I remember when I was discussing a story about fast-charging batteries with someone that there was the conjecture that this was the hurdle to getting electric cars on the road. And I realized it wasn’t — heat dissipation issues aside (charging a cell-phone battery is one thing, but trying to scale that up is quite another) — the real issue is how much energy you need and how quickly you can deliver it. Grid capacity.
Electric cars will travel a few km per kWh of energy, so a 350 km range takes about 100 kWh, or 3.6 x 10^8 Joules. The good news is that this is more efficient than gasoline, which lets you go about 1 km per kWh. A gallon of gasoline has a little over 10^8 Joules stored in it, so 31 mpg is about 50 km/gal, and that makes an electric car with the above specs about twice as efficient. But if I can pump a gallon of gas in ten seconds, that means my energy transfer rate is 10 MW. That’s about 3 orders of magnitude higher than standard electricity delivery.
It’s pretty clear that any electric solution in the near future is going to involve shorter-range vehicles, be they pure electric or plug-in hybrid, which you could recharge overnight.
Challenges to grow with electric cars’ sales: Aging grid needs to handle more power
When a Chevrolet Volt is plugged into a 240-volt outlet, it will use about 3.3 kilowatts of power, or about the same amount of power as a dishwasher or air conditioner.
Most people are already familiar with what can happen when thousands of air conditioners are plugged in and running at the same time during the summer: brownouts.
“The last thing we would want is for everyone to come home … and plug them in at 5 or 6 o’clock on a hot, muggy summer afternoon … when we are at our peak,” DTE Energy Chairman Anthony Earley Jr. told the Free Press in an interview recently.
US residential consumption is about 30 kWh of electricity every day; houses probably more and apartments less. Regardless, 3.3 kW for 8 hours = 26.4 kWh, which is a significant bump.
Government-restricted travel (Homeland Severity in airports discounted) foments riots. Outlaw CO2 and mandate crappy little vehicles sanctified by The Carbon Tax on Everything plus appropriate and appropriately growing user fees. Mission accomplished! Then electronic entry and exit portals plus real time travel monitoring (OnStar!) to “prevent abuse” and “assure a safe commute” (auto-levy moving violation citations). Shift focus from violent crime to political opportunity.
There are some misconceptions about batteries…I have a coworker who has a Tesla Roadster (and I got to drive it, very impressive!).
Regarding your comment that they’d have to be short range vehicles, there’s actually an issue of charge cycles that necessitates longer range batteries. A Li-ion battery can take about 500 complete charge-discharge cycles before it wears out. It’s actually a matter of throughput…if you discharge halfway each time, you get 1000 cycles. Therefore, if you have a car that has a battery that’s good for only 40 miles of driving, it’s not going to last long enough to be viable. So in order to have a reasonable life-cycle, you need to have a higher capacity battery.
It will certainly add substantial loads to the electric grids. However, you can take steps to mitigate the problems. Currently, people pull much more power from the grid during working hours than overnight. Chargers can be coordinated with the power companies if users are flexible. After all, most people only care that a certain state of charge charge is achieved before 7:00 in the morning. And if the car has a 200 mile range (the Tesla roadster’s is 240, IIRC), that provides several days of opportunity for most commuters.
Also, fast-charge technology is already feasible. A 10-minute recharge of an electric vehicle has been demonstrated by the company I work for. And fast-charging has been shown not to affect the life of the batteries.
My worry would be about fast charging infrastructure capacity and the peaky loads they’d experience. Imagine a society in which everyone almost exclusively charges their car at home, but then memorial day weekend hits, and all of a sudden everybody’s road trip necessitates repeated stops at a fast charge station (or perhaps a battery exchange program?). You now have fueling stations that hardly get used except when everybody needs them at once. It would really be feast or famine for the battery charging industry.
I think the grid mandates that they be used mostly for short-range trips in the near future. Your point about the battery capacity shows there are other market forces involved as well.