Weighting 500 g when filled up with ethanol, such fuel cell would offer power for 20 hours, and refilling it will not require connection to a power plug, and could be completed in couple of minutes.
They also offer an external charger, weighting 350 g and featuring 2 USB port in order to charge any device harboring such universal connector:
Despite an unexpected revolution in current battery technologies, fuel cells should become the new standard in 5 to 10 years, especially considering the low cost of ethanol to refill them.
