What is curtailment day?

Last week summer hit the Bay Area with a vengeance. On my commute home on the sweltering CalTrain, I heard one piqued woman complaining to her friend about how hot it was in her office. “It was a curtailment day,” she said, rolling her eyes.

What’s a curtailment day, and is it worth sacrificing your comfort for an afternoon?

A curtailment day, or a peak demand day, occurs when your utility – most likely PG&E in the Bay Area – predicts high demand on the electrical grid. In the Bay Area, curtailment days are most likely to happen on the hottest days of the year when businesses and residents are blasting their air conditioning (AC) to stay cool. On such days, PG&E asks large businesses to curtail – or cut down – their electricity use by turning down the AC’s and turning off lights and any unnecessary appliances in the afternoon.

If you’re like me and you sit directly under an AC vent, you welcome curtailment day as a relief from the frigid, artificial air. But if you’re like most people, you sit at your desk in a dimly-lit office, sweat dripping down your face as you try to get your work done. You’re hot and uncomfortable, and you can’t imagine what the point of curtailment day is.

A curtailment day does, in fact, help the environment in several ways. In times of peak energy use, PG&E has to run additional power plants called “peaker plants.” A peaker plants is an older power plant that uses dirtier sources of fuel (like coal!) than a newer, cleaner power plant does – meaning a peaker plant contributes to bad air quality and climate change more than a new power plant. Conserving energy on a curtailment day reduces the use of these peaker plants and their contribution to climate change and bad air quality.

If businesses did not participate in curtailment day, there would not be enough energy supply to meet peak demand. PG&E would have to build more power plants, which would increase our utility rates. And seriously, who wants a new power plant in their neighborhood or city? Land in the Bay Area is too precious to be used for another power plant.

So when it’s 1 p.m. on a curtailment day – the lights go out and the AC shuts down, and you start to break a sweat – go pour yourself a glass of iced tea and remember that being a little warm for a few hours is better than a warming planet, bad air quality and a new power plant in your community.