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Developing Battery Replacement Infrastructure For Electric Cars
FathomIT sends in a NY Times profile of Shai Agassi, owner of a company named Better Place, who is working to build the infrastructure to support large numbers of small-scale charging spots for electric cars, as well as fast, automated battery swap stations.
"The robot — a squat platform that moves on four dinner-plate-size white wheels — scuttled back and forth along a 20-foot-long set of metal rails. At one end of the rails, a huge blue battery, the size of a large suitcase, sat suspended in a frame. As we watched, the robot zipped up to the battery, made a nearly inaudible click, and pulled the battery downward. It ferried the battery over to the other end of the rails, dropped it off, picked up a new battery, hissed back over to the frame and, in one deft movement, snapped the new battery in the place of the old one. The total time: 45 seconds."
Swappable batteries will stop being cool as soon as the iCar comes out, anyway.
I'm one to keep a car till it falls apart. I feel this might be a problem with a hybrid of sorts due to the battery life. I heard it rumored the battery replacement is a significant cost of the vehicle...not something I would want to deal with I don't think...
Even a stopped clock gives the right time twice a day.
When you buy a litre of petrol, it should take you a set distance. When you fill up on LPG, Hydrogen or whatever, the same is the case. There is one important factor in the battery swapping idea that is fundamentally different though. Batteries degrade and can at times do so in strange ways.
Say, for example, that someone has let a spare battery sit idle for some months, charges it up at home and, knowing it's rubbish now, goes off to the nearest fuel stop to change it. Automated process charges it, dispenses it. You get stuck on the freeway after only a few kilometres.
If you stick to your own battery, then you can tell the condition of the battery over time. No dramas. Even with thorough checking though, battery changing services have a lot of questions in regards to reliability and liabilities if it is to work. Who picks up the tab for a dead battery? The owner or the 'fuel' vendor?
sudo mount --milk --sugar
In future news, Apple announces the release of their new, sleek iCar! With touch-screen capabilities, smooth acceleration, and lots of eye candy. Better Place, however has been stymied by the fact that the iCar's batter is sealed and hidden inside of the frame of the car, and cannot be swapped out. Millions of iCar fans can only hope to travel 250 miles and struggle to find their lost iCar charging adapters, while Microsoft and PC-maker made Windows-Roadsters take advantage of the Better Place swapping program.
gCar and kCar enthusists, while having the first electric cars out there can be seen at the side of the road, can be seen hand-wiring in their own D-cell battery replacements every 100 feet, soldering gun in hand.
The only problem with the Better Place swapping program is that you have to hunt all over the place to find them, answer a stupifying amount of questions to gain access and then accept a GRA (Genuine Roadsters Advantage) tracking device/kill switch to make sure that you don't violate the TOS. The gCar and kCar include a Battery Manager that finds the nearest Power Stop for you, guides you there and charges the car for you when you arrive.
sudo mount --milk --sugar
I was wondering when this would come up. I know way (way) back in the day when they were first almost seriously talking about electric cars, they seemed to indicate swapping the batteries.
A battery swap makes a LOT more sense than recharging in the vehicle. Waiting for an hour or more for batteries to charge would really ruin a road trip, if you had to do it every 300 miles or so. Every 4 hours of drive time on wide open interstates would become 5 hours or more.
Think of a cross country drive. 2500 miles between two places I've driven between a few times takes 41.6 hours, when average 60mph. I could usually average 60 by only stopping to buy fuel and go to the bathroom (same stop). Ya, even those stops really ruin your average speed. That would make it a 52 hour drive instead. I'd rather be at my destination for those 10 hours, rather than still driving. :)
But, there would be other considerations. Does the battery swap location have sufficient batteries to handle peak demand? Like, on a holiday weekend, when everyone's driving electric cars, and they're all going out of town, a swap/recharge facility may be swamped, and not be able to have charged batteries fast enough.
I worked in a warehouse for a while. The battery room not only recharged, but rebuilt the batteries as needed. All the heavy equipment in the warehouse used the same batteries (more or less). We had moments, particularly towards the end of the day, where equipment was being run hard, and they had simply run out of charged batteries. It was simple enough to move people over to doing things by hand if they couldn't use the heavy equipment. In the case of a car, towards the end of a busy day, customers aren't going to be satisfied with "Sorry, we're out of charged batteries. They'll be ready in 2 hours, but we close in an hour. Come back tomorrow, or plug in for the next few hours and charge it yourself."
They will also have attrition to contend with. As batteries fail, they will be pulled out of service. This is a good thing as far as the car owners are concerned. We have the same situation with propane tanks right now. They have a life, where they must be reinspected before use again. There are plenty of places that take your empty tank, and hand you a full one. I've been BBQing for many years with propane, and never had to buy a "new" tank. I have been refused a full tank because they didn't have any though. It's not pleasant to hear that I can't BBQ when friends are already coming over, because I can't get a full tank. Luckily, I've always been able to find another location with available full tanks. It gets tight on holiday weekends though.
Serious? Seriousness is well above my pay grade.
No indeed. It's called a staging-post. It's where a stagecoach would stop, and rather than waiting until the horses were fed and watered and well rested, they'd simply drop off the horses there and take fresh horses for the next stage of their journey.
Real Daleks don't climb stairs - they level the building.
Ah, but which battery did they replace? The Prius uses a small Lead-acid battery for the gas engine in addition to the big main NiMH battery pack used for the electric motor.
Depending on the environment, the Lead-acid battery can need regular replacement. The NiMH battery should not need replacing unless it was defective.
Ah, the "long tail" argument -- that old zombie of electric vehicles. No matter how many times you knock it down, it comes coming at you.
Power plants are more efficient than internal combustion engines. While the engine itself can *peak* at a fairly high effiency number (percentage-wise, as much as the upper 30s for gasoline and mid 40s for diesel), that's not what you get in practice, as that's only for a narrow torque/rpm range. In practice, you also have parasitic and braking losses. Total well-to-wheel consumption is about 14% for gasoline and 17% for diesel. Engines are slowly getting more efficient, but at the same time fuel production is getting *less* efficient as we have to move more to syncrude and deepwater (think tar sands and outer continental shelf). Power plants, however, are only getting more efficient, and fairly rapidly. Well-to-AC power for an average coal plant in the US is 32%, and natural gas is 42%. Those numbers are higher in Europe. Next gen coal plants are over 40% and next-gen natural gas 60%-ish. Coal, the dirty fuel, is only half our generation. After that is natural gas (a very low carbon fuel per unit energy) and nuclear (a near zero carbon fuel). After that is hydro and then wind (both near zero carbon). There's also a smattering of other generation methods such as diesel, solar, geothermal, and biomass that combined make up a couple percent of our grid.
AC power transmission in the US averages 92.8% efficiency. Your typical EV charger is 92-93% efficient (rapid chargers, closer to 90%). Li-ion batteries are generally 96% (rapid charge) to 99% (trickle charge) efficient. Electric drivetrains average 85-90% efficient (they can peak at over 95% on a really good one). And regen braking is pretty much standard. So your net well-to-wheels efficiency is very high, and your carbon is low. And while petroleum gets dirtier, the grid gets cleaner. Last year, for example, over 2/5ths of our new power that went online was wind, and most of the rest was natural gas.
But wait, it gets better. Most EV charging is done at night, on a timer to take advantage of low off-peak rates. Coal power plants take a while to ramp down. In the process, you can sometimes get what's called "spinning standby" -- power generation capacity that's literally wasted because there's nothing to consume it. This mainly occurs in the evenings. Charging off of it is literally free of environmental consequences. Furthermore, most power plants run more efficiently at higher capacity. Evening out the day/night peaks makes the grid as a whole more efficient.
Perhaps having a DOE study conducted at PNL explain it to you will help. Here's a graph comparing the efficiencies of different drivetrain options, and here's one for emissions.
Can this zombie of a notion please accept its headshot and stay down?
There's only one thing I hate about Halloween, which is...
happily, there is a very good solution. ultracapacitors, sometimes known as ultracaps. they hold more than batteries, weigh an order of magnitude less (sometimes 2 orders)
That's pure, unadulterated BS!
The best ultracaps have less than 10% of the energy density of a rechargeable battery: 30Wh/kg as compared to 300Wh/kg for LiIon and 370Wh/kg for zinc-air. To put things in perspective, the gasoline energy density is 12500Wh/kg, 30 times better than the best commercially available batteries...
Ultracapacitors cannot even begin to compete with batteries as the primary energy storage, their role is limited to storing regenerated energy (e.g. from braking).
Imagine if the automobile industry was just starting today, or perhaps was always electric cars but we had to switch away from it (say, discharging batteries were found to cause cancer), just imagine what all the nay-sayers would be saying if someone proposed a system where the average moron could just go to any corner service station and start pumping extremely flammable/explosive liquid that has percent-levels of known highly potent carcinogens (note surface water needs to be in the part-per-billion of such compounds to be considered safe). Imagine the liability of a bunch of grease monkeys managing storage tanks with 1000s of gallons of this toxic stuff.
Puts things in context. Anyone can come up with good reasons for not doing anything. The key is selecting the best of an array of imperfect choices.
You need to give a bit more justification than 'it can be done' if you want people to take you seriously. RTGs have a terrible power to weight ratio. The best one in the article you linked to is around 0.06W/Kg just for the power source. Let's assume that this is a terrible design and we can improve on it by an order of magnitude, giving 0.6W/Kg. Now let's assume that the car and passengers weigh nothing.
The formula for kinetic energy is E = 1/2 mv^s. By dividing both sides by a time factor, we get P = 1/2 ma^2. Divide through by mass, and we get P/m = 1/2 a^2. Substituting in the value from the RTG output (Power / mass) we get 0.6 = 1/2 a ^2, or a = sqrt(1.2), approximately 1.1 metres per second per second.
Remember that this is for a massless vehicle with an RTG with an order of magnitude higher power output than any that anyone has built so far. It would take a little over 26 seconds to reach 60mph. Even a fairly rubbish battery powered car can reach 60mph in under 10 seconds - this hypothetical RTG-powered car would take 13 seconds to go from 0-30mph, which is a dangerously low acceleration for most urban roads. And, note, that this is assuming that the (massless) engine is also 100% efficient. In the real world, you would be lucky to get a tenth of this acceleration, so you'd take more than 2 minutes to go from 0-30mph. Not really a very practical solution.
RTGs are great for applications where they do not have to move (or, as with spacecraft, where the motive force comes from elsewhere), or which have a constant power drain. They are incredibly badly suited to automotive applications. Betavoltaics, as I said, are potentially a viable solution, but RTGs are not. Just because something can give 40W for a number of years does not make it a good replacement for something that gives several kW for a few hours. Sure, the energy output may be the same or greater, but the power output is much lower.
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