Growing fleet of electric cars will strain aging electrical distribution systems

Feb 20, 2014 by Joshua E. Brown
Sending data in small packets revolutionized communications, from the radio to the internet. Now three UVM scientists — Pooya Rezaei, Paul Hines and Jeff Frolik — think packets of power can revolutionize the way electric companies deal with the coming tide of plug-in cars. They’ve applied for a patent on their new invention. Credit: Sally McCay

Selecting a Chevy Volt, Tesla Roadster, Nissan Leaf—or one of many other new models—shoppers in the United States bought more than 96,000 plug-in electric cars in 2013. That's a tiny slice of the auto market, but it's up eighty-four percent from the year before. In Vermont, as of January 2014, there were 679 plug-in vehicles, according to the Vermont Energy Investment Corporation. That's two hundred percent growth over 2013.

This is good news in terms of oil consumption and air pollution. But, of course, every plug-in has to be, well, plugged in. And this growing fleet will put a lot of new strain on the nation's aging electrical distribution systems, like transformers and underground cables, especially at times of peak demand—say, six in the evening when people come home from work.

How to manage all these cars seeking a socket at the same time—without crashing the grid or pushing rates to the roof—has some utilities wondering, if not downright worried.

Now a team of UVM scientists have created a novel solution, which they report on in the forthcoming March issue of IEEE Transactions on Smart Grid, a journal of the Institute of Electrical and Electronics Engineers.

Put it in a packet

"The key to our approach is to break up the request for power from each car into multiple small chunks—into packets," says Jeff Frolik, a professor in the College of Engineering and Mathematical Sciences and co-author on the new study.

By using the nation's growing network of "smart meters"—a new generation of household electric meters that communicate information back-and-forth between a house and the utility—the new approach would let a car charge for, say, five or ten minutes at a time. And then the car would "get back into the line," Frolik says, and make another request for power. If demand was low, it would continue charging, but if it was high, the car would have to wait.

"The vehicle doesn't care. And, most of the time, as long as people get charged by morning, they won't care either," says UVM's Paul Hines, an expert on power systems and co-author on the study. "By charging cars in this way, it's really easy to let everybody share the capacity that is available on the grid."

Taking a page out of how radio and internet communications are distributed, the team's strategy will allow electric utilities to spread out the demand from plug-in cars over the whole day and night. The information from the smart meter prevents the grid from being overloaded. "And the problem of peaks and valleys is becoming more pronounced as we get more intermittent power—wind and solar—in the system," says Hines. "There is a growing need to smooth out supply and demand."

At the same time, the UVM teams' invention—patent pending—would protect a car owner's privacy. A charge management device could be located at the level of, for example, a neighborhood substation. It would assess local strain on the grid. If demand wasn't too high, it would randomly distribute "charge-packets" of power to those households that were putting in requests.

"Our solution is decentralized," says Pooya Rezaei, a doctoral student working with Hines and the lead author on the new paper. "The utility doesn't know who is charging."

Instead, the power would be distributed by a computer algorithm called an "automaton" that is the technical heart of the new approach. The automaton is driven by rising and falling probabilities, which means everyone would eventually get a turn—but the utility wouldn't know, or need to know, a person's driving patterns or what house was receiving power when.

Urgent needs

But what if you come home from work and need to charge your plug-in right away to get to your kid's big basketball game? "We assumed that drivers can decide to choose between urgent and non-urgent charging modes," the scientists write. In the urgent mode the vehicle requests charge regardless of the price of electricity. In this case, the system gives this car the best odds of getting to the front of the line, almost guaranteeing that it will be charged as soon as possible—but at full market rates instead of the discount rate that would be used as an incentive for those opting-in to the new approach.

Why put plug-in cars on "packetized" demand instead of all the other electric demands in a house? Because the new generation of car chargers, so-called "Level 2 PEV chargers" are likely to be the biggest power load in a home. "The load provided by an electric vehicle and the load provided by a house are basically equivalent," says Frolik. "If someone gets an electric vehicle it's like adding another house to that neighborhood."

Imagine a neighborhood where everyone buys a plug-in car. Demand doubles, but it's over the same wires and transformers. Concern about overload in this kind of scenario has led some researchers and utilities to explore systems where the company has centralized control over who can charge when. This so-called "omniscient centralized optimization" can create a perfectly efficient use of the available power—in theory.

But it also means drivers have to either be willing to provide information about their driving habits or set schedules about when they'll charge their car. This rubs against the grain of a century's worth of understanding of the car as a tool of autonomy.

Others have proposed elaborate online auction schemes to manage demand. "Some of the other systems are way too complicated," says Hines, who has extensive experience working with actual power companies. "In a big city, a utility doesn't want to be managing millions of tiny auctions. Ours is a much simpler system that gets the job done without overloading the grid and gets people what they want the vast majority of the time."

Explore further: Silicon Valley sees shortage of EV charge stations

More information: Rezaei, P., Frolik, J., Hines, P.D.H., "Packetized Plug-In Electric Vehicle Charge Management," IEEE Transactions on Smart Grid, vol.5, no.2, pp.642,650, March 2014 DOI: 10.1109/TSG.2013.2291384

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Eikka
1 / 5 (1) Feb 20, 2014
Finally someone else takes this problem seriously.

And also indirectly points out to the elephant in the room: fast charging electric cars on the large scale is simply not possible due to the extra strain it puts on the power grid.

Suppose that out of the ~250 million cars in the US, a mere half a percent of cars were to simultaneously start quick-charging at levels of 16 kW or more. That would require more than 20 full size 1 GW nuclear powerplants to be brought online immediately and then a couple hours later turn them off.

If those same cars happened to be using 160 kW so they wouldn't have to wait for hours on end, it would require all the nuclear powerplants in the US and then some.

You simply can't afford to give people the option unless you build a massive amount of buffer batteries in conjuction with charging stations, which will have to be paid by the EV owners, greatly increasing the cost to drive electric.
kochevnik
5 / 5 (2) Feb 20, 2014
Batteries are used for transitions, Eikka. Hydropumping levels demand and can respond in minutes to extra load demands
Newbeak
5 / 5 (1) Feb 20, 2014
At the risk of sounding like a broken record,this reinforces my argument for decentralized power generation,with small neighborhood level generation of power using Bloom type fuel cells powered by natural gas,or biogas.Eventually people could have these fuel cells in their basement,and demand problems would be a thing of the past,along with worries about grid security,which is more and more vulnerable to terrorists,geomagnetic storms,etc.
Eikka
not rated yet Feb 21, 2014
Hydropumping levels demand and can respond in minutes to extra load demands


First you have to build the hydropumping stations. Dig up lakes and rivers and then flood mountain valleys with water, then deal with the resulting erosion and methane emission when the water levels fluctuate constantly and prevent normal lake ecosystems from forming.

And you need lots and lots of them.

There's now about 127 GW of power available in pumped water storage systems, which wouldn't be enough to supply the demand in this scenario, and that is actually approximately 99% of the grid level energy storage that currently exists in the whole world! The US alone has just 21 GW and all of it is already in use without electric cars anyhow.

There is no infrastructure in existence that would allow the utilization of electric vehicles on the national scale, and practically no technology yet to build one.

You're effectively forced to restrict driving to ~50 miles per 24 hours per car.
kochevnik
5 / 5 (2) Feb 21, 2014
So then time to stop making new wars like the fuckery USA is doing against Ukraine. Instead repair your rotting infrastructure and build more windmills!
Eikka
not rated yet Feb 21, 2014
Why? Because the average American household owns 2.28 cars and consumes 10,837 kWh of electricity per year.

If we're to limit the instant electricity consumption used by charging electric vehicles to no more than double the demand on any given day, we can dish out ~30 kWh per household per day, or 13 kWh per their average car.

13 kWh in a small electric vehicle like a Nissan Leaf will carry you 52 miles. The same amount in a bigger EV like the Tesla S will drive you 37 miles.

This is what the suggestion in the article boils down to, because that's what it's doing: it's limiting the rate at which you can charge your car in order to limit the increase in demand, which in reality means limiting how far you can drive in a day.

If you're poor and can't afford the express rates, you can go no further than 25 miles from your house in an electric car on your electricity rations. It's like there was special gas in the pumps only for the rich that lets you drive out of town.
alfie_null
not rated yet Feb 21, 2014
Finally someone else takes this problem seriously.

And also indirectly points out to the elephant in the room: fast charging electric cars on the large scale is simply not possible due to the extra strain it puts on the power grid.

The effect of this technology will be to emplace an upper limit restraint on the system, which would prevent the catastrophe to which you allude. Then, over time, pressure from increasing numbers of people who can't get sufficient charge will provide impetus to improve the electrical system infrastructure. See? No system collapse, and only a bit of economic discomfort, as we pay to improve our electric system.
antialias_physorg
not rated yet Feb 21, 2014
The electrical system needs to be improved in any case. What do you expect? That we continue using a system that was last upgraded in a major way in the 1950's forever?
If it's done now we can kill tow birds with one stone: Ensure that EVs are a viable option and make the sytem ready for an ever growing percentage of renewables.

The vehicle doesn't care. And, most of the time, as long as people get charged by morning, they won't care either,

I'm not sure the packet approach is feasible. The new VW EV takes 13 hours to fully charge on a regular outlet. If you break that up into chunks then that will take forever. Better upgrade the grid so it can take the strain.
Eikka
not rated yet Feb 21, 2014
The electrical system needs to be improved in any case. What do you expect?


That it won't be possible to improve it to the extent that electric cars would require with all the other requirements on the pipeline as well, such as dealing with massively intermittent renewable energy.

It's just adding another problem on top of a pile of issues.

The new VW EV takes 13 hours to fully charge on a regular outlet.


That's because a regular outlet is limiting the power it can recieve to a couple kilowatts, which is the same thing as the power packet scheme is attempting to achieve.

The problem isn't that you slow-charge your cars from a regular socket, but the fact that people would opt to install power chargers that deliver 16+ kW and if everyone in the neighborhood happens to have their cars plugged in at the same time, there's not enough power for all.

The trick of the scheme is that the power company can then charge extra for actually using the power charger.
antialias_physorg
not rated yet Feb 21, 2014
It's just a good incentive to do it right and not just keep on making hotfixes.
Or do you want to contend forever with the powerouts that are already happening? The systems need to be upgraded to sensible levels which must include a potential for energy storage.
That's not undoable and will create a lot of jobs.
Eikka
not rated yet Feb 21, 2014
It's just a good incentive to do it right and not just keep on making hotfixes.


It's not feasible to upgrade the grid to the level that would allow households to even medium-speed charge electric cars, because it will cause peak demands to rise beyond any reasonable limit.

It's slow charge or no charge without some unkown future technology that would make it economically and practically feasible to put large buffer batteries into every home, or at least in every substation.
Eikka
not rated yet Feb 21, 2014
That's not undoable and will create a lot of jobs


You're greatly underestimating the magnitude of the problem of energy storage on the grid level. Many offical studies are too, because they're only looking at tiny portions of the issue at a time, in isolation, instead of looking at the massive mountain of energy that needs to be delivered to replace fossil fuels in everything.

A good unintentional satire of the situation is in the Off the Grid documentary by Les Stroud, who built himself a house in the woods by airlifting in building materials by helicopter and then installing some pitiful solar panel and batteries which he said he didn't understand anything of, and then proceeds to power the home on propane gas he hauls in from the nearest town on snowmobiles and cars.

"Problem solved."
kochevnik
not rated yet Feb 21, 2014
If you're poor and can't afford the express rates, you can go no further than 25 miles from your house in an electric car on your electricity rations. It's like there was special gas in the pumps only for the rich that lets you drive out of town.
I live one kilometer from work. Americans are accustomed to lifestyle they cannot afford and wars they will not win simply. If you want a war, fight a war against being stupid

Monolithic grid unnecessary when grid is decentralized and local automobiles act as battery back up for the grid
Eikka
not rated yet Feb 21, 2014
I live one kilometer from work. Americans are accustomed to lifestyle they cannot afford


And if you lose your job and have to go further down the road, what then? Do you just keel over and die because you can't afford to drive or move to a new home, or do you go pleading the government for welfare?

In my life I've had to travel varying distances to find employment, and sometimes it has been right next door; sometimes I've had to commute two hours a day just to make the minimum wage. Life isn't always optimal for everyone, and usually less so for the people who are already thin on wealth.

Free movement of labor is one thing that keeps the society running. Otherwise you get structural unemployment where work exists but labor is unreachable. Electric cars with their limited range, high cost and limited recharging rates are part of the problem - not a part of the solution. They're just a huge money and resource sink if you try to push them to the society at large.
Eikka
not rated yet Feb 21, 2014
Monolithic grid unnecessary when grid is decentralized and local automobiles act as battery back up for the grid


So the automobiles themselves will provide the power necessary to quickly recharge the automobiles?

Well, what do we need the grid for, since we obviously have self-recharging electric cars?
Mike_Massen
not rated yet Feb 22, 2014
An interesting lot of comments, well in conjunction with the article, so isnt the solution rather obvious, practical & incrementally robust (in the long term) Eg;

1. Develop improved hybrid vehicles which;
- Focus (more so) upon carbon neutral liquid fuels with suitable internal combustion engines (ICE)
- Allied with electric/battery/super-caps in vehicle to exploit waste heat, braking etc (done?)

Whilst, incrementally grid & decentralised power sources eg Wind/solar augment
main grid supplies for localised power which allows;

2. Gradually less reliance upon ICE whilst transitioning to greater electric according to;
- Increased regional roll-out of charging capacity local demand 'inspires' change
- Adoption of greater practicable renewable integration

The result may well be a homeostatic transport solution which balances carbon neutral
fuels with suitable ICE & appropriate electrics vis a vis motors/battery/super-caps...

Q Arises, how does one manage transition & period ?

Ideas ?
kochevnik
not rated yet Feb 22, 2014
Well, what do we need the grid for, since we obviously have self-recharging electric cars?
Yes the cars are largely self-recharging due to local windmills and solar collectors. You seem to have a odd predisposition toward a centralized, command system reminiscent of the Soviet style
Mike_Massen
not rated yet Feb 22, 2014
kochevnik unfortunately, is a good example of how not to discuss, debate or enter into dialectic with this weird comment
Yes the cars are largely self-recharging due to local windmills and solar collectors. You seem to have a odd predisposition toward a centralized, command system reminiscent of the Soviet style
Where are these local windmills & solar collectors that offer the power needs suggested by Eikka ?

Why kochevnik, can you not see the logistics problems and why must you provoke re bad politics, it does you no credit, please focus on the issue, the power requirements, the means to adapt, the means to overcome local & grid supply hurdles, isn't that a smarter thing to do ?

Isnt it also a more useful thing to do as well ?
Newbeak
not rated yet Feb 23, 2014

You simply can't afford to give people the option unless you build a massive amount of buffer batteries in conjuction with charging stations, which will have to be paid by the EV owners, greatly increasing the cost to drive electric.

Read somewhere there was a plan to use flywheel storage for charging stations,and even offer mobile charging of EVs that have run out of charge.The flywheels would spin up at a sustainable rate,and could dump their stored energy quickly enough to fast charge electric cars.
IamVal
not rated yet Feb 23, 2014
between flywheels, liquid mass displacement, supercapacitors and processing from current to hydrogen and hydrocarbons we could get above the levels required to level the production/demand peaks.
Eikka
not rated yet Feb 24, 2014
Yes the cars are largely self-recharging due to local windmills and solar collectors. You seem to have a odd predisposition toward a centralized, command system reminiscent of the Soviet style


The decentralization argument is moot because these systems have long range correlations that essentially make them act as if one large powerplant that waxes and wanes.

I don't know what kind of fantasy world you live in, but windmills and solar collectors, local or centralized, produce far far more power variance than electric cars have a capacity to store. Solar power has capacity factors around a tenth of their peak output, and windmills at a quarter to a fifth of their peak. You still have the massive issue of transmitting this excess power over the grid to someone who can accept it.

Eikka
not rated yet Feb 24, 2014
The flywheels would spin up at a sustainable rate,and could dump their stored energy quickly enough to fast charge electric cars.


The energy density of flywheel storage is rather poor - i.e. it's not scalable because you need to oversize the system too much to make it work.
Eikka
not rated yet Feb 24, 2014
Besides, all the cars-as-grid-backup schemes essentially assume that all the cars are plugged in to the grid all the time.

Unfortunately most of the road traffic happens essentially during the peak demand and there is no infrastructure in place to have a two-way grid connection at every single parking lot or curb, so the cars aren't there to feed in power to the grid and when they come back home their batteries are empty, so Kochevniks self-charging cars don't actually have anything to give.

It would be interesting to see how much it would cost to put a high power charging socket to every damn parking spot in every city and town and then wire them up with enough capacity. We have heating sockets around residential parking lots here, which are low power 2 kW max, but they too are on timers with 10-15 minute rotation so people can't overload the system by turning all their block heaters on in the morning.

Newbeak
not rated yet Feb 25, 2014
Eikka,you do an exemplary job shooting down the ideas presented here.How about putting forward your own ideas for meeting the electric car charging challenge? I personally like the concept of local power generation,using fuel cells or ICE co-generation:http://www.techno...outages/
Mike_Massen
not rated yet Feb 26, 2014
Newbeak seems surprised by good deductions on a straightforward logistics problems with
Eikka,you do an exemplary job shooting down the ideas presented here.How about putting forward your own ideas for meeting the electric car charging challenge? I personally like the concept of local power generation,using fuel cells or ICE co-generation:http://www.techno...outages/


Eikka is obviously knowledgeable of the industry to a degree & understands technical aspects of potential compromises. Others not educated bark at the soothsayer as if they are 'trying to destroy ideas', they are not - they are telling it like it is, public desperately need education.

In respect of link offered Newbeak, there are costing & installation interconnection issues which still need to be addressed & the issue of economies of scale aren't covered.

Newsbeak, I am a power systems professional, see my Feb 22 comment - your observation ?
Newbeak
not rated yet Feb 26, 2014
Mike,I accept Eikka knows what he is talking about.I only requested some ideas from him that are feasible in his opinion!
Newbeak
not rated yet Feb 28, 2014
There is a story on CNN about charging electric cars with solar cells mounted on their roofs and charging them under a solar concentrator "carport": http://www.cnn.co...pt=hp_c2 See item "10".
Newbeak
not rated yet Feb 28, 2014
There is a story on CNN about charging electric cars with solar cells mounted on their roofs and charging them under a solar concentrator "carport": http://www.cnn.co...pt=hp_c2 See item "10".

Here's a video description of the idea: https://www.youtu...sL8ExY7k
Mike_Massen
not rated yet Mar 01, 2014
Newbeak uttered & from a place of relative isolation re analysis within the industry
There is a story on CNN about charging electric cars with solar cells mounted on their roofs and charging them under a solar concentrator "carport": https://www.youtu...sL8ExY7k
All cute fringe ideas, thought about many times before, I won't resist Eikka's interest in going into relative economy of energy gain vs infrastructure involved, Eikka 4 Newbeak ?

Far more commercial politics than anything actually useful from putting solar panels on cars & it is only marginally more useful to add solar panels to a garage. This combination, although 'cute' does not address any of the economies of infrastructure in relation to energy accessibility in respect of the energy density needed to charge the cars quickly enough so the utility value is moderately useful.

Adding to the public perception is good but, already looked at for 20+ years, not economic.

How about my 22 Feb comment Newbeak ?
Newbeak
not rated yet Mar 01, 2014


How about my 22 Feb comment Newbeak ?

Well,are you arguing for local production of power,such as what I suggested in a previous comment (Feb 20)? If so,I agree that would be useful to solve the problem of charging large numbers of electric cars while not overburdening the grid.The idea of solar cells on the roofs of cars is not "cute". If you read the article/watched the video,you would have learned they want to build fresnel lens (which are quite reasonably priced) solar concentrator carports for the solar cars to park under for recharging.The recharge times would drop dramatically with that arrangement. Granted,there are some problems to be solved,such as heat buildup in the PVs from concentrated solar radiation,and the effect of cloudy days on charge times.
Mike_Massen
not rated yet Mar 01, 2014
Newbeak didn't understand
Well,are you arguing for local production of power,such as what I suggested in a previous comment (Feb 20)?
I proposed a systematised incremental strategy covering a number of issues but, as is normal for those NOT in the industry, your interpretation is naively simplified.

Newbeak again
The idea of solar cells on the roofs of cars is not "cute"
Comparatively speaking it is because it appeals but, doesn't produce useful power - even adding 50% for the 'concentrator' !

Newbeak speaks from sheer ignorance with
If you read the article/watched the video..
Don't be naive & dumb to accuse, thats really stupid.

I am in the industry you are not.

You're naive, untrained & ignorant of what has gone before.

Instead, spend a little time understanding electrical power, watch it again & consider issue of "net present costing" re accelerated panel life, comparative advantages re economics etc

(Sigh) Old hat Newbeak, u are misled so easily by spin !

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