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It seems like people have been hyping the benefits of vehicle-to-grid (V2G) for decades.

The basic premise of V2G is that electric vehicles, when plugged in to the grid to charge, can offer services to the grid operator such as energy storage, demand response, and frequency regulation.

The vehicle owner would then be compensated for this, either through free charging, discounted electric rates, or even payment.

Research on the topic seems to start popping up around the late 1990's. However, in all this time, I haven't heard of any actual programs where a customer with an electric vehicle could enroll with their utility.

Are there any active V2G programs around the world that are accepting customers?

If not -- what's taking so long? Are there technical challenges? policy issues? or something else?

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Yes, there is now such a scheme in the city of Utrecht, The Netherlands.

This Dutch news article (Google's English translation here) says that Utrecht is the first city in The Netherlands to introduce bi-directional loading. It consists of 145 docking stations that can both charge and discharge an electric car. It's a joint effort of Renault and a non-profit organization called 'We Drive Solar'.

In the article a researcher from Eindhoven University of Technology named Auke Hoekstra mentions that there is criticism on bi-directional loading, because it reduces the life span of the battery. However, even with bi-directional loading battery lifespan has increased from 3 years to 30 years, the reseacher says. In this tweet he also claims that the system in Utrecht is

World first: bidirectional charging (V2G) using ISO15118

In the tweets below he explains that:

... they took the complex but promising ISO15118 standard that is being developed by (among others the EU) car makers. Using ISO15118 for bidirectional charging is really important in the EU in order to prepare for future car and battery developments.

and

Our simulations need more work but I currently estimate that with 10-40% of cars becoming EVs and doing V2G, we could provide all the battery capacity needed to compensate for daily fluctuations of a Dtuch grid with just wind and solar.

Recently I thought that was a fanciful idea: it would degrade car batteries too fast. But big strides have been made to combat battery degradation so I think V2G is almost inevitable in the long run.

  • I looked at the article, but it doesn't provide any detail on if these charging stations are free to use for the average EV owner, or if they are compensated in some way when power from their car is used. – LShaver Mar 22 at 13:52
  • I see now it's not open for everyone. People living in Utrecht and surrounding cities can apply for an electric-car sharing subscription via the We-Drive-Solar organization. So the electric cars are apparently owned by We-Drive-Solar. The bi-directional loading is used to lower costs for customers (see also this translated blog). If this disqualifies my answer, I will delete it. – THelper Mar 23 at 7:46
  • This is the first V2G scheme using a brand new European standard, so it's really a testing ground. My guess is that if it's successful others will follow. Often new inventions like this start small and limited, and then open (and commercial) initiatives follow. – THelper Mar 23 at 7:50
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Edit: I recently revised my opinion of V2G implemented with Panasonic 18650 batteries, as used in Tesla cars. It may be possible to achieve good enough lifetime even in solar daily cycling applications. For details, see: http://blog.evandmore.com/lets-talk-about-the-panasonic-ncr18650b/

Of particular importance is this figure: 28 000 cycles from 10% to 90%

If you use only 80% of the battery capacity by using a slightly larger than needed battery, you can theoretically achieve over 75 years of lifetime. Theoretically, as the calendar life may be more limiting than the cycle life.

New cost calculation: 100 USD / kWh, of which you can use 80%, giving 125 USD / usable kWh. If 50% of the days are sunny, you achieve about 180 cycles per year, or 1800 cycles in 10 years (best to limit the considered period to 10 years, as we don't know the calendar life of these batteries, and money has a time value). It's 0.07 USD / kWh then. You need to add 1 USD / watt of solar, with 16% capacity factor, meaning 1 watt produces about 1.4 kWh per year, or 14 kWh per 10 years. So, about 0.07 USD / kWh for electricity production and the same for storage. 0.14 USD / kWh is more than 2x as expensive as the electricity where I live, but the cost is coming down all the time. Perhaps, some day, we will see V2G programs.

Here's the old answer:

Don't consider such stupid ideas! Hype is hype.

Tesla uses a different battery chemistry (NMC, nickel manganese cobalt) for PowerWall products that are intended for grid energy storage. For the vehicle use, Tesla uses NCA (nickel cobalt alunimum), which is cheaper but not durable enough for daily cycling. I guess they have a valid reason for the different chemistries.

And before somebody claims driving is daily cycling, it isn't, because Tesla batteries are so large that driving the car uses an infinitesimal amount of its capacity.

Now, if a NCA battery is already at its end of useful lifetime (like holding only 50% of the capacity), you could use it for grid energy storage for a while until it is finally scrapped and the materials are reused. So, as reuse grid energy storage is a good application, but these NCA batteries degrade very quickly when used for grid energy storage. So anybody planning to reuse batteries needs to have a plan of how to safely scrap them, and needs to be aware of their limited lifetime.

I guess the reason why such programs in general don't exist is that electric vehicle users are well aware of the properties of their expensive toys. Specifically, they are aware of the limited lifetime of batteries when rapidly cycled.

There is one form of cycling that is beneficial and helps stabilize the grid: charge when electricity is cheap, drive on charged electricity when electricity is expensive. Of course, this works only if the battery is large like on the most expensive Tesla cars.

In no circumstance, would I discharge the battery while supplying power to the grid. I could consider supplying power to my own house in an emergency, but not to the grid (unless I get paid really large amounts of $$$).

It is almost always cheaper to use electricity from the grid than to discharge your EV battery, reducing the useful lifetime of the very expensive battery.

Sources:

  • Cycle durability of Li-Ion is 400-1200: https://en.wikipedia.org/wiki/Lithium-ion_battery ...and this means full discharge, then full charge, then repeat
  • It is well known in the automotive circles that shallow cycling allows a battery to last for a very long amount of time. For example, Toyota hybrid batteries that use only ~20% of the battery capacity can do so for 100 000 cycles. Example source: http://www.bitsonchips.com/wp-content/uploads/2017/07/ref33.pdf quoted: "in shallow state of charge (SOC) swing applications (such as hybrid electric vehicle and certain power quality applications) the cycle life can be many hundreds of thousands of cycles"
  • Tesla batteries when used for driving last the lifetime of the car: https://electrek.co/2016/11/01/tesla-battery-degradation/ ...and note this means for driving, not for 100% cycling every day. It is well-known that Teslas have a range of 500 km or so, and typically people drive 50 km or so per day, then charge, using only 10% of the capacity.
  • Tesla PowerWall uses NMC, not NCA: https://teslamotorsclub.com/tmc/threads/something-fishy-about-the-batteries-in-powerwall.75391/ -- "NMC has much better durability (5000+ full cycles vs 500-1000 full cycles), whereas NCA has much better energy density (280 Wh/kg vs something like 150 Wh/kg)."
  • Also: https://medium.com/the-unfortunate-tetrahedron/the-cathodes-of-the-powerwall-6aa52df8cd66 -- "It is speculated that the NCA chemistry is the cell in the Model S. To the best of my knowledge Tesla has not used the NMC chemistry in any car to date."
  • Cost analysis of NCA: $100 / kWh probably will be achieved on a pack level after few years, 500-1000 full cycles, $0.1 - $0.2 / kWh. I guess in some areas where the authorities are insane (preventing the construction of thermal power, necessitating massive building of intermittent renewables), the electricity price can be over $0.2 / kWh or even higher with taxes. I am fortunate to live in an area with 0.06 EUR / kWh electricity.
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    My question is not about the pros and cons of V2G (though I tend to agree with you). I'd like to know of examples of where it's being done in practice. – LShaver Feb 28 at 14:29
  • Thank you for revising your answer. Is there a particular reason why you want your old answer to still be included? People who are interested in how this answer evolved can look at its edit history (that's the link when you click on the "edited <date>" link below a post) – THelper Mar 20 at 15:18

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