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7% maximum *for metal hydride*, period. Whether used as a battery or as a storage tank.

As for carbon fiber, this link sums it up pretty well:

http://www.tipmagazine.com/tip/INPHFA/vol-10/iss-1 /p20.html

Read down where it talks about Carbon nanomaterials. Still a pipe dream, much like cold fusion.

I think my original point still stands - the density of hydrogen you can store doesn't compare well to the energy density of a LiIon battery. LiIon technology is something where every bit of incremental research pays off *today*, across a wide spectrum of consumer electronics. You may not solve the electric car recharge problem overnight (pun) but you'll be pushing a commercially viable and environmentally sustainable enterprise while you make advances down that road. Whereas, any advances that come from stuff like miracle carbon fiber nanotubes will take years to reach commercial viability, if it's even possible.

Fundamentally, I think the main point is we're running out of time. Our environment is going to hell, and the petroleum probably won't last much longer (and we will most likely be perpetually at war to secure what little remains). The car companies and oil companies are being disingenuous by getting behind a "plan" that will transition us to a hydrogen economy a "decade or two away" when even the most promising research can't possibly pay off that quickly, and they've had cars like the GM EV1 that were already reasonably good cars, cars that would be totally acceptable if they used LiIon and could be recharged on a home's 220V AC power instead of just at a handful of special-purpose recharging stations. (Like the ACPropulsion Tzero.)

Another decent summary of energy content in metal hydride vs gasoline...

http://www.tipmagazine.com/tip/INPHFA/vol-10/iss-1 /p20.html

From article, the last paragraph:
Demonstrating these technologies, along with additional ground- and flight-test experiments, will pave the way for affordable and reusable air-breathing hypersonic engines for missiles, long-range aircraft, and space-access vehicles around 2010, 2015, and 2025, respectively.

Uhh? "demonstrating..reusable..engines for missiles" ?

Are we talking 'homing nuke' ?

From the article:
The supersonic combustion ramjet, or scramjet, uses no rotating parts. In a conventional ramjet, the incoming supersonic airflow is slowed to subsonic speeds by multiple shock waves, created by back-pressuring the engine. Fuel is added to the subsonic airflow, the mixture combusts, and exhaust gases accelerate through a narrow throat, or mechanical choke, to supersonic speeds. By contrast, the airflow in a pure scramjet remains supersonic throughout the combustion process and does not require a choking mechanism, which provides optimal performance over a wider operating range of Mach numbers. Modern scramjet engines can function as both a ramjet and scramjet and seamlessly make the transition between the two.
Get the pdf version here

Yes, we do not hear about them, because they do not exist.

Sure, it was First Energy's lines that failed initially, but if it wasn't First Energy, some other utility would have failed eventually. The engineering and the legal descriptions of the current electrical generation and distriubtion system in North America are at odds with one another.

There's a good technical discussion on the failings of the power grid that may interest you.

The software bug was just one piece of a much bigger problem; I wouldn't want to overstate its' role. There were many other factors; here are just a few:

Poor vegetation management probably played an even bigger role as overloaded power lines warmed up, expanded and sagged into trees and bushes that were supposed to have been cut back.

Poor communications between utilities played a major role.

This whole section of the transmission system was known to be unstable.

An inadequate regulatory structure lacked teeth to deal with known problems.

Lack of adequate transmission line capacity

If all these other problems hadn't been in place, the software bug might never have surfaced. And certainly, the rpoblems would have been contained within a much smaller area -- maybe just First Energy's service area.

An article featured on Slashdot last year lays out the underlying complexity of the power grid very well: "The World's Largest Machine"

Slashdot had a great story on the blackout last year:

Guinnessy writes "The latest issues of the Industrial Physicist suggests that 'the vast system of electricity generation, transmission, and distribution that covers the United States and Canada is essentially a single machine -- by many measures, the world's biggest machine.' The article says that because deregulation ignored the physics of the machine, we have blackouts, a fact the industry warned regulators about in 1998. It has some nice hard science data for those interested in why we're going to get some more blackouts in the future unless Congress gets its act together." I work with power utilities -- this is the best single explanation I've seen of the underlying problems of transmission management and regulation in the U.S.

Slashdot had a great story on the blackout last year:

Guinnessy writes "The latest issues of the Industrial Physicist suggests that 'the vast system of electricity generation, transmission, and distribution that covers the United States and Canada is essentially a single machine -- by many measures, the world's biggest machine.' The article says that because deregulation ignored the physics of the machine, we have blackouts, a fact the industry warned regulators about in 1998. It has some nice hard science data for those interested in why we're going to get some more blackouts in the future unless Congress gets its act together." I work with power utilities -- this is the best single explanation I've seen of the underlying problems of transmission management and regulation in the U.S.

Before anybody jumps on this, the better solution is likely to be microwaves. You don't want to be pointing a multikilowatt laser at the Earth, for obvious reasons. The Industrial Physicist magazine had a recent article on this, with a followup article two months later. There were also a number of letters to the editor with responses from the author on this issue.