Environmental Engineering Reference
In-Depth Information
distribution and vehicle fuel systems (White Paper 2007), such as fuel pumps, seals, and elastomers
(Foon et al. 2005).
The ethanol and methanol content is strongly related to the flash point (Foon et al. 2005), which
is already limited in fuel specialization. Namely, biodiesel with a flash point value higher than
100°C will have a methanol concentration less than 0.2% m/m (Mittelbach 1996). For low-methanol
residue biodiesel, typical flash point values exceed 160°C (Rilett and Gagnon 2008). However, a
more precise estimation of these parameters is required to guarantee the safe use of the fuel.
The CEN specification currently limits the ethanol and methanol content of the biodiesel to 0.2%
m/m (EN 14110). The ASTM specification has the same limit but just for methanol. For the case of
ethanol, the flash point is measured and is limited to 130°C minimum. ASTM is working to fill this
gap (White Paper 2007).
9.3 BIoethanol
9.3.1 c
olor
and
a
ppEarancE
Color is an easy and fast way to identify bioethanol (IFQC 2004) because proteins of ethanol give
a natural yellow color to the fuel (White Paper 2007). In some countries, such as Brazil, the use of
orange dyes was proposed. However, their use will not be mandated and in general they will not be
allowed for bioethanol intended for export (White Paper 2007).
Appearance specification aims to ensure that the ethanol is free of suspended and precipitated
contaminants (Chevron 2008; RFA 2009). If these contaminants are not eliminated, they can dam-
age the engine by increasing wear and shortening filter life by causing blockage of the fuel system
(IFQC 2004).
Color specification may vary according to national regulation (WWFC 2008). Appearance spec-
ifications are examined with visual inspection at ambient temperature (WWFC 2008). If a fuel fails
to meet these specifications, it will likely fail to meet the rest because this would indicate poor fuel
handling practices (WWFC 2008).
9.3.2 d
EnSity
Density is a natural characteristic of ethanol (IFQC 2004). It is not strongly linked to the engine
operation or protection and influences only slightly the energy value of the fuel and conse-
quently vehicle performance (De Klerk 2008). With the use of high-purity ethanol with a low
water content,
this parameter is even less important (IFQC 2004). However, density measure-
ment is an easy and quick test (ebio 2006) that can be used for quality monitoring purposes of
the blendstock (WWFC 2008). Density can be used to estimate the purity of the fuel with high
precision in cases when the fuel ethanol contains small amounts of methanol (that has lower
density than ethanol) and/or high alcohols (i.e., C
3
-C
5
alcohols), which have higher density than
ethanol (White Paper 2007).
Currently, CEN and ASTM do not have density specifications for bioethanol. Given that bio-
ethanol contains negligible quantities of water, methanol, and higher alcohols, its density should
be approximately the same as that of pure ethanol. However, a density measurement is needed to
correct volume to a reference temperature and for calculating % v/v results from reported % m/m
results. A recommended value of 793 kg/m
3
maximum at 20°C (ASTM D4052/ABNT NBR 5992)
is provided by the Worldwide Fuel Charter (WWFC 2008).
9.3.3 S
ulfatE
c
ontEnt
Sulfate content and the electrical conductivity of a fuel are interrelated. By regulating electrical
conductivity, detrimental effects of sulfates [present as sulfite (SO
3
) and sulfate (SO
4
)], such as
