[0014]Applicant has determined that blends of vegetable oils can be chosen so that the blend exhibits desirable properties for use as
alternative fuels or as feedstocks for the production of a biodiesel. For example, such blends may be chosen so that, when used as a fuel in a
cold climate, the blend is less likely to freeze. Blends may also be chosen so that the blend is stable at higher temperatures. Further, blends may be chosen to achieve desirable ignition properties when used as a fuel in a vehicle. Some particular examples of features of the blends of oils or fatty acids of the invention are described below. It is understood that the blends of oils or fatty acids within the invention may have any combination of the features described in the below embodiments. In particular the Inventors have determined that certain mixtures of fatty acids have surprisingly beneficial properties for production of biofuels. For example, the Inventors have found that particular balances of medium chain fatty acids and monounsaturated fatty acids can have surprisingly beneficial properties, for example with respect to
cold weather capabilities. In certain embodiments of the
fatty acid mixtures having balanced amounts of medium chain fatty acids (for example C8, C10 and C12) and monounsaturated fatty acids (preferably C16:1 and C18:1), Inventors have found that the presence C16:0 and C18:0 can have particularly unfavorable effects on cold flow properties and therefore reduced levels of C16:0 and C18:0 in a biodiesel can be beneficial for
cold weather capabilities; and that C14:0, C18:2, C18:3, C20, C22 and C24 can also adversely effect cold flow properties; thus, reducing these fatty acids in a biodiesel can also be beneficial. It has also been discovered that certain alkyl esters of oils, blends of oils, and blends of fatty acids have particularly favorable effects on cold flow properties, whereas other alkyl esters are less beneficial.
[0069]In certain embodiments, the
enzyme which is modified is Δ9-stearoyl acyl-ACP desaturase. In preferred embodiments the activity or expression of Δ9-stearoyl acyl-ACP desaturase is increased. In preferred embodiments, the increase of Δ9-stearoyl acyl-ACP desaturase activity in the genetically modified
plant results in the genetically modified
plant producing increased levels of C16:1 and / or C18:1; and / or decreased levels of C16:0 and / or decreased levels of C18:0 as compared to the
native plant. In certain preferred embodiments, the of Δ9-stearoyl acyl-ACP desaturase
gene is modified such that the genetically modified plant produces increased levels of C16:1. In certain embodiments the of Δ9-stearoyl acyl-ACP desaturase
gene is modified such that it exhibits increased activity with palmitoyl-ACP; or in the genetically modified plant is a cotton, flax, peanut, palm, safflower, soybean,
sunflower, Cuphea, castor or corn plant and the increased production of C16:0 is achieved by transformation of
rapeseed with the Δ9-stearoyl acyl-ACP
gene from macadamia (
Macadamia integrifolia), sea buckthorn (
Hippophae rhamnoides) or cat's claw (Doxantha unguis-cati).
[0075]In one embodiment, the genetically modified plant is modified such that the genetically modified plant produces increased levels of medium chain fatty acids (preferably increased levels of C8:0, C10:0 and C12:0 in accordance with preffered fatty acid blends provided herein) and / or decreased levels of
palmitic acid (C16:0) and / or decreased levels of C18:0. In other preferred embodiments, the genetically modified plant is modified such that it produces increased levels of monounsaturated fatty acids, preferably increased levels of C16:1 and C18:1 monounsaturated fatty acids; and produces lower levels of saturated and polyunsaturated fatty acids, preferably lower levels of C16:0, C18:0, C18:2 and / or C18:3. In particularly preferred embodiments the genetically modified plant is modified to produce increased levels of medium chain fatty acids (preferably increased levels of C8:0, C10:0 and / or C12:0); decreased levels of C16:0 and C18:0; and increased levels of C16:1 and C18:1.
[0076]In one particularly preferred embodiment of the above aspects, a
rapeseed plant is provided that is genetically modified to produce an oil having a fatty acid mixture provided herein. In certain preferred embodiments the genetically modified rapeseed plant is modified such that, relative to a native rapeseed plant, the genetically modified rapeseed plant produces increased levels of medium chain fatty acids (preferably increased levels of C8:0, C10:0 and C12:0 in accordance with preffered fatty acid blends provided herein) and / or decreased levels of
palmitic acid (C16:0) and / or decreased levels of C18:0. In other preferred embodiments, the genetically modified rapeseed plant is modified such that, relative to a native rapeseed plant, the genetically modified rapeseed plant produces increased levels of monounsaturated fatty acids, preferably increased levels of C16:1 and C18:1 monounsaturated fatty acids, and produces lower levels of saturated and polyunsaturated fatty acids, preferably lower levels of C16:0, C18:0, C18:2 and C18:3. In particularly preferred embodiments the genetically modified rapeseed plant is modified to produce increased levels of medium chain fatty acids (preferably increased levels of C8:0, C10:0 and / or C12:0); decreased levels of C16:0 and C18:0; and increased levels of C16:1 and / or C18:1.
[0137]The “
cetane number” or CN is a measure of fuel ignition characteristics and correlates to the
ignition delay period. For example, a fuel with a high
cetane number starts to burn shortly after it is injected into the cylinder (i.e., it has a short
ignition delay period). Conversely, a fuel with a low
cetane number has a longer
ignition delay period. Further, a higher cetane number correlates with improved
combustion, improved cold starting, reduced
noise, reduced white
smoke, and reduced emissions of HC, CO and particulate, particularly during early warm-up phase. Commercially available
petroleum-derived diesel is generally found in two CN ranges: 40-46 for regular diesel, and 45-50 for premium.