I made methyl biodiesel from grease derived from beef fat in June 2014 . I made about 3/4 litre . It's in a clear glass storage bottle . At my room temperature of about 26 degrees centigrade there might be 1% white crystals in the bottom of the storage bottle . I made methyl biodiesel from lard in June 2014 also . Lard is grease from swine fat . I made maybe 800 milliliters of product . It's in a clear glass storage bottle . There's maybe 1-2% fall out in white crystals at 26 degrees centigrade . Grease is rendered from fat by heating . The liquid grease may be made into biodiesel by the usual methods . There are longer carbon chain fatty acids present in animal fats with a higher melting point . Vegetable oil has carbon chains 14- 18 in length . Swine fat has a per centage of carbon chains 20 and 22 carbon atoms in length . Generally the higher molecular weight has a higher melting point . Fat can be used to make biodiesel and soap but there are components in the material that turn solid at a higher temperature . I make fairly pure biodiesel . At 26 degrees celcius there is crystalized white biodiesel at the bottom of the bottles . If you want to look up the difference in grease from animal fat compared to vegetable oil look up eicosanoic acid . I believe that was a carbon chain of 20 or 22 carbons in length . There was discussion of a method on biodiesel forum Ireland when biodiesel was slowly cooled then solids removed leaving biodiesel useful at lower temperature . That's called fractional crystallization . I got melting points backwards , so I've modified my writing .
