Norms for the Biodiesel
The users of Biodiesel, from the motors manufacturers to the other interveners parties, need the development of reliable norms to give security in order to facilitate its commercialization.
The countries where these users reside, demand other benefits besides the economic ones such as environmental and of health.
Developed nations as Austria (ORORM C 1190), Germany (DIN V51606) and USA (ASTM D6751) have established similar norms for the Biodiesel with particular specifications as for example, the glicerol quantification, that are not given in the norms for DF.
The European regulatory scheme has the particularity of including the number of Iodine (Iodine Value) since generally, in this continent colza oil is used in the production of Biodiesel.
The acceptable maximum value is IV = 115 that would exclude soy oil and its esters, since these exceed that limit.
They are different types of biodiesel
On one hand there exists the derivated of vegetables oils with a high content of saturated compounds, (low IVs) these possess a CN (Centane number) bigger, while their properties in low temperatures are worse.
On the other hand and also known, is the Biodiesel coming from vegetables oils with a high content of unsaturated compounds, (high IVs) that possess a smaller CN, while their properties in low temperatures are better.
Consequently, the CN and the IVs are inversely proportional. When adding to the norms a maximum of IVs, the minimum CN would be restricted.
Considering that most of the esters have a bigger CN that the vegetable oils and the conventional Diesel fuels, they overcome without any type of inconveniences the minimum imposed by ASTM (CN mÃn = 40).
An argument contrary to the inclusion of the IV in the norms of Biodiesel, is that different compositions of fatty acids give a same IV. For example, pure methyl oleate has the same IV that the mixture 1 to 1 of methyl estearate and methyl linoleate.
The IV ignores structural factors in the fatty compounds where the CN depends on the double link position, longitude of the chain, etc.
To increase the CN of the oils of some plants through the development of new preservatives that are more effective in spite of their high grade of insaturation, is a possible alternative.