4 ms·

Simple: most people charge at night. Sure, fast charging will add some day-time demand, but it's not much. Cheap night-time pricing keeps the charging demand

Simple: most people charge at night. Sure, fast charging will add some day-time demand, but it's not much. Cheap night-time pricing keeps the charging demand off-peak. More even demand curves make generation more economical. It becomes trivial to upgrade distribution where needed.

tw04 6y ago
I still don't see how that works when you're talking EVERYONE charging. Here's a quick example from New England in 2010: https://www.eia.gov/todayinenergy/detail.php?id=830 https://www.eia.gov/todayinenergy/detail.php?id=830 During "peak" hours they're using roughly 17Gw total, and during off-peak, it's at 15Gw so we've only got 2Gw total to buffer electric cars charging. Feel free to tell me how my math is wrong, but let's assume worst case scenario: a tesla charger lists 11.5kW max draw. There are roughly 14m people in New England, if we assume even half of them were charging overnight, that's 86Gw of power draw. Even if you back that off to 25% of the population and half the power draw from the charger, you're at 21.5Gw of power, which is 10x what is available, and more than the total power usage during peak hours. If someone else has some different math I'm all ears but I don't know how we're going to more than double the total power capacity in 10 years - even if you assume we can get there with renewables, the backend infrastructure can't handle it.
- yongjik 6y ago
  2021 Tesla Model S has a 100kW battery and 402-mi range. I searched for "average driving miles per year" and Google says 13,500 miles - assuming this, we have about 37 miles per day, which would mean our Tesla S only needs to charge 9.2kW every day. If they're sitting on a charger 10 hours per day, they can take a leisurely 920W per vehicle (less than a good hair dryer), not 11.5kW.
  - tw04 6y ago
    I'm not sure I agree with that math for a number of reasons. For starters if you want to go strictly by averages, the average household has two cars, so your 9.2kW goes to 18.4kW out of the gate. Additionally that average includes teenagers which drives the mileage down, but households with teens tend to have more cars, so that means either they come out of the average or the 18.4 jumps to 27.6kW/day. The average household uses <1200kWh per month. Adding another 18kW per day increases power usage by almost 50%, which goes back to: the national power grid doesn't have anywhere near 50% spare capacity.
    - theshrike79 6y ago
      To put it another way: The average person can charge their EV for the same amount of power a top-tier gaming PC draws when playing a game =)
      - tw04 6y ago
        Sure.. but for 980Watts you're talking a system with multiple RTX3090 GPUs and a threadripper CPU - and even with that it wouldn't be a 980Watt constant draw, it would spike based on the game and what was happening in the game. I would be surprised if even half a percent of Americans have that kind of setup. If even 50% of Americans suddenly had that setup and all gamed every night for 10 hours a night, I would expect that would also cause the power grid to have issues.
        yongjik 6y ago
        I think it's fair to assume that America's current grid cannot handle 50% of people switching to EV, so obviously we need to build more. However, it's not like they're switching to EV overnight - even with the best (worst?) scenario it will take years, so hopefully we'll be able to ramp up the grid in time.
        gnramires 6y ago
        There are two aspects to it: generation and transmission. The peak power draw will lie somewhere between your estimate (11.5kW/vehicle) and the typical estimate (920W), which would assume everyone charging at home. Clearly not everyone would charge at home (or with a 1kW charger), so the number is in between. Both transmission and generation tend to cost mostly their peak usage. Generation is likely easier to upgrade, given a few years. I would imagine transmission is significantly more costly and complex, since the last mile network is enormous, but transmission likely has much more overhead (it has a soft instead of hard maximum as well due to simply increasing losses and increased thermal stress). I would say we probably are nearly prepared (with significant generation investments) if everyone charges at home at low power -- a 1-2 decade transition would go smoothly (my guess/estimate is 65% more average usage by that date). If most people opt for fast charging, the system will need significant overhaul (with widespread use of buffer batteries helping). It seems very wise for State incentives to increase capacity as soon as possible, to anticipate market demand -- the energy sector is likely slower than the automotive industry.
athms 6y ago
>Simple: most people charge at night. Except the people that don't have a charging station in their garage or folks that have a power outage. Just this week, we had a heat wave (70-80F) and winds up to 90MPH across California that resulted in power outages throughout the state as well as several fires.
- qndreoi 6y ago
  It seems that gas stations would not work during a power outage. Santa Ana winds cause lots of edge case problems.
  - erik_seaberg 6y ago
    “What if all the gas pumps go offline because of power or network outages” was a pretty scary failure mode they were thinking about before Y2K.
  - athms 6y ago
    You are right, but I have cans of gasoline as part of my emergency kit in case of an earthquake or fire.

tw04 6y ago

I still don't see how that works when you're talking EVERYONE charging. Here's a quick example from New England in 2010: https://www.eia.gov/todayinenergy/detail.php?id=830 https://www.eia.gov/todayinenergy/detail.php?id=830 During "peak" hours they're using roughly 17Gw total, and during off-peak, it's at 15Gw so we've only got 2Gw total to buffer electric cars charging. Feel free to tell me how my math is wrong, but let's assume worst case scenario: a tesla charger lists 11.5kW max draw. There are roughly 14m people in New England, if we assume even half of them were charging overnight, that's 86Gw of power draw. Even if you back that off to 25% of the population and half the power draw from the charger, you're at 21.5Gw of power, which is 10x what is available, and more than the total power usage during peak hours. If someone else has some different math I'm all ears but I don't know how we're going to more than double the total power capacity in 10 years - even if you assume we can get there with renewables, the backend infrastructure can't handle it.

yongjik 6y ago
2021 Tesla Model S has a 100kW battery and 402-mi range. I searched for "average driving miles per year" and Google says 13,500 miles - assuming this, we have about 37 miles per day, which would mean our Tesla S only needs to charge 9.2kW every day. If they're sitting on a charger 10 hours per day, they can take a leisurely 920W per vehicle (less than a good hair dryer), not 11.5kW.
- tw04 6y ago
  I'm not sure I agree with that math for a number of reasons. For starters if you want to go strictly by averages, the average household has two cars, so your 9.2kW goes to 18.4kW out of the gate. Additionally that average includes teenagers which drives the mileage down, but households with teens tend to have more cars, so that means either they come out of the average or the 18.4 jumps to 27.6kW/day. The average household uses <1200kWh per month. Adding another 18kW per day increases power usage by almost 50%, which goes back to: the national power grid doesn't have anywhere near 50% spare capacity.
  - theshrike79 6y ago
    To put it another way: The average person can charge their EV for the same amount of power a top-tier gaming PC draws when playing a game =)
    - tw04 6y ago
      Sure.. but for 980Watts you're talking a system with multiple RTX3090 GPUs and a threadripper CPU - and even with that it wouldn't be a 980Watt constant draw, it would spike based on the game and what was happening in the game. I would be surprised if even half a percent of Americans have that kind of setup. If even 50% of Americans suddenly had that setup and all gamed every night for 10 hours a night, I would expect that would also cause the power grid to have issues.
      - yongjik 6y ago
        I think it's fair to assume that America's current grid cannot handle 50% of people switching to EV, so obviously we need to build more. However, it's not like they're switching to EV overnight - even with the best (worst?) scenario it will take years, so hopefully we'll be able to ramp up the grid in time.
      - gnramires 6y ago
        There are two aspects to it: generation and transmission. The peak power draw will lie somewhere between your estimate (11.5kW/vehicle) and the typical estimate (920W), which would assume everyone charging at home. Clearly not everyone would charge at home (or with a 1kW charger), so the number is in between. Both transmission and generation tend to cost mostly their peak usage. Generation is likely easier to upgrade, given a few years. I would imagine transmission is significantly more costly and complex, since the last mile network is enormous, but transmission likely has much more overhead (it has a soft instead of hard maximum as well due to simply increasing losses and increased thermal stress). I would say we probably are nearly prepared (with significant generation investments) if everyone charges at home at low power -- a 1-2 decade transition would go smoothly (my guess/estimate is 65% more average usage by that date). If most people opt for fast charging, the system will need significant overhaul (with widespread use of buffer batteries helping). It seems very wise for State incentives to increase capacity as soon as possible, to anticipate market demand -- the energy sector is likely slower than the automotive industry.

athms 6y ago

>Simple: most people charge at night. Except the people that don't have a charging station in their garage or folks that have a power outage. Just this week, we had a heat wave (70-80F) and winds up to 90MPH across California that resulted in power outages throughout the state as well as several fires.

qndreoi 6y ago
It seems that gas stations would not work during a power outage. Santa Ana winds cause lots of edge case problems.
- erik_seaberg 6y ago
  “What if all the gas pumps go offline because of power or network outages” was a pretty scary failure mode they were thinking about before Y2K.
- athms 6y ago
  You are right, but I have cans of gasoline as part of my emergency kit in case of an earthquake or fire.