Potential Energy

Recharging the Grid with Electric Cars

A utility in Delaware has opened the door to vehicle-to-grid technology.

Kevin Bullis 01/21/2009

  • 12 Comments
Credit: treehugger.com

A utility in Delaware has taken a step toward a future in which electric cars store renewable energy to help make its use more widespread. The city of Newark has approved a system called vehicle-to-grid (V2G), in which the battery pack in a car serves as a place to temporarily store energy from the power grid.

A big problem with renewable sources of power like solar or wind is that they only operate intermittently. For now, renewables provide such a small part of the total electricity supply that other sources can easily make up for the hours, minutes, or days when the wind isn't blowing and the sun isn't shining. But if we're ever to rely on them for a large part of our power, we'll need a cheap way to store the energy that they produce for when it's needed most.

The vehicle-to-grid concept suggests a way to store energy cheaply, since the batteries in electric cars have already been paid for. Most of the time, a car is just sitting around doing nothing. For short-term storage--needed to smooth out fluctuations in power from a wind turbine, for example--a utility could quickly charge a car (or, ideally, distribute a little charge to hundreds or thousands of cars) when the wind is blowing and then take that electricity back a few minutes later when the wind dies down. The more cars that are available, the more energy can be stored. Longer-term storage might also be possible: a car owner could charge up for a discount at night, provided she agreed to keep the car plugged in at work to supply extra power during peak power demand in the afternoon.

Of course, there would have to be some sort of agreement so that energy companies couldn't take so much that the driver ends up stranded, and they'd have to recharge a car before the evening commute. But there are even bigger challenges. There simply aren't many electric cars out there right now. Two-way hookups to the grid would also need to be installed, and the grid may have to be upgraded in other ways. And lastly, all the charging and discharging could shorten the lifetime of the battery (not to mention void the warranty from automakers).

There are probably more issues. But what do you think? Is V2G a good idea?

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dcottrell

1 Comment

  • 1117 Days Ago
  • 01/21/2009

V2G

I think that V2G is a great idea and an idea that's time has come.  Of course there will be challenges, there always are.  This is actually not a new idea.  This has been started in Austin, TX (http://www.austinenergy.com/About%20Us/Environmental%20Initiatives/Plug-in%20Hybrid%20Vehicles/creatingMarketInAustin.htm)

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erbium

338 Comments

  • 1117 Days Ago
  • 01/21/2009

This is part of related concept

car energy use is 7x the electrical grid. Of course if they were all electric which is more efficient might be a smaller multiple.

It's possible that we would use chemical powered on-demand hydrogen generation in cars to produce electricity for the car in a hydrogen fuel cell.

In that case, millions of cars would pull up at night and plug into the house.  Not to recharge but to power the house.  The tanks would be filled with WATER, the hydrogen source and metal;  Aluminum works if a small bit of gallium is inserted, and explosively reacts with water to give off the hydrogen for the car's fuel cell.  Magnesium also works, albeit at a bit higher temperature, somewhat akin to the operating temps for current car engines, where it reacts with water to give off hydrogen.

So you could power peak load or a summer cabin with your vehicle's hydrogen reactor and fuel cell.  And all this would be incredibly safe as the water isn't mixed with the metal in the tank. Rather they'd be mixed in a small reactor that would drop in metal pellets and feed in water as needed, with a slight excess over the maximum rate needed by the fuel cell.  This way in an accident, even if the water and metal mixed they would not react, so would just spilling 35 gallons of water.

Ok, you ask the energy has to come from somewhere.. You'd periodically refill the metal pellets and water at a 'gas station'.  They'd collect the metal oxide slurry from a collection tank to reprocess back into metal pellets.  (yes that uses alot of electricity, and that is where the stored energy is put into the system). The fueling stations would either re-electrolyse the pellets at the station.  (using grid electricty, solar panels or windmills) or put them back into tank trucks that would replace gasoline delivery trucks. 

These fuel delivery trucks would deliver the metal pellets and collect the metal oxide for recycling back into metal, in the empty portion of the tank truck.


My guess is it would optional for you to participate in having your car's fuel cell activated to supply energy back to the grid.  You might want to leave it fully charged with metal pellets for long trips.  If you did want to participate you might be able to set a minimum level of fuel (metal pellets) to leave in your tank.

The advantage of all this, like petroleum fuels, metal and hydrogen is CHEMICAL fuel, NOT BATTERIES so has vastly more energy storage density. Batteries are wimpy in comparison.

In summary I think that the no-moving-part electrical generation of future cars powered by fuel cells, some metal hydrogen-on-demand, and most likely some using methanol fuel cells or fuel cells with small hydrogen tanks for smaller cars could all fit identically into this type of electrical grid.

All this would allow us to get back to normal life.  There is nothing wrong with using energy if done in non-polluting way. 

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swimdad623

8 Comments

  • 1117 Days Ago
  • 01/21/2009

Reduced battery life

I can't see V2G as a viable option because of the limited lifespan of electric vehicle batteries.  LiIon EV batteries only have 1000-2000 usable cycles on them, at best.  If the electric company is wearing them out by using them as electric storage while I'm at work, who covers the cost of the replacement battery when my battery wears out early?  In addition, I can also see potential issues with having to dissipate battery heat, generated by charging and discharging of the battery.

I can see a useful point in load management - charging an EV battery only when the grid has excess power.  But I see more problems than benefits with trying to feed the power back into the grid.

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mrjoe

1 Comment

  • 1114 Days Ago
  • 01/24/2009

Re: Reduced battery life

I have numerous friends who own and drive electric cars.  I have three different friends who are still driving EV RA4s after many years.  One has 116,000 miles on their car.  None of them have had battery problems.

There's lots of whining and complaining about batteries by people who don't own or drive electric cars.

I'm not hearing those some complaints from people who know what they're talking about.

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Bleater

3 Comments

  • 942 Days Ago
  • 07/15/2009

Re: Reduced battery life

If battery cost to utility companies was acceptable to CFO's of those companies, we wouldn't be having this little chat, and there is little reliable information regarding long-term cost of operation for EV's, especially as it relates to battery maintenance or replacement.

J.F. Hayek and Adam Smith thought that consumers need to be fully informed in order to play their role in a 'free' market. To date, I've seen little, if any, discussion about what the cost of operation for EV Li-Ion batterues. No one at any dealership I have been to will do more than speculate.

It's nice that the city of Newark has signed on, but the doesn't do much to educate the consumer, and mrjoe's comment yields no more than anecdotal information. (His ad hominem attack leads me to believe that he's protecting a vested interest.)

I'm glad this business model makes economic sense for utility companies. My question is, how do consumers determine their own costs in order to figure out if it makes sense for them, as well?

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  • 1112 Days Ago
  • 01/26/2009

Re: Reduced battery life

Actually, any realistic V2G system would only very rarely, if ever, drain a significant fraction of battery capacity. The idea isn't to get lots of kWh out of vehicle batteries--it's to supply very small quantities of energy and storage capacity to help utilities regulate frequency and maintain voltage. Think of it as lots and lots of very shallow discharges and recharges occuring in rapid succession. The impact on battery life is actually quite minimal.

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Bleater

3 Comments

  • 942 Days Ago
  • 07/15/2009

Re: Reduced battery life

"The impact on battery life is actually quite minimal."

In theory, this is true... but since you have no real world data, you can't truthfully make this statement.

Back in your box, Mr. Industry Shill!

Reply

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danfoley

1 Comment

  • 1116 Days Ago
  • 01/22/2009

The electric grid isn't ready

Electric cars are a great idea but our infrastructure isn't ready for them. Imagine getting home, plugging in your car at 5 PM as 100 million other people do the same thing. It will be interesting to watch the electric grid melt down literally.

Then there is the problem of replacing high cost batteries every 3 - 5 years at $5,000 to $7,000 a pop.

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cschuman2029

1 Comment

  • 1116 Days Ago
  • 01/22/2009

Re: The electric grid isn't ready

Isn't one of Obamas plans to give something like 8 Billion to the upgrade of our electric grid/infrastructure? What will he be doing along those lines to further our movement to electric transportation?

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dmm

270 Comments

  • 1116 Days Ago
  • 01/22/2009

Even crazier than electrics

All-electrics are a bad idea, at least for a large country like the USA.  Sorry, but it's true.  The energy required to implement them in any reasonable way is WAY more than the energy that would be saved.  Some have pointed out the example of Israel, which is pushing EVs heavily, but LOOK AT ISRAEL!  It is slightly smaller than New Jersey, surrounded by hostiles.  (Sorry for the USA-centric comparison.  For the majority of the world: If it weren't for traffic jams, you could drive the length of NJ in 2 hours, at not-very-fast highways speeds.)  So, using a short-range EV, Israelis could travel anywhere they would reasonably want to drive.  Add a few battery-swapping stations as a backup plan, and you're good to go.
It is often said that EVs would make great commuter vehicles for most Americans.  And that is true, but ONLY IF the EV is ONLY used for commuting and for short errands.  If you want to use an EV to drive to college or go on vacation or visit relatives, you're out of luck.  In a large country like the USA, an EV just doesn't have sufficient range.  You could extend that range, of course, with battery-swapping stations or something similar, but you would need VERY MANY.  Plus, it is a chicken/egg scenario, and the egg (a nationwide network of refueling stations) is huge for the USA (unlike Israel, for example).
All of this is to say that hybrids are the way to go.  Give them an electric drivetrain, powered from batteries for short runs and from a fuel-powered generator (running at best RPM) for long runs.

Reply

darrison

1 Comment

  • 1116 Days Ago
  • 01/22/2009

Re: Even crazier than electrics

The transition from fossil fuels to plug in hybrids, V2G, and electric cars powered by solar energy and renewables is going to be a long and expensive process. It's definitely worth the effort because of the myriad benefits. The multi-decade effort allows the development of new technologies that will contribute to increased efficiencies that we can only dream of right now.

With the inauguration of a new President, we know that dreams sometimes do come true. It's a new day.

Reply

Bleater

3 Comments

  • 942 Days Ago
  • 07/15/2009

Re: Even crazier than electrics

"In a large country like the USA, an EV just doesn't have sufficient range. "

Sufficient for what, when and to whom? The underlying assumption seems to be that life in the U.S. should go on without modification. Perhaps an (un)intended consequence of the transition to a mode of transportation that requires conscious deliberation on the costs of one's individual choices is good.

Why do you believe it might be not-so-good?
Haven't you ever traveled anywhere without a car?

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Bio

Kevin Bullis is Technology Review’s energy editor.

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