V2G Revisited: Big Mistake or Huge Opportunity?

The Chief Technology Officer of Tesla, J.B. Straubel, stated recently that it doesn’t make sense for electric vehicles to send electricity back to the grid.

In the same remarks, he also noted the following:

1. reuse of old EV batteries (so called “second-life batteries”) is not economical either (implying that the best thing to do with them at the end of their life is to send them to the recycling bin)
   
2. dynamic, time-based charging of EVs does make sense, and thus will be coming

What the CTO is criticizing — vehicle-to-grid or V2G -- is essentially distributed energy storage on wheels.

The function It takes advantage of unused EV battery storage capacity to allow for power sales back to the grid, either by draining some power when the vehicles are not in use or reducing the vehicle charging rates.

At a basic level, V2G has three requirements:  
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1. charging station electronics that allow for bidirectional power flows between car and grid
2. real time communication between the grid operator and vehicle owners
3. precise metering software

Vehicle-to-Grid Schematic

Source: Jim Motavalli, The Azimuth Project

The EV technology and services company AC Propulsion, a V2G proponent, outlines the potential benefits of V2G as related to grid services: peak power sales, spinning reserves, base load power, peak power (either as a form of direct load control or to reduce demand charges), and reactive power.

In turn, the EV owners get paid for the energy services provided. But aren’t all of these benefits just the same as those for storage, but in EV form?

​The figure above seems very similar to one that would be drawn for fixed batteries.  

The challenges of V2GSeveral hurdles would have to be crossed in the current market and policy environment for V2G to be commercially viable.

​Among the not-so-attractive characteristics of V2G:

• Additional wear and faster degradation of the EV battery due to more frequent charging and discharging. Whether the car owner could be fully compensated for this -- both for the loss of vehicle value as well as the inconvenience of having to replace it more quickly -- is yet to be determined. Such compensation to the EV owner would have to be in addition to that received for power sales.

• Additional cost of interconnection at the charging site. According to the Tesla CTO, current regulations would treat power downloaded from an EV the same as that coming from a solar system, and the implications could get complicated.

• Finally, unverified availability of EV power. V2G enthusiasts point to a data point often, that most vehicles are parked 23 out of 24 hours of the day. This seems to allow for 23 hours of potential charging and discharging time available to the grid. But what happens when all of these vehicles are unplugged from the charging stations, being driven home during a rush hour commute -- a time that happens to coincide with peak late afternoon electricity demands?   

V2G Lite -- Commercial Fleet Applications

The first of those challenges above could potentially be met with a market-derived refund incentive, though it is unclear how many EV owners would be willing to own a car with a shorter lifespan in exchange.

Alternatively, EV battery manufacturers could design future batteries for more frequent power cycling, but that would require a major and disruptive shift from the current design parameters that do not take V2G into account.

The second challenge would seem to be one of public policy, and conceivably overcome if stakeholders from the EV space were united in pushing for V2G (which they’re not).

The third challenge might be addressed with commercial EV fleets. In this “V2G Lite” scenario, a fleet owner -- who with the help of data analytics has a good sense of the driving patterns of the fleet -- would be able to sign a power supply contract with a utility that guarantees a certain amount of EV battery capacity at different times during the day.

Fleet contracts could be bundled, so risk is spread and utilities only have to deal with a few intermediaries when relying on this stored power source.

Even if a fleet was designed to spend most of the day on the road and most of the night charging, there could still be some battery capacity free at certain times, available to be used by (and sold to) the grid.

Along these lines, Nissan is notably optimistic about V2G’s horizons, and has been so since last spring when it announced cooperation on V2G efforts with Endesa, a subsidiary of the Italian energy multinational Enel.

Now the automaker is working with Enel and the Californian V2G services provider Nuvve to install a commercial V2G hub in Copenhagen, Denmark. The 100 kW project is admittedly small, with 10 Enel 10 kW V2G charging units paired with 10 Nissan EV vans and a Nuvve platform to coordinate when idle vehicles can send energy back to the national grid on demand.  

V2G Strong -- V2G for Everyone? Or, what might be good for the public isn’t necessarily good for Tesla

A group of EV researchers at the University of Delaware is at the leading edge of EV research and those advocating for full V2G penetration.

In one study the numbers and justification for a full V2G push are impressive: if we put 20 million light duty V2G EVs on the road (just 10% of the current total U.S. fleet), and conservatively assume a peak power rating of 50 Kw for the cars, we could have a combined power capacity equivalent to the entire U.S. Electric grid.

Paired with renewables, the V2G EV fleet would bring game-changing results for CO2 emissions and other transportation sector pollution.

The EV future is being built now, with new cars, new charging stations, and new rules and practices.

As this new EV built environment grows and develops, integrating V2G capabilities may just add an additional layer of complexity to the overall project, without a certain return.

​But if we were to make a major push for V2G capabilities to be integrated at the ground level, the benefits for society and the planet could be large.