Bidirectional Electric Vehicle charging - could this be a game changer to support widespread EV adoption whilst strengthening the grid?

There is an increasingly urgent debate on how to accelerate electric vehicle (EV) adoption to reduce CO2 emissions from fossil-fuelled vehicles.

For instance, in the UK, the government is pushing for the transition to zero-emission vehicles, aiming to phase out petrol and diesel cars by 2030 (
https://www.gov.uk/government/news/industry-encouraged-to-shape-uk-transition-to-zero-emission-vehicles#:~:text=The%202030%20phase%20out%20date%20was%20broadly%20supported%20by%20industry,to%20electric%20cars%20by%202030).

One commonly cited challenge is the concern that “the grid can’t handle the power demand of widespread EV deployment.”

But what if each new EV could be an asset to the grid rather than a burden?

In my view, bidirectional charging could be a game-changer, creating a "positive tipping point" for both EV adoption and grid stability. How Could This Work?

Grid Perspective:
Every EV plugged into the grid could provide valuable energy storage. Excess renewable energy (from solar or wind) could be stored in EV batteries during periods of low demand and released back into the grid during peak times, reducing reliance on fossil fuels.

Moreover, if EVs are charged at home or near points of demand, they could provide localized storage, decreasing the need for long-distance transmission and reducing grid losses. 

The Role of AI:
Real-time spot tariffs could be broadcast to smart chargers, allowing them to respond to the grid’s need for additional power. AI algorithms could also predict weather patterns, helping to plan charging schedules based on upcoming energy production from renewables.

Charger-Owner Perspective:
Charger-owners can buy energy at a low spot rate and potentially be paid to take on energy during periods of excess supply. They could then sell energy back to the grid at a higher spot rate during periods of peak demand. If the owner also has solar or wind energy production, the incremental cost of this energy could be close to zero.

Driver Perspective:
The only inconvenience for the driver would be the need to plug in the vehicle. This could happen when they arrive at work or home, and app-based guidance could optimize charging times based on driver preferences.

Vehicle Perspective:
While each EV has embodied carbon from battery production, using the battery for grid storage could maximize the benefits of this "carbon investment." It’s a way of leveraging the vehicle’s potential beyond just emission-free driving.

Material / resource demand Perspective:
By using EV batteries for grid storage, the need for home batteries might be reduced, avoiding the demand for additional storage capacity and the associated environmental impact from mining operations.

Climate Mitigation Perspective:
To mitigate climate change, reducing CO2 emissions is essential. Bidirectional EV charging could create a positive feedback loop, decreasing emissions from both vehicles and the grid. The potential for fewer home batteries would also reduce embodied carbon associated with their production.

Climate Adaptation Perspective:
Severe weather events, intensified by climate change, could disrupt the grid. In such cases, EVs could provide backup power. With advance warning of extreme weather, drivers could ensure their batteries are fully charged. Since EV batteries typically have much higher capacity than home batteries, they could offer autonomy for multiple days in the event of grid failure.

Work and Home Considerations:
The interaction between work and home charging (and the potential for energy consumption at both locations) could introduce complexities, especially around remuneration and tax regimes. This could be addressed by borrowing the "Virtual Private Network" (VPN) concept from telecommunications, ensuring energy billing aligns with both remuneration and tax considerations.

Conclusion:
Many IET members are likely to be involved in this debate, so I would appreciate hearing your thoughts, as well as any corrections or guidance on my use of terminology.
(I am not a professional in this domain but am deeply interested from both a climate crisis perspective and as an enthusiastic EV and "active house" owner.)

Parents
  • I have seen discussions in the past looking at problems of locally overloading part of the distribution network. The load on a cable is usually monitored and controlled at the traditional source point, 800A fuses in the substation for example. A significant V2G source on that cable segment could allow an overload. A depot for EVs could be capable of sourcing a couple of hundred amps.

    The principle you are suggesting, using V2G in a local part of the network to reduce the need for expansion of the wider grid seems to increase that chance of this without significant local monitoring.

  • I have seen discussions in the past looking at problems of locally overloading part of the distribution network.

    There's certainly a risk local imbalance - e.g. while the grid overall and the part of town with little terraced streets may be short of power, just chucking out 32A per car from the other side of town where there are detached houses with two EVs on each drive certainly wouldn't be workable solution at the moment. There may be solutions though. In the short term, EV charge points could be rigged not to export from the overall installation (some domestic charge points currently are connected to a CT on the meter tails and restrict the charge rate to avoid overloading the supply - so same hardware just acting in reverse). The effect on the overall grid might not be quite as beneficial as being able to export all the available power, but simply removing the load of an installation will make a contribution. Or it could be limited to a small export current - maybe 5 or 10A - which the existing networks should be able to cope with.

    Longer term, we already have communication of grid data into the home via smart meters and internet - which is in effect used to encourage or discourage import and export at different times. It shouldn't be beyond the wit of man to feed the amount of spare substation capacity into the formula and pipe the data to the appropriate meters. The DNOs should already know which meters/customers are on which feeder after all.

    Back to my original post, if there were significant storage on the grid (e.g based on millions of  EV batteries), these peaks in demand could be satisfied from stored renewable energy, hence reducing the grid carbon intensity.

    Indeed, but don't forget the primary purpose of an EV - which is to move. A lot of demand is concentrated into the morning and especially late afternoon/early evening peak (e.g. 1600-1900) - just when a many commuter's cars will want to be on the road. Then of those that are actually plugged in when needed (which probably cuts off all those in terraced housing etc who charge at public/supermarket charge points) many will want a decent charge left in the car,so they can use it later on - so me be willing to share only a smaller proportion of the overall capacity for the greater good. So what starts of as looking like tens of millions might shrink quite considerably by the time it's put into practice. Don't get me wrong, I still think it could be a very useful contribution and well worth developing the technology, but I see it as one more brick in the overall much larger solution rather than a game changer all by itself.

       - Andy.

  • So what starts of as looking like tens of millions might shrink quite considerably by the time it's put into practice. Don't get me wrong, I still think it could be a very useful contribution and well worth developing the technology, but I see it as one more brick in the overall much larger solution rather than a game changer all by itself.

    Hi Andy - many thanks for your insightful responses. 

    I guess where I'm coming from is that if each car manufacturer were to build bi-directional charging capability into their car as standard (and I realise there are at least 2 standards out there - based on DC vs. AC interfaces) then that would maximise the opportunity for EVs to become an "asset" to the network (and help with load spreading / demand side management / carbon intensity reduction) rather than the opposite case where EVs without bidirectional charging are a "burden" to the network - with a high proportion needing to be charged at the same time (when travellers arrive at their place of work / residence / shopping). 
    If drivers were sufficiently informed & incentivised, it may even be possible to influence their driving habits (e.g. so that those not needing to drive during peak grid demand periods were "remunerated" for leaving their cars grid-connected.)

    Stuart

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  • So what starts of as looking like tens of millions might shrink quite considerably by the time it's put into practice. Don't get me wrong, I still think it could be a very useful contribution and well worth developing the technology, but I see it as one more brick in the overall much larger solution rather than a game changer all by itself.

    Hi Andy - many thanks for your insightful responses. 

    I guess where I'm coming from is that if each car manufacturer were to build bi-directional charging capability into their car as standard (and I realise there are at least 2 standards out there - based on DC vs. AC interfaces) then that would maximise the opportunity for EVs to become an "asset" to the network (and help with load spreading / demand side management / carbon intensity reduction) rather than the opposite case where EVs without bidirectional charging are a "burden" to the network - with a high proportion needing to be charged at the same time (when travellers arrive at their place of work / residence / shopping). 
    If drivers were sufficiently informed & incentivised, it may even be possible to influence their driving habits (e.g. so that those not needing to drive during peak grid demand periods were "remunerated" for leaving their cars grid-connected.)

    Stuart

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