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Captain Hybrid
Slideshow: Electric Car Batteries Get Bigger
2/10/2012

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The electric DeLorean's battery bay houses the vehicle's electric motor and half of its battery pack.   (Source: DeLorean Motor Co.)
The electric DeLorean's battery bay houses the vehicle's electric motor and half of its battery pack.
(Source: DeLorean Motor Co.)

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iturner
User Rank
Iron
Energy in - energy saved
iturner   2/25/2014 5:54:44 PM
NO RATINGS
I think there should be some kind of metric that compares the incremental cost to build an EV, (in terms of oil/energyequivalents), to the savings in the cost of energy over it's life.  I suspect that this would be a small and possibly even negative number for most EVs today and probably for many green energy projects. Note that as energy costs go up any savings do not increase significantly since the cost of making the vehicles and batteries will be higher also. Finally, a proportion of the cost savings today is really just the difference between the delivered cost/watt of coal generated electricity and the cost of a watt produced by a gasoline or diesel engine.

 

William K.
User Rank
Platinum
Re: electric vs gasoline power
William K.   7/22/2013 8:27:05 PM
GeorgeG, I keep hearing that statistic about burning coal and I wonder about where it comes from because nobody except those who wish to attack seem to use it. So where are these poor folks dying and what is the actual mechanism of their demise? I realize that coal mining is a dangerous profession and in China much more so. Or is thgat statistic 9one of those numbers invented by somebody who claims to b able to predict reality based on a very small set of data? That would be my guess, based on the general hysteria that goes along with those folks.

 

Dave Haynie
User Rank
Iron
Re: Electric car batteries. Larger.
Dave Haynie   7/22/2013 10:14:26 AM
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This is SOP on Toyota-style "full" hybrids. There are two motor/generators. The smaller one revs the ICE up to 1,000 RPM before starting it, which is what allows the ICE to shut of at stops or while coasting. There's no mechanical neutral, but if both motors are off, the ICE puts no load on the drivetrain. In fact, there's a special "B" mode on a Prius transmission to allow the ICE to drag as an "engine brake", since ordinarily, it does try to coast when conditions permit.


Once going down a steep mountain in North Carolina, I drove for over a half hour without the ICE coming on once, in the 35-45mph range, and wound up at the bottom will a full battery.

Dave Haynie
User Rank
Iron
Re: Batteries are far ffrom ready.
Dave Haynie   7/22/2013 9:43:56 AM
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If you're proposing the "nuclear batteries" (RTGs, radioisotope thermal generators) used in spacecraft like Curiosity, I agree about the "can't be used to make a bomb" part only to a small extent... you can't make an A-Bomb or an H-Bomb. But a couple of these would make a dandy dirty bomb. The one on Curiosity uses Pu-238, which is the most effective material; Sr-90 is also an option, though with a lower power density (actually higher in pure form, but it's super reactive with water and oxygen, so it's always used in some compound form, like strontium flouride. And even better dirty bomb potential -- Sr-90 is a bone seeker, and the most dangerous component nuclear fallout.

These batteries are a pretty simple concept... the hot nuclear material is surrounded by thermocouples, which turn a temperature gradient into electricity. The problem is efficiency... thermocouples are always below 10% efficient, to date.

You'll see about 90% of the original power level from the cell after 10 years, about 50% after about 90 years (87.7 years, the half life of Pu-238). They don't last forever. The power density is about equivalent to Li-ion cells.. about 0.57kW per kg. The fact it's useful for a thermal battery is relatively rapid decay. Sr-90 has about 1/3 the half-life of Pu-238, though it's cheaper to make.

Of course, Pu-238 is also extremely rare. NASA bought a total of just over 16kg from Russia, but Russia has stopped making it. The DOE is gearing up to make 1.5kg per year in the USA. Without this, we stop exploring space much beyond Mars. And there is no way in the world you'd really want large amounts of Pu-238 rolling around on the highways. Take a small BEV like the Nissan Leaf, which is driven by an 80kW motor. So to back this motor, you'd need 140kg of Pu-238.  Even if you decided that the thermal battery only needed to actually supply 1/4 peak power (perhaps draining it constantly into a conventional battery or some advanced supercapacitor), that's still 35kg or Pu-238 per vehicle. Again, this ain't Mr. Fusion. The spacecraft powered by these use a few hundred watts.. nothing like a car.

Based on the costs of making Pu-238, a 50W supply runs about $1,000,000, so your 90-year Nissan Leaf would cost $400,000,000 - $1,600,000,000 for the power supply, and it would take the USA 23 years just to make enough Pu-238 for one car. Strontium is an abundant element, but Sr-90 too is manmade; with a 28.8 year half-life, you don't find it in nature. It's a more plentiful byproduct of nuclear fission than Pu-238, but not dramatically so.


There are actually Tritium batteries available commercially... Tritium has a 12-something year half life. These run in to the thousands for a battery that put out power in the microwatt range, but again, for a really long time if you only need a few microwatts... you don't even want to go there in terms of cost for a BEV... even a cellphone battery would run $20 million on this technology. Today. These are actually "beta batteries"... they're capturing the electrons released due to beta decay, not using thermal means. M

But any old EV is likely to have enough power for your house. The average home in the USA has 100-200Amp service at 220Vac, which is only 22-44kW, and you're rarely if ever going to run your home at peak.

Dave Haynie
User Rank
Iron
Re: Batteries equal brute force=exercise in futility
Dave Haynie   7/22/2013 8:58:02 AM
NO RATINGS
The point most people miss in the whole discussion -- a Toyota style hybrid simply lasts longer, and has a much lower cost of maintainence. The three-phase AC motors will outlive the life of the car. At least coming on 200,000 miles on my 2003 Prius, the traction battery shows every sign of doing likewise... and I'm also approaching twice the useful life of any other car I've owned. There's no transmission or conventional starter motor to wear out. The ICE is always run at optimal efficiency, far lower RPMs than in a conventional vehicle, so it lasts long. My first tuneup was at 120,000 miles.


I agree that full BEVs are a far tougher nut to crack well, given the lack of fast charging, widespread charging infrastructure, current battery power to weight ratios, and battery life when run full cycled (hybrids only use a 40-60% charge/discharge cycle, which keeps the batteries going indefinitely).

But progress has already been significant, and it's not such a bad thing that this is a generational transformation. After all, at current personal vehicle use rates, the electric power output of the USA would need to double for everyone to go BEV. And that's before you consider commerical and industrial vehicles.

danharres
User Rank
Silver
All-Electric Vehicles Don't Make Sense
danharres   5/7/2013 10:25:41 AM
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The great thing about internal combustion engines is that one of the two reactants needed to create mechanical energy, namely oxygen, does not have to be stored in the vehicle - it's in the air.  Battery power, on the other hand, requires that both reactants be stored.  The result is the huge payload of batteries that must constantly be transported in the vehicle.

fiallok
User Rank
Iron
Re: Batteries are far ffrom ready.
fiallok   3/22/2013 1:09:27 PM
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 don't forget the waste heat which is a huge component of global climate change and the possibility of of a rupture, the potential for the crazies to make a dirty bomb if the radioactive material  becomes readily available

GeorgeG
User Rank
Platinum
Re: electric vs gasoline power
GeorgeG   3/21/2013 10:05:47 AM
"the burning of coal which is indirectly responsible for thousands of deaths annually" - that's a low ball estimate and some are not so 'indirect'. So many people run off on this tangent - the problem is not the electrification of vehicles: the problem is dirty power generation and an industry that has been allowed to compete with exemptions to many environmental laws that othe industries must meet - even the auto industry. The current configuration of the US power industry is a choice not a necessity - there is always the opportunity to make other choices; there is even the opportunity to use coal much more efficiently and cleanly but then you have Republican fanboys that go entirely the other way proclaiming that the EPA and/or the environmental regulation should be scrapped. As it stands you have smog in Yosemite and Grand Canyon. Burning fossil fuels in motor vehicles is a very inefficient means of converting latent energy into motion: there are ways to improve on this but as you can see from comments by tucsonics and many others, it's all about what's cheapest and ignoring the fact that technology always rides an experience curve with the cost of a capability declining in proportion to cummulative sales - thank heaven for early adopters who choose value over cost. Dirty power is a choice made by every American: compare the reduction in emissions and improvements in fuel economy achieved by auto manufacturers as compared to the fossil fuel power sector over the last few decades - only one has made great  advances; there is no excuse.                      

jackiecox
User Rank
Platinum
Re: Batteries equal brute force=exercise in futility
jackiecox   6/12/2012 7:42:15 PM
Charles Murray
User Rank
Blogger
Re: Batteries equal brute force=exercise in futility
Charles Murray   6/4/2012 4:43:37 PM
NO RATINGS
I completely agree with you, Tusconics. Big batteries get depleted, and then you're driving around with a 1,200-pound dead battery in the back, which wastes energy. The wild card in all this is the emergence of government mandates. Automakers are going through this exercise because they fear the imminent 54.5-mpg mandate, which is supposed to take effect in 2025. I can't provie it, but I think a lot of people in the auto industry are waiting to revisit the 54.5-mpg topic in 2018, and maybe ratchet it down a bit.

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