Mini fuel cell from Sony
Sony has the prototype of a hybrid fuel cell introduced. 50mm times 30mm size, 10 mililitre Methanol for 14 hours operation of a MP3 device.
When the Sony methanol fuel cell has the same efficiency as the one from EFOY, than 10ml are 9,1 Wh.
This 3 Mignon AA rechargeable batteries for just 15.-EUR have the same energy capacity. The top performance is much higher than the 3 Watt specified at the fuel cell.