BIODIESEL
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10.0 BIODIESEL Biodiesel (mono alkyl esters) is a cleaner-burning diesel fuel made from natural, renewable sources such as vegetable oils. Biodiesel operates in compression ignition engines like petroleum diesel thereby requiring no essential engine modifications. Moreover it can maintain the payload capacity and range of conventional diesel. Biodiesel fuel can be made from new or used vegetable oils and animal fats. For more information on biodiesel please refer to our PARIVESH newsletter on Biodiesel. |
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10.1 Emission Characteristics:
Biodiesel is the only alternative fuel to have a complete evaluation of emission results and potential health effects submitted to the U.S.EPA under the Clean Air Act Section 211(b). Comparision of emissions from biodiesel and petrodiesel is given in Table-17.
Table-17: Biodiesel Emissions Compared to Conventional Diesel|
Emissions |
B100 |
B20 |
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Regulated Emissions |
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Total Unburned Hydrocarbons |
-93% |
-30% |
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Carbon Monoxide |
-50% |
-20% |
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Particulate Matter |
-30% |
-22% |
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NOx |
+13% |
+2% |
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Non-Regulated Emissions |
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Sulphates |
-100% |
-20%* |
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Polyciclic Aromatic Hydrocarbons (PAH)** |
-80% |
-13% |
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NPAH (Nitrated PAHs)** |
-90% |
-50%*** |
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Ozone Potential of Speciated HC |
-50% |
-10% |
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Life-Cycle Emissions |
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Carbon Dioxide (LCA) |
-80% |
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Sulphur Dioxide (LCA) |
-100% |
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***2-nitroflourine results were within test method variability.
10.2 Advantages of biodiesel:
The benefits of biodiesel are:
- The lifecycle production and use of biodiesel produces approximately 80%
less carbon dioxide emissions, and almost 100% less sulphur dioxide. Combustion
of biodiesel alone produces over a 90% reduction in total unburned hydrocarbons,
and a 75-90% reduction in aromatic hydrocarbons. Biodiesel further provides
significant reductions in particulates and carbon monoxide than conventional
diesel fuel.
- Biodiesel is the only alternative fuel that runs in any conventional, unmodified
diesel engine.
- Needs no change in refueling infrastructures and spare part inventories.
- Maintains the payload capacity and range of conventional diesel engines.
- Diesel skilled mechanics can easily attend to biodiesel engines.
- 100% domestic fuel.
- Neat biodiesel fuel is non-toxic and biodegradable. Based on Ames Mutagenicity
tests, biodiesel provides a 90% reduction in cancer risks.
- Cetane number is significantly higher than that of conventional diesel fuel.
- Lubricity is improved over that of conventional diesel fuel.
- Has a high flash point of about 300 F compared to that of conventional diesel,
which has a flash point of 125 F.
10.3 Disadvantages of biodiesel:
Some of the disadvantages of biodiesel are:
- Quality of biodiesel depends on the blend thus quality can be tampered.
- Biodiesel has excellent solvent properties. Any deposits in the filters
and in the delivery systems may be dissolved by biodiesel and result in need
for replacement of the filters.
- There may be problems of winter operatibility.
- Spills of biodiesel can decolorize any painted surface if left for long.
- Neat biodiesel demands compatible elastomers (hoses, guskets, etc.).
Indian initiative on biodiesel, safety issues and storage/handling for biodiesel is described in our earlier publication PARIVESH on biodiesel. Properties of biodiesels from various feedstocks are given in Table-18.
Table-18: Some properties of different biodiesel fuels|
Biodiesels |
Melting Range,( Degrees Centigrade) |
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Oil/Fat |
Me. Ester |
Et. Ester |
Iodine No. |
Cetane No. |
|
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Rapeseed oil, h.eruc. |
5 |
0 |
-2 |
97-105 |
55 |
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Rapeseed oil, I.eruc. |
-5 |
-10 |
-12 |
110-115 |
58 |
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Sunflower oil |
-18 |
-12 |
-14 |
125-135 |
52 |
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Olive oil |
-12 |
-6 |
-8 |
77-94 |
60 |
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Soyabean oil |
-12 |
-10 |
-12 |
125-140 |
53 |
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Cotton seed oil |
0 |
-5 |
-8 |
100-115 |
55 |
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Corn oil |
-5 |
-10 |
-12 |
115-124 |
53 |
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Coconut oil |
20-24 |
-9 |
-6 |
8-10 |
70 |
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Palmkernel oil |
20-26 |
-8 |
-8 |
12-18 |
70 |
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Palmoil |
30-38 |
14 |
10 |
44-58 |
65 |
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Palm oleine |
20-25 |
5 |
3 |
85-95 |
65 |
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Palm stearine |
35-40 |
21 |
18 |
20-45 |
85 |
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Tallow |
35-40 |
16 |
12 |
50-60 |
75 |
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Lard |
32-36 |
14 |
10 |
60-70 |
65 |
