RTGs don't provide enough energy to power a car. You're looking at 1kW electrical maximum. The one on mars lander Cruiosity provides about 100W electrical power nominal.
But the main reason is that people are stupid and some would inevitably pull theirs apart and contaminate their surroundings with pretty nasty radioactive material. There's no engineering or practical reason why we wouldn't have RTGs for a heap of civilian applications, the reason is that people suck.
NASA is currently working on a 'micro' scale fully self contained fission reactor for the next mission to meet the higher power demand of the craft.
That's only about a factor of 10 from being useful. If you have a 10kW battery, or 10 1kW batteries, you can use that to charge a Lithium battery for a day which will get you 100 kW for 2.4 hours per day, which sounds pretty damn useful for typical urban commuter use.
I was going to reply saying I don’t want tiny pieces of radioactive material all over my house/globe, but then realized I have a tiny explosive (battery) in my hand and littered all of my house.
People freak out when they hear "nuclear" and "radiactive", but there are 3 types of radioactivity.
Alpha and low energy beta emitters such as those used in nuclear batteries are not dangerous at all if shielded properly. In fact they are MUCH easier to shield than shielding a Lithium battery from the possibility of fire.
It's gamma emitters that are much harder to shield properly.
> Alpha and low energy beta emitters such as those used in nuclear batteries are not dangerous at all if shielded properly.
Read: if there is no feasible route for them to be aspirated, ingested, or get into your eyes.
Making a new device that has this property seems to be a pretty straightforward problem that we know how to do. The problem comes when an old device has been damaged or destroyed kinetically or via pyrotechnics.
It's more complex than that in case of a failure, because ingesting an alpha or beta emitter - directly, or through the food chain - is going to be dangerous to health. Can't exactly line your intestines with lead.
And while giving RTGs to general population isn't the brightest idea, it's stupid to consider these issues as a wholesale dealbreaker for nuclear technologies.
The danger depends somewhat on the type of radioactive material used and how much of its radiation is alpha, beta or gamma, it's toxicity (independent of its radioactivity, plutonium is one of the most toxic substances in existence), half-life etc. But really, the main problem with proliferation of RTGs is dirty bombs. If you used them in cars or homes you can imagine the kinds of issues you might have with a serious collision or wildfires.
Having lots of them around, means still lots of radioactive accidents, because of normal accidents.
And to actually power your car, I believe they have too little power output, so they would only make for a expensive and dangerous car batterie, but one you do not have to charge.
Use the nuclear battery to charge a secondary lithium battery, and that is the battery that the car actually uses to drive.
Considering cars are typically used for <10% of the day, the battery's static output wattage only needs to be about 1/10 of a car's operational wattage.
Basically when you get home and park your car, it just starts charging on its own from its nuclear battery. Optimize the nuclear battery size to minimize excess. If that battery gets full, release the excess as heat to the ground or sky, and also use some of it to maintain the lithium battery at optimal temperature. It will be only 1/10 of the driving wattage, so it will be much easier to do something with it.
Or plug in the car when you get home and it can power a good fraction of your home.
