Distant view of substation with transmission towers

Conventional Sources

Three highly efficient and flexible natural-gas-fueled power plants contribute to PG&E’s diverse portfolio of generation resources. As we add more renewable energy to our power mix, these cleaner conventional plants can increasingly act as a backstop. With their ability to generate power quickly and safely, they provide the operational flexibility needed to integrate variable renewable resources such as wind and solar.

Our Approach

PG&E operates three natural-gas-fired plants with emissions levels that are best-in-class and use air for cooling to minimize water use:

  • Humboldt Bay Generating Station
  • Colusa Generating Station
  • Gateway Generating Station

As combined-cycle power plants, the Colusa and Gateway Generating Stations play a key role in PG&E’s efforts to successfully integrate more renewable resources into the energy grid. When wind or solar production changes throughout the course of a day, these facilities can ramp up quickly to generate the energy that our customers need.

2015 Milestones

In 2015, PG&E continued the safe operation of our three natural-gas-fired plants:

  • Humboldt Bay Generating Station

    Humboldt Bay Generating Station: This 163-MW natural gas plant is 30 percent more efficient than the older fossil-fueled plant it replaced. It employs technology that emits significantly less SO2, NOX and CO2 than the previous facility.

    The plant is located in a relatively isolated section of California’s north coast region and provides a significant majority of the area’s electrical capacity. The plant’s design—selected for the region because of its flexibility and low emissions—uses reciprocating engines that are air-cooled, reducing water use by eliminating the need for “once-through” cooling from Humboldt Bay.

  • Colusa Generating Station

    Colusa Generating Station: This 657-MW combined-cycle natural gas plant features cleaner burning turbines that allow the plant to use less fuel and emit significantly less CO2 than older plants. “Dry cooling” technology allows the facility to use 97 percent less water than plants with conventional once-through water cooling systems.

    The plant has 530 MW of base capacity and approximately 127 MW of low-cost peaking power that can be used at times when demand is high or in emergencies. In addition, the plant is designed to lower its output when power from renewable resources like wind and solar becomes available. The plant uses a zero-liquid-discharge system that recycles wastewater and further reduces its water consumption.

  • Gateway Generating Station

    Gateway Generating Station: This 580-MW combined-cycle natural gas plant has 530 MW of base capacity and 50 MW of low-cost peaking capability. On average, the plant yields dramatically less NOX, SO2 and CO2 for every megawatt-hour of power produced compared with older fossil-fueled plants. Gateway also uses dry cooling technology.

Measuring Progress

In 2015, PG&E’s natural gas power plants provided safe, reliable and low-cost electricity to our customers. The following performance data represents the average availability factor of our natural gas power plants.

Natural Gas Power Plant Availability Factor Footnote 1
2013 2014 2015
Gateway Generating Station 94.4% 93.1% 94.7%
Colusa Generating Station 93.8% 87.7% 92.7%
Humboldt Bay Generating Station 95.4% 95.2% 93.0%
  • 1. Refers to the proportion of hours in a year that a plant is available to generate electricity. Return to table

Looking Ahead

Clean and flexible conventional power generation will continue to play an integral role in meeting our state’s evolving energy needs, especially as more renewable sources come online. Our focus remains on maintaining, upgrading and safely operating our current facilities while further increasing the flexibility of our units to support continued growth in renewable and distributed energy resources.





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