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What if Energy was (Nearly) Free?
anvilmark asks: "Sci-Fi and sci-fi games often incorporate the romantic idea of 'free trader' ships with ports of call on a myriad planets across the galaxy. Recently I was toying with the physics of propelling such ships and their cargos out of a gravity well and realized the astronomical amounts of power it would take to do it (not to mention interstellar travel). This led naturally to contemplating how cheap energy would have to be in order to make this activity profitable. To make a long story short (too late!), I began wondering what would happen if the introduction of fusion power takes energy costs from pennies per kilowatt hour to pennies per megawatt hour (or GWH)? How do you envision the world changing if energy costs became a trivial part of economic equations?"
I've done a lot of thinking about this myself, and it turns out to have some interesting implications.
First, it turns out that the cost of electric at the wall-socket is not dominated by the cost of production, but by the cost of the power grid. If the power were completely free, cost/kW-h at the home would only go down by about 50 percent.
On the other hand, cost of electricity does dominate the cost to make aluminum, steel, and many chemicals: profits would immediately go up, and costs would quickly drop precipitously for everything from cars to Tylenol.
Free electric power wouldn't in itself make space travel cheaper, but if you have cheap fusion you can either make fusion rockets, or extend VASIMR. If you can get thrust high and exhaust velocity very high -- say tens to hundreds of km/sec -- then you can quickly start doing things like going to the Moon with constant acceleration. In other words, a trip from Earth to Moon could be quicker than a trip from New York to Boston today.
Waste disposal would change radically -- give me enough power and I'll just do mass spectroscopy on a plasma made from the wastes. Call it 'mass mass spectroscopy' -- out the end comes pure (isotopically pure, if you care to do it) oxygen, hydrogen, carbon, and so on. This will be very handy for Lunar exploration, as it makes possible the easy separation of 3He from 4He; 3He makes for good fusion fuel, and 4He ("depleted helium"?) makes for cheap reaction mass or lots of other things. On the other hand, it makes uranium enrichment much easier as well -- throw in yellowcake, and out the other end comes O2 235U and 238U.
If lunar 3He production is economic, so is production of hydrogen (either from fossil water or as a byproduct of 3He production) as well as oxygen, nitrogen, argon, potassium, thorium, and so on. (See KREEP.) Add O2, N2, and lights to a lunar lava tube, and you've got living space and farms -- with cheap power.