Auxiliary Power

More power-source thoughts.

• That last post, and a Facebook discussion on a thorium-powered steam-driven car (which actually heats its steam by pumping a laser with the radiation from a heat-boosted thorium sample), gave me occasion to look around radioisotope thermoelectric generators (RTGs).
  
  I'm not sure where, if at all, my humans will use RTGs; their rockets are designs whose main problem is what to do with all that extra energy, and you'd have to be nuts to put most RTGs on a ground- or air-vehicle. Then again I don't really go into teeny-weeny space station outposts (all the space-stations I mention are colonies along the lines of "O'Neill Island" designs), maybe some of the smaller ones use RTGs. I imagine the big colonies use some mix of solar and fusion, maybe some fission (presumably thorium-fueled).
• Another thing I realized is that zledo would probably have made much more use of strontium-90 in their RTGs (back when they still used 'em), since the main danger of strontium-90 exposure (if you don't physically crack open the containment capsule in an RTG with your hands, or aren't nearby when the capsule is opened by an accident) is that it gets into the soil, where it is incorporated into plants and water, where you can eat or drink it—and then your metabolism incorporates it into your bones. Their bones are made of a type of biogenic silica, so they don't have to worry about that.
  
  Of course, they probably have to worry more about tin-126 (since it's in the same line as silicon on the table), albeit chiefly as a nuclear-fallout component, since it doesn't really form in ordinary fission power-plants, and they never used nukes on planetary surfaces. They did use them in space, both for weaponry and to ignite Orion rockets—actually, I'm considering making them have used Orion rockets from planetary surfaces, since you can do that relatively safely by putting an even bigger armor plate under the rocket, and coating both armor plates in a thick layer of graphite. (The one flaw with that link, by the way, is it says we're "more than prepared" to use nuclear bunker-busters, when in actual fact absolutely nobody seriously considers doing that.)
• One other thing? I think I'm going to have zled equipment powered by regular mainsprings, rather than "dilaton alternators" or Planck-scale mainsprings. Cool as the dilaton alternator is—it gets around the relative inefficiency of gravity as a power-source (consider how much water has to move through typical hydroelectric plants) by going down to the scale where gravity's force is much greater, before it leaks into other parts of space-time geometry—I'm doubtful as to whether it would be very portable ("giant lab apparatus", etc.).
  
  The mainspring of a windup-radio provides 4 watts for 25 minutes, which translates to 1 and 2/3 W/h...which is six kilojoules, meaning (the power of a spring is proportional to the change of its length i.e. to the tightness of its winding) a just slightly longer or more tightly-wound spring is enough for four shots of 1.6 kJ laser. A little research into windup phonographs reveals they often had multiple springs in their motors, so maybe zled lasers just use regular, non-nano-material springs, with, say, four extra springs in the hand-laser and a big ol' stack of, say, twelve in the long one (reducing the number of shots per magazine—or "barrel" as the housing of a mainspring is actually known—from 18 to 16 and from 50 to 48). Don't know if they're gonna call 'em "barrels" when they're being used to power what is basically a gun, that's just likely to cause confusion.