V2G - Vehicle to Grid nonsense

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reikiman's picture
Last seen: 2 years 3 months ago
Joined: Sunday, November 19, 2006 - 17:52
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V2G - Vehicle to Grid nonsense

V2G: Smart grids meet electric vehicles is repeating this rosy vision that I think is a crock. Here's the pitch:-

In the future, utilities will pay you to plug in your vehicle. Millions will plug in their electric vehicles (EVs), plug-in hybrids (PHEVs), and fuel cell vehicles (FCVs) at night when electricity is cheap, then during the day when energy is expensive, sell those extra electrons at a profit. Vehicle-to-Grid (V2G) technology is a bi-directional electric grid interface that allows a plug-in to take energy from the grid or put it back on the grid. V2G helps solve the major problem that demand for electricity is high during the day when everything from industrial plants to air conditioning is running full blast and then excess electricity is wasted at night.

The idea keeps cropping up and I think PG&E keeps pushing it. At least the local newspaper has occasional pieces with PG&E doing a dog and pony show trying to convince people that vehicle-to-grid is a great and wonderful idea.

The problem I see with this is the charging time. Peak power demand happens in the middle of the afternoon. During the summer that's when it's hottest outside and therefore when the air conditioners are at their busiest moving heat from inside buildings to the outdoors (making the outdoors even hotter). That makes it likely the power company would tap batteries in EV's in the middle of the afternoon, leaving the EV's unable to drive for several hours later due to the required charging time.

I suppose they figure most EV's would actually be a plug-in hybrid. And that the car engine would fire up to keep the battery topped. And in that scenario the utility would be outsourcing their pollution to PHEV owners who participate in the program.

There's an interesting comment on the article: Just out of curiousity, but why don't we construct buildings with large battery rooms that charge at night to offset daytime cooling/heating requirements? Shouldn't that be a cost-incentive priority for electric companies? Indeed.. so very simple. Why make the battery systems for peak demand be mobile? Why not build them into the infrastructure?

V2G: Smart grids meet electric vehicles

V2G: Smart grids meet electric vehicles

V2G: Smart grids meet electric vehicles

V2G: Smart grids meet electric vehicles

V2G: Smart grids meet electric vehicles

V2G: Smart grids meet electric vehicles

V2G: Smart grids meet electric vehicles

davew's picture
Last seen: 4 years 6 months ago
Joined: Monday, November 20, 2006 - 20:13
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Re: V2G - Vehicle to Grid nonsense

You make a number of good points. One I'd like to add is cycling batteries shortens their life. Is the power company going to chip in for the replacement pack?

"we must be the change we wish to see in the world"

jdh2550_1's picture
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Re: V2G - Vehicle to Grid nonsense

Yeah, I'm not sure who actually started the idea of V2G. I think it might be the guys over at AC Propulsion - I know their high end controller supports it ($25K for controller and motor). They are also usually at the forefront of this stuff.

Some observations on V2G:

(a) I don't think the V2G system will drain your batteries - I think you can set a minimum threshold and it will stop drawing power at that point

(b) Talk about "running before you can walk"!!! Let's get a LOT MORE freakin' BEVs on the road before we talk about turning them into portable emergency back up units.

(c) I'm also pretty sure that they are NOT assuming PHEV's - because PHEV's have puny little batteries. V2G will need the big, manly batteries required by a BEV... ;-)

(d) I do think that if I had an AC based car that I would want the ability to personally tap into a 120VAC supply - but I don't see the point of "selling it back to the grid" - I'll keep it for my own use thanks...

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andrew's picture
Last seen: 10 years 6 months ago
Joined: Tuesday, November 28, 2006 - 17:21
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Re: V2G - Vehicle to Grid nonsense

The idea is catchy, but just about useless for now. I can't really see the logic because you are just sacrificing vehicle range when you'd most need it as you point out. Or you'd be using another form of energy to generate electricity for the power company which is counterintuitive unless they have a crisis (like with the CA gray outs).

Now an EV service station could use V2G for battery cycle analysis, but that's about all I can think of.

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Last seen: 11 years 5 months ago
Joined: Monday, October 1, 2007 - 10:04
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Re: V2G - Vehicle to Grid nonsense

There's an interesting comment on the article:

Just out of curiousity, but why don't we construct buildings with large battery rooms that charge at night to offset daytime cooling/heating requirements?


I find this to be interesting because I know a lot of large buildings already have certain things such as
"crack units" or otherwise known as; Libert systems (canadian name)
These are cooling systems for their buildings and computers. A lot of buildings also convert part of their basements etc into "disaster recovery rooms"

I remember also having to check libert temperatures as they are to remain a specific temp

Last seen: 11 years 1 month ago
Joined: Tuesday, November 21, 2006 - 13:01
Points: 137
Re: V2G - Vehicle to Grid nonsense

I too agree V2G is nonsense. It evolved rather as a response to all the critics arguing that electrical vehicles are not a realistic option BECAUSE the grid won't hold for the load. By just saying "V2G", you silenced that bunch, and in principle they are the only target audience for the V2G discussion. The rest of the population immediately understands that if we are out of oil in a few years, reinforcing the grid will be the smallest of our challenges. (The bunch however probably to day still drive their 3000kg+/10mpg- truck 30000 miles a year, with a confident smile on their face saying stupid EVs are not feasable.)

And yes, the grid in large parts of US is too weak, and needs reinforcement anyway. But if we manage to replace all cars with electric, in this process there is plenty of time (20 years?) to reinforce the grid by some 5% that would be needed. Which is much less than average increase of power consumption due to other factors, during that time. V2G or not, you normally charge at off-peak hours, so extra load will be minimal. The 5% figure is btw. from a report by the Swedish federal power company Vattenfall, investigating the impact of electrical cars on the power grid.

So if V2G is not NEEDED, is it possible? Well, assuming that most people would want a battery pack sized as in the Tesla (53 kWh), and in normal commuter driving keeping SOC around 50%, I guess there is some room to support the grid an hour or two per day. Dropping the SOC a few percent at times won't affect battery life much. It would only be needed on really hot days. Cars with small battery packs would not want to participate.

Last seen: 9 years 4 months ago
Joined: Wednesday, March 25, 2009 - 18:55
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Re: V2G - Vehicle to Grid nonsense

Late to the party on this thread, but thought I'd throw in my two cents.

(Picking numbers out of the air with no knowledge of actual rates.) Let's say standard rate is 12cents/kWh, but you charge your EV at a nightly rate of 9cents/kWh. Unless the power company is going to guarantee that it will pay you at least 9cents/kWh to buy back this electricity you're going to lose money. And if they do then they're going to lose money. Which do you think they would prefer?

Mik's picture
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Joined: Tuesday, December 11, 2007 - 15:27
Points: 3739
Re: V2G - Vehicle to Grid nonsense

Since the recent announcements of improved battery technology, with claimed charging rates much too high for standard power outlets, there could a new variant:

Recharging station to Grid = RCS2G

A powerful battery bank which puts a near constant load on the grid, but stops recharging itself during peak power demand and feeds power back into the grid if needed. Feeding power back would be much less efficient than regulating the power draw of the large battery bank according to available surplus grid power.

This same battery bank would be capable of recharging EVs with as much current as they can safely accept, up to hundreds or thousands of amps with the right cables. Recharging in minutes.

So the super-fast EV recharging stations can serve as buffers between grid and EVs, for times of over supply of grid power; that would allow power stations to run at a much more constant and efficient load.

This information may be used entirely at your own risk.

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