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It would take days to fully charge an EV from a typical RTG and there's no way an RTG could put out enough power to even keep an EV rolling on a flat highway at
by moftz 5y ago
It would take days to fully charge an EV from a typical RTG and there's no way an RTG could put out enough power to even keep an EV rolling on a flat highway at highway speeds. They are good for remote, unmanned stations but not much else.
- jandrese 5y agoAn RTG powered electric car may not be able to drive cross country at highway speed, but most cars spend the vast majority of their time parked. Having a RTG constantly top off the battery of an electric car would probably work quite well, assuming you worked out the many, many issues surrounding the RTG itself first.
- stickfigure 5y agoA "large" RTG puts out a few hundred watts of electrical. A very efficient electric car might consume 25 kWh/100 miles, so about 250 watt-hours per mile. If your car sits parked 6 days per week, it might work. Also: RTGs are typically 3-7% efficient, so your trunk will put out thousands of watts of waste heat continuously. Hope you live in a cold climate.
- jandrese 5y agoSo if you're charging at a rate of 2 miles per hour you can drive 48 miles a day on average, which is a fair bit more than most cars do. Even a 1 mile per hour charge rate would be enough for some people, although at that point you'll probably supplement with solar panels or something. One advantage over solar charging is that this won't be affected by the weather and works all night long. The excess waste heat is a problem, but it is way down the list of problems with running a RTG.
- stickfigure 5y agoThat still sounds incredibly optimistic. The most modern RTG: https://en.wikipedia.org/wiki/Multi-mission_radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Multi-mission_radioisotope_the... Puts out 125W electrical, 2KW thermal, and costs $109M each (!) Most cars could support 600w of solar panels. Even in bad weather you'd still come out ahead.
- eloff 5y ago> Also: RTGs are typically 3-7% efficient, so your trunk will put out thousands of watts of waste heat continuously. Hope you live in a cold climate. Ouch. It might be possible to harness some of that with e.g. Thermal to electric circuits to improve the efficiency.
- duskwuff 5y agoThe RTG is a thermoelectric generator -- it's already doing all it can with that thermal energy.
- jandrese 5y agoRTGs also avoid having moving parts or working fluids. More efficient energy recovery systems are available if you're willing to accept some maintenance items.
- eloff 5y agoI don't see how you can have it both ways. Either there isn't much waste heat, or there is lots of it and you can potentially harness that still.
- stickfigure 5y agoLet me make an analogy: Your petrol car has a heat engine. It converts about 20% of the heat energy released by combustion into mechanical energy. The rest goes out the tailpipe. Yet harnessing that remaining energy is not so simple because the temperature gradient is (relatively) small. The thermoelectric effect also requires large temperature gradients, and efficiency is proportional to the gradient.
- eloff 5y agoI think the car is a bad example because the temperature gradient is high and it should be possible to harness some of that waste heat. We just don't try. With hybrids we could definitely put that electricity to use, so I'm surprised no attempt is made to harness it. Especially for long haul trucking it could be worth it, but they're aren't diesel electric hybrid trucks that I'm aware of. Or at least they're not common. I do understand your point though.
- moftz 5y agoThe work required for moving the RTG up a slight hill might just negate the energy you gain from it. An RTG is not really meant to move itself very fast. Consider the Mars rovers, they move extremely slow but benefit from the stable, long term power supply.