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Proven at PJM: Vehicle to Grid (V2G) and Power System/Transportation Synergies

Victor Udo's picture
Manager, Business Planning and Research, Pepco Holdings Inc

Dr. Victor Udo has over 20 years of experience in the generation, transmission, distribution and utilization of electricity including the engineering, system planning, business, environmental...

  • Member since 2007
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  • Nov 17, 2008

In his pre-election interview with Rachel Maddow, President– Elect Barrack Obama envisioned an enhanced grid whereby plug-in vehicles are able to inject power into the electric power system. The President-Elect has articulated his commitment to create a longer term economy based on environmentally sound energy infrastructure that includes smart grid, renewable energy and the electrification of transportation through plug-in vehicles.

However, the electric power system represents both an aging and a critical infrastructure that is complex and lacks energy storage capacity such that electricity must be simultaneously produced and consumed with the resulting load-frequency control problem (Ref 1). Automobiles are basically distributed energy storage in the form of liquid fuel today but such storage can be transferred to electricity (Ref 2) if adequate public policies are implemented. Such transfer will allow wind power and solar power to be stored as electricity in the cars when parked, drive the cars when needed and give back the power to the grid when called for by the system operators. This scenario has been tested and proven in our study summarized herein.

While the power system is designed to meet peak demands, automobiles are designed to move a limited number of people (one to five) from one point to the other within less than one to four hours a day. In other words, most cars are parked most of the day doing nothing. Hence the actual level of utilization of both assets (power system and automobiles) is less than 100% most of the time – especially urban and local commute vehicles. Although the electric power business has undergone restructuring, the fundamental engineering aspects of the power system infrastructure remain the same. The load and the generation in the system must be balanced at all times. To accomplish this real time balancing, several functions have been established to manage the system effectively.

With restructuring, some of the balancing functions - such as spinning reserve and frequency regulation - have become marketed services. Other functions, includes voltage control and reactive power management. Spinning reserve and frequency regulation are termed ancillary services, abbreviated A/S, in well-established power markets such as PJM and other Independent System operators (ISOs). Given the right pricing, A/S can be the most effective market incentive for actualizing the synergetic advantage of re-electrifying transportation.

The biggest challenge with electric vehicles has been the battery that stores the energy needed to drive the vehicle in terms of initial cost and life cycle. However, a drive system has been designed by AC Propulsion of California which uses mass-produced 18650 lithium-ion batteries and patented power electronics with the capability for two way powerflow between the car and the grid. This two-way power flow is termed Vehicle-to-Grid (V2G). This drive train has been used to manufacture all electric vehicles with conversions cars and original cars by an OEM.

Based on the above background, Pepco Holdings, Inc (PHI) co-funded the theoretical analysis of the concept of V2G at the University of Delaware in 2003. This effort was built on the seminal work at the University, published in 1997 (Ref 2), and a burst of activity in 2000-2001 funded jointly by the California Air Resource Board and the LA Department of Water and Power. The results of those analyses were published in international journals between 2002 - 2005 (Ref 3 & 4). In 2007, PHI, University of Delaware, PJM and other partners, established the Mid-Atlantic Grid Interactive Car Consortium (MAGICC) to prove the V2G concept practically. MAGICC activities are funded by awards from the Delaware Green Energy fund, PHI, and In October 2007, a team of PHI, PJM and University of Delaware engineers and officials successfully interconnected an AC Propulsion “eBox” (a converted Toyota Scion xB) to the PJM grid using a direct signal from the PJM control center to dispatch the vehicle as a frequency regulation resource, like other traditional generators. The set-up and key players on the research are captured in Figure 1.

This technical breakthrough was demonstrated publicly for the first time on October 23, 2007 to FERC Commissioners and staff at their Washington offices. Since then it has been tested in several distribution systems. A full report covering this innovative green initiative capable of helping with oil independence, global warming reduction and energy security is due out in the next several weeks. If adequate funding is received, the next phase of the test will included expansion to several vehicles that are dispersed in different parts of the PJM grid performing frequency regulation and storage for renewable but intermittent resources such as wind and solar.


  1. Udo, Victor E., Adaptive Hierarchical Control Strategy for Large Scale Interconnected Systems, Master Thesis, Howard University, Washington D.C., 1991
  2. Kempton, W. and Steven Letendre. 1997. "Electric Vehicles as a New Source of Power for Electric Utilities" Transportation Research 2(3): 157-175.
  3. Letendre, Steven and W. Kempton, 2002. "The V2G Concept: A New Model for Power?" Public Utilities Fortnightly 140(4): 16-26.
  4. Kempton, W and Tomic, J. 2005. “Vehicle to Grid Power Fundamentals: Calculating capacity and net revenue”. Journal of Power Sources. Volume 144, Issue 1, pp 268-279.
Len Gould's picture
Len Gould on Nov 17, 2008
Excellent, if slow, progress.
Jude Clemente's picture
Jude Clemente on Nov 18, 2008
PHEVS present a tremendous opportunity to reduce oil dependence. From a homeland security perspective this alone is enough to pursue. We need reliable electricity to power our automobile fleet. Coal provides this. Clean coal offers us a realistic and safe way to move forward. There has been a number of studies indicating coal powering our automobiles is cleaner than conventional ICE vehicles.

The National Resource Defense Council and the EPRI found in a study last year that if extra electricity is needed from our coal-based national grid, PHEVs are much cleaner than conventional automobiles. Further, a study by the University of California at Davis found that the cost to plug-in a vehicle at night is equivalent to 75 cents per gallon of gasoline – far cheaper than the high fuel prices U.S. drivers continue to face.

Isaac Udotong's picture
Isaac Udotong on Nov 19, 2008
Great Job, Victor. This article is well timed to coincide with the new energy initiative and global warming interests that dominated the just concluded US Presidential Election 2008 Campaign.

Inspite of the recent fall in oil prices, I strongly believe that President-Elect Barack Obama has the political will to bring to pass this new Energy initiative.

Once again congratulations!

-Isaac Udotong

William Quaintance's picture
William Quaintance on Nov 26, 2008
ISOs dispatch traditional generators using security constrained economic dispatch methods. These methods rely on knowing exactly where each generator is connected in the grid. If every single 120 or 240V AC outlet becomes a potential connection point for V2G storage devices, how will this be managed? No one would be studying V2G without hoping that it will become popular and significant on the grid. Significant amounts of storage will need to be modeled accurately. I hope the forthcoming report touches on this aspect of V2G. One optimistic possibility is that the V2G devices will be located where the people are at the moment, which is where the load is centered at that moment (workplaces during the day and residences at night, etc.).
Jack Ellis's picture
Jack Ellis on Nov 26, 2008
It's one thing to demonstrate a single vehicle taking power from the grid at certain times and injecting it at others. Pulling off a similar feat with hundreds of thousands or millions of vehicles is a much more complex undertaking that neither grid operators nor utilities nor vehicle manufacturers nor policymakers have explored in much detail.

For example, there's the challenge of coordinating all of these nodes so that they don't create a new peak demand when their owners all arrive home within an hour of one another. There's the challenge of compensating vehicle owners for the use of their batteries when employed to provide ancillary services and/or peaking power. There are metering and billing challenges. If the grid operator discharges vehicle batteries during the day, an all-electric vehicle owner could find him- or herself without transportation. A few such horror stories will quickly consign the V2G concept to the dustbin of nice ideas that didn't work out.

Several years ago one researcher claimed that the batteries could be paid for by selling ancillary services to the grid operator. Perhaps, but as the number of electric vehicles increases, so does this supply of ancillary services, which in turn decreases the market price. In other words, early adopters will probably earn enough to offset the premium they will have to pay for their vehicles, but those who buy later may well be disappointed by the compensation they receive for V2G services.

I believe it is possible to pull this off, but I'm not convinced the usual suspects are capable of the out-of-the-box thinking that will be required.

I would love to see this idea succeed, and in fact my new home will have 220V circuits run to the garage in anticipation that they might become available in my lifetime. However I am perhaps a bit more realistic than V2G's promoters about the difficulties that lie ahead.

Malcolm Rawlingson's picture
Malcolm Rawlingson on Nov 28, 2008 THIS makes sense to me. Distributed storage via vehicle batteries rather than distributed production is a much more viable and sensible solution than all the rest put together....because the vehicle is both a storage device and a production device.

But the huge and indisputable advantage is that it overcomes the immense inertia for applying DG systems because the capital cost required (purchase of the car) is something people do anyway. They don't need to change - just buy a new car.

In addition replacement of vehicles say every 5 years or so allows the introduction of more advanced systems much quicker than if you have sunk a whole pile of cash into a solar PV array on your roof. Replacement of the car an a more frequent basis probably coincides with the required replacement of the battery.Replacement of the battery in a DG system is an added expense but replacing the car for a better one is considered a nice thing to do for most people even though it is costly and an expense...but people are alreaady doing it anyway.

While I am not a fervent supporter of renewables - spending all that capital for such low capacity factors seems crazy economics to me - it does allow them to be more cost effective and helps with one of the major drawbacks which is their intermittency. Tam Hunt will probably give me a big hug for saying that.

But the real reason I like this idea is it is the perfect fit for nuclear power generation and will lower the overall cost of electricity by eliminating (or at least reducing) the requirement for expensive peak power systems which are almost always coal oil of gas fires....and expensive. Big base load nuclear is the lowest cost emissions free electricity but it does not respond to load changes very well (that is why it is base load of course). Storing the power in cars overnight while keeping the nuclear generators at full rated capacityand near 100% capacity fac tors is the perfect fit. Reliable emissions free transportation coupled with reliable emissions free electricity system - well who can argue with that.

Well done Victor, this is an excellent article and I assure you that when the new Chevvy Volt comes into production (if GM does not go broke first) I will be the first to buy one.

I really really like this concept. It will work because the public will readily embrace it.

If the Chevy Volt was out now I would be driving one. I drive less than 60km a day so a perfect fit for me.


Malcolm Rawlingson's picture
Malcolm Rawlingson on Nov 28, 2008
Jacks post above raises some interesting questions. I think rather than create a new peak (which is a distinct possibility) it is more likely to have the effect of load levelling and will probably increase the base load requirement while decreasing the peaks. I will take a read of the links that Len posted here to see if the research agrees with that.

Also since millions of people are not going to replace their cars overnight I think the grid systems across North America will have time to adjust to this change over a long period of time. I do agree however that it will not be without it's challenges and we may be in for some unexpected outcomes.


Malcolm Rawlingson's picture
Malcolm Rawlingson on Nov 28, 2008
Regarding the law of unintended consequences think on these issues.

The first is what to do with all the gasoline we no longer consume? Since barrels of oil are not 100% gasoline the fractional distillation process used by oil refineries will create a product that we now no longer have a use for..and I do not agree with the assumption made that it will lower dependence on oil. Where do we get the raw materials for plastics from - the same barrel of oil that gasoline comes from. So let us stop equating a reduction in gasoline consumption with a reduction in oil consumption. It must occur with roughly a proportional reduction in consumption of ALL oil based products and that is a very very long list and gasoline is but one item on that list. We will STILL be dependent on oil with or without gasoline powered cars.

Secondly consideration must be given to the economic impact on economies of shutting down every gas station and distribution centre in the country. All gas delivery drivers are now out of work, all gas station attendants are now out of work, people that make and install exhaust systems will be out of work, all gas station owners will be bankrupt, people that make, install and service gas pumps are all out of work. Oil companies will take a massive financial hit - probably they can afford it....but it will lower their share values in which your pension fund are invested.

And a third thought is tax. Let us not forget the good old taxman who reaps huge rewards from our addiction to gasoline. Indeed Governments NOT the oil companies are the biggest beneficiaries of that addiction and if we are using electricity do you REALLY think Governments are not going to step in and take the same piece of pie from you as they got from the oil companies. The 75 cents a litre equivalent is NOT a direct comparison because it does not include comparable fuel taxes. Energy for energy (excluding taxes) gasoline is probably cheaper then electricity.

So I do applaud the idea from a technical and engineering view but the economic disruption that this will cause to economies needs to be carefully thought out.

Does anyone have any numbers showing how much revenue is obtained from gasoline taxes. Once I know that number I can tell you exactly how much of the tax burden will be transferred to owners of electric vehicles...precisely the same amount. So don't expect a free ride - it ain't gonna happen.


Jim Beyer's picture
Jim Beyer on Dec 1, 2008
A few quick points.

V2G is an extremely expensive way to provide power to the grid. I'm not gonna say it can't happen, but it's very pricey. Assuming $300/kw-hr for the batteries, which are good for 1000 cycles. (This would be a very inexpensive battery pack.) That means 30 cents per kw-hr for providing power in this way. Is a utility going to pay that? Other bright folks like Roger Arnold and Engineer-Poet have said there are other factors, like the utility being able to call this capacity, etc. which I won't argue with, but from the raw economics, it would only be done on rare occasions. (Note that a sheddable demand might be more responsive if the price went up to 30 cents per kw-hr.) The connect for the vehicle (the 2 grid part) is also not completely trivial, though doable.

If the vehicles had u-caps on them, note that this may help with short term glitches, and also not affect battery life. I DO see a future in that, at least theoretically.


Any decline in gasoline use will be so slow that refineries can easily adjust the mix. In general, it is not hard to change the ratios you are citing; they just need to move the chemistry around a bit. This isn't easy to do quickly, but it can be done. A few years ago, they got the ratio of gasoline to diesel wrong, which caused some price spikes in diesel (or was it gasoline?). The oil companies are far too smart to just throw something like that away.

Your point on gas tax is well-taken, however. You can't tax electricity, because clever folks can get around that. (Unlike kerosene for heating, you can't dye the electricity blue!) They might need to go with something like a tire tax, or maybe some kind of odometer thing on electric cars. I don't know. But they will do SOMETHING, and it is probably better to be proactive about that rather than to think they will just forget about it. (It is interesting how the gov't may be collusive in automakers efforts to avoid CAFE, as they benefit more with each gallon of gas burned.)

Jack Ellis's picture
Jack Ellis on Dec 2, 2008
Len, I must confess that I have not read the four links you posted earlier in any detail yet but after skimming over the first one very quickly, I'd agree you're on the right track if this is about decentralized decision-making rather than having the TSO (or ISO or RTO or pick your acronym) make all of the decisions. Too much information and too many variables for any reasonable amount of computing power in a single location to address.

Malcom, I can tell you with a fair degree of certainty that absent some form of distributed decision-making, there will be a new peak in the evenings as folks plug in. The only realistic way for EVs to level the load is if there's a clear economic signal that tells consumers plugging in and charging in the early evening is going to be costly. As for the existing infrastructure that supports internal combustion engines, I agree with Jim Beyer. The change will be gradual enough to avoid causing much economic dislocation as investment dollars and jobs transition to infrastructure that supports EVs.

I think electric vehicles will have their place, assuming someone doesn't figure out how to economically produce a gasoline substitute from algae or some other fast-growing organic matter. I'm not as sure V2G makes economic sense at current (well ok, last year's) prices for gasoline, renewable energy and batteries. Electric vehicles are likely to fail once again if utilities approach the problem with their usual bias for central planning and control.

Len Gould's picture
Len Gould on Dec 2, 2008
Excellent comments Jack. You've summarized the high points very concisely.
Len Gould's picture
Len Gould on Dec 2, 2008
I also agree that vehicle-to-grid is not in any way economical for frequent use. What I do believe is that the new infrastructure (eg. IMEUC or alternative) needs to provide for it inherintly, because it does provide an excellent source of auxiliary services to the grid, items such as spinning reserve, vars, and perhaps even occasional voltage stability support. The rarity of those services actually being called on, combined with a) the near-zero cost of incorporating the capability in the auto using TZero's (admittedly proprietary but very smart) design; and b) the requirement for the local metering and communications capabilities to be provided anyway in order to encourage the many upcoming varieties of DG such as SOFC or Stirling gas-fueled CHP, solar thermal CHP with thermal storage, even solar PV, etc. etc. all of which must be encouraged to the maximum strategically and are best if economically incented to operate as peaking resources as much as possible.
Malcolm Rawlingson's picture
Malcolm Rawlingson on Dec 2, 2008
If electric vehicles become popular (as I am sure they will) gasoline consumption will likely not drop as slowly as one would imagine. Once the mass marketers get to work with the slick ads etc the drop in consumption could potentially be precipitous. It would make for an interesting study and would depend for example on the mass production rate for these vehicles.

I did some Googling to get a ball park figure. US passenger car production ranges from a max of 9.34 million to a minimum (2004) of 4.23 million. The average is 6.06 million. There are about 160 million passenger cars registered in the USA. So that would argue that it would take 160/6 or 26.4 on average years to replace this fleet with electric cars if one relied solely on US manufacturing plants. That appears to support your argument that indeed the transition would be rather gradual. However once companies like Toyota, Honda, Tata and the Chinese get into the act AND people have a means of getting back at the oil companies (who most believe have been ripping them off over many years) and you have the makings of a force majeur that will make this process very rapid.

As a recent example - how long since the last Cathode ray tube TV was made?Plasma and LCD units have almost completely replaced them in less than 10 years. And the cost savings were zero and initiall costs were very high. ...but 10 years is all it took. What will drive electric car purchase is low running costs and no trips to the gas station. While I am sure that once these vehicles become popular the consumption of gasoline will fall off more rapidly than we expect but it will not have the same proportional effect on oil consumption.

The point still needs to be considered that a barrel of oil is not the same as a barrel of gasoline. I agree with Jim that oil refineries can adjust the chemistry and the proportion that ends up as gasoline may vary (it does anyway as it is dependent on the oil feedstock to the refinery so my friends in the business tell me). However the 1:1 relationship portrayed by the media (and which many politicians have bought into) is false. A reduction of 50% in the consumption of gasoline is not a reduction of 50% in the consumption of oil.

Jack Ellis makes a good point in that the PHEV's may create a larger peak demand in the early evening (an interesting thought). But the load will continue through the night so I think overall it will have the effect of flattening out the load profile by raising the overnight lows for most regions - good for nuclear plants. A fascinating thought Jack nevertheless.

And Jim, Oh yes you CAN tax electricity. The Canadian Government introduced a tax called Goods and Services Tax (GST) which was 7% but now stands at 5% and applies to electricity consumption. Every single electricity consumer in the country pays it. It is simply a click on the computer screen to make it whatever you like to replace the revenue from lost gasoline sales. As soon as gasoline sales start to fall Governments will do what all Governments do which is get it from somewhere else....and GST on electricity is the obvious choice. All European Governments do the same except it is called Value Added Tax or VAT.

I am in general agreement with the V2G ideas noted above - clearly harder to do - and much harder to control - similar problem to windmills.


Len Gould's picture
Len Gould on Dec 3, 2008
I would also note that in the IMEUC meter design, a powered anti-islanding disconnect (or disconnecting electronics if thats ever affordable) is the first (eg. outer) element in the meter system. The vehicle charging connection(s) and local DG connection are inside that disconnect. The first reaction of the meter to a power failure is to isolate the premises from the grid, shut down all non-critical loads, then start up any local resources available, eg. DG first, then vehicles if available. It then watches the market to see if there are any calls for available generation to re-connect to the grid (at it's user-programmed acceptable price) to help supply excess power to neighbours, while displaying for the local owner the actual costs of the power being extracted from the vehicle, and if available, the amount of battery and/or fuel still available in the vehicle. If the home is in night security mode, then it may, if allowed, sound an alarm or call a phone number and play a recorded message to get the owner to decide what steps to take from there.
Len Gould's picture
Len Gould on Dec 3, 2008
Regarding gasoline road tax replacement, it should be very easy with IMEUC to substitute a comparable levy on only electricity which is used to charge vehicles, and to rebate same for VtoG electricity taken from the vehicle. Given, eg. in Canada, I think about 32% [ ] of our today's 90 cents / litre is taxes including 13% GST/PST (VAT), then the actual tax levy is 10.5 cents / litre VAT and 11.5 cents / litre "road taxes", leaving the supply chain the remaining 68 cents / litre ($2.58 / US gallon).

Assume that in the US, only the 10.5 cents / litre (40 cents / gal) is levied, giving a retail price of $2.98 / gallon. Tax about 14.5% on the pre-taxed value. Is that about where it is now on average?

The equivalent tax on elctricity for vehicle use, given it's purpose is to support road maintenance, should be scaled to collect about the same amount per mile driven as the gasoline tax, so should have a multiplier on percentage of about the inverse of electric to gasoline efficiency. Say 85/25 = 3.4. Comparing a gasoline auto getting 28 mpg paying (40/28 x 40 cents = 1.43 cents / mile) with an electric auto having 15 kwh available of batteries able to go 40 miles on a charge, the tax charged per kwh on vehice use electricity should be 40/15 x 1.43 = 3.8 cents / kwh.

(Open to corrections here. Experience is I often make mistakes in this sort of calc first time).

So if the US gasoline road tax is 14.5% on the pre-taxed value of gasoline then the US electricity road tax should be 3.8 cents / kwh. Of course all governments, to encourage penetration, should leave that tax off until the percentage of electric vehicle miles gets above perhaps 10% of total.

Jim Beyer's picture
Jim Beyer on Dec 3, 2008
Annual vehicle production is more like 16 million units/year, domestically (U.S.). Could be as low as 12 million in a slow year. Takes about 15 years to replace the vehicle population.

Of course you can tax electricity. But I meant specifically adding road taxes to electricity going to vehicles. That might be a little harder.

But it occurs to me that the same interconnect that would provide all these V2G benefits could at the same time be a taxable plug. So if you want those benefits, your electricity gets taxed. If you charge the vehicle some other way, then maybe you avoid them. Probably would work out.

Len Gould's picture
Len Gould on Dec 3, 2008
Jim: My discussion was entirely based on taxing only the net electricity supplied to any vehicles, a system which if planned into IMEUC would cost little if any extra. Not exactly a taxable plug, more sub-metered circuit(s) of the meter with PLC or etc. communications from the vehicle(s) to the meter to identify the account to charge or credit for electricity, and that the electricity should carry road taxes. Set up this way, the same meter design as used in small services could also act as parking meters in public locations etc., obviously installed remotely to avoid vandalism.

In an excellent system, the auto would have a card reader on the dash which would allow credit cards etc. to override the default account in a given location, eg. reverts to car owners account after pressing a button or moving 100 feet. Would work for car rentals, lending cars to relatives and friends, etc.

Len Gould's picture
Len Gould on Dec 4, 2008
My apologies, I didn't express that very well. My difficulty with the words "taxable plug" is that it would only take half the population 10 minutes to figure out they could beat the road tax simply by running an extension cord from the dryer plug in the laundry room or from their private onsite DG/CHP unit, and many of them would. What I'm proposing is a system of two-way communication from the auto to the meter, where the auto continually "confesses" to the "meter controller in charge of that circuit" the amount of energy it has consumed, and who's account, with details such as encrypted account number, to charge for it including tax. The autos are set up by manufacturers to refuse to charge unless they can get a handshake from a "MCICC" or an emergency override command of some sort. The meter then accurately measures total site consumption for the site serving the auto charger debit the site owner, then a transaction to transfer the auto's confessed consumption (or supply) from that account to the confessor's account, plus an appropriate tax transaction to the auto's account.

The only real problem with that system is that the auto would refuse to charge unless it connected to an appropriately controlled circuit, and particurly during a transition, many legitimate locations wouldn't have such controllers. That's why my suggestion "governments, to encourage penetration, should leave that tax off until the percentage of electric vehicle miles gets above perhaps 10% of total"

Victor Udo's picture
Thank Victor for the Post!
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