaking units, but can still power up faster and more efficiently, according to a utility spokesperson. “The project not only can reach full power quickly, it also automatically adjusts its output, much like a combined-cycle plant, to follow dips and peaks in demand,” said Apex Power vice president Dave Jenkins.

The California Energy Commission began reviewing the Pio Pico project in April, and if approved, it could start construction in 2013 and operations the following year, the SDG&E spokesperson said.

Quail Brush consists of 11 units, each 9 MW, and is slated for development near a large regional landfill. The peaking complex is being designed so it can operate at any level between 5 MW and 100 MW. Like Pio Pico, it could be operating by 2014.

The Escondido project is a repowering of an existing facility, calling for the installation of a new 45 MW combustion turbine generator replacing a vintage gas turbine generator. It will be built on Wellhead’s existing facility site. This project, with its 25-year contract with SDG&E, is slated to start commercial operations next year. This is the third fast-start, gas-fired project Wellhead has done involving SDG&E.

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