Palm Oil As Diesel Substitute

Many researchers have investigated the possibility of using vegetable oils (straight or blended) as a diesel substitute. A good account of their attempts was reported in the 1983 JAOCS Symposium on Vegetable Oils as Diesel Fuels (Klopfenstein and Walker,

1983; Pryde 1983; Strayer et al., 1983). The symposium revealed that vegetable oils have good potential as alternative fuels if some problems could be overcome satisfactorily. These include high viscosity, low volatility, and the reactivity (polymerization) of the unsaturated hydrocarbon chains if the oil is highly unsaturated. These will give rise to coking on the fuel injectors, carbon deposits, oil ring sticking, and thickening and gelling of the lubricating oil as a result of contamination with vegetable oil.

It is possible to reduce the viscosity of the vegetable oil by incorporating a heating device with the diesel engine, as has been successfully demonstrated by the engine manufacturer Elsbett (Basiron and Hitam, 1992). Other factors that may have long-term effects on the engine are free fatty acids and gummy substances, which are found in the crude vegetable oils. The incomplete combustion residues may contribute undesirable deposits on the engine components, and the gummy substances may cause filters to plug. This will call for more regular and frequent servicing and maintenance of the engine.

Various blends of crude palm oil and palm oil products such as refined, bleached, and deodorized palm olein with medium fuel oil (MFO) and petroleum diesel, respectively, have been evaluated as boiler fuels and diesel substitutes (Hitam et al., 2001). Crude palm oil (CPO) and refined, bleached, and deodorized palm olein (RBDPOo) were blended with MFO and petroleum diesel, respectively, at various ratios by volume. The resultant fuel blends, CPO/MFO and RBDPOo/petroleum diesel, exhibit advantages and fuel characteristics that are better compared with those when the individual CPO, RBDPO, RBDPOo, MFO, and petroleum diesel are used solely as fuel (Table 14.7, Table 14.8, and Table 14.9) (Basiron, 2002). Currently, field trials using MPOB's in-house vehicles are being conducted to evaluate blends of RBDPOo/petroleum diesel (up to 10% of the former) as a diesel substitute. No technical problems have been reported so far.

TABLE 14.7

Fuel Characteristics of Crude Palm Oil (CPO), Medium Fuel Oil (MFO), and Blends of Crude Palm Oil/Medium Fuel Oil (CPO/MFO)

TABLE 14.7

Fuel Characteristics of Crude Palm Oil (CPO), Medium Fuel Oil (MFO), and Blends of Crude Palm Oil/Medium Fuel Oil (CPO/MFO)

CPO/MFO

Property

Method

Unit

MFO

CPO

(50:50)

Gross heat of combustion

D 240

Btu/lb

18,350 Min

17,064

17,692

kJ/kg

42,680 Min

39,690

41,150

Sulfur

D 4294

wt%

3.5 Max

0.03

1.55

Viscosity @ 50°C

D 445

cSt

180 Max

25.6

67.3

Flash point

D 93

°C

66 Min

268

99

Ash

D 482

wt%

0.1 Max

NA a

0.012

Pour point

D 97

°C

21 Max

21.0

-6

Carbon residue

D 4530

wt%

13.0 Max

8.5

7.0

Density @ 15°C

D 1298

kg/l

0.98 Max

0.9140

0.9408

Sediment by extraction

D473

wt%

0.10 Max

NA a

0.02

Water by distillation

D 95

vol%

0.5 Max

NA a

0.25

a NA: not available.

a NA: not available.

TABLE 14.8

Fuel Characteristics of RBD Palm Olein (RBDPOo), Petroleum Diesel, and Blends of RBD Palm Olein/Petroleum Diesel (RBDPOo/Diesel)

Test Conducted

ASTM D1298 Sulfur content (wt%) IP 242

ASTM D445 Pour point (°C) ASTM D97 Gross heat of combustion (kJ/kg) ASTM D240 Flash point (°C) PM cc D93

RBD Palm

Olein (RBDPOo)

0.9150

38,975 326

Blends of RBDPOo/Diesel

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Responses

  • haylom
    Does palm oil make a good replacement for diesel?
    7 years ago

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