There seems to be two types of limitations (among many) to switching to electric cars. One is the total electricity supply, and the second might be the transmission grid (though the second would be variable depending on where you live). Has anyone looked at what proportion of electric cars the US could sustain with present infrastructure?
I was thinking about the supply of lithium…if lithium ion batteries are the solution, how much lithium is there? As far as I know, lithium is a pretty common element-is there enough or 100’s of millions of battery packs?
The grid supply for this would not be a significant problem, because most of the recharging of electric cars would take place at night, which is off-peak time for the electric grid. Currently, the electric companies shut off some generators are night, because of the reduced demand. When enough electric cars are present, the utilities would just keep some of them on at night. Presumably, there would be a point where the utilities would need additional generators to supply this, but by that time there might be a lot of excess oil/gasoline that could be used for electrical generators.
Even with current infrastructure, there’s no practical limit, since most cars will be charged overnight, when electricity usage is currently far below peak. This will, of course, mean that more electricity total will be consumed, from power plants operating at closer to full capacity 24 hours a day, but most electricity in the US comes from coal, hydroelectric, or nuclear (in that order), and we’ve got plenty of all three for centuries or more.
Back o’ the envelope calculation for how far the current spare energy supply would go:
Total generator capacity for the US is about 1 terrawatt. Total consumption is about 10 terrawatt hours per day.
If people somehow manage to time the charging of their electric cars to keep the power stations running at full capacity, that’s gives the remaining 14 terrawatt hours per day to charge electric cars. I’m going to round that down to 10 TWh each day to [del]keep the math simple[/del] account for transmission bottlenecks.
Now, how far will that go? This little car is apparently the most prevalent electric car right now. It goes 50 miles on a 9.6 kWh charge. For simplicities’ sake again, let’s say that it gets 5 miles/kWh. That 10 TWh of spare capacity could run two billion miles of driving each day. Each year, you could get 730 billion vehicle-miles.
Total traffic volume in 2008 in the US was 2,921 billion vehicle miles. Of that, 730 billion vehicle-miles is about 25%.
This is completely ignoring any transmission issues, and assuming that all spare capacity could be used to charge electric cars is pretty optimistic. Still, you could theoretically replace a quarter of all the driving in the US with electric cars. Even if that was only an eighth or a sixteenth once all was said or done, that could represent a much larger fraction of city driving. If I’m reading this chart correctly, in 2008 the total traffic volume on city roads (not interstates or other highways) was 428 vehicle-miles.
thanks lazybratsche for that as I have never seen those sort of figures before. So probably a significant number, but not all.
FWIW, coal, natural gas, nuclear, and hydro.
I’m confused - did you divide when you meant to multiply? Using your numbers: 10 TWh is 10 trillion watt-hours, or 10 billion kWh. If I can get 5 miles per kWh, I should be able to 50 billion miles on 10 billion kWh, not 2 billion. Which is 18 trillion miles a year off the country’s spare electrical capacity.
Yep, my mistake. Huh. I guess that goes to show how efficient electric cars are… 5 miles/kWh * 33.4 kWh/gallon gasoline = 167 miles/gallon. Of course, that number will go down when you have an electric car that can carry more than two people at highway speeds.
So: revise that answer to “more than enough spare energy capacity”.
You may well be right-- but wouldn’t that sort of defeat the purpose of switching to electric cars in the first place? 
No, because you get a lot more efficiency and a lot more clean by burning hydrocarbons at 1000 plants than 200,000,000 individual vehicles.
As for the grid charging cars during off-peak times, why do people always assume this? I’m going to want my work place to provide a metered power source so I can actually get home. Supposing that that’s not available, or that ranges are extended to be more useful, then I’m still going to plug in my car to recharge it the second I get home, just like my iPod and cellular phone. Of course, I suppose we could add the ability to program the car to not draw current until midnight, but then it would involve the cooperation of everyone to do so, and I’d probably not do so because I’d want my car charged and ready in case I decide I have to head to the country when the aliens start attacking.
Apparently, it’s not a common element at all. Leastwise in quantities that are economic to recover. See these two Channel 4 (UK) articles.
Frankly it’s because there isn’t nearly as much spare power during peak demand. Hell, parts of California didn’t have enough capacity for normal demands a little while back.
The easy way to get everyone charging off-peak is to just change the pricing scheme, and then let people program their chargers so they use the power when it’s cheapest. If they want, they can pay extra and charge up during the day. Besides, the current crop of electric cars are really only suitable for short-range, low-speed driving. In denser cities a 50 mile range would be plenty for a one-hour commute in the morning and evening, and a few quick errands at the end of the day, so you wouldn’t necessarily even need to charge up at work.
Ah, yes… time of day meters and rolling blackouts. Since we have neither, I overlooked them. The TOD meters would indeed tend to coerce correct behavior. :smack:
Power is cheaper at night because there’s less demand. That price advantage would end when lots of people start charging their cars at night.
The DOE concludes that the current
Of course there are regional variations and we do not expect all vehicles to become grid-powered overnight if ever.
“Smart grid technology” would help assure that vehicles were charging during demand troughs and in a related concept the utilities would love to see that integrated with vehicle to grid (V2G) capacity so that short spikes in local demand could be met with less need for spinning reserves while still leaving a vehicle at a desired charge level upon its disconnect. The question is making that worth the vehicle owner’s while. The stimulus package helps fund this.
Wasn’t that mostly due to Enron’s naughtiness?
Quoth Una Persson:
Huh, I hadn’t realized that natural gas had gotten so big. Those are primarily used for load balancing, I’m guessing? Still, we’ve got lots of natural gas, too, so I think my point still stands.
Quoth dropzone:
Ah, yes, nobody ever goes there any more because it’s too crowded. Eventually, the price would reach some sort of equilibrium, at whatever price point would be necessary to keep the grid as balanced as possible.
There is a lot of natural gas out there, and much of it comes as a byproduct of oil extraction. In Soviet Russia, mandates to produce more oil meant that Siberian refineries/oil wells didn’t bother finding ways to tap natural gas and they burned it all off. The amount of gas burned off as a byproduct could have powered the entire country if they’d had the ability to move it where it was needed. In the early 1900s, some of the towns in Texas started using natural gas for the same reason - someone had to burn it, and they decided to pipe it home and burn it for heating and cooking.
Quite true. I already get a price break on electricity during the summer because I let the electric company install a remote switch they can use to turn off my air conditioner for 1/4 of each hour during peak times.
Timer outlets that recharge only during the middle of the night could be easily installed, or remote switches controlled by the utility – these would help balance the load on the grid.