Ten fundamentals about bioenergy: Part 2
Print
EmailEditor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Fundamental #2: Autotrophically derived carbon-hydrogen (C-H) bonds are the “currency” of renewable bioenergy fuels.
This is the second in a series of brief articles regarding ten fundamental components of bioenergy. Last week
we introduced the concept of autotropically derived energy, which
simply means the energy was created from organisms using inorganic CO2
and sunlight in the process we call photosynthesis. We may recall from
our middle school biology class that the chemical formula for the
photosynthetic process is:
Photosynthesis (Ps): 6CO2 + 6H2O + (light energy) → C6H12O6 + 6O2
The “light energy” which of course comes from the sun, is effectively
stored as chemical energy in the C-H bond of the autotrophically derived
six carbon sugar molecule we call “glucose.” The same C-H bond is the
primary currency for energy in gasoline, ethanol, diesel, biodiesel, and
interestingly in the bagel you had for breakfast this morning. When the
C-H bond from fuel is burned in your engine, or for that matter from
the bagel in your stomach, the H bonded to the C is replaced by oxygen
(O).
The cleaving of the H bond actually takes a little bit of energy (the
spark or compression in your engine), but the formation of the C-O bond
in CO2 gives off energy. In your engine this process is called
combustion, and the resulting energy from the formation of the CO2 is
converted from chemical energy to mechanical energy when the oxidative
explosion forces the piston down thus providing torque to the
crankshaft. The somewhat similar though much less violent process going
on inside your body from ingesting your morning bagel is called
respiration. Like your engine, the body oxidizes the C-H bond, but
unlike your engine, your body transfers the chemical energy to a storage
molecule known as ATP.
You = Respiration:
C6H12O6 + 6O2 → 6CO2 + 6H2O + (energy)
Your E-85 car = Combustion:
2C2H6O + 7O2 → 4CO2 + 6H2O + (energy)
Next issue’s discussion: “The finite supply of fossil fuel.”
Read part 1, part 3, part 4, part 5, part 6, part 7, part 8, part 9, part 10 of this series.
