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http://www.visionengineer.com/env/fc_efficiency.ph p

A nice graph of fuel cell efficiency.

Practical fuel cell efficiency is around 50% (it is temperature dependent), less if you are using methanol instead of pure hydrogen.

"Clean" does not apply to anything you need to take a huge amount of care to contain
Clean isn't a word you can really apply to any industrial process anyway
In my definition, as long as you contain any dangerous waste, it's not an issue, other than the fact that the cost ends up in the expense column.

You are comparing apples and aardvarks - it's a small purpose built (solar)plant in a very remote area designed to be as maintainance free as possible.
photovolatic cells are the expensive way to go
Except that you're wrong on a couple points:
a: It's a 200Megawatt plant, not a small installation.
b: The plant features not one photovoltaic cell. It's a mirror-tower type that uses mirrors to heat water to steam in a tower, which is then run through a conventional steam turbine.
At about $400 million for 200MW, it runs about twice as expensive as a PBMR plant, and in a high-sun location, at that.

You don't build nuclear plants to save money, you do it for other reasons, but hopefully pebble bed will change all of that.
I hope they do turn out well. But we still have reactor designs generations better than the ones used in the USA at the moment. Simpler, Safer, cheaper, more fuel efficient...

How about this, minus the political regulations, when you consider wind, solar, hydro, as well as nuclear, nuclear makes sense if you don't want to be burning hydrocarbons?

Those all all good engineering points, but sadly, higher combustion temperatures mean more NOx. So, the overall engineering intent is to find the sweet spot between NOx production and efficiency... which leads to losses in performance and fuel economy.

And Exhaust gas Recirculation *IS* used primarily for NOx reduction.

You are probably thinking of the system where an air pump pumps air into the exhaust system to burn off the residual fuel products. This page gives a pretty good overview of emission control systems on cars.

Come on guys, this is home defense, geek style. You have twenty seconds to comply.

Weird stuff . . .

It works just like a "normal" electric motor (that turns into a alternator on breaking). Check the Transrapid Hompage and click on "Technology" (stupid "clever" link auto-redirects to homepage), or this site. The flywheel is the moving train, just that the momentum of inertia is linear instead of angular.

An orbiting array of solar cells with intense microwave power transmission downlinks to mid-ocean electrolysis plants. Not feasible now, but in the next 10, 20 years it could happen.

Your entire last paragraph is wrong. Fuel cells are not batteries; they do work on the same very basic electrochemical rules, but a fuel cell doesn't have a self-contained store of reactants; also, fuel cells use the much more energetic 2 H2 + 02 -> 2 H2O reaction, instead of a lower-energy ionic redox reaction like batteries (If I'm speaking Greek, get an intro chem text and read up on electrochemistry, then look at the potentials for various half-reactions). AFAIK, it's also impossible to build a "rechargable" cell that will take H2O and electricity and spit out H2 and O2; it is possible to build a rechargable battery. Fuel cells are actually a hell of a lot (potentially an order of magnitude) more efficient than internal-combustion engines; fuel cells go directly from chemical energy -> electrical energy, while an ICE has to go chemicals -> thermal -> mechanical -> electrical energy.
Now for the numbers *hunts down PChem text (PW Atkins, Physical Chemistry, 7th ed.)* OK, the maximum theoretcal efficiency for a Carnot cycle engine is around 80%, depending on the delta-T between the engine and the environment; 80% is reached at around 900-1100C, at less than 100C it's limited to around 20%. Fuel cells are more efficeint at lower T, theoretically greater than 90 percent at less than 100C. Here's a pretty good summary page; the bottom graph is really good. Brush up on your thermodynamics, you're a clearcut case of a little knowledge being a dangerous thing :P

The efficiency differences between the two methods of usage can be quite large. Here's a decent article on the subject.

The bottom line is for a practical, real world application, the crossover point is somewhere between 800C and 1000C, a level that doesn't generally get reached in a car or home generator. At a much more reasonable 200C, fuel cell efficiency is around 80% while Carnot limited internal combustion engines are only about 30% efficient.

As for electricity transport, you're right, that requires an inverter (which is pretty standard stuff) and there are some efficiency losses there. However, the home generation route is likely to be popular as you could reduce your electric bill by using a fuel cell stack as a natural gas powered water heater and coincidentally, home fuel cell generators would have the fewest demands put on them during the daytime (when industrial demand is high) and could run full blast during power price spikes to aleviate rolling blackouts or brownouts. GE is allied with a company called Plug Power to do exactly that sort of thing with their upcoming HomeGen line of fuel cells.

How about the idea of solar chimneys.. ..they cost alot to build but could be the answer.

A once working prototype
And another link

I'd rather go for the Pino and the GPLd Open Pino Platform Pino
The platform is far more impressive.

Hmm...America has massive ocean frontage. We have massive energy usage, too, so I don't know how that balances out.

Wave energy is a less intuitive approach to this problem; for a even less intuitive approach think tides...

Sorry to burst your bubble, but fuel cells do have the same limitations -- known as Carnot efficiency, btw.

No they don't - see here

You are talking drivel about the engine efficienies also - see here

My source for info? a good introductory thermodynamics class.

Introductory? A little knowledge is a dangerous thing.