Nuclear

Great! Fission or fusion? What fuel cycle? What reactor design? Is it proven? Experimentally? Prototype? In production?

What's the fuel availability look like? How about issues with proliferation, waste disposal, plant accidents, and plant decommissioning?

I didn't spell out my alternatives in detail, but yes, nuclear is an option for electrical generation (I suppose you could also run a power loom or stamping gin off of one if you really wanted to). However of the options:

• Fusion's not there yet. Tokamak, NIF, or Polywell. Nothing but the shortest experimental possible ignitions yet. Nothing remotely commercializable. Several fuel cycles are fairly constrained.

• Uranium/plutonium LWR fission has a pretty critical fuel shortage. 80 years at present usage, 6 if we go 100% nuclear at present energy consumption rates. Scale in anticipated global energy growth rates and it's less than that. Waste, decommissioning, and accident issues are significant.

• Breeding uranium or plutonium might extend fuel supplies but creates significant weapons-grade material proliferation concerns.

• The TeraPower "nuclear candle" is a nice bridge technology ... if it works, but that only lasts until our existing nuclear waste is consumed (which raises the point: you don't want to be too good at disposal: the stuff might come in handy).

• Thorium has a vocal and occasionally demented lobby on the Intarwebs, but even the optimistic Chinese see MSR as 25 years out from commercialization.

And I see energy needs coming to a head Real Soon Now -- rather less than 25 years, at any rate.

And none of these technologies, nor wind, solar, geothermal, hydro, or tidal power give you liquid fuels, which is what planes, trains, automobiles, trucks, buses, boats, construction equipment, furnaces, generators, back-up power systems, and remote energy applications rely on. Sure, you've got Fischer-Tropsch, the Sabatier reaction, and other solid-to-liquid, gas-to-liquid, and fuel synthesis processes. All of which, scaled to the 100 million barrels of oil consumed daily globally would represent an absolutely massive investment of capital and energy.

Conventional crop biofuels, wastestream-to-energy, sewage-to-energy, and advanced algael biofuels all suffer from the challenge that your dealing with net captured flux of around 10 W/meter^2, maybe 100 W/meter^2 for algae, of photosynthetic efficiency. And you've got to capture that on land that's not already producing food you're planning on eating, or ecosystems you're planning on sustaining, you know, the rest of the Earth's biosystems.

The 100 quadrillion BTUs the USofA consumes annually corresponds to 29,307 TWh of energy, which at 10W/m^2 and 8 hours of effective insolation (a typical 30% duty cycle) means you're looking at 1,115,186 km^2 ... or a square 1056 km on a side (430,576 square miles, or 656 miles on a side, for the non-metric).

Sure, NYC of 1894 had 200,000 horses pumping out, literally, 5 million pounds of horseshit daily (https://ffbsccn.wordpress.com/2009/11/17/superfreakonomics-a...). And the straight estimates were accurate: keep that up and you'd be buried in the stuff (you already were knee deep in places).

Thing is: it's possible for things to get that bad. Ever been to India? Or just seen the opening sequence of Slumdog Millionaire? Because that's how a lot of people live: combing through trash heaps and swimming in shit (not equine, either).

And the reason NYC didn't drown in brown is because of this one-time lottery winnings of uncomposted Carboninferous lignan-laced pulp and algae decay which we've been talking about here (if decomposers had evolved slightly faster, we'd be discussing this in a small agrarian village somewhere). Technology, as I said, followed that windfall, it didn't create it (Colonel Drake's oil rig: borrowed from the Chinese who'd been drilling 1000 feet for salt since the year 1000). That rabbit's already been pulled from the hat, and we've been looking for a long time, pretty thoroughly, without finding many more rabbits for, oh, 40 years or so. The automobile didn't "come along", it was pumped from an oil well that's now running dry despite fracking fluids leaking into your water supply.

Technology doesn't create entropic gradients, it taps them. And we've got a pretty good idea of what provides useful energy: Moving stuff, falling stuff, blowing stuff, bright light, chemical bonds, and nuclear bonds. And it's mostly the bright light and chemicals that seem to work well for us, higher up it's not sufficiently dense or reliable, lower down and it's too complex. I don't see gradients (flows or stocks) we can tap with the ease and usefulness we have for the past 250 years.