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V2G in a robotaxi world


Well-Known Member
Aug 29, 2018
Apologies for opening up the V2G debate again but I need to get this off my chest.

Background to robotaxi model:
Tesla Network / Robotaxi Business Model

New discussion from Warren - 40 mins in:

Thought experiment 1:
100 million Tesla owned robotaxis plugged into the grid - either charging or discharging whilst waiting for a ride. 10 Terawatts of discharge capability that Tesla can call upon. My calcs tell me this could power the world for a 5 hour power outage.
This truly enables wind and/or solar only.

Thought experiment 2:
20 year old Tesla (Tesla owned) with 900k on the clock is parked at a lone charger servicing a tiny community as a robotaxi for 1% of the time and V2G for 10% of the time.

How is this not a good thing.

One reason why Elon has not yet fully committed to V2G is because he is waiting for robotaxi in combination with V4 supercharger etc. He is pushing Powerwalls for homes so that homes have emergency power in a world were we don't own the vehicle and therefore can't use V2H.
Something interesting I discovered today, relevant to the powerwall business...
This is a map of the hourly electricity price auctions in Europe:
I presume its price per MWH.
At 5am in the UK today, power was £1.90/MWH. At midday it was £60! I think its because it was SUPER windy early this morning, so our wind farms were probably going bananas at 5AM. Anyway... if I had a smart meter and a powerwall and a flexible tariff, I could have totally filled the car/powerwall at 5AM today and used that sweet cheap power all day...
Thats a HUGE price variance...
V2G can make sense for consumer cars which sit parked 95% of the time. Smart charging at home and work is enough to always have a huge buffer for grid operators to use. The whole point of Robotaxis is to stay on the road 24x7, thus not really useful for V2G.
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Off-peak isn’t what it used to be.
Exhibit 1: Live map of electricity consumption and production sources (pretty accurate for the EU, don’t know about their data for the rest of the world): Live 24/7 CO₂ emissions of electricity consumption
Exhibit 2: EU spot electricity pricing for next day delivery (updated around noon EU): Market Data | EPEX SPOT
I’m most familiar with the situation in Belgium. The biggest part of our electricity production is nuclear, and needs to be replaced by something else in the coming years as we’re closing our nuclear power plants. The ‘something else’ will be import from other nearby countries, natural gas and a huge amount of new wind and solar capacity.
Even with the bulk of our electricity from nuclear energy we see huge swings in electricity pricing. We now typically have negative pricing during weekends and holidays. On workdays, we see the lowest pricing from 12h00 to 18h00. Off-peak charging is changing from charging during the night to charging during the afternoon.
Given the need for far more (unpredictable) renewable energy production than what we have now, I think it’s clear that we’re going to have near free charging for EV’s, because EV’s are the only things we have that can shift their electricity consumption.
Stationary home batteries can help a bit, but the sizes are typically an order of magnitude lower than EV battery sizes: 10kWh versus 100kWh. But stationary home batteries are expensive compared to EV’s: if you’d want 50kWh of storage, it would be cheaper to buy a car with a 50kWh battery and V2G support.
Tesla may not be supportive of the V2G idea because it places too much stress/wear on the batteries, but hopefully that argument expires with the availability of 1 million mile batteries. I’d buy any Tesla with V2G support immediately.
Note that the mentioned spot pricing is the pricing for the energy component of the electricity price. You still need to pay the transport/network costs. Where I live, the network cost price structure is changing from a per kWh pricing to peak capacity pricing. I.e. if you need 11kW peak (because you charge your car at that speed) you pay 11x50 euro yearly (independent of the kWh used). So the grid operators currently want you to spread your electricity usage during the day so that they need less peak capacity (actually so that they don’t need to increase peak capacity as much by giving a financial incentive to treat peak capacity as a scarce resource).
With the foreseen evolution, I expect extra financial incentives by grid operators and electricity producers for the right to control when your car charges, because it gives them a massive fine grained resource to balance grid load, production and consumption. There’s already a company in Belgium/The Netherlands (Jedlix) that gives you 1 cent/kWh for the right to control when your Tesla charges (and it’s always at the cheapest time).
EV’s are not a problem for the grid, they’re the saviours of the grid.
One reason why Elon has not yet fully committed to V2G is because he is waiting for robotaxi in combination with V4 supercharger etc.
I think this also needs single crystal cathode - 4 Million mile batteries.
With those cells the Robotaxi probably has more cycles than it can use driving people around,

The need to manage a schedule of charging the Robotaxi batteries up to close to full during daylight hours.
Say on average a Robotaxi battery ends the day at 80%, it needs to use 30% on average on overnight and early morning trips, that allows 50% of the battery to be discharged into the grid overnight,

IMO a likely typical Robotaxi format is small battery in a compact car say 40 kWh, in a compact car.
So say 20 kWh per battery overnight, x 1 million Robotaxis in the US, 20 GWh on a regular basis, handy but not game changing,
10 Million Robotaxis in the US 200 GWh, more substantial.
100 Million Robotaxis worldwide 2 TWh.

What is more important, is each individual cycle has a low marginal cost, using it for V2G doesn't significantly shorten the operational life of the Robotaxi.
In addition to these reasons for recycling R&D and scaling is Jeff Dahn saying vehicle to grid (V2G) will play an important role especially if scientists do not discover a viable solution for sodium-ion batteries as an alternative to lithium. He argued that the looming lithium raw material shortage and the explosive growth of solar and wind favors V2G coming into the scene to majorly add to grid storage capacity.

Dr Dahn said that with high-quality NMC cells with current technology can make it 10k cycles without terrible degradation, or more, if managed properly, which translates to over two million miles for a normal EV battery pack. In fact, this is true for older technology from a few years ago because some of the battery longevity experiments at Dalhousie have been going on for years. The car will generally die long before the battery.

V2G would change this. Then you might make cycles far more often. Autonomous vehicles too because of more usage per day.

Tesla is this close to Toyota without:
  • Large SUV that can actually go off road
  • Pickup truck
  • Minivan
  • Sport coupe
Toyota sales in these segments (thousands):

Tacoma 38​
Highlander 26​
4Runner 12​
Sienna 11​
Tundra 10​
Total: 88​

Toyota gross total 2022 sales: 289
Less segments unserved by Tesla: 201​
Tesla gross total: 187

So, Tesla is already almost past Toyota, and in Q4 Tesla probably did pass Toyota but we don’t have data so granular in this report. This happened despite Tesla not even having vehicles for segments that make up about one third of Toyota’s sales and despite much higher prices for the 3&Y than Toyota has for the Corolla, Camry and RAV-4. The Model 3 by itself is almost outselling the Corolla and Camry combined even though the Corolla is half the price.

If Tesla can extend their dominance to trucks, minivans and big SUVs, Tesla will sell far more vehicles than Toyota ever did in California. Globally, Toyota peaked at about 11 million cars sold in their best year. If California with its 17% EV adoption in 2022 is representative of where the whole world is going…
There's a great debate for the vision of the future.

Vision #1:
Everyone has electric cars that can charge homes during emergency events. During an emergency event, no one's gonna get pissed that power goes out when the car drives out because the car's going to stay there and provide emergency power for grandma / the newborn / keep freezer alive. And a Cybertruck's worth of batteries can keep a house powered for long enough for the grid to go back online.

Vision #2: Every home has a dedicated Power Wall and becomes a virtual power plant, which disintermediates utility companies (when combined with backup megapack energy storage) and effectively enables Tesla to BE the utility, as it manages the software and takes a % cut of power re-direction. Cars can't do this because it will mess up their batteries if it's used this often.

Elon WANTS vision #2, the problem is...I don't believe costs will lower enough in the next 4-6 years for that future to occur. And if that doesn't occur, then other car makers with far less ambition will provide this functionality and have a genuine, meaningful Pro vs. buying a Tesla car. Tesla Powerwalls are prohibitively expensive for most, even if you reduce the price by 50% it's still expensive on an absolute basis (vs. grid-powered energy) and STILL more expensive than batteries from China (and don't give me that BS about the "brand" of Tesla Powerwalls, everyone buys cheap stuff from China at Walmart and Amazon and price ultimately rules mostly everything).
Or vision 3 - RTs
At scale, V2G won't be needed as much, as charging will be such a significant portion of energy usage. At that point, toggling between charging and not charging will be sufficient to smooth the grid and even act as a battery to manage the daily cycle. ie. cars will charge during the day when solar is available but not at night. This will make overnight usage of vehicles to sleep whilst driving an extremely cost effective option.