Page 48 - Biofuels Refining and Performance

Energy and Its Biological Resources 31

2+
H , Mg , ATP
2
CH 3 − S − CoM CH + HS − CoM
4
Methyl reductase
+2H/2e − +2H/2e −
CO 2 + MH MCOOH MCHO MCH 2 OH
–H 2 O
+2H – H O
2
+2H
CH OH + MH –H O MCH 3 MH + CH 4
3
2
−2H
Barker’s pathway −CO 2
CH COOH + MH
3
OH H H
| 2e − | 2e − | 2e −
CO + MH O = C – M O = C – M HO−C−M CH −M CH + MH
4
3
H O | H O
2
2
H
Gunsalus pathway
MH (reduced metabolite/reduced coenzyme/reduced enzyme complex)
Figure 1.10 Methanation.

is the starting material for anoxic fermentation to flammable gas, it is
called gobargas. Before a scientific and technical approach was given to
this promising field, the technique was developed in the southern part
of India in a very crude way. Partly dehydrated animal excreta, when
ignited, produces fumes and burn for a short duration with a partially
sooty flame a little above the solid fuel. Slurried excreta, when stored
in closed earthen vessels for a while, produced flammable gas. Based on
these observations, villagers developed techniques of producing gas sim-
ilar to illicit brewing.
Perhaps the greatest benefits of gobargas projects are secondary in
nature. It takes out the pollution and ecologic problems and yields better
biomass as compost and manure. The primary product, the biogas, has
of course become very important in the present energy perspective. The
fuel value of the gas, though not very high, is relatively safe and pollu-
tion free. Out of the many reports available so far, the positive and
encouraging points leading to successful implementation of gobargas
projects are very restricted. The negative points or factors which make
the progress slow down are many, and a few are difficult to overcome.
It may be useful to mention a few of them. These points are by no means