CHAPTER IV BIODIESEL BLENDING SCENARIO
Introduction
Biodiesel has similar physical characteristic with diesel engine fuel so that it can be utilized as substitute fuel for diesel engine vehicles. Biodiesel and its
blends with petroleum-based diesel fuel can be used in diesel engines without any significant modifications to the engines. Biodiesel can also be used as combustion
fuel since it has a minimum of 37 MJkg of combustion heat, while fossil fuel has 42.7 MJkg. Biodiesel and diesel fuel differ in their chemical compositions. Diesel
fuel typically consists of about 30-35 aromatic hydrocarbons and 65-70 paraffin and traces of olefins C10 to C16 content. Whereas, biodiesel primarily
contains C16-C18 fatty acid methyl esters with one to three double bonds per molecule.
Biodiesel has many advantages comparing to diesel fuel, with respect to improved lubricity, higher cetane number, bio-degradability and cleaner emission:
a. Exhaust emission: Combustion is a chemical oxidation process requiring sufficient oxygen to
achieve complete combustion process to yield carbon dioxide CO
2
gas and water vapor H
2
O. Incomplete combustion process will produce carbon monoxide CO gas or carbon residue C. Biodiesel is an oxygenated fuel that can adds its oxygen
content during combustion process, and hence, it produces better emission. Data from the numerous research reports and test programs showed that generally the
emission decreased considerably with the increase in biodiesel blend ratio. b. Sulphur content:
Sulphur content in biodiesel is lower than in diesel fuel as shown in Table 13. Sulphur content in fuel can influence in the content of SO
2
emission yielded from the combustion.
c. Cetane number: Cetane number is a measure of fuel combustion quality. The higher the
cetane number of any diesel fuel is, the better combustion quality become. Cetane number of biodiesel is higher than that of fossil diesel fuel as shown in Table 4.
46 Table 13. Comparisons of Fossil Diesel Fuel FDF and Biodiesel Fuel BDF
characteristics
No. Parameter
Unit FDF
1
BDF
2
1 Density
kgm
3
820 - 870 15°C
850 – 890 40°C
2 Kinematic viscosity 40 °C
Mm
2
s cSt 1.6 - 5,8
2,3 – 6,0 3
Cetane number min. 45
min. 51 4
Flash point °C
min. 60 min. 100
5 Cloud point
°C max. 18
6 Pour point
°C Max. 18
7 Copper strip corrosion
Rating 3 hours at 50°C
max. no 1 max. no 3
8 Carbon residue
- in undistilled sample, or - in 10 distillation residue
mm mm
- max. 0.1
max 0,05 max. 0,30
9 Water and sediment
-vol. max. 0,05
max. 0,05 10
90 vv recovered at distillation temperature
°C -
max. 360 11
95 vv recovered at distillation temperature
°C max. 370
- 12
Ash content sulfated ash mm
max.0,01 max.0,02
13 Sulfur content
Ppm-m mgkg max. 5000
max. 100 14
Phosphorous content Ppm-m mgkg
- max. 10
15 Acid number
mg-KOHg max.0,6
max.0,8 16
Free glycerol mm
- max. 0,02
17 Total glycerol
mm -
max. 0,24 18
Ester content mm
- min. 96,5
19 Iodine number
mm g-I2100g -
max. 115 20
Halphen test -
Negative Note: can be separately tested as long as sediment content maximum 0.01 -vol.
1. Automotive Diesel Oil, www.pertamina.com accessed 19 June 2006. 2. SNI Biodiesel No. 04-7182-2006, based on ASTM D 6751 EN 14214.
d. Bio-degradability: Degradability of Biodiesel is four times faster than fossil diesel fuel or any
other diesel fuel. Blending biodiesel to petroleum diesel fuel can accelerate its biodegradability. For example, B20 fuel blend of 20 biodiesel and 80 fossil
diesel fuel can be degraded twice as fast as pure petroleum diesel fuel [44]. e. Lubricity and cleaning power to the engine:
Naturally, biodiesel is more viscous than ordinary petroleum diesel fuel. As a result, biodiesel has more lubricant characteristic to the engine than petro-diesel
fuel has. Moreover, biodiesel also known as fatty acid methyl ester FAME is characterized as a solvent methyl ester which has the ability to clean combustion
47 area and components in the engine. However, engine componentparts made of
naturalnitrile rubber can be influenced reacted with biodiesel [44]. The most significant hurdle for broader commercialization of biodiesel is its
cost. In current fuel price policy in Indonesia especially fuel for transportation, the higher percent of biodiesel in blend will increase the price of blends fuel.
Study on the determination of optimum biodiesel-petrodiesel blend fuel performed by Wirawan et al. 2008 [45] concluded that B20 is the most optimum
blending composition which can be used in existing unmodified diesel engine. The objective of this study is to assess the optimum blends of biodiesel with
petroleum-based diesel fuel from technical and economical consideration.
Materials and Methods
The study was performed through the simple quantitative and qualitative methods. The quantitative method was performed based on the measurement
result of various study sources, whereas the qualitative study was performed through the literature survey activity to collect initial information concerning the
advantages and shortcoming of various biodiesel-petrodiesel blending composition to the emission, engine performance and fuel selling price. The
collected data is then arranged by the rank of composition characteristic from the best to the worst composition. Besides the emission and engine performance
characteristics, to determine the best blending composition also depends on the fuel price. In current fuel price policy in Indonesia especially fuel for
transportation, the higher percent of biodiesel in blend will increase the price of blends fuel. Each parameter emission, engine performance and fuel price will be
given a specific weight based on the priority and its importance. The optimum blending composition is then determined from the overall score collected. The
highest score of a given composition indicates that such a blending composition is the optimum blending ratio of biodiesel and petro-diesel. A flowchart of the
methodology is shown in Figure 24.
48
Figure 24. Optimum Blending Determination Flow Chart
Result and Discussion The characteristics of petrodiesel, biodiesel and its blends
As explained in previous chapter that the biodiesel quality in Indonesia has been standardized by the National Standardization Agency No. SNI 04-7182-
2006. The standard was initially developed by referring to existing international standards especially American and European standards. The quality of biodiesel is
determined by the objectives to keep the good and safely long engine operability. Generally, the standard of biodiesel covered the parameters that influenced to the
engine performance and engine safeguard. Viscosity, density and cetane number are the parameters related closely to the engine performance. Although the
calorific content and lubricity are not included in the standard, those parameters also affect the engine performance when using the biodiesel blend.
The parameters which will determine the security of engine operability usually in the form of undesired contaminant content, such as methanol content,
free and total glycerol, acid, sulphur, phosphor, water and sediment. The biodiesel will be safe to be used if all those above mentioned contaminant composition
parameters are still in the range of biodiesel standard. In this study, only the parameter influencing the engine performance will be considered in determining
the optimum composition of biodiesel-petrodiesel blends. Currently in Indonesia, biodiesel can be blend up to 10 in maximum to the petrodiesel as long as the
Emission reduction data
Fuel consumption and torquepower data
Fuel price Effect on fuel price
score
Ranking of Optimum
Blending
Engine wear and deposit
Effect on long term engine score
Effect on engine performance score
Effect on emission score
Effect on short term engine score
49 finish blending product properties are still in the range of petrodiesel
specification issued by Directorate General of Oil and Gas [8]. Based on a comprehensive assessment to various biodiesel-petrodiesel
blend, The Engine Manufacturers Association EMA from USA has proposed the
standard of 20 biodiesel blends with 80 petrodiesel B20 [46]. The
comparison of B20 standard proposed by EMA and Indonesian biodiesel standard is shown in Table 14.
Tabel 14. Comparison of SNI 04-7182-2006, and B20 EMA
No. Test Parameter
SNI B20 EMA
1 Flash Point,
o
C min. 100
52 2
Water and sedimentt, vol , max. 0.05
0,05 3
Physical Distillation, T90,
o
C, max 360
343 4
Kinematic Viscosity, cSt 40
o
C 2.3 – 6.0
1.9 – 4.1 5
Ash, mass, max. 0.02
0.01 6
Sulfur, wt, max. 100
Per regulation
7 Copper strip corrosion rating, max.
No.3 No. 3
8 Cetane Number, min.
51 43
9 Cloud point
o
C, max 18
Per footnote
1
10 Ramsbottom carbon residue on 10 distillation residue, wt,
max. 0.30
0.35 11
Lubricity, HFRR 60
o
C, micron, max -
460 12
Acid Number, mg KOHg, max. 0.8
0.3 13
Phosphorus, wt, max 10
mgkg 0.001 wt
14 Total Glycerin mm, max
0.24 NA
15 Alkali metals Na+K, ppm, max
- Nd
16 Alkaline metals Mg+Ca, ppm max
- Nd
17 Blend Fraction, vol
- +- 2
18 Thermo-Oxidative Stability, insolubles, mg100 mL, max
- 10
19 Oxidation Stability, Induction Time, hours, min.
- 6
1
The maximum cloud point temperature shall be equal to or lower than the tenth percentile minimum ambient temperature in the geographical area and seasonal timeframe as defined by
ASTM D975
Up to now, no agency or institution that has issued the specification or the requirement for blending more than 20 biodiesel [46]. Beside the technical
consideration, to legalize the specification require the involvement and agreement of all related institutions including the producers and consumers of biodiesel,
diesel engine manufacture and government as a regulator. The result of engine and vehicle test indicated that the utilization of biodiesel blends more than 20 would
affect both engine performance and engine endurance. The followings are several
50 parameters which should be considered when utilizing the biodiesel blends
more than 20 B20 [47]. 1. Cold flow properties for biodiesel blend more than B20 resembles to the pure
biodiesel B100. This will cause the biodiesel blends to form the gel and blocking the fuel filter at low temperature. The utilization of biodiesel
produced from both oil palm and jatropha curcas, which has a relatively higher cloud point 10-15
o
C, must be treated more carefully if used in cold area mountain range. The study performed by Joshi et al. 2007 [48] has proved
the relation between the increasing of dynamic viscosity of biodiesel and its blends with the decreasing slope of temperature.
2. Biodiesel will soften and degrade certain of elastomers and rubber compound over time. Using blends higher than B20 can affect fuel system components
primarily fuel hoses and fuel pump seals that contain compounds incompatible with Biodiesel. Therefore, when the blend higher than B20 is
used, some modification such as changing the rubber hose and seals by compatible materials like synthetic rubber viton is strongly recommended.
3. Biodiesel has a characteristic as a cleaning agent that can dissolve the deposit and sediment usually form at the tank base and fuel pipe. The higher biodiesel
content in the blend will increase the cleaning power. The dissolved deposit will result the fuel filter clogged and the need to change filters more frequently
until the whole system has been cleaned of the sediments left by the petrodiesel.
4. Oxidation stability of blends will decrease as the biodiesel content level is increased. Industry experts recommend that biodiesel to be used within six
months of manufacture to ensure that the quality of the fuel is maintained. Fuel degradation pathways for biodiesel are more likely with higher
concentration blends due to the higher presence of the biodiesel, so stability concern and issues fuel system deposits, clogged filters, etc are likely to be
higher and may occur faster as the blend level is increased. There have been very few field reports of stability related problems with B20 and lower blends
when the biodiesel meets standard prior to blending and the fuel is used within six months.
51 5. Blends higher than B20 may cause a larger amount of unburned fuel to
make its way past the piston rings and into the oil pan. This is due to the slightly higher viscosity and the slightly higher density of biodiesel compared
to petrodiesel. High levels of biodiesel present in the engine oil may polymerize over time and cause serious engine problems. The interval of
engine oil change may need to be shortened significantly if using high blends of biodiesel. The viscosity and density of B20 and lower blends are very
similar to that of the pure petrodiesel, and this phenomenon has not been problematic with blends of B20 or lower so no changes in engine oil intervals
are needed with B20 or lower. As discussed in the study performed by Wirawan et al. 2007 [49], viscosity values of biodiesel mixtures were
predicted from the viscosities of the individual components by a logarithmic equation. Therefore, the relative error for viscosity parameter prediction is
slightly higher than that of density and Cetane Number parameter prediction. In Indonesia, maximum 10 volume of biodiesel can be blended with mineral
diesel oil as long as the mix fuel parameters still in the specification range of mineral diesel oil 48. The list of parameters for diesel oil 48 is shown in Table
15. Table 15. Diesel oil 48 specification
No. Parameter
Method Value
1 Density 15
o
C, kgm
3
ASTM D-1298 815 – 870
2 Cetane Number
ASTM D-613 Min. 48
3 Kinematic Viscosity 40
o
C, cSt ASTM D-445
2 – 5 4
Pour point,
o
C ASTM D-97
Max. 18 5
Sulphur content, mm ASTM D-2622
Max. 0,35 6
Copper Strip 3 hrs at 212
o
C ASTM D-130
Max. No. 1 7
Carbon Residue, mm ASTM D-4530
Max. 0,10 8
Water content, mgkg ASTM D-1744
Max. 500 9
Sediment, mm ASTM D-473
Max. 0,01 10
Ash content, mm ASTM D-482
Max. 0,01 11
FAME content, vv Gas Chromatograph
Max. 10 12
Flash point,
o
C ASTM D-93
Min. 60 13
Total Acid Content, mg KOHg ASTM D-86
Min. 40 Source: Ditjen Migas, 2006 [8]
52
Price consideration
Currently, biodiesel in the blend form has been sold by PERTAMINA with the trademark of BIOSOLAR in almost all public fuel filling stations in Java and
Bali. BIOSOLAR was initially launched in 2006 in B5 composition. The sharply increasing palm oil price has caused the price of biodiesel to be higher than that of
petrodiesel. The reason is that biodiesel is still classified as other fuel, which should be sold at the economic price without any subsidy. To reduce potentially
higher financial loss as a result of biodiesel blends difference, the PERTAMINA has decreased biodiesel content gradually to B2.5 and B1 since 11 April 2008. As
the price of palm oil and biodiesel continued to decrease, PERTAMINA is starting to raise the biodiesel content back to B5.
As explained above, it can be concluded that commercialization of biodiesel in Indonesia is influenced largely by pricing factor, especially on biodiesel raw
material price. The advantages of biodiesel as a renewable energy with lower exhaust gas emission and make longer engine lifetime is less considered.
Estimated increasing price of biodiesel-petrodiesel blend as influenced by the level biodiesel content is shown in Table 16.
Tabel 16. Price of biodiesel-petrodiesel blend
Note: 1. Subsidized petrodiesel price Rp. 5.500lt per May 2008
2. Average price of CPO Rp. 7.000kg per September 2008 from various sources 3. Estimated biodiesel production cost based on APROBI Association of Indonesian Biofuel
Producer is about US 140 - 150MT 4. Biodiesel production cost = Price of CPO + APROBI’s biodiesel production cost
5. Price of Biodiesel-petrodiesel blend BX = X 8.500 + 100–X5.500
Determination of optimum blending composition
The optimum blending composition is determined by considering the advantages and disadvantages of biodiesel blends utilization. The parameters to be
analyzed are categorized in two aspects. The first are technical parameters related
Composition Price per liter
Rupiah Price difference compare to
subsidized petrodiesel Rupiah
B0 5,500
B10 5,800
300 B20
6,100 600
B30 6,400
900 B50
7,000 1,500
B100 8,500
3,000
53 to the engine performance and emission. The second are non-technical
parameters that are closely related to the fuel pricing. The technical parameters were then grouped into long term and short-term parameters.
Considering its suitability for application in Indonesia, consideration of technical parameter in this study is based on the palm biodiesel blends. Fuel
emission and engine performance test result has been reported by previous
researchers [29, 33]. The general results were consistent with the data from the
numerous research reports and test programs in which the decrease in emission of hydrocarbons HC, carbon monoxide CO, sulphur dioxide SO
2
and particulate matter PM were found as the proportion of biodiesel in the blends were
increased. On the contrary, the palm based biodiesel test result showed lower NO
x
emission as well as higher torque and power for biodiesel blend compared to that of pure petro-diesel fuel. These results however, were different from the generally
non-palm based biodiesel test results, which tend to increase the NO
x
emission and lower the power and torque. The slope of emission reduction of various
blending composition can be estimated based on the test results reported by Wirawan et al., 2008 [29] and shown in figure 14. The value of emission
reduction is still need to be multiplied by the weight of toxicity level of each pollutant. The most dangerous pollutant for health is PM and followed
respectively by NO
x
, SO
2
, HC and CO as the lowest toxicity pollutant as shown in Table 17, while the estimation of technical parameter as a result of emission
reduction value and toxicity weight multiplication is shown on Table 18. As an example, the value of B10 for SO
2
emission is the 10 emission reduction multiplied by its relative toxicity weight = 1010028.0 = 2.8. By the same
calculation method, the value of the other composition can be determined.
Table 17. Relative toxicity of air pollutant
Pollutant Tolerance Level
μgNm
3
Relative Toxicity CO
HC SO
x
NO
x
PM 40,000
19,300 1,430
514 375
1 2.07
28.0 77.8
106.7 source: Babcock, 1971 in Fardiaz, 1992 [50]
54 Table 18. The value of emission parameter
BXX SO2
PM HC
CO NOx
TSE ER
RT S
ER RT
S ER
RT S
ER RT
S ER
RT S
B0 28
107 2
0.0 1
0.0 78
B10 10
28 3
40 107
43 12
2 0.2
5 1
0.1 5
78 4
50 B20
20 28
6 45
107 48
48 2
1.0 10
1 0.1
2 78
2 56
B30 30
28 8
50 107
53 60
2 1.2
20 1
0.2 8
78 6
69 B50
50 28
14 60
107 64
62 2
1.3 25
1 0.3
12 78
9 89
B100 100
28 28
70 107
75 77
2 1.6
30 1
0.3 23
78 18
122
Note: ER : Emission reduction of each pollutant in based on Figure 14.
RT : Relative toxicity of each pollutant based on Table 17. S
: Score = ER x RT TSE : Total Score for emission = SSO2 + SPM + SHC + SCO + SNOx
The value of engine performance parameter can be estimated from fuel consumption, power and torque data. Reduction of fuel consumption data was
taken from Wirawan et al. study [29]. As can be seen in Figure 13 that the reduction of fuel consumption as a function of biodiesel blend composition B10,
B20, B30, B50 and B100 were 6, 9, 16, 22 and 33 respectively. Consistent with almost previous studies results, the result of Wirawan et al. study
[29] also shows that the power and torque of B100 was 10 lower than the power and torque of pure diesel oil. Totaling of the value of emission and the value of
engine performance parameters is defined as the short-term engine effect value as shown in Table 19.
The result of the road test performed by Wirawan et. al. 2005 [33] indicated
that the deposit and wearing out of the engine component caused by utilization of palm biodiesel blends up to 30 B30 is still in the standard requirement range.
The test results and a long experience of American B20 users indicated that the utilization of blending higher than B20 in the long period would need engine
modification and special engine maintenance. The utilization of blending higher than B20 is recommendable only for private users non-commercial who have
wide knowledge in biodiesel and diesel engine. Applying several consideration mentioned above, the value of each composition for engine long term effect
parameter can be estimated as shown in Table 20.
55 Tabel 19. The value of emission and engine performance parameter
short-term engine effect
BXX Emission
Fuel Consumption Torquepower
TSS FSS
TSE FCR
S
1
TPR S
2
Short term effect B0
0 0 10
B10 50
6 6 1
9 65
13 B20
56 9
9 2 8
73 15
B30 69
16 16 3
7 92
18 B50
89 22
22 5 5
116 23
B100 122
33 33 10
155 31
501,7 100
Note: TSE : Total Score for Emission parameter based on Table 18.
FCR : Percentage of Fuel Consumption Reduction based on Figure 13 data. TPR : Percentage of Torque and Power Reduction based on the assumption that
the power and torque of B100 was 10 lower than diesel oil. Torque and power are assumed decrease proportionally with the increasing of
biodiesel content in the blend.
S
1
: Score of Fuel Consumption parameter is assumed equal to FCR S
2
: Score of Torque and Power parameters based on TPR data. The score is assumed decrease proportionally with the increasing biodiesel content in
the blend.
TSS : Total Score for short term engine effect = TSE + S
1
+ S
2
FSS : Final Score for short-term engine effect is normalized TS. Example: FSSB10 = TSSB10501.7100 = 13
Table 20. The score for long term engine effect
BXX Effect to the engine
SL FSL
B0 4
19 B10
5 24
B20 6
29 B30
3 14
B50 2
10 B100
1 5
21 100
Note: SL
: Score for long-term engine effect based on the study literature. FSL : Final Score for long-term engine effect is normalized SL.
Example: FSLB10 = SB1021100 = 24
56 From the difference of biodiesel blends price as shown on Table 16, the
score of price parameter can be estimated as indicated in Table 21. Table 21. The score for price parameter
BXX SP
FSP B0
3,000 26
B10 2,700
23 B20
2,400 21
B30 2,100
18 B50
1,500 13
B100 11,700
100
Note: SP : Score for price parameter based on the price difference between B100 and
BXX based on table 16 data. Example: SB10 = 3000 - 300 = 2700
FSP : Final Score for price parameter is normalized SP. Example: FSPB10 = SPB1011.700100 = 23
The optimum blending composition is ranked by total final score of short- term effect, long-term effect and price parameter. The result of the calculation of
optimum biodiesel-petrodiesel blends ranking is shown in Table 22. Table 22. The ranking of optimum biodiesel-petrodiesel composition
Parameter score Total
Score Ranking
BXX Short term effect
Long term effect Price
B0 19
26 45
5 B10
13 24
23 60
2 B20
15 29
21 65
1 B30
18 14
18 50
3 B50
23 10
13 46
4 B100
31 5
36 6
Conclusion
3.The study of biodiesel-petrodiesel blending optimum composition has been done through simple quantitative and qualitative methods. The quantitative
method was performed based on the measurement result of various study sources, whereas the qualitative study was performed through the survey literature
activities. The survey was meant to collect information concerning the advantages
57 and shortcomings of various biodiesel-petrodiesel blending composition with
respect to the emission, engine performance and fuel selling price. The study concluded that for the time being B20 is the optimum blending
composition, which can be used, in unmodified diesel engine. In the future, when the cheaper biodiesel raw materials and the lower cost of biodiesel production
technology already are available, the price of biodiesel will be more competitive than the one of petrodiesel. By improving the engine technology, the problem
associated with higher content of biodiesel composition hopefully can be overcome. Therefore, in the future, the utilization of biodiesel-petrodiesel blend
fuel with higher than B20 could possibly be implemented. Based on the study result, the proposed scenarios analyzed in this research
of external cost is the base case, B10 and B20 for the year of 2005, 2010, 2015, 2020 and 2025. Scenario blending of B50 and B100 were also analyzed to
anticipate the higher biodiesel-petrodiesel blends composition implementation and the conservative effect of maximum biodiesel utilization.
CHAPTER V EMISSION DISPERSION MODEL
Kategori