Well, I found "good enough" batteries. A mix of fuel cells and SMES for "around the energy density of gasoline." Nuclear isomer batteries for the higher-energy stuff. It's a good tech for story-telling purposes because while the theoretical energy density is slightly shy of nuclear fission, we haven't really engineered any right now and the isotopes we've been playing with are...somewhat less than that. So right now, a writer can peg it pretty much anywhere from "almost as good as a lead-acid battery" to "atom bomb in a box."
That led to the next problem, and a couple of slow days at work spent reading high frontier stuff, Charlie Stross being cranky and practical, lots more Atomic Rockets, and running into such delightful concepts as "Dutch Disease."
And...it's really hard to justify a space colony. That power problem is there again. When you peg your energy resources high enough to allow getting all that stuff out there to start a colony, there are a lot of other options you could take instead. Or as Charlie puts it, colonize the Gobi; it's nearer and cheaper.
There's a concept I've started calling the Saturn V margin. You see, you can't get into orbit with a rocket. The energy density of rocket fuels is slightly lower than the ultimate kinetic energy of that rocket in orbit. The only way we can work that trick is with multi-stage rockets (SRBMs are a similar solution).
What I've been working on for the stuff underlying all the engineering that shows up in the story is the overlap between different regimes. For instance, it is only economical to run your spaceship off some ultra-high-density thing (like He3, or even antimatter) that was manufactured somewhere close to a much bigger power plant. (Our wormhole-physics vacuum-energy extractor thing.)
But you can, just barely, refuel with a fission power plant you build at a smaller poorer colony world. Which itself can run any kind of power-hungry planetary vehicles, construction machines, or in-system (aka strictly interplanetary) spacecraft.
Which, in a pinch, can be refueled with petroleum tech. It just takes a lot of it and you need to be patient. This goes all the way down to being able to turn a crank or pedal a stationary bike to recharge the SMES in your emergency radio...because food is within a single magnitude of gasoline, even if you have to add a few more doublers for conversion efficiencies.
The hidden point here is that you can only jump one system. There is no way in hell that stationary bike will ever get you off the planet.
This also ties in with what I've been calling the Fairy Ring model. Not the right metaphor, but there's nothing sufficiently sonorous about the ecological succession I'm thinking of. So you've got a place with built-up industry and a good customer base but raw materials are getting uneconomical.
So you start an extraction colony. Send a bunch of Spanish peasants to dam up rivers and run a mining operation getting silver out of the New World. Eventually there are enough people there, they get their own government and their own industry and their own higher standard of living, and they go looking for somewhere to purchase mining rights that's cheaper than going after the dregs they have in this new home.
The ring of colony growth and industrialization spreads out. It's a fun model. Looks a little silly when you think about the energy needs of getting the stuff across a solar system, much less to another star. If nothing changes the physics, its gonna be easier to mine the ocean floor than mine the moon.
The usual futurist claim is the stuff is heavily automated, probably self-replicating, and made "with local materials" so basically all you have to do is send one little rep-rap printer out to the Moon, plug it into an RTG, and before you know it ingots of lunar gold are raining down from the skies.
That probably doesn't work, for a lot of reasons a lot of people smarter than I am have been discussing for quite a few years. It also, more to the point for the writer, doesn't look a hell of a lot like the Alaskan Gold Rush, or a Cuban plantation, or any of the other cool historically-influenced settings you find crawling around golden age science fiction.
(If for no other reason than our local Bat Durston with his trusty space-mule and atom-pickaxe is wielding what is basically nuclear technology.)
I have what may or may not be two steps in this ecological succession of colonization. The setting for the stories is a as-yet unnamed consortium of worlds founded a bunch of generations back from Earth. Lately, they've been expanding into their own resource-extraction colonies...except that the new space they've sent their prospectors and oil-rig like extraction platforms and company towns has its own thriving ecosystem of several different alien races.
Highly opinionated ones. Friction ensues, plus the pace of the expansion is revealing all sorts of problems of policy and tech, from drill strings snapping to software licensing issues to miner's strikes to...
So what I really want for this is that the Core Worlds are basically on their own. Earth isn't actively dictating policy or sending technical assistance (or demanding their colony send more molasses for the Triangle Trade). And I also want this push, one that is happening fast enough so that nobody is really prepared for it. They haven't done enough local research to understand the problems they are getting into.
And while initially people are going "I hear there were some problems out on the frontier" those problems do not stay local. Eventually that trouble involves the Core Worlds.
The problem is, I don't see a clear way for this to have arisen out of the underlying economics and physics of the setting as so far developed. I could easily argue that there is some sudden rush of Manifest Destiny causing a huge rush of people wanting to get out the Conestogas, but it just doesn't feel organic.
