In my post Dear Deniers and Cranks: Earth Hour Made a Difference, I said "Gas and coal fired plants dial up and down all the time to adjust for peak load, so an event like Earth Hour is actually turning down the dirtiest fossil fuel burners, taking it right off the top."
Many commenters disagreed, saying "Usage may have gone down but generation did not change. Generators have schedules and don't react to a small change such as this." and "Come on, man-up and own your mistake. The plants did not reduce output due to this, you know that."
Are they right or am I?
I spoke with Tanya Bruckmueller-Wilson of Toronto Hydro, which had a big campaign in support of Earth Hour, and she told me "Earth Hour is symbolic, and shows people that little actions can make a big difference." The idea is to promote conservation; Tanya notes that if people cut back their consumption then Toronto Hydro buys less power, and on Saturday night they did. However she said I should go higher up the distribution ladder. She turned me on to Terry Young of IESO, the Independent Electricity System Operator, who "balances the supply of and demand for electricity in Ontario and then directs its flow across the province's transmission lines."
I asked him if less electricity was produced as a result of Earth Hour. He said absolutely, but also sort of confirmed what some of the commenters said.
Electricity gets produced to according to schedule, and the schedule for Saturday night included a forecast of the expected reduction in demand.
The reduction turned out to be 920 megawatts. They based their projections on last year's results and ran Saturday evening on water power, wind and nuclear. Mr. Young said that absolutely and unequivocally, less electricity was produced in the Province of Ontario. And Terry Young turned out his lights for Earth Hour.
So I admit I was wrong in my statement "Gas and coal fired plants dial up and down all the time to adjust for peak load," but not about the fact that Earth Hour did make a difference- both in the way it delivered a message about conservation, and in the real production of electric power.