Page 130 - Materials Chemistry, Second Edition

116 K. T. Lee and C. Ofori-Boateng

The main energy supply to the palm oil mill includes diesel, electricity, and
steam. PPF and PKS which are regarded as wastes from the palm oil mill are
normally used to produce energy. Figures 10 and 11 summarize the energy con-
tributions of various inputs into the various production stages excluding the
transportation stages. Figure 12 shows the contribution of the total energy inputs
by the four main transportation stages associated with the production of biodiesel
from palm oil. Due to the conversion of solar radiation to biomass by means of
photosynthesis, the chemical energy content of the harvested FFB and other bio-
mass exceeds the energy input through the farming system. Oil palm is therefore
regarded as a net source of useful energy (Corley and Tinker 2003). From Fig. 10,
the consumption of water, fertilizer, pesticides, and chemicals as well as human
work was highly recorded in the oil plantation stage. For chemical (including
major input materials such as FFB for oil mill, wood chips for plantation) con-
sumption, the energy inputs between FFB and wood chips were high which trig-
gered the high values for the oil milling (57 % of total chemicals) and plantation
(21 % of total chemicals) stages, respectively. The PPF and EFB (as part of
chemical inputs in this chapter) from the mill with dry calorific values of
19.22 MJ/kg and 20.47 MJ/kg, respectively (Yusoff 2006), are used as fuel to
produce steam and electricity for use within the mill.
Though the transesterification stage consumes many chemicals, the energy
contents of these chemicals are quite low (10 % of total input chemicals), hence
reducing the total energy consumption from chemicals in that stage. On the other
hand, CPO refinery stage consumes activated clay with high heating value, hence
increasing the energy contents of the chemical use (12 % of total energy of
chemicals used) within that stage.
The oil mill, however, recorded the second highest (13 % of total input fuel
excluding transportation) consumption of energy (including fossil and non-fossil
fuel from EFB, PPF) compared to all the other stages. Since it was assumed in this
chapter that 1 kg biodiesel was used in the ‘‘end use’’ or combustion stage, the

Fig. 10 Percent energy contribution of inputs into PME production by the various production
stages (without transportation stages). Chemicals include catalyst, methanol, H 3 PO 4 , RPO, FFB,
activated clay, etc. Energy includes diesel fuel, electricity, steam