Bewaretheicespiders t1_j4wgtna wrote
Kinda failing to consider that charging the EV is expected to create the peak demand. As far as I could read, they only consider what capacity of battery would be plugged and charged on average. But they dont consider when that coincides or not with peak demand.
Your EV can't stabilize the grid at peak demand if thats when its charging.
edit: It doesnt address the economics of it either. Whats the benefit for the ev owner to see his car battery discharged when plugged? You're going to have to pay to charge it later, and your EV might not have the range you need when you need to use it. You arrive at work, you plug it, AC (and EV charging...) cause peak demand during the hot afternoon, you get out of work and your battery is not fully charged to go back home.
I dont see drivers buying into this. The utility of a fully charged EV is too high.
beezlebub33 t1_j4wls9p wrote
>Kinda failing to consider that charging the EV is expected to create
>
> the peak demand.
How so?
Take a look at the duck curve. The idea is that you charge at work which means that it charges during the middle of the day, when solar is greatest.
The peak demand is in the evening 6-9 pm or so. That's when you want to discharge back to the grid, and then charge the car again 3-6 am.
The only place where there is overlap between high grid usage and people wanting to charge their car is immediately after they get home from work. It's easy to disincentivize that with variable rates.
Bewaretheicespiders t1_j4wpyt5 wrote
>The peak demand is in the evening 6-9 pm or so.
That varies greatly depending on where you are and the season.
https://www.eia.gov/todayinenergy/detail.php?id=42915
In Texas for example, the smallest margins between supply and demand happens during hot summer afternoon where you lose wind power and AC runs the hardest. Just before people need their car to go home.
In cold climate where they dont use gas for heating (e.g. Quebec, and assuming we want to get rid of fossil fuel, every cold climate area will eventually use electricity for heating) the smallest margins are in winter just before sunrise, when you dont have solar either. Just before people need their car to go to work.
beezlebub33 t1_j4xeugq wrote
I will agree that it definitely depends on where you are and the grid.
BTW, I don't think that's the link you wanted to include. Although OpenCV is really cool. Nerd on, bro.
Bewaretheicespiders t1_j4xfoaj wrote
Haha that's been in my bookmarks for years after having to make a quick demo. Dont know how I ended up pasting that instead of the link. Computer vision kinda is my day job.
rhymeswithcars t1_j4wkhen wrote
Why.. would it charge at peak demand? You want the opposite of that, low price off peak juice.
Bewaretheicespiders t1_j4wlz8d wrote
Because the charging will be causing the peak demand. Charging schedules are dictated by commute hours, not hourly rates.
nostrademons t1_j4wzuk5 wrote
They don't have to be. Your car is commuting ~1 hour per day, at work ~8 hours/day, and at home ~15 hours/day. Why should it happen to pick the first 4 hours of that time at home to start charging? Any sane software would randomly distribute charging times through the off-peak hours. (Not to mention all the folks who can charge at work.)
dontpet t1_j4xeii4 wrote
I could imagine some of us cheeky sods topping up the battery at work during the day and selling a good portion in the evening when we get home.
DM_me_ur_tacos t1_j4z5914 wrote
I think that you underestimate how flexible demand can become. With adaptive pricing from utilities and adaptive charging from smart consumer devices, demand and supply should be able to be matched.
And if there is still more demand during sunny daylight hours, there is an obvious solution to that
iqisoverrated t1_j4zsqeg wrote
>Kinda failing to consider that charging the EV is expected to create the peak demand.
Not really. Most EVs charge at night when demand is very low and wind energy is, relative to that, overabundant. It's win-win. Alternatively you plug in at work and shave off the peak PV production at midday.
>Whats the benefit for the ev owner to see his car battery discharged when plugged?
He gets paid for the energy. The point with V2G is to plug in even on days where you don't need to charge (i.e. when you have either spare energy you won't need that day or spare empty capacity to soak up excess production). With V2G you can always override to say "I need to be charged to x% by time y". You don't open up your entire battery for V2G but only the capacity you do not need. E.g. if your daily drive is 50 miles but you have a 300 mile battery then you can open up the top 100 miles for V2G and still have more than enough buffer to feel safe.
No one is in danger of being stranded just because they participate in V2G.
Bewaretheicespiders t1_j509uj1 wrote
>Not really. Most EVs charge at night when demand is very low and wind energy is,
The demand is going to be high at night when ev adoption is high
Demand is going to be highest at night in northen latitudes if people abandon fossil fuel for heating the house. See Quebec.
You gain some wind at night (unreliable) but you lose all solar
People will want their car charged in the morning.
Batteries degrade with each charge and discharge cycle.
EV adoption guarantees that peak demand will drift towards the times when people charge their time. Its a self-defeating scheme.
iqisoverrated t1_j50ffqg wrote
>The demand is going to be high at night when ev adoption is high
Which is good. Better utilization of assets. You can do the calcs quite easily how much the total power draw over night would be with a 100% EV fleet (hint: it isn't nearly enough to stress the grid in any way)
>You gain some wind at night (unreliable) but you lose all solar
Offshore wind is pretty reliable. Yes, we'll need storage (we'll need that anyways)...but if we didn't have those additional consumers at night we'd need a lot more storage or curtail wind production (both of which would drive up the price of power).
>People will want their car charged in the morning.
Sure, but even so: Most people know what kind of mileage they will require the next day. Having 100% (or even 80%) SOC isn't required. EVs are exceptionally suited to level out such short term variability because for the overwhelming majority of the time they carry around a lot of unneeded battery capacity.
>Batteries degrade with each charge and discharge cycle.
Sorta. Really depends on how much you stress the battery. Charging/discharging at 0.1C is different than going in at 3C.
In a V2G (or V2H) mode you're dealing with such low C rates that there's no real stress there. Batteries are also far longer lived than the life expectancy of cars. From an LFP battery you can expect 1 million miles service life. From an NMC/NMA about 500k miles. The average car sees the scrap yard after 150k miles. If you consider yourself even close to 'average' then you have plenty of cycles to spare.
...and, of course, you're making a buck while serving the grid.
​
>EV adoption guarantees that peak demand will drift towards the times when people charge their time.
If you think about just plugging in? Maybe. But if you do it via smart meters/smart chargers (which is e.g. what they are subsidizing where I live - not the dumb ones) then that use pattern can be shifted without any impact on user comfort. If everyone charges from 18:00 to 24:00 then that's an issue because there's a lot of demand in the 18:00-20:00 slot. But if everyone charges from 23:00 to 5:00 it's no biggie.
And if you don't feel like mandating V2G/V2H you can always regulate it via time of use metering and offer low power prices at night.
Almost no one will care which slot the car charges in as long as there's adequate SOC in the morning.
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