PG&E Corporate Responsibility and Sustainability Report 2017

Conventional Sources

PG&E’s natural gas-fired power plants provide a safe and reliable source of energy for customers and contribute to PG&E’s diverse portfolio of generation resources. Their flexibility—including the ability to ramp up once solar generation decreases late in the day—means that they play an important role as we integrate variable renewable energy sources into our power mix.

Our Approach

PG&E operates three natural gas-fired plants with best-in-class emissions levels and reduced water use via dry cooling:

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

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

2016 Milestones

In 2016, PG&E continued the safe operation of our three natural gas-fired plants.

  • Colusa Generating StationColusa 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 NOX, SO2 and 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 StationGateway Generating Station: This 580-MW combined-cycle natural gas plant has 530 MW of base capacity and 50 MW of low-cost peaking capability. Like Colusa, the plant yields dramatically lower emissions for every megawatt-hour of power produced compared with older fossil-fueled plants. It also uses dry cooling technology, which minimizes water use.
  • Humboldt Bay Generating StationHumboldt Bay Generating Station: This 163-MW natural gas 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.

Measuring Progress

In 2016, 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
2014 2015 2016
Gateway Generating Station Footnote 2 93.1% 94.7% 81.6%
Colusa Generating Station 87.7% 92.7% 94.6%
Humboldt Bay Generating Station 95.2% 93.0% 92.4%
  • 1. Refers to the proportion of hours in a year that a plant is available to generate electricity.
  • 2. The decrease in Gateway Generating Station’s availability factor in 2016 was due to its first comprehensive maintenance upgrade.

Looking Ahead

The flexibility and reliability of conventional power generation will continue to play an integral role in meeting our state’s evolving energy needs, particularly as more renewable sources come online. We remain focused on maintaining, upgrading and safely operating our facilities, while further increasing their ability to flexibly support continued growth in renewable and distributed energy resources.