You’re kidding, right? These guys are suggesting using them in pacemakers, and you’re worried about electric cars? 
I’m not “worried.” I think that it’d be great if they were used in electric cars! Imagine only needing to “fill” your car up once every 10 years! I just don’t think that the enviroweenies will allow it, considering they get bent out of shape about a few picograms of radioactive material being sent into space, imagine the kind of strokes they’d have if every SUV on the road was powered by these things.
Err… that’s exactly what I meant. Wouldn’t it be much worse if people were wandering around like portable nuclear bombs?
On second thought, I guess car-sized batteries would probably pack more of a punch. And would probably be more of a security issue… shrug
There have been hundreds of nuclear pacemakers implanted since the 70’s. It is something funeral homes check before they cremate someone.
And don’t forget the kid that came “this close” to building his own nuclear reactor by using smoke detector batteries. The small amount stuff with weird names like “Americurium” doesn’t scare people. It’s when you get into the mass quantities, or use in non-everyday items like space probes, where people begin freaking out. IIRC, there’s been a couple of threads where people have had a hard time understanding that depleted uranium shells weren’t radioactive.
Tuckerfan, what makes you think depleted uranium isn’t radioactive? And what makes you think a beta battery large enough to power a car would ever fit on a car? This isn’t some revolutionary superbattery, it’s just a vast improvement in an already existing technology, increasing its miniscule trickle of current to a somewhat less miniscule trickle of current.
Depleted uranium isn’t radioactive enough to be considered a health hazard. If you want to consider things of extremely low level radiation to be “radioactive,” nearly everything out there is radioactive. And given that space probes can be much larger than a car, yet the RTGs are quite small, it seems reasonable to me that you might be able to stuff something like this in a car.
Cite? Natural uranium gets only 2.2% of its activity from U-235; depleted uranium has fully 60% of the activity of natural uranium.
Yeah, you could stuff it in a car, and it would run the radio and the instrument panel quite nicely; maybe even the headlights. But space probes are driven by rockets, and that little solar-cell-cum-battery ain’t gonna do 0-60 in under a minute.
Did you forget about this thread? It’s not exactly healthy stuff to play with in certain forms, but the biggest danger comes from the fact that it’s a heavy metal, and not the radiation.
Space probes use rockets to blast off from Earth, but use electromagnetic propulsion methods to add thrust as they travel through the solar system (along with gravity assists), saving chemical thrusters for things like orbital manovers. Cassini carries a mere 72 lbs of plutonium onboard.
In poking around, I can’t find anything on how much power Cassini generates (other than it has a 30 V electrical system), but I note that Voyager 1, using much older technology generates 470 W of power, using about the same amount of plutonium. Given that the average automobile engine weighs at least a couple of hundred pounds, you could easily double the amount of plutonium and still not come close to the weight of a modern engine. With an electric motor, you can scrap the weight of things like the cooling system, transmission, and alternator, if you’re converting a rear wheel drive vehicle, then you can scrap the weight of the driveshaft as well. That should give you plenty of wiggle room to stuff one of these things under the hood.
“Radioactive” doesn’t mean “stuff that can kill you instantly.” Depleted uranium isn’t as dangerous as some think, but it still contains isotopes that decay and emit measurable amounts of radiation. Therefore it’s radioactive. (And yes, so are cinder blocks and bananas, but that’s hardly “nearly everything”.)
The Cassini probe used chemical rockets to enter the transfer orbit, and hydrazine thrusters and gravity assist to get to the final destination. The RTGs are for powering the instruments and guidance systems, not propulsion.
Some newer probes use ion propulsion, but these are powered by solar panels. I don’t know of any probe that uses a RTG-powered ion thruster.
Cassini has three RTGs, each containing 24lb of plutonium and initially generating 285W each. So that’s a total of about one horsepower.
Here is a picture of a Cassini RTG. As you can see, it’s a lot more to it than just a lump of plutonium. Part of the reason is that RTGs convert temperature difference into electricity, so it needs a fairly elaborate cooling system. A 1-horsepower motor can probably move a cart carrying three of these RTGs plus a driver, but not very fast.
Voyager or Pioneer used an electron stream as propulsion. The idea being that while it’s only a tiny amount of thrust, it’s going 24/7, and thus is better than a chemical rocket. Totally impractical for things like orbital manovers, but sufficient for adding thrust while traveling between planets.
Electric motors have different torque outputs than ICEs, so comparing the HP between the two is a bit more difficult than saying it’s 1 HP vs 100 HP. I can’t find a decent online source at the moment, but the book I have on electric vehicles suggests a 70 HP electric motor for a Ford Ranger pickup converted to electric power, and about 500 lbs or better of batteries (20 6 Volt batteries). I think that GM’s Ev1 used something like 1000+ lbs batteries in it’s design.
Note that the Ford Ranger is simply a conversion, which retains the transmission and isn’t a ground up electric design like the Ev1, which didn’t have a transmission.
I’ll have to call for a cite on this, because I can’t find any. I recall Deep Space 1 was widely touted as the first probe propelled by ion thrusters. Some communications satellites use them for stationkeeping and attitude control as well, but my understanding was that they weren’t used in space until the past decade or two.
The standard engine for the Ranger is 145 horsepower, up from the 98-horsepower engine in the 1993-1997 model. So that’s not a huge difference.
Electron stream, not ion, which is about 1,000 wimpier or so than an ion stream, and danged if I can find any details on it. NASA’s site is a royal PITA to dig around on.
Yeah, but the book I’ve got indicates that the 70HP motor will offer better performance in terms of acceleration, than the original motor. Additionally, I under reported the battery weight of the thing. It’s actually 1,200 lbs of batteries. So, if 72 lbs of plutonium yields 470 W of power, then 1,200 lbs of plutonium would yield (roughly) 7849 W of power. At 10 times the efficiency, we’d get 78490 W out of the thing, at 200 times we’d get 1569800 W out of the thing.
Note, too, that the pick up conversion I mentioned retains the tranny for simplicities sake, and that a purpose built vehicle could dispose of a tranny altogether by using an electric motor which was reversable. The amount of energy stored by the batteries in the pick up is 26 to 29.3 kWh, but remember, that’s to give it a couple of hours operating time, the actual current draw during use is going to be much lower, so with something that’s going to be continuously kicking out power, like a nuke battery, you’ll be able to get away with a lot less juice.
I find all this talk about Plutonium, Americium and depleted Uranium amusing. Didn’t anybody actually read the article? These batteries are powered by Tritium gas and emit beta particles. Tritium is an isotype of hydrogen… the lightest element in the universe and Tritium is one of the safest radionuclides around because the beta particles that it emits cannot even penetrate human skin. You and everybody you know is exposed to Tritium daily… if you drank the stuff you’d probably be ok with maybe a SLIGHTLY elevated risk of cancer down the line. I’d rather throw back some tritiated water before I’d smoke any cigarrettes. These improved batteries have alot of nifty applications but not for high powered devices… maybe topping out at your laptop. (which would in itself be pretty cool… 10 years between charges :>)
Yeah, but it’s a nuclear battery, and the average idiot can’t seperate between the highly dangerous stuff, and the safe stuff. Remember, radium in watches isn’t dangerous to the wearer, it’s dangerous to the folks who licked their brushes to paint it on. And I don’t think that speculating if can be put into an electric car is all that unreasonable. Yeah, I realize that the batteries don’t have a lot of juice in them, but they’re small. How much juice would one of these things put out if it weighed a 1,000+ lbs like the battery packs of electric cars? The article doesn’t mention it and is that because the researchers hadn’t thought of it or is it because they checked and there’s just not enough juice behind them? The article doesn’t say.