Page 28 - Biofuels Refining and Performance

Energy and Its Biological Resources 11

their productivity and receptivity. Later by scientific manipulation,
new strains have been developed for cultivation.
It is justified to discuss certain established facts for making suffi-
cient conceptual clarity for special topics. Some aspects of energy rela-
tions in living systems will be discussed in detail. Some other aspects
will not be discussed in detail because existing “know-how” is rather
limited.

1.5 Biological Energetics
The study of bioenergetics leads us into a world of novelty and greater
significance and has found new encouragement in industry. The biogas
generation by anaerobic fermentation has also led to new interest in
research in the light of bioenergetics.
The study of energy relations for each chemical step in the living
system may be an item of bioenergetics. The energy change can be
calculated in terms of calories or joules per mole. This is applicable for
catabolic processes, for example, the anaerobic or glycolytic paths or
oxidative phosphorylation. The anabolic paths are equally fitting, e.g.,
the carbon fixation or the photosynthesis and nitrogen fixation by the
symbiotic organisms [1].
The accounting and balancing of free energy change of certain reac-
tions may lead to some fruitful conclusions. When glucose is oxidized in
a bomb calorimeter (an almost one-step reaction),

C H O 6O → 6CO 6H O 686,000 cal (pH 7.0)
2
6
2
12
2
6
is produced in a biological system (through a
but when equivalent CO 2
multistep reaction),
H O 6O 38ADP 38H PO → 6CO 38ATP 44H O
C 6 12 6 2 3 4 2 2
382,000 cal (pH 7.0)

A noteworthy departure is the conservation of –304,000 cal/mol of glu-
cose and gain of 38 moles of ATP, energy-rich (bond) compounds, i.e., 800
cal/mol of ATP. It also means 50,666 cal of energy are wasted if, on aver-
age, 1 mole of carbon dioxide produced chemically is wasted in the form
of heat, an inferior quality of energy.
A simple calculation will reveal that each nutrient has some specified
energy or calorific values. This can be compared to the different energy