Posted by Big Gav
WorldChanging compares the relative merits of batteries and fuel cells. At this point batteries appear to win hands down.
The last few years have seen boundless hype for fuel cells, but remember, no fuel cells are affordable or robust enough for vehicle use yet, and are barely affordable enough for high-end building use. Most people think that battery technology is maxed out, with no breakthroughs to be made, but most people have not been paying close attention. And worse, the people setting research budgets haven't been paying close attention, following the herd down fuel cell boulevard.
High-pressure hydrogen gas has an energy volume-density of about 400 watt-hours per liter, not counting pressurized container or fuel cell volume (which in a car-size system would probably cut the system energy density by 1/3 to 1/2). Status-quo lithium ion batteries have an energy density of 150 Wh/L, but emerging thin-film lithium polymer batteries created in labs by Solidcore, Cymbet, NASA Glenn Research Center, Voltaflex, ITN, and others have energy densities up to 900 Wh/L. They also claim to have "virtually unlimited re-charge capability", unlike status-quo batteries which degrade after several years of normal use.