Use of EV Batteries for Grid Power Smoothing

[gnuarm]

I've had discussion about the use of EV batteries (while still functioning in the cars) for smoothing the power peaks on the grid. Cars can be charged when supply exceeds demand and discharged when demand is higher. This can potentially eliminate the capital and operational expense of "peaking" generation without dedicating large battery packs to this function. Some people say, "The batteries are sitting there unused. Why not use them to our advantage?" Others feel it would be hard for the utility to properly compensate EV owners for wear and tear on the batteries and other equipment and may make it hard to properly use their cars if they can't count on the battery being full when they need it. Then there are issues of who takes responsibility if the battery fails early.

I've left several options for compensation and charge management. The assumption is that even at worse case, you will be able to set reservations for your planned use of the car and it will be adequately charged at that time. Since at some point there will be a lot more cars on the grid than would be needed for peak reduction, it might be practical that any given car could participate in a minimal way by only allowing the grid to use, say 5% of the EV capacity which would very seldom even be noticed.

If you have any other thoughts I can try to accommodate those ideas as well if there is an option to alter the poll.

 

[eprosenx]

This is a logical evolution!

It may not be feasible or practical for a long time (or ever) to do the “push back to the grid” thing. Tons of gotchas to that (not the least of which is that you need an inverter which is added weight and cost beyond the existing rectifier).

But the good news is that you could do this TODAY on the demand side. All the Tesla’s have Internet connectivity and they know where they are GPS wise. They could be instructed to charge or not charge to smooth the grid.

I would be especially willing to do this on the demand side since I have to charge my car anyway, so the battery is going to be “Cycled”. The key is that I could give my power company a wide range of flexibility about when to accomplish that charge. I am the perfect use case. I ALWAYS plug in at home, I have a Max amperage charging setup (wall connector at 48 amps) so I can charge in a small window if needed, and I have a relatively short commute (30 miles round trip) daily so I have TONS of extra battery capacity.

I suspect programs will let the EV owner say: I need 70% battery capacity by.8am every weekday. Then the power company can figure out how to get there.

Just like everything else though, there have to be financial incentives to do it. Either discounts on charging rates, or pure cash payments. Very few will be willing to “donate money to the power company” in the long run. These grid balancing services have value and so some of it should flow through to the participants.

The impact to battery longevity is an interesting question (more relevant to if you are also discharging into the grid than just controlling charge timing). The impact is real, but hard to quantify. At the end of the day, the power company will need to compensate participants well above the expected cost of accelerated degradation in order to drive adoption. Could be a sticky issue though due to the massive incremental cost to replace a pack, but the payment stream comes over time...

I today participate in Portland General Electrics program to let them control my Nest. They send me a check periodically for my participation. At the same time though, I come home and plug in my M3 every day during peak demand. If they had a decent program with a financial incentive then I probably would sign up for that too.

 

[jjrandorin]

I said no, as I am not interested in that. I used to participate in my local utilities program that would allow them to cycle my air conditioner during the summer "during high demand", before I got solar.

I live in california, work in san diego, and live in a city called temecula that is inland. Summer days at my home are generally high 90s low 100s, (think 95-106 or so). When this cycling program started, there was not that much cycling, but every year it got worse.

I got nest thermostats also (bought them myself, not given from utility) and signed up for the "nest rewards" thinking that it would work in conjunction with the cycling. It certainly did, but not in any way that benefited me.

The utility would cycle my nest off (and set my air conditioning to a higher temperature so it would not come on), around noon or so, then the utility would cycle off my air conditioner from 2-6 or 7pm). By 7pm my house was 90+ inside, and almost impossible to cool off for a comfortable evening. They did this often too, not "4-5 times in the summer" but like once a week or so on the worst days.

It was the final driver to push me to get solar, and I got a leased solar system from solar city at the time, because It was the easiest to implement with no initial cost to me, and I was not going through another summer letting my utility have that control over my AC for a $70-80$ total compensation.

I even made solar city size my system over my yearly usage because I told them I was buying an EV... in 2015.. when I knew I could not get a model S or X because they were out of my price range new, and I like new cars. So from 2015-2018 my system generated 110% or so of my electrical needs, and I use a "decent amount" of electricity.

I have zero interest in letting my utility "automatically control" anything with my system, given my experience. I want to buy my solar system, and install a couple of power walls, so that I am pulling as little power as possible from them, and for the last 3 years I have been a "net generator" as I did not have an EV. I expect to be very close to neutral this year. I feel I am doing my part enough, and have no desire to have them TAKE from me, as there is no way they would incentivize me enough to do so.

 

[jjrandorin]

Just read @eprosenx response, and while I am not interested in letting the utility take (as I said), I would be onboard with the EVs charging or not charging to smooth the grid, based on the premise that the car would have my set power when I left in the morning.

I got a Tesla wall connector and have it set for the maximum input the Model 3 can receive (60amp circuit providing 48amps, 44 MPH charge), mostly because the wall connector looks cool, AND it helped tremendously to combat any range anxiety I might have. Knowing I can charge my car for my daily commute (80 miles actual, 100 miles used by the car), in about 2.5 hours means that I can pretty much drive without thinking about having enough charge, unless I were to go on a road trip or something.

The biggest challenge there would be , people plugging things in, expecting them to charge, walking out later, and finding out it had been shifted off. Its fine if YOU set it that way... not fine if something did it "to" you even if notifications etc were setup.

The incentive would have to be very nice... something like an even lower cost per kW to charge (significantly lower) or something. That works in california with our high electricity prices.. but how much lower will matter in places with .10 a kW or something?

 

[ewoodrick]

This is a logical evolution!

It may not be feasible or practical for a long time (or ever) to do the “push back to the grid” thing. Tons of gotchas to that (not the least of which is that you need an inverter which is added weight and cost beyond the existing rectifier).

But the good news is that you could do this TODAY on the demand side. All the Tesla’s have Internet connectivity and they know where they are GPS wise. They could be instructed to charge or not charge to smooth the grid.

I would be especially willing to do this on the demand side since I have to charge my car anyway, so the battery is going to be “Cycled”. The key is that I could give my power company a wide range of flexibility about when to accomplish that charge. I am the perfect use case. I ALWAYS plug in at home, I have a Max amperage charging setup (wall connector at 48 amps) so I can charge in a small window if needed, and I have a relatively short commute (30 miles round trip) daily so I have TONS of extra battery capacity.

I suspect programs will let the EV owner say: I need 70% battery capacity by.8am every weekday. Then the power company can figure out how to get there.

Just like everything else though, there have to be financial incentives to do it. Either discounts on charging rates, or pure cash payments. Very few will be willing to “donate money to the power company” in the long run. These grid balancing services have value and so some of it should flow through to the participants.

The impact to battery longevity is an interesting question (more relevant to if you are also discharging into the grid than just controlling charge timing). The impact is real, but hard to quantify. At the end of the day, the power company will need to compensate participants well above the expected cost of accelerated degradation in order to drive adoption. Could be a sticky issue though due to the massive incremental cost to replace a pack, but the payment stream comes over time...

I today participate in Portland General Electrics program to let them control my Nest. They send me a check periodically for my participation. At the same time though, I come home and plug in my M3 every day during peak demand. If they had a decent program with a financial incentive then I probably would sign up for that too.

Go take a look at the Leaf and their strategy. They've has it in place in Japan for a few years and just bringing it to the US with the newest Leaf.

 

[mspohr]

Engie vehicle to grid

 

[gnuarm]

Great video. Thanks. I noticed they discussed degradation of the battery, but really just glossed over it without any real detail.

The only way I would participate in such a program would be if the owner of the grid "owned" my battery in the sense that they would take financial responsibility for the cost of replacement I think. Actually, even that would not likely satisfy me. Tesla warranties the battery, but they don't consider it "failed" until it has degraded 20%. If my battery degrades even just 15%, it will have a significant impact on the number of times I will have to stop to charge on trips. Right now I can't drive much more than 200 miles with a 100kWh battery because of the cold weather. Knock 30 miles off that and I will have to stop at nearly every charger along any route I wish to take. The short winter range is already a burr in my side.

 

[gnuarm]

I should have included another choice in the poll. "Yes, if I get free charging for all my trips". Not sure the power company would be down with that. While a commercial company would look at the averages and see potential for profit, utilities tend to be more conservative and want to see profit on every transaction. I'm not sure they would do that deal, but they might do something where you get free charging at home say. Essentially they promise to keep your tank full for routine driving if you let them utilize your battery for grid leveling.

 

[Nocturnal]

I do consulting work for Utilities, mostly around billing and metering systems. This concept has been in progress for quite some time and makes a lot of sense if it is setup correctly. Most major utilities already have the smart grid tech to do this and it would just require some changes to your system to convert you to a net metering setup.

A few thoughts. Those of us that drive electric partly because of the environmental benefits should be very keen on this. Mass grid storage provided by millions of EVs could make the switch to solar/wind far easier in the long run. In the short run it will reduce the need for inefficient/costly peaker plants. Regarding battery wear, Tesla's guidance on this is that it isn't a big deal right? At least judging by the recommendation to plug in whenever possible.

Peak energy usage occurs at about 6pm, when people get home from work turn on appliances, do laundry etc. I could definitely see a tiered system in place where you sign up for the highest refund or lowest rate and your car is tapped into first and if demand goes above a certain level then the 2nd tier cars would be tapped. There is no technical reason why you can't set your car up to not discharge below some set level for the emergency drive to the hospital or a beer run. I'd definitely want that control and no reason the owner can't retain that.

The hard part of all of this will be getting Utilities and their local Public Utility Commissions to build something that is attractive to EV owners and useful to the grid. Designing and requesting new rate structures is NOT an easy process. If you are interested in this sort of thing it may not be a bad idea to contact your electric utility and PUC. Set me up on a rate that gives me effectively free power for my car and maybe offset my other energy usage and I think I'd be on board. Marginal cost of energy to the Utility during non-peak times is very low so "free" power for your car should be very doable in return for smoothing out peaks.

One of my customers has something that isn't too far off right now. They give you a free Nest thermostat (a few hundred dollar value) and in return they can cycle your AC off for 15 minutes at a time a couple times a month. When it happens you receive a notification so nobody is caught off guard. Same would apply to auto charging. If you want to see how difficult peak demand for utilities really is then just look at commercial demand rates. The price difference can be quite dramatic.