Reducing peak demand: It's five o'clock somewhere

Photo by laura adai on Unsplash

This article was first published in Castanet May 28, 2024

When you plug something in, you just want it to work. You don’t think about the fact that it is 5 PM and everyone is turning on and plugging in: lights, ovens, stoves, clothes washers. You don’t need to worry about it because the utility does. How does the utility make sure there is enough electricity? The utility separates demand into baseload, the normal, flat, day to day electrical demand; and a fluctuating demand called peak demand. 

If fluctuating demand sounds scary, keep in mind that the electrical grid has always had fluctuating demand and used a fluctuating supply to meet it. In a cool climate, like British Columbia, the largest increase in load comes at the end of the workday Monday through Friday. People leave work around 5 PM and drive home. Once they get home they make dinner, wash clothes and run dishwashers. They may also reach for the thermostat, setting the AC to lower temperature during the summer or turning up the heat during the winter.

It’s not just our workday that drives demand. There’s also our hobbies. “TV pickup” is a great example of variable demand. In the UK entire populations would watch TV shows, then take a break at commercial intermissions to turn on electric kettles to make tea. The largest TV pickup happened July 4, 1990 just after the end of a penalty shootout during the FIFA World Cup, causing a sudden 2800 megawatt demand (this is the equivalent of 1,120,000 kettles). The National Grid Energy Balancing Team actually monitors TV schedules, trying to anticipate the “tea events”. 

Utilities could respond to these rises by building more capacity -- more hydro dams or more natural gas “peaker” plants that can be called into service on short notice. However, having plants that are idle 90% of the time is really expensive. Luckily there are other ways of addressing variable demand. For instance, the utility can practice demand side management, where the utility signals users that there is a peak and users reduce their electricity usage. This can be done in two ways. 

The simplest way is to charge more for electricity during the peak load so that customers have direct incentives to reduce peak electricity use. Commercial and industrial customers already have pricing that includes a higher charge for periods when they use the most electricity, called a demand charge. In 2024 BC Hydro will be offering an optional “time of use” pricing to residential customers. This “time of use” rate will provide an incentive to use electricity off peak from 11 p.m. to 7 a.m. and a surcharge for electricity used during the on-peak period from 4 pm to 9 p.m. How would you shift your habits to benefit from time of use pricing? Rather than start your dishwasher after dinner use the four hour delay so it goes on after 11 pm. Make sure your EV is charging during the off peak hours, rather than when you plug it in after work. Run the clothes washer/dryer in the morning or midday on the weekends.

The second way utilities can do demand side management is by direct communication between the utility and smart appliances. For example, during a peak event you could help by turning down the heat by 4 C. However, the utility can get the same savings from turning down the heat for 100 customers by 0.04 C -- a difference that nobody will notice. Fortis actually has a program, “Power Hours Rewards Program”, for people with smart thermostats and electric vehicles. People who enroll get a text message for each Power Hour event and can opt out by texting back or just by adjusting the temperature manually. Customers are paid to enroll and get seasonal bonus if they support 80% of the Power Hours.

BC Hydro has a more extensive program called “Peak Rewards'' which supports central air conditioners, electric baseboard heat and electric vehicles. Like Fortis BC, Peak Reward customers can opt out of peak events by readjusting their thermostats or unplugging and replugging in their electric vehicle.   

If your demand response program is big enough you might completely eliminate the need for a new power plant. By communicating and rearranging electricity use you have a virtual power plant, displacing fossil fuels. The newest and largest virtual power plant is Renew Home, a merger of Google Nest Renew and OhmConnect. OhmConnect has 226,000 homes on its platform in California, Texas, and New York. In California and Texas, both hot climates, peak demand comes early in the afternoon when air conditioners are struggling to keep buildings cool. One of the tricks Renew Home can use is precooling -- turning on air conditioners before the peak so the house is a comfortable  temperature when you get home. 

Next time you walk into the house and switch on the lights know that you are a peak event. You can be the peak, or you can be the virtual power plant. 

 

Articles and cartoons on Teaspoon Energy by Kristy Dyer are licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License You may reprint this as-is for free.