*bump* I have been looking to the biodiesel in i30 issue myself. I though I would post the information here that I have discovered so others can make an informed choice on what fuel they use in their car.
First of all, the official line is that commercial biodiesel fuels compliant with the standard are acceptable up to 5% concentration mixed with traditional diesel. The exact wordings are in your owners manual.
This is a document from the major that list their concerns with biodiesel as a fuel.
http://www.scribd.com/doc/22125979 or
http://www.journeytoforever.org/biofuel_library/FIEM.pdf. Basically they list these problems with biodiesel -
- Free methanol
- Dissolved and free water
- Free glycerin
- Mono and di glycerides
- Free fatty acids
- Total solid impurity levels
- Alkaline metal compounds in solution.
- Oxidation and thermal stability
From my research it seems that these are valid concerns and all of these problems could cause problems in a modern diesel engine. These problems / contamination's occur when biodiesel is created from the wrong base oils or are reacted incompletely or are not "washed" and "dried" correctly. Washing is the process where excess chemicals from the reaction are removed using water and drying is the process where water is removed from the diesel leaving the fuel only.
In Australia, the government has put in place regulations that clearly setout the specifications of biodiesel ( and also specifications of normal diesel ) that ensure that the biodiesel sold in Australia does not have these problems. The Australian fuel standard (summary) specification is found here -
http://www.environment.gov.au/atmosphere/fuelquality/standards/biodiesel/summary.html. There are also links to the full standard on this page.
If you read the summary you can see that all of the fuel system manufactures concerns have been addressed in the Australian standard. The standard sets very low limits on the amount of impurities that are allowed in biodiesel sold in Australia.
When biodiesel is mixed with diesel as in a B5 mix, the biodiesel component must meet the biodiesel standard and then the whole mix must comply with the Australian diesel standard -
http://www.environment.gov.au/atmosphere/fuelquality/standards/diesel/I think a lot of confusion around the term "biodiesel" on the Internet is that it's sometimes hard to know if people mean "biodiesel - the stuff I brewed up in my back yard" or "biodiesel - the commercially manufactured fuel that complies with the Australian standards".
Why would anybody want to use biodiesel anyway? Well there are a few reasons. It is renewable, it has good engine lubrication properties, it (typically) has a higher cetane index which means it ignites more easily under compression ( less diesel noise ) and it's often cheaper. It supports local industry and promotes recycling and reuse.
Hope this information will be helpful to people.
