The sun's energy production is 3.846x10^26 W, nearly all of which is produced in its core which has a volume of 2.207x10^25 m^3. This gives the sun's core a power density of 17.43 W/m^3.
The average human male has a basal metabolism rate of about 81.3W, with a volume of 0.0664 m^3. This gives an energy density of 1224W/m^3.
So by volume, a human produces over 70 times the energy of the sun's core.
(Source: Various queries to Wolfram Alpha.)
a) Net free energy flux per volume, and
b) Complexity
a) Is basically the measure being discussed here (free energy flux = useful energy that crosses the boundary)
The author then listed a bunch of stuff in increasing order of a), and it roughly corresponds with our notions of complexity (or at least "interesting" or "directed" complexity, some similar concept). The list (smallest to largest) went about like this:
Stars
Planets (measured by change in energy of the light reaching vs leaving it)
Life-bearing planet (only one example, obviously)
Plants
Fish
Mammals (I'm skipping a few here)
Humans
Human brains
Human societies
Cars
Airplanes
Power plant turbines
Airplane engines
Computer chips
(Pretty neat correlation)