Re: Can Radioisotopic thermal-electric generators power electric cars?

RTG units are a safe, effective means for providing power for spacecraft. They are virtually required for any spacecraft that goes past the orbit of Mars. RTGs use thermocouples embedded in a radioisotope (usually plutonium oxide) to provide power for spacecraft. Each thermocouple produces only millivolts, but by linking them together in series reasonable voltages, i.e., 5 volts for computers, can be generated. Each RTG will last decades before the power drops below usable levels.

For an automotive application, the main problem is the perception by the general public that all nuclear power is dangerous. Looking past this to the technical considerations alone, the question becomes "Can the RTGs provide sufficient power to power a car?"

A GPHS-RTG provides approximately 286 watts of electrical power at the beginning of its life. Each unit weighs 56 kg (123.2 lbs.), and they can be connected in series or parallel to provide the necessary power to an electric motor. In comparison, a typical lead-acid battery in a car can provide 450 amps at 12 volts or 5400 watts of power and weighs about 20 kg (44 lbs.).

Designing an electric car is a very complex process. There are many techniques such as using braking to recharge the batteries that cannot be used with RTGs. So this analysis is greatly simplified.

Looking at the Ford, GM, Honda and other current electric vehicles as a baseline, you would need around 100 kilowatts of power for the car. That power is provided by about 30 lead acid batteries weighing 600 kg (1320 lbs.). If these batteries are exchanged for RTGs, it would require at least 350 RTGs weighing 19,600 pounds to produce the equivalent power. Obviously this weight is too great to be practical. Even the largest SUVs currently made are less than half the weight of the RTGs alone.

So while there could be benefits to using RTGs such as never having to fuel the vehicle while you own it, the weight considerations make them impractical.