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 nearly 40 percent of annual electricity needs. In fact, in-state natural gas generation comprises about 10 percent of greenhouse gas emissions statewide. Reaching our long-term energy and climate goals means ramping up renewables and at the same time turning down our gas.
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 than 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 generators to provide data on the hourly change in emissions, startups, shutdowns, and cycling. Many plants are required to report hourly emissions data to the US EPA, but the data 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 analyze, using this data, how power plants are currently operating and likely to operate in the future, to ensure air quality protections are included in applicable permits. SB 64 would also require air districts to limit generation from the dirtiest power plants on days with poor air quality as long as the needs of the grid can be met with other resources. Since the worst air quality days are often the hottest days with the highest electricity need, limits on power plant dispatch must not jeopardize grid reliability.
- Require the state to plan for how it will reduce natural gas generation and accelerate the eventual retirement of gas plants, placing a priority on reducing natural gas generation in communities most impacted by air pollution.
Because 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.
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, and an explicit mechanism in law for air districts to coordinate with grid operators to reduce the dispatch of natural gas power plants on the worst air quality days. SB 64 would ensure 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.
Posted in: Energy
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