Optimizing charge times to reduce demand on the grid - podcast

[wayner]

This week's Arc Energy Podcast has a good segment with a Univ of Calgary professor talking about how to optimize EV charge times to reduce demand on the grid.

CAN THE GRID HANDLE EVS?​

Produced by ARC Energy Research Institute | January 31, 2023
This week on the podcast our guest is Blake Shaffer, Assistant Professor in the Department of Economics and School of Public Policy at the University of Calgary.
We cover a range of topics about Alberta and Canada’s electricity markets. Including revisiting the tight power market that Alberta experienced during the December 2022 cold spell, the issues and opportunities that come from the ramp-up of Electric Vehicles (EV), and finally the prospects for achieving net-zero electricity by 2035 in Canada.
Here are some of the questions Peter and Jackie asked Blake: Does Alberta’s Electricity Systems Operator (AESO) need a better system for asking residential consumers to reduce their demand in times that the power system is in short supply? How are electrical system distributors preparing for the coming influx of EVs? Will people adjust their charging behavior to help the electrical system accommodate more EVs? Do you think Canada can achieve net-zero electricity by 2035? Will large transmission lines between provinces be required to achieve net-zero? How could net-zero impact consumer’s utility bills in 2035?

Can the Grid Handle EVs?

www.arcenergyinstitute.com

 

[Vawlkus]

To which I respond with “can the grid handle clothes dryers?”, as it is functionally the same question.

 

[wayner]

One estimate that I have seen is that a dryer load uses about 3kWh per load. So if you do 5 loads per week then that is 15kWh. I would guess that the average EV would do more like 40kWh per week.

So yes, it is like having a dryer, but it is more like adding two more dryers to your house. Or running your existing dryer 2-3X as often.

 

[ilovecoffee]

To which I respond with “can the grid handle clothes dryers?”, as it is functionally the same question.

Yeah but the way Teslas specifically handle Off-Peak charging is to aim to finish right before the Off-Peak time is over.

So unlike dryers which operate at any time throughout the day, with a lot of EVs you suddenly end up with a spike in energy usage if they all operate on the same or similar charging schedule logic.

Imagine everyone suddenly running their dryer at 5 am

 

[wayner]

The ideal situation, which they discuss on the podcast, is sort of a randomized charge start time from 11pm to 5 am or so - that way the charging is off peak, but you have enough time to fully charge.

But I personally prefer the finish before off-peak, which is about the same time as I leave home as that is better for energy consumption as your battery is warm when you leave.

The other thing that they discuss a bit is two-way charging. This could be a game changer for the grid if you can incentivize people to sell out of their car battery, but you need the charging stations to handle it. WFH may help with this as being plugged in at home is probably a better solution than having to build hundreds of two way charging stations in every parking lot and garage.

 

[Lon12]

One estimate that I have seen is that a dryer load uses about 3kWh per load. So if you do 5 loads per week then that is 15kWh. I would guess that the average EV would do more like 40kWh per week.

So yes, it is like having a dryer, but it is more like adding two more dryers to your house. Or running your existing dryer 2-3X as often.

I remember reading an article that said Hydro Quebec indicated that the average EV would use the same amount as an electric hot water tank.
My clothes drier uses closer to 4-5 kWh per load on the normal setting. Wish I could convince my wife to use a heat pump model!

 

[Big Earl]

So far in 2023, we’ve used the following:

Tesla: 510 kWh
Water heater: 427 kWh
Clothes dryer: 52 kWh

House total: 3,702 kWh (straight electric heat)

The highest loads on the grid are in the morning when people get up, shower and buildings heat for the day, and in the evening when people come home and make dinner. I’ve verified this by monitoring grid voltage - around here, morning is typically higher load than afternoon.

It seems to me that using scheduled departure is probably pretty hard on the grid. I don’t have time of use rates, so I just charge whenever, but usually in the early overnight hours when load is lowest.

 

[wayner]

I do have TOU and have my car set to start charging at 4am. The majority of my usage is in the off-peak period. My water heating is tankless gas so that won't really show up as electrical usage.

During winter I prefer to charge closer to departure time, but in summer I don't really care what time I charge, as long as it is off-peak. There is about an 8 cent differential between on-peak and off-peak.

I have solar panels, but I don't use my solar power directly - it is sold back into the grid at a premium price.

 

[Lon12]

In Alberta we get to sell our solar back to the grid for HALF price.... So I try and use it all up myself.

 

[wayner]

Ontario used to have a program called microFIT. My panels were installed in 2015 and I get $0.381/kWh by selling it back to the grid for 20 years. My all-in costs at peak to buy from my utility, Toronto Hydro, is around $0.20/kWh or so.