**2.3 Utilization of PEFB**

The utilization of PEFB can be divided into two groups: PEFB utilization for non-energetic purposes and PEFB utilization for energetic purposes.

## **2.3.1 PEFB utilization for non-energetic purposes**

PEFB contains a variety of nutrients, e.g. phosphorus (P), potassium (K), magnesium (Mg), Nitrogen (N), etc. It is reported that the nutrients in PEFB consist of 0.06 % P, 2.4 % K, 0.2 % Mg and 0.54 % N (Heriansyah, n.d.; Prasertsan & Sajjakulnukit, 2006). As a result of this, PEFB is a good source of organic matter. By which PEFB is widely used in Thailand as a substrate for mushroom cultivation and as an organic mulch as well as supplementary fertilizer for oil palm plantation. As a substrate for mushroom cultivation, PEFB is pressed in a rectangular block and mushroom spores are inoculated into PEFB block. Finally the block is covered by plastic sheet to maintain moisture content and limit sunlight. PEFB

Elemental compositions and some properties of PEFB are different by sources of feedstock. Table 5 shows and compares proximate and ultimate analysis of PEFB from Thailand and

Moisture % wt. 8.34 8.75 Volatile matter % wt. 73.16 79.65 Fix carbon % wt. 12.20 8.60 Ash % wt. 6.30 3.00

C % wt. 43.8 48.79 H % wt. 6.20 7.33 O % wt. 42.64 40.18 N % wt. 0.44 0 S % wt. 0.09 0.68 Others % wt. 0.53 0.02 Ash % wt. 6.30 3.00 Lower Heating Value MJ/kg 19.24 18.96

From Table 5, it can be noticed that there is no significant difference in composition of PEFB by sources. Moisture content is measured to be approximately 8 % wt. based on air dried basis. Volatile matter and fix carbon varied from 73 to 80 % wt. and 8 to 12 % wt., respectively, while ash content in PEFB from Thailand is higher than ash content in PEFB from Malaysia. The chemical composition of PEFB from Thailand calculated by ultimate analysis is C3.6H6.2O1.3, whereas the chemical composition of PEFB from Malaysia is C4.1H7.3O1.3. The lower heating value of PEFB from sources is almost identical and is around

The utilization of PEFB can be divided into two groups: PEFB utilization for non-energetic

PEFB contains a variety of nutrients, e.g. phosphorus (P), potassium (K), magnesium (Mg), Nitrogen (N), etc. It is reported that the nutrients in PEFB consist of 0.06 % P, 2.4 % K, 0.2 % Mg and 0.54 % N (Heriansyah, n.d.; Prasertsan & Sajjakulnukit, 2006). As a result of this, PEFB is a good source of organic matter. By which PEFB is widely used in Thailand as a substrate for mushroom cultivation and as an organic mulch as well as supplementary fertilizer for oil palm plantation. As a substrate for mushroom cultivation, PEFB is pressed in a rectangular block and mushroom spores are inoculated into PEFB block. Finally the block is covered by plastic sheet to maintain moisture content and limit sunlight. PEFB

Table 5. Proximate and ultimate analysis of PEFB from different countries

Thailand (air-dried) (Own investigation)

Malaysia (air-dried) (Hamzah, 2008)

Malaysia.

Proximate analysis

Ultimate analysis

19 MJ/kg.

**2.3 Utilization of PEFB** 

purposes and PEFB utilization for energetic purposes.

**2.3.1 PEFB utilization for non-energetic purposes** 

mulching material on soil surface for oil palm plantation can reduce soil temperature and conserve soil moisture to improve growth and crop yield. The residue from mushroom cultivation or mulching material for oil palm plantation is the composting PEFB which can further be served as organic fertilizer. After a long duration of composting, the nutrients containing in PEFB will substantially increase, e.g. after 32 weeks composting N, P and Mg in PEFB increase from 0.54 %, 0.06 % and 0.19 % to 2.22 %, 0.355 % and 0.67 %, respectively (Heriansyah, n.d.). Another possibility is the utilization of PEFB ash as fertilizer or soil conditioner. However, this method is non-preferable because white smoke caused from high moisture content in PEFB has an aesthetic effect to the environment (Yusoff, S., 2006).

Since the PEFB has a highest fiber yield and its fibers are clean, biodegradable and compatible than other wood fibers, besides using for agricultural purposes, fiber of PEFB can be served as raw material for pulp and paper, fiberboard, mattress, cushion, building material, etc. (Law et al., 2007; Nasrin et al., 2008; Prasertsan & Sajjakulnukit, 2006; Ramli et al., 2002 ). Anyways, there are some limitations of using PEFB fiber. The fiber must be dried to the moisture content of 15 % and oil content has to be removed from fiber in order to improve the mechanical and physical properties of PEFB fiber.

Although, there are many applications of PEFB fiber, the utilization of PEFB fiber as raw material receives only few interests in Thailand, because there are a lot of agricultural products used for this purpose available and gain the technical knowledge in commercial scale, such as eucalyptus for pulp and paper industry, rubber wood or other wood species for fiberboard and particle board, coconut fiber for mattress.

#### **2.3.2 PEFB utilization for energetic purposes**

According to the increase in crude oil price, depletion of crude oil reserves and environmental concerns, especially global warming, many studies focus on the attempt of looking for alternative energy sources to partly replace crude oil. There are many processes for converting biomass to energy, including mechanical process, thermo-chemical process and biological process, as shown in Figure 8.

In mechanical process, as received PEFB is dried, grounded and fed into pelletting/briquetting machine in order to produce pellets/briquettes. These PEFB pellets/briquettes has good properties for using as fuel in conventional stove or co-firing plant compared to as received PEFB. It exhibits high energy content due to the decrease in moisture content, uniform size and superior combustion behavior as well as high mechanical strength (Nasrin et al., 2008). Although there are several pathways of thermo-chemical process, the direct use of PEFB in commercial plants has rarely been found. Currently, thermo-chemical technology for converting PEFB into energy has been studied in laboratory or bench scale. Many studies nowadays focus on the pyrolysis of PEFB for bio-oil production in lab-scale, both fixed bed and fluidized bed reactor and it can be evidenced that the maximum yield of bio-oil produced from pyrolysis of PEFB without catalysts occurs at the temperature of about 500 °C and the lower heating value of bio-oil is approximately 20 MJ/kg (Abdullah & Bridwater, 2006; Abdullah et al., 2007; Azizan et al., 2009; Sukiran et al., 2009; Yang et al., 2006). The utilization of catalyst can promote the pyrolysis reaction and the maximum bio-oil can be obtained at lower temperature of about 300-350 °C with shorter residence time (Amin & Asmadi, 2008). Due to its higher moisture and ash content, lower energy content compared to palm oil shell or some types of biomass feedstock as well as its non-uniform shape (Knoef, 2005), there are a large amount of experimental studies and modeling focusing on combustion, co-firing as well as gasification of PEFB in order to investigate the feasibility of using above mentioned technologies to convert PEFB into energy in term of operating conditions, configuration of reactor, emission and efficiency (Hussain et al., 2006).

Fig. 8. Pathway for energetic utilization of biomass

as gasification of PEFB in order to investigate the feasibility of using above mentioned technologies to convert PEFB into energy in term of operating conditions, configuration of

reactor, emission and efficiency (Hussain et al., 2006).

Fig. 8. Pathway for energetic utilization of biomass
