Cheaper and more efficient just to run contact wheels over electrode patches on the road. Self driving cars should be able to align with contact regions and feedback interlocks can ensure the power is off unless a moving vehicle is passing by. You might even be able to use conductive structures in the main tires.
Induction methods not only have efficiency problems but are like to be order(s) of magnitude more expensive to embed in the road. You need resonant coils and reflectors, careful alignment, high current pulses modulated to track moving cars - far more complex than an embedded conductor path with safety interlocks.
Main drawback of contacts is likely to be in northern regions subject to snow.
I don't think swapping would work too well as someone would inevitably get stuck with a dud battery that won't get his car to the exchange station. If I were an operator of an exchange station, I wouldn't want the dud either. Years ago I bought a brand new full acetylene B tank. Since it takes a long time to recharge these tanks, the practice is to go to a depot and swap for a full one. One day I got stuck with the last rusty old tank. Now nobody will take it in exchange accusing me of neglecting it. As a footnote, the acetylene B tank has been around unchanged since the 1800s judging by the one on display at one welder supplier. Unlike oxygen tanks that need to be regularly pressure tested, these tanks have no rules regarding inspection.
Unfortunately, neither race track handling tests nor safety crash test results agree with highway fatality statistics.
The Insurance Institute's website www.iihs.org has both sets of data. Driver death rates http://www.iihs.org/iihs/topics/Driver-death-rates tell quite a different story from the crash tests.
A most glaring example of the real world not following theory is in the April 17, 2007 Status report, which showed the safest vehicle on the road at the time to be the Chevy Astro van as based on driver deaths per million registered vehicle years. This van, virtually unchanged in design since 1985, which came almost dead last in crash tests, braking tests, and handling tests proved to be the safest vehicle on the road with an overall death rate of 7 per million registered vehicle years!
In comparison, Mercedes E class was 14, Ford F150 was 118, Ford Excursion was 115, Chrysler 300M was 115, Dodge Neon was 161, Volvo S40 was 89, VW Golf was 45 and on and on. Overall, large mini vans as a group were 66, proving the old design almost ten times safer than the newer ones.
Since contractors drive a lot of Astro vans pretty hard, overloaded and poorly maintained, its primitive design must hide some life saving secrets.
In science and engineering, when a theory bears no resemblance to the real world, one throws out the theory and starts again. A good place to start is to do a careful analysis of the Chev Astro van to figure out why it did well and change the crash and handling tests based on the results to more closely resemble the real world. Once this is done, new designs can be expected to be significantly safer.
Perhaps one secret to the Astro van is its lack of distracting electronics and straightforward controls, not requiring one to take one's eyes off the road. At any rate, when it comes to vehicle safety, the only thing that counts is the death rate on the road. Let me repeat, for all you engineers out there, this isn't a time wasting endeavor, but is a matter of life and death.
The inductive-charging scheme wirelessly beams power to receiving coils on an electric vehicle. More specifically, a coil built into an electric vehicle will pick up an electromagnetic pulse as the EV runs over a copper pad buried in the ground.
So, if we bury those pads on streets, yeah, you probably won't have to go to a refueling station!
Lithium Ion batteries are only "toxic" if they burn in which case they do release toxic chemicals. On their own they are considered non-hazardous waste and can be put into a land fill.
There are also many lithium ion chemistries and their potential for catastrophic failure varies considerably. Your typical cobalt electrode lithium ion cell has the potential for thermal runaway if mechanically damaged or through manufacturing defect. LiFeP04, on the other hand, is fairly immune to abuse.
That 400V "cage" requires obviously a positive and negative connection in order to be a shock hazard. I am not saying a shock hazard is impossible, just the likelyhood of an isolated power source becoming a shock hazard is remote. Even if one of the power leads shorts to the metal body, where would be the return path for a shock?
- Vehicles like the Tesla-S have ranges and others likely with swappable battery packs will have ranges of 250+ miles or on the order of 1/2 to 1/3 of the majority of todays cars.
- You do not need to store a days worth of batteries, only enough for the (Peak car rate) / (Charging time). If your charging times are on the order of 60-90 minutes, then the storage will be reasonable.
- Battery swap may be the exception, not the rule. Most of the time you will recharge at home, work, etc. Your interstate comment is correct. It is for long haul trips that the swaps will be needed.
Most of the posts I would agree with, but with the following caveats:
1. Gas vs. Toxic chemicals - Most newer cars have Li-ion batteries. Though they are the best bang for the buck these days, they are also an environmental disaster. Very toxic So, being marred by burns cause by gasoline, vs. dying a horrible death from toxic poisioning - you pick.
2. So you're driving around in this big battery in a metal car. Hmm, get in an accident, and something shorts out - you think EMS will have the necessary gear (rubber insulated gloves) to exricate you from your 400V DC "cage" - Hmm. . . Think about it next time you take your Pirius for a drive in the country side. . . Maybe in the big city you'd survive. . .
The one surprising note: Given that most vehicles (especially Tesla) have to be re-designed specifically to be E-cars, to get the crash rating they do at this point in their "life" is truly amazing. Hopefully, in 10-20 years, "all" cars will be much safer. Of course, that depends much on the driver, which is still the weakest link in the chain. . .
Whatever happened to fuel cell? Chrysler worked on them years ago (even had a F-1 car IIRC) - but there's not been much to do. . . Sure, talk about safety here - but where are all the NASA engineers? How about a "next-gen" fuel cell: Pour in water, get power out, emit only water/steam. . . Now THAT would be truly wonderful.
And while were at it, can we ditch the wheels and go verticle? Traffic these days is murder!
I look forward to the day when I'll never have to go to a refueling station. The whole idea of having to go somewhere to refuel is so 20th Century. IMO it's like having to walk to the post office to pick up your e-mail.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.