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I like the idea of the buses providing power back to the grid when they're not being used in the late afternoon, but the article's author seems to think that ev

by kelnos 2y ago

I like the idea of the buses providing power back to the grid when they're not being used in the late afternoon, but the article's author seems to think that even privately-owned passenger cars should be participating in this as well. I'm not sure how practical that would be, though. For school buses it's easy, because you know exactly the range of times during the day, every (week)day, when they're going to be out on the road. Late afternoon/evening use as a grid source is perfect, because they've already brought all the kids home, and won't be needed until the next morning, and there's plenty of time to charge them back up after they've sent energy to the grid. But for my own private vehicle, I don't use it on a schedule. Well, sure, there's some scheduled use, but there's also random unplanned use, or even just random planned use that might not conform to when the grid wants to pull from my battery. If I'm leaving at 6pm to start a 3-hour drive to visit out-of-area family for a few days, for example, I certainly don't want the grid pulling from it, say, from 3pm to 6pm. And on top of that is battery wear and tear. I would assume that, all else being equal, a car participating in a vehicle-to-grid program will need its batteries replaced sooner (maybe much sooner) than a car that isn't. And given how utilities seem to want to pay less and less for power that residential solar sends back to the grid, I can't imagine any paltry sum they pay for vehicle-to-grid use would offset the very real costs to the car's owner.

rahimnathwani 2y ago
> And given how utilities seem to want to pay less and less for power that residential solar sends back to the grid, I can't imagine any paltry sum they pay for vehicle-to-grid use would offset the very real costs to the car's owner. But maybe it would be different during peak usage hours (when solar is unavailable).
bryanlarsen 2y ago
All those same concerns apply to the existing Tesla virtual power plant's (VPP) in California and Texas. People buy Tesla power-walls to have emergency power that would be useless if their battery has been emptied by the VPP. And those PowerWalls are more expensive per kWh than a car is. The solution for the first is a simple power limit, typically 50%. So the VPP never drains the battery below 50%, leaving a nice margin for emergencies. The solution for the second is pricing: the VPP typically pays 50 cents per kWh, in return for about 0.1 cents/kWh of wear and tear on the battery.
russdill 2y ago
I work from home. I can look out on my residential neighborhood street at any time of day and see a lot of parked cars.
r00fus 2y ago
Do you happen to own an electric vehicle? Modern EVs simply have tons of battery. My newest EV has the equivalent of 5.7 Powerwall 3 home batteries. Much of this is excess - if you commute 50mi/daily, given the range at 80% is est. 300mi, that's 5/6 of the battery remaining (assuming I charge it nightly which I do). Also if you need to drive long-distance, there is fast-charging infra out there. Sure, people should be incentivized to share - but if we did (say at 3-5x the max rate) then you'd have tons of people sign up. Make this a win-win and it'll be successful.
rgmerk 2y ago
You might not use your car on a schedule, but if you aggregate thousands of private vehicles you can build a statistical model that gives you pretty high confidence that a certain amount of charge will be available. Yes, the fraction of total charge that you could plan on being available this way is going to be a lot smaller than the school buses, but there is a lot of electrical energy available in EVs so even a small fraction of it is a big deal to grid stability. Furthermore, a lot of the potential for EVs as grid balancers isn't for the day-to-day variations in supply/demand - it's for those few hours a year of demand peaks, and in open electricity markets the wholesale price of electricity goes to pretty crazy levels (thousands of dollars per megawatt-hour depending on the market design). Those few hours of crazy-high prices pay the costs of peaking generation that only operates at those times. In Australia, the market is capped at $15,000 per MWh. Say you configured your car so that it would sell back into the market only when the market was above $1000/MWh. In one winter month I looked at, applying these rules you could make about $60 from a total discharge of about half the car's battery capacity (and not all of the high-priced period was contiguous). That sounds like adequate compensation for fairly minimal degradation of the battery capacity.
- xp84 2y ago
  You're right that it could be constructed in a way that would be more than fair, even attractive. And I would think that some kind of app that let you block out times would solve the "don't drain my battery if I might need it" problem (You could schedule it to be unavailable to the grid on a date when you plan on leaving for a vacation after rush hour, and never enabled on Thursday nights when you drive a long distance in the evening) The GP though is probably right that our [insert expletive] utilities would pull the same type of crap they did nerfing net metering and find a way to rip off those participating in the scheme. Power is worth what, 46 cents a kWh now when I'm buying it, but if I had panels and was selling it during peak A/C usage time, suddenly it's worth 6 cents right. Uh huh.

by kelnos 2y ago

rahimnathwani 2y ago

> And given how utilities seem to want to pay less and less for power that residential solar sends back to the grid, I can't imagine any paltry sum they pay for vehicle-to-grid use would offset the very real costs to the car's owner. But maybe it would be different during peak usage hours (when solar is unavailable).

bryanlarsen 2y ago

All those same concerns apply to the existing Tesla virtual power plant's (VPP) in California and Texas. People buy Tesla power-walls to have emergency power that would be useless if their battery has been emptied by the VPP. And those PowerWalls are more expensive per kWh than a car is. The solution for the first is a simple power limit, typically 50%. So the VPP never drains the battery below 50%, leaving a nice margin for emergencies. The solution for the second is pricing: the VPP typically pays 50 cents per kWh, in return for about 0.1 cents/kWh of wear and tear on the battery.

russdill 2y ago

I work from home. I can look out on my residential neighborhood street at any time of day and see a lot of parked cars.

r00fus 2y ago

Do you happen to own an electric vehicle? Modern EVs simply have tons of battery. My newest EV has the equivalent of 5.7 Powerwall 3 home batteries. Much of this is excess - if you commute 50mi/daily, given the range at 80% is est. 300mi, that's 5/6 of the battery remaining (assuming I charge it nightly which I do). Also if you need to drive long-distance, there is fast-charging infra out there. Sure, people should be incentivized to share - but if we did (say at 3-5x the max rate) then you'd have tons of people sign up. Make this a win-win and it'll be successful.

rgmerk 2y ago

You might not use your car on a schedule, but if you aggregate thousands of private vehicles you can build a statistical model that gives you pretty high confidence that a certain amount of charge will be available. Yes, the fraction of total charge that you could plan on being available this way is going to be a lot smaller than the school buses, but there is a lot of electrical energy available in EVs so even a small fraction of it is a big deal to grid stability. Furthermore, a lot of the potential for EVs as grid balancers isn't for the day-to-day variations in supply/demand - it's for those few hours a year of demand peaks, and in open electricity markets the wholesale price of electricity goes to pretty crazy levels (thousands of dollars per megawatt-hour depending on the market design). Those few hours of crazy-high prices pay the costs of peaking generation that only operates at those times. In Australia, the market is capped at $15,000 per MWh. Say you configured your car so that it would sell back into the market only when the market was above $1000/MWh. In one winter month I looked at, applying these rules you could make about $60 from a total discharge of about half the car's battery capacity (and not all of the high-priced period was contiguous). That sounds like adequate compensation for fairly minimal degradation of the battery capacity.

xp84 2y ago
You're right that it could be constructed in a way that would be more than fair, even attractive. And I would think that some kind of app that let you block out times would solve the "don't drain my battery if I might need it" problem (You could schedule it to be unavailable to the grid on a date when you plan on leaving for a vacation after rush hour, and never enabled on Thursday nights when you drive a long distance in the evening) The GP though is probably right that our [insert expletive] utilities would pull the same type of crap they did nerfing net metering and find a way to rip off those participating in the scheme. Power is worth what, 46 cents a kWh now when I'm buying it, but if I had panels and was selling it during peak A/C usage time, suddenly it's worth 6 cents right. Uh huh.