Environmental Engineering Reference
In-Depth Information
9.3.14 i
ron
and
S
odium
c
ontEnt
Iron (Fe) as well as copper (Cu) and sulfates (present as SO
3
and SO
4
) form a gum with petrol and
result in scale in engine pipes.
Sodium (Na) accumulates in the vehicle combustion chamber and causes corrosion. Na is used
in the form of NaOH to regulate the pHe of the fuel when it is too low to meet pHe specifications
(IFQC 2004).
The Fe and Na contents of hydrated ethanol are limited only by Brazilian specifications.
Although Fe and Na contents are important parameters, they will probably be eliminated because
they are covered by electrical conductivity and chloride content specifications (White Paper 2007)
(see Section 9.3.6). ICP spectrometry could be used to measure Cu, Na, Fe, and phosphorus (P) in
one test (WWFC 2008).
9.4
Fuel qualIty varIatIon By Feedstock and By country
9.4.1 f
uEl
q
uality
By
f
EEdStock
In general, the fuel quality required for bioethanol depends on the process, which is in contrast
to biodiesel, for which some quality specifications are influenced only by the feedstock or by the
process or by both. The main reason for this difference is that bioethanol is one chemical product;
that is, the ethanol content is more than 93.9% v/v (see Section 9.3.7), whereas biodiesel is a blend
of many FAMEs or FAEEs.
The chain length and the number and place of chemical bonds of esters that compose biodiesel
vary, in addition to the percentage of each of them present in the raw material (the feedstock) that
derives the final product (Table 9.A1). The fuel quality of the fuel derived varies according to these
variations of the feedstock. The biodiesel quality is improved with lower levels of polyunsaturated
fatty acids [e.g., linolenic acid (18:3)] or saturated fatty acids [e.g., palmitic (16:0) and stearic acid
(18:0)] and by higher levels of monounsaturated fatty acids [e.g., oleic acid (18:1)]. The more that
these criteria are met, the higher the oxidation stability will be and the more improved winter oper-
ability the fuel will have (Körbitza et al. 2003).
Currently, there are several feedstocks commonly used for the production of biodiesel. All of
them could be clustered into two categories mostly on the basis of the saturation of biodiesel:
1. Vegetable oil such as rapeseed oil, sunflower oil, soy oil, and palm oil.
2. Used oil and animal fat such as tallow, grease, poultry fats, and fish oils.
Table 9.6 presents the main properties of biodiesel by the feedstock used.
There are other raw materials used as a feedstock for the production of biodiesel. However, their
production is, at least for the moment, very low; they have some promising results, but they are not
currently traded or they are still on the research level. These include oils from algae, artichoke,
coconut, cottonseed, flaxseed, hemp, jojoba, karanj, kukui nut, milk bush, pencil bush, mustard,
neem, olive, peanut, radish, rice bran, safflower, sesame, and tung (http://www.bdpedia.com/
biodiesel/plant_oils/plant_oils.html). The blend of more than one of these oils could improve the
quality of the biodiesel produced.
9.4.2 f
uEl
q
uality
/S
tandardS
By
c
ountry
The fuel quality of biofuels varies from country to county to meet the corresponding variations in
fuel regulation. The fuel regulation of each country is based on the specifications of standardiza-
tion organizations. These can have an international (i.e., ISO, CEN, and ASTM) or national range
of application.
