Environmental Engineering Reference
In-Depth Information
33
Vegetable Oils
Gerhard Knothe
U.S. Department of Agriculture
contents
33.1 Introduction ......................................................................................................................... 793
33.1.1 Fatty Acid Profile/Fuel Properties ............................................................................ 794
33.1.2 Historical Perspectives ............................................................................................. 796
33.2 Examples of Emerging Vegetable Oil Feedstocks ................................................................ 798
33.2.1 Pongamia ................................................................................................................. 798
33.2.2 Mahua ....................................................................................................................... 802
33.2.3 Moringa Oil .............................................................................................................. 802
33.2.4 Rice Bran Oil ........................................................................................................... 802
33.2.5 Olive Oil ................................................................................................................... 803
33.2.6 Oils with Varying Fatty Acid Profiles ...................................................................... 803
33.2.7 Jojoba .......................................................................................................................804
33.2.8 Tall Oil ......................................................................................................................804
33.2.9 Renewable Diesel ...................................................................................................... 805
33.3 Conclusions and Future Prospects ....................................................................................... 805
References ..................................................................................................................................... 805
33.1 IntroductIon
Numerous vegetable oils and their derivatives, most commonly biodiesel, the mono-alkyl esters of
oils or fats, have been investigated for their suitability as fuel, mainly for transportation purposes,
although some reports exist on the use of vegetable oils or biodiesel as heating fuel. Indeed, in
addition to the commonly applied biodiesel standards ASTM D6751 (United States) and EN 14214
(Europe), a separate standard when using biodiesel as heating oil has been developed, EN 14213
(Europe). The standard ASTM D396 (fuel oils) now covers blends of up to 5% biodiesel with fuel
oil if the biodiesel used satisfies the specifications in D6751.
Classical commodity oils such as soybean, canola (rapeseed), palm, and some other oils used as
energy sources are covered in other chapters of this topic. This chapter deals with less common oils
that have been studied for their potential to provide a source of energy. A few other oils will also be
briefly discussed if, although commercialized for reasons such as economics, they are not usually
considered to be biodiesel feedstocks. Some of the feedstocks discussed in this chapter have also
been used untransesterified or transformed to what is known as “renewable diesel.”
Several driving forces are causing the search for additional feedstocks for biodiesel (or biofuels
in general). Although it is beyond the scope of this chapter to discuss these driving forces in
detail, they can be summarized as the needs to increase the potential supply of energy feedstocks
in light of diminishing petroleum reserves, to provide domestic sources of renewable energy to
decrease dependence on imported petroleum, and to enhance economic development by providing
a source of jobs and income, an aspect of particular interest in more indigent sections of developing
countries. Issues that have also affected this search are the food-versus-fuel discussion, i.e., the
793
