Production of Biogas from Fermentation of Organic Waste
It is estimated that about 28 m3 of biogas is generated for every m3 of palm oil
waste in the waste treatment plant of palm oil mills.
In the palm oil mills, solid wastes are burned directly in the boilers to
generate steam. These solid wastes include the fiber, shell and empty fruit
bunch (EFB).
However, there are a large quantity of water based wastes that are not able to
burn by themselves. These waste have to be processed or digested in the waste
treatment plant in order to comply to the Department of Environment regulations
before they can be allowed to be discharged into the water course.
During the fermentation process, biogas is the unavoidable but valuable gaseous
product of such a process. The biogas from this fermentation contains 60%~70%
methane, 30%~40% carbon dioxide and a trace amount of hydrogen sulphide.
The chart below shows the great potential of using palm oil waste to generate
biogas.

Exhaust Gas NOx produced as a result of Combustion of Fuels
Compared to the burning of diesel fuels, bi-fuels using a mixture of natural gas
and diesel oil have shown lower levels of NOx produced and discharged in the
engine exhaust.
This means that bi-fuels are more environmentally friendly and should be
encouraged.

Properties of Gaseous Fuels
The chart below compares the properties of biogas, natural gas obtained from
mining, and liquefied petroleum gas.
Of special note is the gross calorific value of biogas. It is quite high and
comparable to the natural gas found from the gas fields. This is because it
contains a high percentage of methane.
|
Property |
Biogas |
Natural Gas |
Liquefied Petroleum Gas |
| Gross
Calorific Value (Kcal/Nm3) |
4740-6150 |
9070 |
24000 |
|
Specific Gravity |
0.847-1.002 |
0.584 |
1.5 |
|
Ignition Temperature (°C) |
650-750 |
650-750 |
450-500 |
|
Inflammable Limits (%) |
7.5-21 |
5-15 |
2-10 |
|
Combustion Air Required (m3/m3) |
9.6 |
9.6 |
13.8 |