Flipping the Switch on Electric School Buses: Working with Electric Utilities: Module 2 (Text Version)
This is a text version of the video for Flipping the Switch on Electric School Buses: Working with Electric Utilities: Module 2.
Welcome back to Part Two of the Flipping the Switch on Electric School Buses series, where we are providing an introduction to working with your electric utility. If you've been following along to Part 2 of the Flipping the Switch series, "Working with Electric Utilities," you'll already know that it consists of two modules. Module 1 provided an overview of how to begin the conversation with your utility and how to assess your power needs for future charging infrastructure. Module 2, which we're reviewing today, will discuss the various utility rate structures that you need to be aware of. Now let's get started with Module 2, of Working with Electric Utilities, with a focused discussion on utility rate structures.
One of the most important things with utility rate structures is to understand the terminology. There are many different charges associated with different types of utility bills, and understanding the basic elements is important to understanding how EV charging can impact your monthly bill. The most common of these is the energy charge, which is directly related to the energy consumed over each billing period. This is most common in households and is typically what you'll be associated with many residential loads. However, there are many other rates that include demand charges, where the peak power is of most concern here. And this is determined by the peak power consumed over each billing period, where the rate is in dollars per kilowatts, and a higher peak power each month is going to be associated with a higher demand charge, regardless of how much energy is consumed. The demand charge can significantly impact EV charging utility bills if many vehicles are charging at the same time. However, it is possible to mitigate these concerns through managed charging solutions that distribute EV charging throughout vehicle dwell periods.
Understanding your utility bills is really important to assessing whether or not EV charging will significantly impact how much energy costs for your facility. We'll look at this particular example, where there is a facility load with the potential for an EV charging load profile that could be stacked on top of that facility load to determine whether or not the peak demand is a large concern. A 24-hour load profile is a great way to understand what a peak demand is and how EV charging could increase these demand charges, and also how to mitigate an increasing peak load. The blue bars represent a typical home baseload, with a typical morning routine requiring power in the early morning; a base HVAC load operating each hour; and a spike in the evening, when the house may need to cool off and provide power for cooking and entertaining. The purple brackets represent the vehicle dwell period, when it is parked in the garage, and the red, yellow, and green bars represent the poor, moderate, and great opportunities for EV charging. The red periods are times when EV charging would coincide with facility or home peak demand and actually increase that monthly demand charge. As you can see here, based on typical rate structures where a flat charge of $15.00 a month, a demand charge of $2.00 per kilowatt, and an energy charge of $0.10 per kilowatt-hour, the calculations below really help you understand how demand charges can impact the final cost of the utility bill, and how increasing those demand charges from coincident EV charging can really increase how much energy costs for your facility.
The specific rates for energy and demand charges change throughout the country and across different utilities, with many utilities offering multiple rate structures that focus more on demand charges or energy charges. Although there's quite a lot of variability throughout most of the U.S., these rates are relatively similar, with only a few notable exceptions. The price variability is regionally dependent, but for most of the U.S., the average energy cost is approximately $0.10 per kilowatt-hour.
An example of the impact these rate structures have on the cost to charge an EV, consider this fleet that experimented with a few different rates. Two out of three of the rates incorporated demand charges, which for this fleet created a relatively high cost to charge. However, when the rate without a demand charge was incorporated, the cost to charge decreased. This third rate also saw a relative increase in the portion of the charging costs that came from the energy charge. This displays how choosing the appropriate rate structure for your fleet can have significant impacts on a vehicle's operating costs and the overall energy cost for the facility.
A few key takeaways from this module are: Demand charges are dependent on peak demand, and that is certainly important to consider whenever you're going to have EV charging that may occur at the same time your facility is already consuming its peak demand. And this is determined by the highest level of power demanded at one site in a billing period, so that peak demand is going to change each month as potentially your power requirements change throughout the year. So it's important to also understand how your energy demand at the facility changes throughout the year, as well as your fleet charging may change throughout the year, and whether or not your peak demand may be different in, say, the summer or the winter. Finally, a higher coincident charging of buses will increase peak demand and demand charges, and this is relatively straightforward. The more buses you have charging at the same time, the more your peak demand is going to be, and the higher your demand charges will be.
Thank you for listening. That concludes Module 2 of Part 2 of the Flipping the Switch series, "Working with Your Electric Utility." That concludes all modules of Part 2 of this series.
Now that you've completed Part 2 of the Flipping the Switch series, "Working with Electric Utilities," you'll wanna see what's coming next. In the following parts we'll discuss vehicle requirements, charging infrastructure, infrastructure planning and solutions, vehicle in-use performance, training for both drivers and technicians, and then, finally, cost factors.
As a reminder, you can find all the content for the Flipping the Switch on Electric School Buses series, including each part of the series in associated modules, as well as handouts with a summary of information and links to all the resources mentioned today, on the Alternative Fuels Data Center's Electric School Bus page.