Electric vehicles will play a large role in environmental efforts as we aim to create a sustainable future. While drivers see EVs as a way to reduce their carbon footprint, utility companies see them as a flexible grid asset.
By managing their charging load, utilities can use EVs in two ways:
- to mitigate the use of peaker plants during peak periods by shifting charging off-peak
- as a dispatchable load to maximize utilization and storage from renewable generation sources.
This can be achieved either through a customer-controlled method, such as a time-of-use (TOU) rate program, or by managing the load themselves using direct load control. Both methods have strengths and weaknesses, as well as differing timelines as to when they will be viable to implement at scale. Before either can be applied, utilities need data.
See also: BYOC: Bring your own car and thinking of electric vehicles as flexible assets for the grid
What is influencing behavior in your service territory?
There are many different factors that will shape both charging and driving behavior. For example, both regional climate and seasonal weather will influence EV drivers. This was a topic of the Geotab Energy study “The Geography of EV Charging.” It found that within North America people who live in warmer climates will on average drive more miles daily.
It also found that regardless of the region, EV owners will drive more miles in the summer than winter months. Interestingly this doesn’t mean they will have a larger impact on the grid. The data from the study indicated that EVs, particularly in colder regions, use the most energy in the winter. This is most likely a result of EVs having reduced range as more energy is used to heat the cabin of the vehicle.
2019 Average monthly charging energy (kWh) in winter and summer.
There are also lifestyle choices that will affect how an EV owner charges their vehicle. Some drivers may live in the suburbs and have a longer commute. Others may live in condos in urban areas without access to a home charger.
Both of the scenarios can occur in the same service territory and behavior can vary greatly even between owners of the same vehicle make and model. Suburban drivers are more likely to charge at home and charge every day. Alternatively, urban drivers tend to rely more on public charging and charge more sporadically.
All of these factors combined will create a unique landscape with different barriers and benefits to consider.
The challenge of trying to model future EV charging load
The entire EV ecosystem has gone through significant changes over the last few years and it has caused some growing pains. Improvements in battery and charging technology have led to an increase in long-range battery electric vehicle (BEV) sales. These vehicles have a much larger impact on the grid than EVs of the past.
Newer BEVs have larger battery capacities and in order to maintain reasonable charging times they require more powerful charging capabilities. For example, a 2014 Nissan Leaf had a 24 kWh battery with a maximum charging capability of 6.6kW. The current top selling EV in the U.S. is the Tesla Model 3, which has a battery capacity between 50-75 kWh and has a maximum charging capability of 11.5 kW.
These technical changes, along with the change in vehicle market share, has resulted in the average power per charging session doubling.
Average power per charge session, 2014 versus 2019.
There are more significant changes on the way with numerous automakers recently announcing the launch of light-duty trucks including Ford, Hummer and Rivian. These vehicles will most likely drive similar changes in the EV ecosystem.
The Ford F series trucks have long been the top selling vehicle in the U.S. with almost 900,000 sold in 2019. Given the benefits that come with EVs over their ICE counterparts, like improved torque and fuel savings, it seems logical that the F-150 BEV will become very popular. The specifics around the F-150’s battery capacity and charging capabilities have not been released yet, but the similar Rivian R1T boasts a 180 kWh battery which is twice the size of any existing consumer EV.
Technological advances are increasing both the number of EVs on the road and the impact they have on the grid. In order to create accurate profiles for load forecasting, utilities need an ongoing source of current data.
What is the value of shifting EV charging load?
A crucial step in planning any load management program is conducting a cost benefit analysis to ensure it is viable. This is not a simple task and there are additional concerns when dealing with new technology like electric vehicles.
Currently, most utilities will apply the same methods used for traditional Demand Management initiatives. However, there are some within the industry that are advocating for an alternative approach when dealing with Distributed Energy Resources (DERs).
In August 2020, The National Energy Screening Project (NESP) released “The National Standard Practice Manual for Benefit-Cost Analysis of Distributed Energy Resources.” This manual provides the necessary framework to better evaluate the societal benefits of DERs, which are becoming a larger component of the analyses.
Regardless of which method is used, the first thing that needs to be established for an EV program is the value of EV charging load. The only way this can be determined is by reviewing data collected through load profiling. By reviewing EV-specific data, utilities can determine the average load contribution per vehicle during peak.
It is important that utility companies create load profiles specifically for their own territory. The average load per vehicle can change substantially based on the type of EVs being included. Long-range BEVs have a larger impact, as they utilize higher-power charging equipment. This means there will be a higher average if they make up a higher percentage of the total number of EVs.
You need data before an EV can be considered Distributed Energy Resource
Real-world data is needed to better understand how EVs are currently affecting the grid and to model future load impact. This data is also critical for accurately determining the value of shifting EV charging load. Every service territory will have unique factors that will influence both charging and driver behavior.
These differences mean that any cost benefit analysis for these programs will be territory-specific as well. This is why load profiling is an essential first step in seeing EVs as a DER.
To learn more about starting your own load profiling study visit geotab.com/energy.