A Renewable Fuel
Biodiesel fuel represents one of the most researched alternative fuels in the world, and holds plenty of promise for vehicles equipped with the compression-igniton Diesel engine.
Properties
Liquid, nontoxic, biodegradable
Production
Biodiesel begins with virgin vegetable oils (such as soybean, rapeseed, palm, or coconut oils), animal fats and fish oils, or recycled cooking oils. Manufacturers rely on a chemical reaction called “transesterification” in which they react the chemically acidic vegetable oils with methanol (a base) and add a catalyst. Fat molecules in the oil are broken into fatty acid methyl esters (FAME) or alkyl esters.
CO2 Emissions
Zero Net Emissions
The only CO2 released during biodiesel combustion is the CO2 originally absorbed by the biological material (plants etc) during its development. However, fossil fuels are currently used in the production process.
Fuel Blends
Yes.
Biodiesel can be blended with conventional diesel at any ratio, either at the refinery or at the tank. However it is typically blended starting around 2% (B2) to 20% (B20). Blends higher than B5 make demands on the user, requiring modifications and special handling.
Infrastructure
In Place.
Sort of. It can use the existing road transport system for conventional diesel, but its corrosive capacity is problematic for the pipeline system.
Compared to Diesel
It has a higher density, lower heating value, lower sulfur content, lower oxidation stability, and is about 92% as efficient as conventional diesel (meaning it has 8% less energy per volume).
Advantages
• Biodiesel is already largely compatible with existing conventional diesel engines and some of its infrastructure.
• Combustion contributes no additional CO2 to the atmosphere.
Disadvantages
• Burning B100 (100% biodiesel) may release excess nitrogen oxides.
• Certain metals may oxidize in contact with biodiesel, creating sediments and fuel system problems. It can also affect some plastic types and paint.
• Currently, overall costs related to biodiesel are prohibitive.
The Future…
… is bright for biodiesel. Across the world, it is a rapidly expanding industry and is considered one of the most promising emerging fuels at the moment. In the US alone there are currently over 140 biodiesel plants in operation, and another 96 under construction2 .
Future Fuels Resources
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