STM317
HalfDork
10/12/16 10:11 a.m.
alfadriver wrote:
The person who parks their car in front of my house isn't going to get a charge. Heck, most street side parking isn't going to get a charge at all. There are not enough poles out there to support the modular idea.
I just went for a drive around western Wayne county. I didn't see that many easy opportunities for charging stations other than garages or individual homes.
If it's 2030, and most of these EVs are automated, will the people that live in a dense enough area to park on the street even own vehicles? It seems like there is a lot of money being hedged toward the assumption that ride sharing or a subscription service will become more prevalent than it currently is. If that's true, how is the number of vehicles on the road impacted if at all? And how would that change the need for infrastructure?
GameboyRMH wrote:
z31maniac wrote:
GameboyRMH wrote: I'm sure they'd be happy to install charging stations for profit.
Because ripping up the sidewalk and possibly roads to attach a charging station to the existing power grid is cheap and easy.
Do you actually understand the billions of dollars it would take to do this across the country?
Each charger could pay itself off in a few years. A common level-2 charger can fully charge a present-day EV overnight (say 8 hours of charging) and won't be obsolete for decades. Say each meter, purchased and installed, costs $4k and draws 80c worth of electricity per hour. Charge $1.50 per hour of charging, each charger can generate $5.60 per day and over $2k per year, paying itself off in just under two years.
If the chargers use a modular design with a unit on a pole, when they have to be upgraded a new unit can just be placed on the pole.
Do you have any real numbers?
Even if the charger only costs $4k, how much is it going to cost to install?
alfadriver wrote:
GameboyRMH wrote:
Liquid fuel cells would get around the hydrogen infrastructure nightmare, but won't do much for the environment - from a purely environmental perspective, it's effectively no different from an ultra-low-emissions ICE. It doesn't make vehicles energy-source-agnostic and allow them to be cleaned up centrally like an EV does.
Right now, the claims are 20-30% more efficient than stationary diesels. Which is more efficient than moving diesels, and is more efficient than gas cars. So it would not be equal.
And, like batteries- fuel cells are developing fast, too. Fast enough that they are going on passenger ships in 2022, as they are cost effective compared to large scale diesel engines.
So from a CO2, HC, CO, and NOx perspective, I see all of them going down compared to a SULEV car.
And it totally solves the charging issue- be it the physics or the location and cost of the charging system. Again, given how they work, they are ok on bio fuels- which is also getting better.
To me, from a total system perspective, fuel cells look like a more likely solution.
So let's say switching to liquid fuel cells would cut emissions from cars in half. What's the way forward from there to zero emissions? I don't see how biofuels can work as a drop-in replacement for gasoline and diesel at anywhere near present consumption levels simply due to the amount of farmland required in a world with an ever-increasing population.
We could end up taking a big step forward and then finding ourselves stuck again, once more deep in the diminishing returns and looking for a completely different technology to make any further meaningful emissions cuts. The maximum theoretical thermal efficiency of a fuel cell is 83%, well over 10% less than a present-day EV, and there would be only limited energy savings in the fuel supply for liquid fuel cells on top of that. It keeps all the middlemen around and means a carbon-neutral grid would do nothing to reduce automotive emissions.
Anything that uses fossil fuels is a dead end and anything that uses biofuels has to be a niche application. Transporting and storing hydrogen is a nightmare. Therefore most cars in the future will have to get their power, directly or very nearly directly, from the grid somehow.
I think even hydrogen cars with on-site hydrogen production from grid power could be a better idea than liquid fuel cells running from fossil fuels and biofuels.
z31maniac wrote:
Do you have any real numbers?
Even if the charger only costs $4k, how much is it going to cost to install?
All my estimates there were based on real numbers. The $4k is an estimate of the cost of the charger itself AND installing it in the street, based on the cost of installing a street lamp.
BA5
New Reader
10/12/16 3:15 p.m.
In reply to tuna55:
So we want to transfer 6 MJ of energy:
Let's say we do it over a reasonable amount of time. 5 minutes seems reasonable enough. We can go shorter, but the math works out reasonably.
6,000,000 J / (5 * 60s) = 20,000 W
P = I * V, we can split it up any way we'd like.
20 A @ 1000 V
200 A @ 100 V
Either of those can be made perfectly safe. You'd only need maybe a 1/4" diameter copper conductor to safely conduct 200 A for 5 minutes without overheating. 1000V can be withstood by only a few millimeters of cheap plastic. Of course there's some failure mode stuff that would have to be analyzed to make it suitable for consumer consumption, but it's hardly anything that can't be overcome.
1 gallon of gas = 2.8kg.
Energy density = 45 MJ/kg
Assuming that 2/3 of that energy is wasted in the ICE process, we only need 1/3 of it + the inefficiencies of the electric powertrain, say 10%. So .33 * 1.1 * 45MJ = 16MJ
So you need 16 MJ. Per gallon. So to store the energy content to go roughly 200mi on the highway, you'd need the equivalent of say 4-6 gallons of gas or 64 - 96MJ of energy.
tuna55
MegaDork
10/12/16 3:23 p.m.
BA5 wrote:
In reply to tuna55:
So we want to transfer 6 MJ of energy:
Let's say we do it over a reasonable amount of time. 5 minutes seems reasonable enough. We can go shorter, but the math works out reasonably.
6,000,000 J / (5 * 60s) = 20,000 W
P = I * V, we can split it up any way we'd like.
20 A @ 1000 V
200 A @ 100 V
Either of those can be made perfectly safe. You'd only need maybe a 1/4" diameter copper conductor to safely conduct 200 A for 5 minutes without overheating. 1000V can be withstood by only a few millimeters of cheap plastic. Of course there's some failure mode stuff that would have to be analyzed to make it suitable for consumer consumption, but it's hardly anything that can't be overcome.
alfadriver wrote:
GameboyRMH wrote:
Well in terms of the charging system, that's right, dumping such massive amounts of energy into a car will become a bigger problem than having the car store all that energy. You might say we're already at the point where the charging system is becoming the bottleneck in charging speed - you can't quick-charge an EV at home right now unless you happen to have 3-phase power.
At home, 220v charging will do the job well enough for just about everyone, but at gas stations you'll probably see these things happening to help EVs charge faster:
1. On-site energy storage, using supercapacitors, compressed air storage or flywheels buried under the parking lot just like the gas tanks are now. This way a car can charge faster than the gas station can take energy from the grid.
2. Ever-increasing charging voltages...480V for starters, to keep the cable beefiness and waste heat down.
3. Possibly some extremely beefy charging cables. Think like 2 gas filler hoses going into a car, but the hose is all wire. The cables for a Level-3 480v "quick charge" system are already collectively about the width of a gas filler hose.
So in the most optimistic versions of EV, they get about 100mpge. Given that EV's are only 85% efficient, that's still pretty high, but good enough for numbers.
For a 300 mile range, you would need the energy equivalent to 3 gallons of gas.
Most people can fill their cars between 1-2 min.
So do that at 10min.
Give or take, that's 360,000 KJ. To deliver that in 10 min, that's 6,013kW, or about 6,000,000 W.
There are some power of ten errors between your math and alfadrivers.
If it's 360,000Kj then it's 600KW, not 20KW as you stated or 6,000KW as he stated, so you need 600 amps for that 1000 volts.
Ian F
MegaDork
10/12/16 5:49 p.m.
tuna55 wrote:
GameboyRMH wrote:
What's the way forward from there to zero emissions?
There isn't one.
Period.
Well, yes and no. One of the arguments for bio-fuels is they can be somewhat "emissions-neutral" meaning that the carbon emitted by combustion is absorbed by the next plant generation. Of course, this assumes that all you're emitting is CO2, but you get the point.
BA5
New Reader
10/13/16 8:17 a.m.
In reply to tuna55:
Admittedly I didn't really check the 6 MJ number, so let's try this again. ProDarwin's number look decent: let's round it up a hair and go with 100 MJ
100 MJ in 5 minutes is 333 kW. That's (you guess it!) 333 A @ 1000 V. The quarter inch conductor I mentioned above could easily push the 300A as well. Again, insulating against 1000 V is not difficult or bulky.
I think the primary obstacle in making EV's 'functional' is the on board storage, not the transfer or usage. Current batteries can't be charged as fast as we're able to pump electricity into them, so we have to wait while they slowly fill up.
and again, judging by the vast leaps we have made so far in ev tech in the past couple of years, the 2030 number might be moot by the time we get there. things are changing almost daily and the tech is getting better and better.
mad_machine wrote:
and again, judging by the vast leaps we have made so far in ev tech in the past couple of years, the 2030 number might be moot by the time we get there. things are changing almost daily and the tech is getting better and better.
Pretty much this, and then add in consumer acceptance. I work at a University, and most of the students here seem to want electric cars at some point in the future.
tuna55
MegaDork
10/13/16 9:19 a.m.
BA5 wrote:
In reply to tuna55:
Admittedly I didn't really check the 6 MJ number, so let's try this again. ProDarwin's number look decent: let's round it up a hair and go with 100 MJ
100 MJ in 5 minutes is 333 kW. That's (you guess it!) 333 A @ 1000 V. The quarter inch conductor I mentioned above could easily push the 300A as well. Again, insulating against 1000 V is not difficult or bulky.
I think the primary obstacle in making EV's 'functional' is the on board storage, not the transfer or usage. Current batteries *can't* be charged as fast as we're able to pump electricity into them, so we have to wait while they slowly fill up.
So I'm thinking double that amount and hence my 600A number at 1000V.
Now I am being taught something as I did not know there was a legitimate way to transfer that much power with cables you can hold onto and connect by hand. Can you show me a picture of what this thing is going to look like? All of the connections I know of for that sort of power come from power plants.
tuna55
MegaDork
10/13/16 9:21 a.m.
ChrisHachet wrote:
mad_machine wrote:
and again, judging by the vast leaps we have made so far in ev tech in the past couple of years, the 2030 number might be moot by the time we get there. things are changing almost daily and the tech is getting better and better.
Pretty much this, and then add in consumer acceptance. I work at a University, and most of the students here seem to want electric cars at some point in the future.
I want an EV now, but make no mistake, this math we're doing isn't "tech", it's not going to "be improved", it's physics. If we're using electricity, and charging a battery with it, we may be able to change how fast the battery can take in energy, how heavy and efficient it is at giving that energy back, how hot it gets during charging and use, but we cannot change Ohm's law.
BA5
New Reader
10/13/16 2:36 p.m.
In reply to tuna55:
Here's a 1000V, 600A connector.
https://www.alibaba.com/product-detail/Anen-Industrial-Round-Connector-IC300-300A_60491688129.html
It's about 6-1/2" long and costs $99.
tuna55
MegaDork
10/13/16 3:00 p.m.
BA5 wrote:
In reply to tuna55:
Here's a 1000V, 600A connector.
https://www.alibaba.com/product-detail/Anen-Industrial-Round-Connector-IC300-300A_60491688129.html
It's about 6-1/2" long and costs $99.
The link says 300A. I was hoping for something other than an alibaba link. Granted it's smaller than I thought it would be. What's the size of the cable?
BA5
New Reader
10/14/16 9:47 a.m.
Here's an actual data sheet for one.
http://www.amphenol-industrial.com/images/datasheets/IDS-34%20ePower.pdf
It even mentions being intended for us in EV's. Again, they're only 200 and 400 A connectors, but note that rating is for continuous use. For 5 minute intervals you could go much, much higher than the continuous rating.
Cable would probably be just some sort of heavy jacketed welding cable. Again, for a non-continuous duty cycle you can push a lot more current though a conductor than it's normally rated for.
Interesting....so the limit to charging speed might not be how fast a charger can dump energy in, but how fast we're comfortable dumping energy in.
BA5
New Reader
10/14/16 12:34 p.m.
How quickly the storage media can accept the energy we're dumping in. I think that's really the current limitation.
I read an interesting analogy once: batteries aren't an energy storage tank, they're more like an energy storage sponge. A tank you can stick a hose in and turn on and it'll fill as fast as you can pump it in. A sponge has to soak it up and will slowly get fully saturated.
tuna55
MegaDork
10/14/16 12:42 p.m.
Absolutely batteries currently could not handle that fast of an energy input, but I stand corrected about the difficulties regarding transferring that energy. Apparently it's reasonable. Of course for mass consumption, it will need to be bigger than that and have a failproof connector, but it's there.
BA5 wrote:
Here's an actual data sheet for one.
http://www.amphenol-industrial.com/images/datasheets/IDS-34%20ePower.pdf
It even mentions being intended for us in EV's. Again, they're only 200 and 400 A connectors, but note that rating is for continuous use. For 5 minute intervals you could go much, much higher than the continuous rating.
Cable would probably be just some sort of heavy jacketed welding cable. Again, for a non-continuous duty cycle you can push a lot more current though a conductor than it's normally rated for.
I would have expected 5-10 minutes to be "continuous". It is when we're talking about full throttle What would you consider to be the minimum time to be considered "continuous" in the electricity world? I'm just curious, different industries are interesting.
BA5
New Reader
10/14/16 1:36 p.m.
Continuous means when the temperature of the conductor stabilizes. The temperature of the conductor needs to stabilize below certain temperatures, like below the annealing temperature of copper, or below the service temperature of an insulator it's in contact with, or if it needs to be handled then below some handling temperature. It takes several hours for a conductor temperature to fully stabilize.
BA5 wrote:
How quickly the storage media can accept the energy we're dumping in. I think that's really the current limitation.
Definitely right now it is, but I'm thinking in the future when we have batteries that can take a full charge in 5 minutes or something like that, what will become the limiting factor.