Definitions for "Specific Energy"
Energy, specific
The energy output of a battery per unit weight, usually expressed as Wh kg–1.
The energy storage ability of a battery on a weight basis, usually expressed in watt hours per pound (or kilogram); sometimes given on a volume basis in watt hours per cubic foot (or liter).
Keywords:  tank, fuel, mass, supplied, converter
in a fuel cell, ratio (in Wh/kg) between the electric power supplied by time unit and the converter mass, including the fuel tank