My envelope calculations show that we would need 8,334 km^2 (roughly 3% of Nevada) of plant space at 20k liters/day to roughly cover global jet fuel consumption. (I welcome sanity checks on this math.) That's actually an encouraging and apparently achievable number.
However the first fusion plants, will probably dump excess production in the form of dense hydrocarbons for all the reasons listed here (lowers CO2 footprint, saves production energy for 'later', can be easily transported.)
http://www.dtic.mil/cgi-bin/GetTRDoc?doc=GetTRDoc.pdf&AD=ADA...,
http://en.wikipedia.org/wiki/Carbon-neutral_fuel#Renewable_a...
You can see why the technology would appeal to the US Navy, even if it's not quite price-competitive with other means of getting jet fuel: they're keen to untether their carrier groups from the supply chain as much as possible, which is partly why they have the convenient nuclear reactors already.
Carrier operations require operating at near flank (top) speed for takeoffs and landings. You couldn't fight and fuel at the same time. Even task-switching between modes would be at best cumbersome.
The US NRL's own research materials propose a fixed-site pilot, perhaps powered by OTEC (ocean thermal energy conversion) as a renewable energy source (this provides constant 24/7 power based on sea temperature gradients from sites such as the Hawaiian Islands with proximate shallow and deep-water zones at large temperature differential). Similarly any electrical power source, most conceivably renewable solar or wind, or nuclear, could be used for fuel synthesis. My back-of-the-envelope calculations suggest that supplying the equivalent of present-day US petroleum consumption would be plausible. It would require a few thousand km^2 of solar capacity, a roughly 10m tall by 4.5m square processing plant, and capital of roughly $8 trillion (based on USNRL's estimates) for synthesis and likely 1-2x that for the solar capacity.
In either case, you'd still have tankers and tenders transporting fuel, what you'd eliminate is the specific reliance on routes from existing petroleum extraction and refining sites.
Overall efficiency should be vastly better than the levels discussed here. Limiting point seems to be hydrogen electrolysis, which is 60% efficient (in terms of hydrogen energy potential) based on existing operational data. The Fischer-Tropsch reaction is pretty low in energy demand, or net positive. There are _vast_ volumes of seawater which would have to be processed, and pumping of that could be a significant energy cost (or perhaps tidal flows and some clever one-way-flow solid-state valves could be used to accomplish this: http://makezine.com/2012/01/05/the-tesla-valve-one-way-flow-...).
It's not clear to me what the actual efficiency of the USNRL's method would be, though it seems clear that 60% net energy recovery is a theoretical maximum. I'd suspect 20-50% might be reasonably attained -- and that's far, far higher than the 1.7% claimed by the article referenced by this HN post.
How do they compare to the space available inside and on top of the latest post-Panamax container ships? Even having a handful of ships like that (with their own nuclear reactors) trailing after the carrier to supply the requirement might be somewhat viable.
If the entire world worth of jet fuel was obtained from Nevada, it would inject around 4 billion dollar per year into Nevada's economy, or around $1500 per capita every year. I can imagine them choosing the money over the land.
I used Nevada as an example because it's a low population density, highly undeveloped, sunlight-rich state, which makes it ideal for solar production plants. I'm sure other production facilities will spring up in the California desert and similarly situated regions around the world.
What excites me most about solar energy plants is that it's ideal for our empty desert regions - Lots of sunlight, lots of undeveloped land, low population.
Edit: The $4 billion figure seems off. If global demand is 60 billion liters, that's $45.6 billion at $0.76/liter. Am I missing something?
http://www.indexmundi.com/energy.aspx?product=jet-fuel&graph...
I think the difference comes from global vs US numbers.
Already rising fuel costs have vastly affected the industry. US "peak aviation fuel" occurred in 1999. Peak departures was in 2005. 2012 consumption is _half_ of what was forecast in 2000, and departures 30% of the trend as of 2005 (even allowing for recession).
I first ran into this fact in January while looking into a biofuel "breakthrough" touted by Boeing (breakthrough or not it's wholly inadequate for needs): http://redd.it/1wo2hl
The departures data comes from a presentation by Steven Kopits made in February which I didn't come across until April: http://energypolicy.columbia.edu/events-calendar/global-oil-...
While passenger miles are still up, net, from 2000 levels, that's only on account of more efficient aircraft and higher load factors (that reduced legroom isn't just in your head).
So that's the problem scope.
Electricity is largely a solved problem: we can generate it with solar, wind, geothermal, hydro. Even nuclear for some bridging potential (though fuel availability even for thorium is decidedly limited as I calculate it http://redd.it/23nvqs).
Other than air travel, most transport needs are also tractable. Personal transport can be addressed via denser development, bicycles, electrified mass transit, personal electric vehicles, and other means. Rail can be electrified. Drayage (non-rail overland transport) is trickier, but might be addressed through EVs, biofuels, and even animal locomotion in a pinch.
Ocean shipping might return to use of sail or solid biofuel in the form of pelletized fuels.
But you cannot fly planes which carry appreciable cargos of people or freight useful distances reliably at speed without liquid fuels. So addressing that is of interest (an alternative would be to forgo flight or switch to lighter-than-air craft).
Personally I find the prospect of seawater-based fuel synthesis far more likely than air-based technologies: much richer carbon source, and likely far higher efficiencies.
This is like spending effort for cufflinks when it's -20 C and you aren't wearing any pants. Pants first. Cufflinks later.
Happy to be corrected, just commenting for the sake of discussion. This is how I understand the 'efficiency' of such experimental energy to be determined.