9 ms·

1) This only works when the overlap peak electric demand and peak vehicle demand do not overlap. Night time, when the cars sit idle, is also a low demand time o

by fwungy 4y ago

1) This only works when the overlap peak electric demand and peak vehicle demand do not overlap. Night time, when the cars sit idle, is also a low demand time of day, and the afternoon energy demand peak coincides partially with the evening commute. 2) The loss of value to the owner based on cycles used needs to take into account that the failure of the battery in a vehicle can be what causes its final retirement, i.e. the condition of the vehicle itself does not justify a new battery expenditure. EVs are more like cell phones than ICE cars, which can have lifespans of over 30 years in the right climate. So losing 10% of your cycles to grid support could mean buying a car at nine years instead of ten years. Take a $40000 EV with half of the value being in the battery. Financed, say it's $600/month on a six year loan. With a ten year life span that's four years of no payments. With V2G say you lose 10% of your cycles, so you have three "free" years instead of four. Your real cost is 12 * $600 = $7200. You can't just calculate the pure cost of the battery with V2G, you need to take into account the depreciation on the entire vehicle as it relates to the battery. In fact, we know very little about how BEVs will depreciate.

trompetenaccoun 4y ago
And keep in mind it's to store energy from renewables (minus hydropower), i.e. mainly solar and wind. Solar is nonexistent at night. And although it varies, wind is generally strongest during the day and delivers less energy at night. But night-time is exactly when the vehicles are charged in people's homes, at least currently that's the situation and it would necessitate a ton of new infrastructure to change that. High voltage charging everywhere - ideally even DC charging and the necessary transformers, power cables etc. Even for street parking, because that's where a lot of cars are parked. So assuming there will be more EVs and we want to reach those net zero goals politicians always talk about we'd need charging stations everywhere. Meanwhile in the real world, here is the result when the green revolution doesn't go as imagined, due to failures in planning and mismanagement. Case study Germany: https://www.euractiv.com/section/energy-environment/news/growing-demand-puts-eu-electricity-grid-under-pressure/ https://www.euractiv.com/section/energy-environment/news/gro...
- themitigating 4y ago
  Any major change is going to have problems. The green revolution isn't just one event that has failed in Germany is a progressive change.
- ciphol 4y ago
  Charging at work seems like the thing to do. Not only is there excess solar energy at that time, but workplaces are more concentrated than homes so the installation costs for chargers should be less.
  - fennecfoxy 4y ago
    Yeah, I mean if you really think about it, this sort of concept would still work very well. If everyone has an electric car and that car is always plugged in when not in use, regardless of where you are, then car batteries are only out of grid use while they're being driven. The electrical grid must be such a difficult thing to manage, even with cars acting as local grid storage we'd need supplemental neighbourhood/regional storage units as well as a way to handle any unexpected peaks. I mean I know there's the whole "Coronation Street finishes and everyone turns their kettles on" thing but imagine if at x time on x day everyone collectively did turn their kettles on - literally everyone, every single household. It would blow the grid no matter what the operators tried to do. In a way we need grid storage in the form of batteries to enable better use of green/local energy sources, but I think it would be smart to include some sort of chemical based generation capacity with that local storage, some way for us to store energy in a solid form say, then never use it apart from very unexpected peaks where the system needs to scrabble to find more juice. Unfortunately a lot of potential fuels are also flammable, not really the best thing to have a huge stockpile of in your neighbourhood. Maybe a huge flow battery fed by massive underground tanks, if we ever manage to improve that technology...
  - iso1631 4y ago
    Even with US levels of 11,000 miles of driving per vehicle per year, or 30 miles a day, that's about 10kWh a day. Why can't you charge that with a 1kWh draw over 10 hours you park the car overnight?
neuronexmachina 4y ago
Regarding (1), this is a few years old but has some pretty interesting charts showing typical electricity consumption as a function of time-of-day, US region, and season: https://www.eia.gov/todayinenergy/detail.php?id=42915 https://www.eia.gov/todayinenergy/detail.php?id=42915
rippercushions 4y ago
> Night time, when the cars sit idle, is also a low demand time of day Not if you schedule your EV to top up the battery at night.
reissbaker 4y ago
A sibling comment mentions (but maybe doesn't realize the importance of) what battery storage is primarily useful for: night power. Solar is cheap and easy for power when the sun is up, but doesn't exist when the sun sets. The "evening commute" is mostly during the time when the sun is up; where you run into issues is: 1. After the evening commute in the early hours of the night, people are still awake at home using energy. 2. Homes are less efficient than offices + schools for many reasons (human density is generally more power efficient than everyone being spread out and not sharing resources), so demand goes up. 3. And that demand goes up precisely as supply — due to sunset — goes down. In that light, EVs are actually great for energy storage, assuming you get appropriate compensation from the utility companies for the cost of battery degradation — which also could be in the form of "demand pricing" where it's cheaper if you don't draw power from the grid at certain times. They are available for use right when there's a supply problem: early in the night. And then you could schedule them to recharge when demand drops late at night and the grid has excess power... Or, as more charging infrastructure gets built, you could also charge while at work and the sun is up. In some places there might be parts of the year where you still face a supply issue with solar: if the sun regularly sets before 5pm for part of the year, you'll still face some supply issues (although at least only when people are crowded in offices and schools, so demand is lower). California has hourly graphing of electricity demand vs supply, which is quite useful: https://www.caiso.com/TodaysOutlook/Pages/default.aspx https://www.caiso.com/TodaysOutlook/Pages/default.aspx You'll notice that while demand begins to climb at around 4pm, it's still fairly low at 5pm, and really only peaks at 7:30-8pm. By midnight demand has bottomed out again, which is a great time to have your car schedule charging time, leaving you with plenty of juice for the morning commute — a standard US dryer outlet will charge a Model 3 at about 30 miles per hour; assuming you leave at 8am that's 240 miles of range, so even if you ran it to zero — and probably you should not do that and only run it to 20%! — just about anyone would be be to make it into their workplace, since the average American round-trip commute distance is less than 50 miles.
- causality0 4y ago
  A standard US dryer outlet is rated for 30 amps at 240v. For a sustained rating of 80% that's 5760 watts, which at 4 miles per kwh is 23 miles per hour, not 30. Frankly it would take a hell of a lot to convince people to be ok with getting home, plugging their car in, and having the charge level go down instead of up. I certainly wouldn't be comfortable with it.
sundvor 4y ago
Absolutely. As an EV owner who wants to keep his car for at least ten years, it doesn't make sense to me to dull out the high capacity batteries to support the grid. It seems to me that it would be better to use recycled batteries for home PV storage etc. I'm not too obsessed but it was easy enough to look up the data on what charge states result in the least loss of range over time.
- chii 4y ago
  or not just recycled EV batteries, but alternative batteries that don't need to have good weight ratios. PV storage should maximize the cost-efficiency, since that is the determining factor, not weight ratios like in a car would optimize for.
- Maakuth 4y ago
  What if you were reimbursed 5x your meter price for the power you sell back to the grid? With electricity spot market, this sort of money is around and should of course go to the vehicle owners, at least a big share of it. Only a fraction of the total battery capacity would be involved in this scheme and with light load, so the battery degradation would not be that big. And this would not happen daily.
  - friendzis 4y ago
    > With electricity spot market, this sort of money is around This happens precisely because of supply-demand - peak dispatchable bulk generation is more expensive. VtG brings a lot of cheap supply bringing prices down and causes balancing stress on distribution grid, increasing distribution costs. 5x sounds like an absolute pipe dream
    - Maakuth 4y ago
      The price level would be determined in the market of course, maybe most vehicle owners would be ready to participate with lower reimbursement ratio. Anyway, I doubt this would cause a lot of stress to the distribution grid as the vehicle batteries are probably closer to the loads than the large scale power stations. The EVs powering neighbourdhood ACs and so on. So at least the distribution transformers could easily see lower load than without V2G.
jillesvangurp 4y ago
V2g has a a few challenges of course but people seem to not be aware that their EV batteries are much better than they think. The early ones from ten years ago had no battery management systems and had issues with wearing out relatively fast. But the newer ones have battery management. So, the wear and tear is a lot less these days. A typical car battery is rated for thousands of cycles. 3000 cycles is a number you hear often. If you have an EV that has a range of 300 miles, we're talking about 900000 miles. That's more miles than the vast majority of cars will drive over their lifespan. The average driver drives less than 15000 miles per year. The car will die before the battery typically, not the other way around. And the battery isn't completely dead at that point, it should still be good for 80% of its original charge. The vast majority of EVs ever produced are still driving with their original batteries and will be for years to come. A second point is that EV batteries are designed to discharge in a few hours to drive the car. There is no way you'd discharge at that speed via v2g. Most home connections charge/discharge only at a few kw. It's a comparatively light load for the battery and the wear and tear is pretty modest. Battery degradation happens a lot faster if you stress the battery. There are some indications that suggest that v2g discharging has only a very minimal impact on battery life. You wouldn't fully discharge the battery. Not even close. A third point is that with smart chargers, you would be able to control when the battery is allowed to discharge and how much. A million cars contributing just a single kwh each is 1 gwh. That's a huge amount of power. You would not fully cycle the battery typically but maybe only a few percent. If you start with 3000 cycles and you use 10% of that every day (which would be a lot), you could do that for 30000 days. That's longer than most humans live. Finally, instead of providing power to the grid, you could use a system like this to power your house and make save significant amounts of money in the evening by using your car instead of expensive grid rates using power that you got from your solar panels during the day for free. Those savings can really add up over the years. If it worries you, you can invest in a house battery instead. In the end the argument has to be financial and v2g is probably cheaper overall than that. People are spending tens of thousands of dollars to put solar on their roofs. So, throwing their car battery in the mix is a comparatively small step and a perfectly rational thing to consider. But the numbers have to make sense for people to opt in to that.
- deleted 4y ago
  [deleted]
babypuncher 4y ago
> EVs are more like cell phones than ICE cars, which can have lifespans of over 30 years in the right climate. So losing 10% of your cycles to grid support could mean buying a car at nine years instead of ten years. I feel like we should be mandating easy and near-cost replacement for EVs to make sure that this is less of a problem. Battery wear aside, EV's have the potential to greatly outlast ICE's. We should be treating batteries just like tires and brakes. I agree that using EV batteries as grid storage isn't a particularly great idea.
- rich_sasha 4y ago
  Right now AFAIK batteries are placed deep in the guts of the car, cf the "electric skateboard" design. This is because they are large and heavy so you have to spread the weight around. Thus hard to replace.
julienfr112 4y ago
As other parts of the EV have a longer lifespan, like an electric motor, it may be more common to do a battery exchange mid-life ?

by fwungy 4y ago

trompetenaccoun 4y ago

And keep in mind it's to store energy from renewables (minus hydropower), i.e. mainly solar and wind. Solar is nonexistent at night. And although it varies, wind is generally strongest during the day and delivers less energy at night. But night-time is exactly when the vehicles are charged in people's homes, at least currently that's the situation and it would necessitate a ton of new infrastructure to change that. High voltage charging everywhere - ideally even DC charging and the necessary transformers, power cables etc. Even for street parking, because that's where a lot of cars are parked. So assuming there will be more EVs and we want to reach those net zero goals politicians always talk about we'd need charging stations everywhere. Meanwhile in the real world, here is the result when the green revolution doesn't go as imagined, due to failures in planning and mismanagement. Case study Germany: https://www.euractiv.com/section/energy-environment/news/growing-demand-puts-eu-electricity-grid-under-pressure/ https://www.euractiv.com/section/energy-environment/news/gro...

themitigating 4y ago
Any major change is going to have problems. The green revolution isn't just one event that has failed in Germany is a progressive change.
ciphol 4y ago
Charging at work seems like the thing to do. Not only is there excess solar energy at that time, but workplaces are more concentrated than homes so the installation costs for chargers should be less.
- fennecfoxy 4y ago
  Yeah, I mean if you really think about it, this sort of concept would still work very well. If everyone has an electric car and that car is always plugged in when not in use, regardless of where you are, then car batteries are only out of grid use while they're being driven. The electrical grid must be such a difficult thing to manage, even with cars acting as local grid storage we'd need supplemental neighbourhood/regional storage units as well as a way to handle any unexpected peaks. I mean I know there's the whole "Coronation Street finishes and everyone turns their kettles on" thing but imagine if at x time on x day everyone collectively did turn their kettles on - literally everyone, every single household. It would blow the grid no matter what the operators tried to do. In a way we need grid storage in the form of batteries to enable better use of green/local energy sources, but I think it would be smart to include some sort of chemical based generation capacity with that local storage, some way for us to store energy in a solid form say, then never use it apart from very unexpected peaks where the system needs to scrabble to find more juice. Unfortunately a lot of potential fuels are also flammable, not really the best thing to have a huge stockpile of in your neighbourhood. Maybe a huge flow battery fed by massive underground tanks, if we ever manage to improve that technology...
- iso1631 4y ago
  Even with US levels of 11,000 miles of driving per vehicle per year, or 30 miles a day, that's about 10kWh a day. Why can't you charge that with a 1kWh draw over 10 hours you park the car overnight?

neuronexmachina 4y ago

Regarding (1), this is a few years old but has some pretty interesting charts showing typical electricity consumption as a function of time-of-day, US region, and season: https://www.eia.gov/todayinenergy/detail.php?id=42915 https://www.eia.gov/todayinenergy/detail.php?id=42915

rippercushions 4y ago

> Night time, when the cars sit idle, is also a low demand time of day Not if you schedule your EV to top up the battery at night.

reissbaker 4y ago

A sibling comment mentions (but maybe doesn't realize the importance of) what battery storage is primarily useful for: night power. Solar is cheap and easy for power when the sun is up, but doesn't exist when the sun sets. The "evening commute" is mostly during the time when the sun is up; where you run into issues is: 1. After the evening commute in the early hours of the night, people are still awake at home using energy. 2. Homes are less efficient than offices + schools for many reasons (human density is generally more power efficient than everyone being spread out and not sharing resources), so demand goes up. 3. And that demand goes up precisely as supply — due to sunset — goes down. In that light, EVs are actually great for energy storage, assuming you get appropriate compensation from the utility companies for the cost of battery degradation — which also could be in the form of "demand pricing" where it's cheaper if you don't draw power from the grid at certain times. They are available for use right when there's a supply problem: early in the night. And then you could schedule them to recharge when demand drops late at night and the grid has excess power... Or, as more charging infrastructure gets built, you could also charge while at work and the sun is up. In some places there might be parts of the year where you still face a supply issue with solar: if the sun regularly sets before 5pm for part of the year, you'll still face some supply issues (although at least only when people are crowded in offices and schools, so demand is lower). California has hourly graphing of electricity demand vs supply, which is quite useful: https://www.caiso.com/TodaysOutlook/Pages/default.aspx https://www.caiso.com/TodaysOutlook/Pages/default.aspx You'll notice that while demand begins to climb at around 4pm, it's still fairly low at 5pm, and really only peaks at 7:30-8pm. By midnight demand has bottomed out again, which is a great time to have your car schedule charging time, leaving you with plenty of juice for the morning commute — a standard US dryer outlet will charge a Model 3 at about 30 miles per hour; assuming you leave at 8am that's 240 miles of range, so even if you ran it to zero — and probably you should not do that and only run it to 20%! — just about anyone would be be to make it into their workplace, since the average American round-trip commute distance is less than 50 miles.

causality0 4y ago
A standard US dryer outlet is rated for 30 amps at 240v. For a sustained rating of 80% that's 5760 watts, which at 4 miles per kwh is 23 miles per hour, not 30. Frankly it would take a hell of a lot to convince people to be ok with getting home, plugging their car in, and having the charge level go down instead of up. I certainly wouldn't be comfortable with it.

sundvor 4y ago

Absolutely. As an EV owner who wants to keep his car for at least ten years, it doesn't make sense to me to dull out the high capacity batteries to support the grid. It seems to me that it would be better to use recycled batteries for home PV storage etc. I'm not too obsessed but it was easy enough to look up the data on what charge states result in the least loss of range over time.

chii 4y ago
or not just recycled EV batteries, but alternative batteries that don't need to have good weight ratios. PV storage should maximize the cost-efficiency, since that is the determining factor, not weight ratios like in a car would optimize for.
Maakuth 4y ago
What if you were reimbursed 5x your meter price for the power you sell back to the grid? With electricity spot market, this sort of money is around and should of course go to the vehicle owners, at least a big share of it. Only a fraction of the total battery capacity would be involved in this scheme and with light load, so the battery degradation would not be that big. And this would not happen daily.
- friendzis 4y ago
  > With electricity spot market, this sort of money is around This happens precisely because of supply-demand - peak dispatchable bulk generation is more expensive. VtG brings a lot of cheap supply bringing prices down and causes balancing stress on distribution grid, increasing distribution costs. 5x sounds like an absolute pipe dream
  - Maakuth 4y ago
    The price level would be determined in the market of course, maybe most vehicle owners would be ready to participate with lower reimbursement ratio. Anyway, I doubt this would cause a lot of stress to the distribution grid as the vehicle batteries are probably closer to the loads than the large scale power stations. The EVs powering neighbourdhood ACs and so on. So at least the distribution transformers could easily see lower load than without V2G.

jillesvangurp 4y ago

V2g has a a few challenges of course but people seem to not be aware that their EV batteries are much better than they think. The early ones from ten years ago had no battery management systems and had issues with wearing out relatively fast. But the newer ones have battery management. So, the wear and tear is a lot less these days. A typical car battery is rated for thousands of cycles. 3000 cycles is a number you hear often. If you have an EV that has a range of 300 miles, we're talking about 900000 miles. That's more miles than the vast majority of cars will drive over their lifespan. The average driver drives less than 15000 miles per year. The car will die before the battery typically, not the other way around. And the battery isn't completely dead at that point, it should still be good for 80% of its original charge. The vast majority of EVs ever produced are still driving with their original batteries and will be for years to come. A second point is that EV batteries are designed to discharge in a few hours to drive the car. There is no way you'd discharge at that speed via v2g. Most home connections charge/discharge only at a few kw. It's a comparatively light load for the battery and the wear and tear is pretty modest. Battery degradation happens a lot faster if you stress the battery. There are some indications that suggest that v2g discharging has only a very minimal impact on battery life. You wouldn't fully discharge the battery. Not even close. A third point is that with smart chargers, you would be able to control when the battery is allowed to discharge and how much. A million cars contributing just a single kwh each is 1 gwh. That's a huge amount of power. You would not fully cycle the battery typically but maybe only a few percent. If you start with 3000 cycles and you use 10% of that every day (which would be a lot), you could do that for 30000 days. That's longer than most humans live. Finally, instead of providing power to the grid, you could use a system like this to power your house and make save significant amounts of money in the evening by using your car instead of expensive grid rates using power that you got from your solar panels during the day for free. Those savings can really add up over the years. If it worries you, you can invest in a house battery instead. In the end the argument has to be financial and v2g is probably cheaper overall than that. People are spending tens of thousands of dollars to put solar on their roofs. So, throwing their car battery in the mix is a comparatively small step and a perfectly rational thing to consider. But the numbers have to make sense for people to opt in to that.

deleted 4y ago
[deleted]

babypuncher 4y ago

> EVs are more like cell phones than ICE cars, which can have lifespans of over 30 years in the right climate. So losing 10% of your cycles to grid support could mean buying a car at nine years instead of ten years. I feel like we should be mandating easy and near-cost replacement for EVs to make sure that this is less of a problem. Battery wear aside, EV's have the potential to greatly outlast ICE's. We should be treating batteries just like tires and brakes. I agree that using EV batteries as grid storage isn't a particularly great idea.

rich_sasha 4y ago
Right now AFAIK batteries are placed deep in the guts of the car, cf the "electric skateboard" design. This is because they are large and heavy so you have to spread the weight around. Thus hard to replace.

julienfr112 4y ago

As other parts of the EV have a longer lifespan, like an electric motor, it may be more common to do a battery exchange mid-life ?