Alkali Metal Thermal Electric Conversion (AMTEC)

[sanman]

Here's an interesting technology I came across:

http://en.wikipedia.org/wiki/Alkali-metal_thermal_to_electric_converter

So, from this I take it that a means of high-power conversion of nuclear thermal energy to electricity could be achieved. It says it only works upto 1400C, but that seems fine enough for conversion of nuclear thermal energy.

The nice thing is that it's thermally regenerative, which will facilitate continuous operation over long periods. It seems like it would be a nice way to allow nuclear-electric propulsion for spacecraft .

 

[anorlunda]

The thermo electric effect is real. It is used on the Voyager 1 and 2 spacecraft .

I once heard an admiral propose nuclear thermo electric for submarines. It is less than 5% efficient, but that matters little. What does matter is lifetime, simplicity, reliability, and simple end-of-life disposal of waste. The admiral saw all four of those measures as favorable for the idea.

 

[etudiant]

The idea has some advantages, as ocean water could serve as the cold end of the thermoelectric circuit.
The challenge is the low power output of the concept with current materials. There is also a real loss of stealth if the sub pumps 95% of the reactor energy into the creation of a thermal plume

 

[anorlunda]

There is also a real loss of stealth if the sub pumps 95% of the reactor energy into the creation of a thermal plume

Good point. But how to calculate relative stealthiness compared to dumping 67% of the energy as a thermal plume?

 

[etudiant]

There have long been rumors that nuclear subs leave long lasting contrails of slightly warmer water behind them, trails that sometimes can eventually be detected by satellite IR sensors, presumably at night when sun glint is not an issue. So I'd expect the submariners to be reluctant to dump 20x more heat per effective horsepower rather than 2x.