Utilities commission approves diesel generators to protect California public health, safety

In a recent decision, the California Public Utilities Commission will allow California’s utilities to continue to rely on diesel standby generators to provide reliable electricity supply during planned outages known as public safety power shutoffs. Near-zero emissions diesel backup generators coupled with low-carbon renewable diesel fuel will address environmental concerns while keeping the lights on for many Californians, according to the Diesel Technology Forum.

“As a result of the unprecedented wildfire and summer heat events of 2020, diesel technology played a central role in mitigating negative impacts from public safety power shutoff events that deenergized portions of the grid to mitigate further widespread outages,” said Allen Schaeffer, executive director of the Diesel Technology Forum, a not-for-profit association representing manufacturers of diesel engines and equipment, key suppliers of emissions control and other technologies, and fuel producers. “Based on this success and the availability of near-zero emissions diesel options, the Public Utilities Commission made the right decision to allow utilities to continue to rely on diesel standby generators to protect public health and safety for communities across California as work continues to develop next-generation zero-emissions solutions.”

The decision issued by the Public Utilities Commission requires utilities to transition to the latest near-zero emissions diesel standby generators over the next two years.

“Diesel is the gold standard for emergency backup electrical power and we appreciate the recognition of by the Public Utilities Commissioners of the unique role diesel technology will continue to play to protect public health and safety while reducing emissions for communities across California,” Schaeffer said. “Other options cannot today provide the same ready-to-go power on demand within seconds of an outage. Today’s modern diesel technology can be sized for any location, deployed, maintained and supported at any location, maintain continuous operation, deliver superior performance and durability while producing near-zero emissions.”

The latest near-zero emissions diesel technologies are now available in standby diesel generators, and these solutions reduce smog-forming compounds (NOx) and fine particles (PM 2.5) 90 percent below standards required over a decade ago. “These near-zero emissions diesel solutions have been integrated into commercial vehicles and off-road equipment for nearly a decade with great success, and we strongly encourage California’s utilities to work with generator dealers and suppliers quickly to gain access to these Tier 4 diesel standby generators in advance of future outages,” Schaeffer said.

The Public Utilities Commission also encourages utilities relying on diesel standby generators to fuel these units with renewable diesel fuel, sometimes referred to as hydrotreated vegetable oil (HVO).

“Renewable diesel fuel is a unique low carbon liquid fuel that is playing an outsized role in reducing greenhouse gas emissions in California,” Schaeffer said.

Renewable diesel fuel is derived from waste vegetable oils and animal fats and may be used as a replacement to petroleum-based diesel fuel to reduce greenhouse gas emissions from diesel engines by upwards of 80 percent. The use of renewable diesel fuel, coupled with biodiesel fuel, has eliminated far more greenhouse gas emissions than the switch to electrified cars, trucks and buses according to the latest data published by the California Energy Commission. Reliance on diesel Tier 4 standby generators coupled with the use of renewable diesel fuel means cleaner air for communities where these units are located while minimizing the carbon footprint of their operations and keeping the lights on throughout California in the event of a widespread power outage.

“Diesel technology has also been an important solution to backstop clean microgrid applications in California,” Schaeffer said. “The decision issued by the Public Utilities Commission requires that utilities operating diesel standby generators commit to future investments in clean microgrid solutions that rely on renewable sources of power, and diesel technology will continue to play a role in these clean microgrid applications.”

Schaeffer noted that, in many instances, diesel generators are often deployed as part of sustainable microgrid installations to generate critical power when renewables are off-line and battery storage is depleted. “As an example, the city of Camarillo, California, recently determined that the integration of diesel generators in many of the microgrids deployed across the city delivered necessary power, while relying primarily on renewable sources of power without generating excess emissions and delivered lower operating costs relative to the integration of diesel alternatives,” he said.