I got curious and did the math: US gas pumps do 10 gallons per minute, which give us 0.61 L/s. Density is about 0.7kg/L, energy content is about 46.7 MJ/kg. Multiplying the three we get juuust under 20MJ/s or 20MW or about 80 times more energy than this kind of electric charger
Whoa. That is a lot of efficiency with EVs. But then, that electricity, when coming from a coal powered plant means that the overall "earth to wheels" energy efficiency is somewhere around 30%.
True. But also, this decouples cars from fossil fuel dependency. So switching to something cleaner, like nuclear or wind/solar wouldn't require uprooting cars as a whole.
In the USA, outside of West Virginia, the grid tends to be much more low-carbon — at least biased towards natural gas in most places, but with a fair amount of nuclear even in states that claim not to believe in clean energy.
I need a reminder because I never pay attention to how long it takes. It’s just full every morning. A total paradigm shift from the old way of having to go somewhere to refill your car.
I thought about that right after I posted, and you're right. It's probably that gasoline is more of a familiar experience than 1000 amps flowing into lithium batteries.
People might find it slightly inconvenient when their keys get torn from their pants and watches ripped from their wrists every time they charge their car.
>The power of the Tesla coil lies in a process called electromagnetic induction, i.e., a changing magnetic field creates an electric potential that compels current to flow. Conversely, flowing electric current generates a magnetic field. When electricity flows through a wound up coil of wire, it generates a magnetic field that fills the area around the coil in a particular pattern, shown with lines below: [...]
>Eventually so much charge has accumulated that it breaks down the electrical neutrality of the air in the middle of the spark gap. The circuit closes for a fleeting second and a huge amount of current blasts out of the capacitor and through the coils. This produces a very strong magnetic field in the primary coil.
Which leads us to ask: Fucking magnets: How do they work?
Done with 2/0 cable. It's rarely, if ever, 1 400 amp panel.
1. There is no way you would get "1000amp service" at 250v. It would be a minimum of 480v 3 phase (and not 1000amp). You may even want a lot higher, because as you'll see, getting that many amps is ... very very hard.
2. You can't even buy 1000amp cable gauge anywhere commercially, because it would be insane.
The NEC ampacity table doesn't go anywhere near that high
it tops out at 2000kcmil, 665 amp cable.
Due to various factors[1], doubling the cable mils will only get you a hundred or so amps here, so it's probably close to 4500kcmil (i'm too lazy to do the mm^2 math, it's 1.89" conductors)
Which doesn't really exist for purchase (if you really needed it, you have the means to make it :P).
To try to also put the size in perspective:
2/0 cable has conductors that are about 3/8" in diameter.
2000kcmil cable, which again, tops out at 665 amps, has conductors 1.6" in diameter (they are often also segmented, so while the bare size may be 1.6" in theory, you don't find that).
Generally the insulation size on them is ridiculous as well (because they are usually used for like 10kv+ applications)
[1] Current is related to surface area of conductors, or combined surface areas of all the strands in a conductor. So you'd need to double diameter, at least, to come close.
My local utility seems to offer it, though they prefer that you install a transformer. They also offer 3-phase for residential usage. Yes, this is in the USA. From what I can tell, most likely you'd get 480 volts at 500 amps.
There is actually a home not far from me that gets 3-phase. It is hooked up to a commercial-style air conditioning unit (huge house) and has a separate power meter; the home has separate 2-phase service as well.
(I'm going to abuse the hell out of terminology to make this understandable)
I'm sure there are some utilities somewhere that will offer you that :)
480 volt at 500 amps is actually fairly reasonable in terms of cable requirements (it only requires 800 kcmil cable, which, while, i'd never want to buy a ton of it, is not completely bonkers). I would be a little surprised if they offer 500 amps though, because that's a lot more than you'd ever need.
Remember that a 3 phase amp carries a lot more kilowatts than a single phase amp.
In particular, 20 amp 240 single phase = 4800watts
But 20 amp 240 three phase is a factor of sqrt(3) more = 8313 watts
so 500 amp 480v 3 phase would carry 415692.19382 watts, while 500 amp 480v single phase (which nobody uses) would only carry 240000 watts.
So you'd be getting 415kw service out of that, not 240kw service. Which is a lot of power.
Usually i've seen them offer 250kw service (IE not in amps) and let you do the stepdown. This would step down to 300 amp 480v 3 phase.
240v 3 phase in residential areas is also more common (I can get it), but it's only 100-200 amp service at least here, and i pay for power factor, blah blah blah.
make me believe they'd end up with some medium voltage application here (IE take it in as somewhere between 3.3kv and 45kv and do step down themselves)
The Tesla supercharging cables are pretty short, so they can also tolerate the higher losses associated with a thinner cable. They were even experimenting with a liquid cooled cable at one point in order to get thinner conductors and a more flexible cable by allowing to to be less efficient.
Ha! I started to suggest "or they're using small copper and cooling the heck out of it," but that would waste energy so I assumed they wouldn't do it. Wrong, apparently.
Sure, but they are probably buying >1 KV service, which is not, as the comment I responded to claims, a thing any of us would/could buy similar to "house service".
No. Because if there is too much power demand the overload results in some people getting no power. You dont often hear of rolling blackouts or brownouts in North America.
Everyone can use as much power as they have subscribed to whenever they want. Your panel is rated for a certain amount of power and protected by a breaker or fuse if too much is used. Same for the transformer your panel is connected to. Same for the distribution line your transformer is connected to. Same for the transformer it is connected to. And so on.
There is enough capacity in the system to meet the demand. If there wasn't the lights go out due to some overload.
When demand grows more capacity has to be added before the limit is reached. Capacity takes years to build. Utilities have planning departments that decide where they need to add capacity next and how much.
Which would be a problem when everyone gets an electric car and every night the owners will request 20 kW for up to 8 hours (hence sustained, not peak). For a condo that could easily be half a megawatt.
That is an unreasonable number. That is 160 kwh of power which is double the largest model 3 battery. This would require everyone to drive nearly 600 miles a day at highway speed. Roughly nine hours of driving a day at 75miles an hour.
The expectation is that people drive 30ish miles a day. This is about 11kwh. Over 8 hours a night, well within reasonable limits.
I was thinking of 10 kW * 2 cars, but actually even for a single car you need 120 kWh to charge 85 kWh. You're right that it won't happen every night for 8 hours, I was wrong about that.
Problem is that you have to size for the worst case, which may happen only once a year, but it will happen. Everyone coming back after Thanksgiving. Everyone reaching a vacation place on a Sunday evening in the summer. Bam, 20 kW sustained for a few hours.
It takes only a few big condos before you need to bring 400 kV lines downtown...
Although your power requirements are somewhat overblown, this is one reason that companies like EMotorWerks are developing grid-connected EVSE’s (“Chargers”) that can be centrally controlled to manage load. Ultimately, EV’s will be plugged in for the 20+ hours a day that they aren’t being driven, and the grid will use them as a giant variable load to soak up excess solar and wind power and shed load when everyone turns on the A/C on a hot day.
Lots of plugged EV’s are also the perfect pairing to rooftop solar — in Hawaii, they’ve had to stop people from installing panels on their homes because the neighborhood feeder circuits can’t handle the power being generated by all of the homes. Just redirect that power to the EV in the driveway (or your neighbor’s driveway), problem solved!
Yes, although it not really "promised". A 200A residential service isn't a promise you can consume 200A 24/7, it's just the "never exceed" rating. If you need significantly more power than normal residential needs, I'm sure the utility will be happy to talk to you about your requirements.
A moderate distribution substation is probably more like 50 MVA.
A house with a 200A service at 240 V is about 50 kW. You might see a 250 kVA padmount transformer feeding half a dozen big houses but that is not the same thing as a substation.
I have worked at an electricity utility. "Distribution substation" is the term of art for a 250KVA padmount transformer and associated HV and LV switchgear (or even just a 50KVA pole mount transformer). A 50MVA installation is what we would refer to as a Zone substation.
5KVA per residential lot is not an uncommon allocation rule. The network is simply not designed to supply every house 200A simultaneously (the same is true of water services: the maximum flow rate of your connection to the water main cannot be sustained if every house in your neighbourhood tries to consume at that rate).
We must live in different climates. Electric heat is common around here and a house can easily have over 10 kW of heat. An electric range gets a 50A 240V circuit (12 kVA). An electric clothes dryer has a 30A 240V circuit (7.2 kVA). All it would take to exceed 5 kVA per house is for everyone to be cooking christmas dinner on a cold night. Maybe somebody has a shower (electric water heater turns on) and then uses the hair dryer (1.5 kW).
Granted you can probably overload a transformer a fair bit on a cold night. I'll ask next time I'm talking to someone in distribution what their allocation rule is.
I feel like I'm used to seeing a 3 x 33 kVA cans feeding only a few houses (that incidentally had natural gas heat and hot water...)
My house has 200 Amp service. But I never use that much at once. The average US home uses an average of about 1.2KW at any given time [0]. So I was wrong above. It's more like 200 houses.
There's no way you're only getting 20 amps to your house.
A microwave will consume 8-12 amps. A desktop computer is around 3-5 amps. I don't know what my electric stove used when I still had one, but it needed a 40 amp breaker on its own.
The standard home contract in Italy is 3.3kW, at 230V it's less that 15 amps for a resistive load. The meter will allow you to go over the allotted power for some time before disconnecting you though (the amount of time is inversely proportional to how much your going over, and I don't think you can ever go over 4kW).
Heating and stoves are gas based (ovens usually not though); going over the limit is not usual, the only common problem is when using air conditioning in summer which is becoming more widespread, and so are higher power contracts (we're not talking more than 6kW, though).
According to my utility, I consume annually 2660kWh, that is 300W average, much less than the 1.2KW for an American household.
Note that for home contracts the limit (and billing) is on power, not amps, so using inductive or reactive loads will not penalize you.
Here in Spain we're paying a lot for the power allotted to the contract, being around 30 to 40% of the bill.
So, I'm paying around 20€ (before taxes) just for having a 5.75kW contract, and then I have to add my kWh consumption. So reducing your consumption doesn't reflect that much on your bills.
Here it is 2 €/month/kW, my total bill was 40-50 €/month before I had a solar roof installed. I consumed about 400 W on average in a house (with solar the consumption is up by 60 W because of the inverter, but I save 30 to 70% plus I can sell a little surplus).
Italy used to be strange in that there were two electric feeds per house: One for low-power loads and one for high-power loads. Is that system gone now?
That's internal, right now. You don't get two lines from the grid. But you have multiple internal lines, and usually one 10A lines is mostly for the lights, other include more hungry appliances.
You mean there are multiple circuits inside the house? Isn't that totally normal? My small bungalow has 24 circuits on 200 amp service, plus a subpanel feeding the shop and sauna.
Remember there are some Europeans around running 240v ;) Also, at least on the bigger European cities, apartments and flats are more popular than houses, son usually the energy need is lower. And, of course, energy prices!
Here, in Madrid, most of my friends are running 10 to 20 amps. I'm an outlier, running 25amps (5.75 kW) because all my stuff is electric (water heater, cold/hot air conditioning, microwave, glass-ceramic stove...).
My Ryzen 5 desktop is consuming 0.3 to 0.5amps (being 50 to 120watts at 220V), supposing you're using 110volts your desktop computer must be a big gaming rig if it's consuming 350 to 550watts ;)
> supposing you're using 110volts your desktop computer must be a big gaming rig if it's consuming 350 to 550watts ;)
Yup. :-D
Not a BIG rig, but certainly respectable. i9-9900k [0], GeForce GTX 1070 [1], 32 gig of DDR4, 1 TB NVMe, 1 TB SSD, 2 TB HD.
[0] Yes, I know I don't need an i9 for gaming. I don't even need an i7. But I wanted future proofing and bragging rights.
[1] "An i9, but only a GTX 1070?" you might ask. I got the 1070 for free by winning a contest sponsored by MSI. At the time I had an i7-3770k. When I upgraded to the i9 in December, I didn't feel it was worth spending hundreds of dollars for an RTX 2080 (or even 2070) as the performance difference wasn't enough. I'll probably get something from the next gen RTX (3080? 2180? Whatever they call it).
I have a relatively simple GPU with my Rizen, it's ok for my use and GPUs are damn expensive, I understand ;)
BTW, have you metered your consumption? Doing some math on the top of my head, on regular use you "shouldn't" go over 200W and I don't think you should get over 400 in your use peaks. Just out of curiosity because I'm not used to those relatively power hungry GPUs :)
Are you sure your intake fuse is only 20A? Where I live it is normal for each circuit to have 16A, and if you have induction stove at least 20A for it. My intake fuse is only 55A (230V) since I have an old house, but should be upgraded
I checked now and the fuses are 15 A + 15 A, but the utility company disconnects me if I go over about 4 kW (18 A), or over 3.3 kW for more than a few minutes.
My sister-in-law has an induction stove, so she gets 40 A and the stove is connected directly to a separate bigger fuse.
That is really strange. Here, the utility company would be happy to have you buy lots more power.
Are you lacking a meter? Is the utility company unable to read your meter remotely and unwilling to send a truck out to read it? This would explain things, in which case you'd want to charge batteries (for free!) whenever you don't need all the power you have purchased.
Fuses are weird too. Those went out of style 60 years ago.
Maybe you will find this weird: I have a device that lets the utility company cut the power to my water heater. They can remotely activate it if they are having problems. In exchange for having this, I get a discount.
No, they can remotely read it. Italy had one of the first smart grids in fact.
It is just the standard here to only buy 3.3 kW unless you have induction stoves. Having more power available costs a little more, and on top of that you pay for what you consume.
As to "fuse", my mistake as I am not a native speaker. I meant breaker.
