California Power Generation Trends 2001 to 2020

Note: the workflow behind this report is the case study used in a review of Workbench:

I scraped this data from It's actually available at but that's often not the case, so I wanted to check out Workbench's scraper. It's quite capable. In this case the data is split across two HTML tables on the site; Workbench enabled me to scrape them separately and then join them.

The site uses a stacked area chart, which Workbench doesn't do, but a line chart does a nice job here and is arguably a better way to compare trends.

Nice to see coal almost gone from the mix. The biggest surprise to me is the size of the natural gas component. Next biggest: wind hasn't grown since 2014.

My first question is about the impact of losing Diablo Canyon. According to, "the twin 1,100 MWe reactors produce about 18,000 GWh of electricity annually." Since Diablo is the only remaining nuke, that's in the ballpark of our 16,280 GWh for 2020. What's the % contribution it's making to the mix? About 9%.

2020 percentages all major sources

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It's a bigger chunk relative to renewables.

2020 percentages renewable

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My next question is about hydro. It's highly variable, I'd expect a correlation with drought. To explore that correlation, I found data on reservoir levels at I couldn't find an all-up aggregation but I picked Lake Mendocino as a proxy, scraped the table, and scaled its numbers 2x for comparison. We don't yet know the hydro output for 2021 but I've included the average reservoir level for this year so far.

The Large Hydro and Natural Gas lines from the first chart move oppositely, so I expect we'll be burning a lot more gas over the next few years to compensate for the lost hydro.