This new ultra-capacitor technology could be in cars by 2008. It could also be useful for space systems and other applications.
Digital Crusader analyzes the numbers that are claimed Texas-based company EEStor has finally revealed some details of it's ultra-capacitor technology. They claim that an automobile using their energy storage system (and some electric motors) could drive 500 miles on $9 worth of electricity, and require only a 5 minute recharging time. Furthermore, this storage system plus the motors is claimed to cost only $5200. They need to be 30x the voltage at 1/10th of the weight of a leading competing system (Tesla roadster using lithium ion batteries).
About 300kg for 88.5kWh. 300 Wh/kg. Energy density up with some fuel cells and the best batteries. Power density up with the other ultracapacitors.