4 ms·

Yeah, lots of things sound like perfectly great ideas until you actually run the numbers and find out they're hopelessly inadequate. And electric cars actually

Yeah, lots of things sound like perfectly great ideas until you actually run the numbers and find out they're hopelessly inadequate. And electric cars actually tend to get charged at night, while people sleep, when solar isn't generating.

WalterBright 5y ago
> electric cars actually tend to get charged at night, while people sleep, when solar isn't generating. Because there's no incentive to do otherwise. Of course people don't time shift their electric use when there's no incentive to.
- crystalmeph 5y ago
  The only way most people can time-shift charging their electric cars to the daytime is if their parking spot at their job has a charging station. Practically, that means a very large fraction of office building parking spots will need charging stations. That sounds prohibitively expensive. Incentives can only nudge so far before you run into genuine problems of logistics.
  - caoilte 5y ago
    Much cheaper than nuclear
  - erer3433443 5y ago
    Building charging stations isn't that expensive, definitely not prohibitively so.
  - adgjlsfhk1 5y ago
    charging stations for building parking don't need to be high speed, so the cost is just putting in an outlet (probably a 240 volt one)
  - WalterBright 5y ago
    Charging stations can be installed and can make money by charging the commuters to charge their cars while they work. If the price differential between day & night is enough, it will be worthwhile for both the parking lot owner and the car owner.
- kwhitefoot 5y ago
  A few commuters to the little town I live in can charge their electric cars during the day while they are at work. If every parking space had a 7 kW connection (230 V, 30 A single phase) almost all cars could be fully charged while their owners were at work. In fact even an ordinary 3 kW connection would be enough for most people; even my 2015 Tesla Model S adds more than 12 km per hour at 3 kW.
  - WalterBright 5y ago
    Drive around any residential street during the day. You'll see lots of pahked cahs. They're not all off at work.
  - DennisP 5y ago
    If car owners are paying for that power, then you need more than just electrical outlets. You need something that takes payments. If car owners aren't paying for the power, then who is? And either way, what does it cost to wire up all the parking spaces?
    - WalterBright 5y ago
      > You need something that takes payments. Paid parking lots solved that problem eons ago. > what does it cost to wire up all the parking spaces? I wonder how people ever managed to electrify street lamps, any exterior powered things, even the per-stall electric parking meters I've encountered.
      - DennisP 5y ago
        Charging a car takes way more power than running a parking meter. All I'm saying is, the costs of these sorts of demand management measures for renewables should not be overlooked in comparisons with the cost of nuclear, which doesn't need them.
        WalterBright 5y ago
        > Charging a car takes way more power than running a parking meter. True, you'll need a heavier wire. And the cost of installing wire far exceeds the cost of the wire. When my house was wired up, the cost of the installation was 40 times the cost of the reels of wire.
- DennisP 5y ago
  Yes but "you can charge it while you sleep" is a pretty popular selling point of electric cars. You're arguing that we should purposely make electric cars less attractive. People talk about "demand management" as if it's free. Not much power available, just shut down some factories. But if you're running your factories only half the time, you need to build twice as many factories to make the same stuff. You're making renewables look artificially cheap by externalizing costs to their customers.
  - WalterBright 5y ago
    > Yes but "you can charge it while you sleep" is a pretty popular selling point of electric cars. You're arguing that we should purposely make electric cars less attractive. Instead, "you can charge it while you work". Not many people drive more than an hour a day - that's 23 hours where it sits. I see lots of cars parked in residential streets during the day. Paid parking lots catering to commuters can also offer charging services. > just shut down some factories That's your strawman. I didn't propose that.
    - DennisP 5y ago
      Any factory wants to run full-speed 24/7. How are you going to manage their demand without reducing their production? Same principle applies to most things. If electricity stops being readily available all the time, then you're introducing a new constraint that people have to optimize for. If that means they change their behavior, then they're doing something more expensive than whatever they were doing before, when they optimized without that constraint. That extra cost generally isn't figured into the optimistic estimates of how cheap renewables are, but it's still a cost that society pays. Building lots of charging stations at employer parking lots is also a new cost, that doesn't get counted against renewables.
      - WalterBright 5y ago
        Have you ever noticed that pump gas prices vary every day? That's demand shaping. It works. > Building lots of charging stations at employer parking lots is also a new cost, that doesn't get counted against renewables. The cost needs to be compared with building grid storage batteries.
adgjlsfhk1 5y ago
Also night is a pretty good time for grid load since wind does decently at night, and power use is very low. (since most offices/factories don't use power at night)
ptha 5y ago
Also if your home has a "NightSaver" meter (just what they're called here in Ireland, but basically a day and night meter), the night rate is often nearly half the day rate, so it makes sense to charge at night.

WalterBright 5y ago

> electric cars actually tend to get charged at night, while people sleep, when solar isn't generating. Because there's no incentive to do otherwise. Of course people don't time shift their electric use when there's no incentive to.

crystalmeph 5y ago
The only way most people can time-shift charging their electric cars to the daytime is if their parking spot at their job has a charging station. Practically, that means a very large fraction of office building parking spots will need charging stations. That sounds prohibitively expensive. Incentives can only nudge so far before you run into genuine problems of logistics.
- caoilte 5y ago
  Much cheaper than nuclear
- erer3433443 5y ago
  Building charging stations isn't that expensive, definitely not prohibitively so.
- adgjlsfhk1 5y ago
  charging stations for building parking don't need to be high speed, so the cost is just putting in an outlet (probably a 240 volt one)
- WalterBright 5y ago
  Charging stations can be installed and can make money by charging the commuters to charge their cars while they work. If the price differential between day & night is enough, it will be worthwhile for both the parking lot owner and the car owner.
kwhitefoot 5y ago
A few commuters to the little town I live in can charge their electric cars during the day while they are at work. If every parking space had a 7 kW connection (230 V, 30 A single phase) almost all cars could be fully charged while their owners were at work. In fact even an ordinary 3 kW connection would be enough for most people; even my 2015 Tesla Model S adds more than 12 km per hour at 3 kW.
- WalterBright 5y ago
  Drive around any residential street during the day. You'll see lots of pahked cahs. They're not all off at work.
- DennisP 5y ago
  If car owners are paying for that power, then you need more than just electrical outlets. You need something that takes payments. If car owners aren't paying for the power, then who is? And either way, what does it cost to wire up all the parking spaces?
  - WalterBright 5y ago
    > You need something that takes payments. Paid parking lots solved that problem eons ago. > what does it cost to wire up all the parking spaces? I wonder how people ever managed to electrify street lamps, any exterior powered things, even the per-stall electric parking meters I've encountered.
    - DennisP 5y ago
      Charging a car takes way more power than running a parking meter. All I'm saying is, the costs of these sorts of demand management measures for renewables should not be overlooked in comparisons with the cost of nuclear, which doesn't need them.
      - WalterBright 5y ago
        > Charging a car takes way more power than running a parking meter. True, you'll need a heavier wire. And the cost of installing wire far exceeds the cost of the wire. When my house was wired up, the cost of the installation was 40 times the cost of the reels of wire.
DennisP 5y ago
Yes but "you can charge it while you sleep" is a pretty popular selling point of electric cars. You're arguing that we should purposely make electric cars less attractive. People talk about "demand management" as if it's free. Not much power available, just shut down some factories. But if you're running your factories only half the time, you need to build twice as many factories to make the same stuff. You're making renewables look artificially cheap by externalizing costs to their customers.
- WalterBright 5y ago
  > Yes but "you can charge it while you sleep" is a pretty popular selling point of electric cars. You're arguing that we should purposely make electric cars less attractive. Instead, "you can charge it while you work". Not many people drive more than an hour a day - that's 23 hours where it sits. I see lots of cars parked in residential streets during the day. Paid parking lots catering to commuters can also offer charging services. > just shut down some factories That's your strawman. I didn't propose that.
  - DennisP 5y ago
    Any factory wants to run full-speed 24/7. How are you going to manage their demand without reducing their production? Same principle applies to most things. If electricity stops being readily available all the time, then you're introducing a new constraint that people have to optimize for. If that means they change their behavior, then they're doing something more expensive than whatever they were doing before, when they optimized without that constraint. That extra cost generally isn't figured into the optimistic estimates of how cheap renewables are, but it's still a cost that society pays. Building lots of charging stations at employer parking lots is also a new cost, that doesn't get counted against renewables.
    - WalterBright 5y ago
      Have you ever noticed that pump gas prices vary every day? That's demand shaping. It works. > Building lots of charging stations at employer parking lots is also a new cost, that doesn't get counted against renewables. The cost needs to be compared with building grid storage batteries.

adgjlsfhk1 5y ago

Also night is a pretty good time for grid load since wind does decently at night, and power use is very low. (since most offices/factories don't use power at night)

ptha 5y ago

Also if your home has a "NightSaver" meter (just what they're called here in Ireland, but basically a day and night meter), the night rate is often nearly half the day rate, so it makes sense to charge at night.