The California electrical grid avoided large-scale blackouts Monday as residents heeded officials’ calls to reduce their electricity consumption amid the scorching heat. California’s grid operator (CAISO) had warned the extra demand on the grid could force as many as 3 million households offline and warned projected peak electrical demand will be even higher on Tuesday with demand outstripping supply by as much as 5,000 MW.

While not nearly as bad as when 2 million Californians lost power in August 2020 because PG&E mistakenly shut down a gas-burning power plant, not everyone’s lights (and air conditioning) stayed on. Nearly 67,000 Bay Area customers lost power when transformers blew because of the extreme heat.

Grid not prepared for climate change

Climate change is threatening the California grid — which, despite investments in renewable energy, is still powered largely by fossil fuels — in multiple ways in addition to increasing demand from air conditioning in the face of extreme heat. The historic megadrought across the American West is reducing hydroelectricity production from dams powered by shrinking reservoirs, and wildfires — supercharged by vegetation desiccated by heat and drought — threaten generating stations and transmission lines. Some 45 new wildfires ignited across the state on Sunday alone.

“We designed the grid and wrote reliability requirements for the 20th century,” Mark Dyson of RMI told Vox. “We didn’t know that the weather was going to get a lot more extreme, both cold and hot. And what we’re seeing in particular is large, aging fossil fuel plants showing their weaknesses.” (Heatwave straining grid & demand reduction requests: Sacramento Bee $, San Francisco Chronicle, LA Times $, San Francisco Chronicle, Axios, AP, LA Times $, E&E $, CNN, Grist, CNN, Bloomberg $, HuffPost, Bloomberg $, New York Times $, Reuters, Sacramento Bee $; Tuesday shortfall: AP; Overall climate grid threats: Vox; Transformer failures: Axios, NBC-Bay Area; Heat and fire grid threats: Wall Street Journal $; New wildfires: AP; Hydropower: TIME; Climate Signals background: Extreme heat and heatwaves, Wildfires, Western megadrought)