Hey California, Let’s Spare the Air and Turn Down the Gas

June 14, 2018 | 10:00 am
The Glenarm natural gas plant in Pasadena, California. Source: Wikimedia
Laura Wisland
Former Contributor

UPDATE [August 31, 2018] Today, the California legislature failed to pass Senate Bill 64, which would have provided the state with better tools to understand how natural gas power plant operations are changing over time as we bring online more renewables and how to manage the shift away from natural gas generation in a reliable, cost-effective and socially equitable way. Despite the bill not passing, UCS will continue its work to understand what the inevitable shift away from natural gas electricity generation looks like, and identify the data, research needs, and policy tools necessary to make that transition a success.


On March 4, California set a new record by supplying nearly half of the state’s electricity needs from renewables. That’s just the latest payoff of the state’s admirable clean energy investments, thanks to plentiful solar power and strong policies like the Renewables Portfolio Standard (RPS).

But California still relies on fossil fuels, via natural gas power plants, to provide 33 percent of annual electricity needs. In fact, in-state natural gas generation comprises about 10 percent of greenhouse gas emissions statewide. Natural gas–fired power plants supply a substantial portion of California’s current electricity demand and support grid reliability, natural gas generation will continue to play a role on California’s electricity grid for some time. But reaching our long-term energy and climate goals means ramping up renewables and at the same time turning down our gas. (More information about the role of natural gas in California’s clean energy future can be found in UCS’s new analysis.)

In many cases, gas plants will be turned off during the day, when renewable generation is most abundant. However, as the sun sets, solar generation decreases and natural gas plants must be turned on—or, if they’re already operating, they must ramp up generation to meet the evening demand spike.

The solution to this evening ramp problem is to:

  • Build cleaner alternatives to gas that can produce power in the evening
  • Build more energy storage
  • Use load shifting and increased energy efficiency to reduce evening electricity demand
  • Enhance coordination between grid operators to gain access to a larger pool of resources to provide evening electricity needs

Many of the state’s natural gas power plants were constructed to provide baseload power, meaning they were designed to stay on all day, nearly every day. Most of California’s natural gas plants were not designed to be turned on and off daily, nor was their frequent cycling anticipated in their original air quality permits. A natural gas plant starting up can produce as much as 30 times more nitrogen oxide (NOx) emissions than it will after it has been running for a few hours.

Nitrogen oxides are the particles visible in smog. They irritate lung tissue, exacerbate asthma, and make people more susceptible to chronic respiratory diseases like pneumonia and influenza. Starting up gas plants more often could increase air pollution concentrations and should be considered in their air permits.

To make sure California’s clean energy transition also reduces criteria air pollution from natural gas plants, UCS is proudly co-sponsoring legislation—Senate Bill 64 by Senator Bob Wieckowski—with the California Environmental Justice Alliance, the Asian Pacific Environmental Network, and the Clean Power Campaign. The legislation aims to do three things:

  • Require data that is currently reported to the US EPA on facility hourly startups, shutdowns and cycling to be made available for local air districts and the public on the California Air Resources Board (“CARB”) website. The data reported to EPA is not in a user-friendly format and it’s difficult to ascertain how power plant operations are changing over time without some complex analysis. More accessible information about how power plants are actually operating, as opposed to how they were predicted to operate when they were first permitted, is an essential first step to better decisions about how dispatch of natural gas power plants are impacting local air quality.
  • Require local air districts to report on hourly emissions from cycling, impacts of cycling on ambient air, and current permit limitations related to cycling.
  • Require the state agencies to work together to identify ways to reduce global warming and criteria air pollution emissions from natural gas plants, with a priority on reductions in communities most impacted by air pollution.

California is charting new territory for other states and countries in terms of the level of renewables on the grid, and making a dramatic shift away from natural gas generation will not happen overnight. But, Californians are already starting to feel the impacts of climate change, and communities in California breathe some of the unhealthiest air in the country.

For these reasons, it’s critical that the state shift to cleaner sources for all of its energy needs including electricity. The state needs better tools to understand how changing natural gas plant operations may impact air quality. SB 64 is an important step towards ensuring that California’s ramp-up in clean generation does not lead to the unintended consequence of frequently cycling natural gas power plants in a way that leads to increased air pollution.