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Oil yields and characteristics

Vegetable oil yields:
-- ascending order
-- alphabetical order
Other oil crops
Oils and esters characteristics
Iodine Values
-- High Iodine Values
-- Talking about the weather
-- Summary
Hydrogenated oil, shortening, margarine
Quality standard for rapeseed oil fuel
Cetane Numbers
National standards for biodiesel
-- standards and the homebrewer
-- standard testing
Fuel properties of fats and oils
Fuel properties of esters
Fats and oils -- resources

Vegetable oil yields

Biodiesel yield = oil yield x 0.8 approx.

Note: These are conservative estimates -- crop yields can vary widely.

Ascending order

Crop kg oil/ha litres oil/ha lbs oil/acre US gal/acre

corn (maize) 145 172 129 18

cashew nut 148 176 132 19

oats 183 217 163 23

lupine 195 232 175 25

kenaf 230 273 205 29

calendula 256 305 229 33

cotton 273 325 244 35

hemp 305 363 272 39

soybean 375 446 335 48

coffee 386 459 345 49

linseed (flax) 402 478 359 51

hazelnuts 405 482 362 51

euphorbia 440 524 393 56

pumpkin seed 449 534 401 57

coriander 450 536 402 57

mustard seed 481 572 430 61

camelina 490 583 438 62

sesame 585 696 522 74

safflower 655 779 585 83

rice 696 828 622 88

tung oil tree 790 940 705 100

sunflowers 800 952 714 102

cocoa (cacao) 863 1026 771 110

peanuts 890 1059 795 113

opium poppy 978 1163 873 124

rapeseed 1000 1190 893 127

olives 1019 1212 910 129

castor beans 1188 1413 1061 151

pecan nuts 1505 1791 1344 191

jojoba 1528 1818 1365 194

jatropha 1590 1892 1420 202

macadamia nuts 1887 2246 1685 240

brazil nuts 2010 2392 1795 255

avocado 2217 2638 1980 282

coconut 2260 2689 2018 287

oil palm 5000 5950 4465 635

Alphabetical order

Crop kg oil/ha litres oil/ha lbs oil/acre US gal/acre

avocado 2217 2638 1980 282

brazil nuts 2010 2392 1795 255

calendula 256 305 229 33

camelina 490 583 438 62

cashew nut 148 176 132 19

castor beans 1188 1413 1061 151

cocoa (cacao) 863 1026 771 110

coconut 2260 2689 2018 287

coffee 386 459 345 49

coriander 450 536 402 57

corn (maize) 145 172 129 18

cotton 273 325 244 35

euphorbia 440 524 393 56

hazelnuts 405 482 362 51

hemp 305 363 272 39

jatropha 1590 1892 1420 202

jojoba 1528 1818 1365 194

kenaf 230 273 205 29

linseed (flax) 402 478 359 51

lupine 195 232 175 25

macadamia nuts 1887 2246 1685 240

mustard seed 481 572 430 61

oats 183 217 163 23

oil palm 5000 5950 4465 635

olives 1019 1212 910 129

opium poppy 978 1163 873 124

peanuts 890 1059 795 113

pecan nuts 1505 1791 1344 191

pumpkin seed 449 534 401 57

rapeseed 1000 1190 893 127

rice 696 828 622 88

safflower 655 779 585 83

sesame 585 696 522 74

soybean 375 446 335 48

sunflowers 800 952 714 102

tung oil tree 790 940 705 100

This data is compiled from a wide variety of sources. The yield figures are most useful as comparative estimates, crop yields vary widely.

High yield is not the only factor in farming, maybe not even the most important factor. See: How much fuel can we grow? How much land will it take?

Typical oil extraction from 100 kg. of oil seeds

Castor Seed 50 kg
Copra 62 kg
Cotton Seed 13 kg
Groundnut Kernel 42 kg
Mustard 35 kg
Palm Kernal 36 kg
Palm Fruit 20 kg
Rapeseed 37 kg
Sesame 50 kg
Soyabean 14 kg
Sunflower 32 k

Other oil crops

NewCrop SearchEngine at the Center for New Crops & Plant Products at Purdue University -- Search for "oil". Results: "The following pages containing 'oil' were found -- hits 1-20 of 200". Results are hyperlinked to detailed factsheets.
http://www.hort.purdue.edu/newcrop/SearchEngine.html

Plants For A Future -- Database Search -- See "Search by Use - Select any of the following uses. Or select none and use the plant criteria below." Select "Other Use" - oil. Results: "Other Use: Oil (460)". Results are hyperlinked to detailed factsheets.
http://www.ibiblio.org/pfaf/D_search.html

Oils and esters characteristics

Oils and esters characteristics

Type of Oil Melting Range deg C Iodine
number Cetane
number

Oil / Fat Methyl
Ester Ethyl
Ester

Rapeseed oil, h. eruc.
5

0

-2

97 to 105

55

Rapeseed oil, i. eruc.
-5

-10

-12

110 to 115

58

Sunflower oil
-18

-12

-14

125 to 135

52

Olive oil
-12

-6

-8

77 to 94

60

Soybean oil
-12

-10

-12

125 to 140

53

Cotton seed oil
0

-5

-8

100 to 115

55

Corn oil
-5

-10

-12

115 to 124

53

Coconut oil
20 to 24

-9

-6

8 to 10

70

Palm kernel oil
20 to 26

-8

-8

12 to 18

70

Palm oil
30 to 38

14

10

44 to 58

65

Palm oleine
20 to 25

5

3

85 to 95

65

Palm stearine
35 to 40

21

18

20 to 45

85

Tallow
35 to 40

16

12

50 to 60

75

Lard
32 to 36

14

10

60 to 70

65

Liberty Vegetable Oil Company lists the fatty acid composition of their oils as well as other details such as the Iodine Value, SG, Flash point etc -- Sweet Almond Oil, Pecan Oil, English Walnut Oil, Hazelnut Oil, Macadamia Nut Oil, Soybean Oil, Oleic Sunflower Oil, Canola Oil, Peanut Oil, Sunflower Oil, Corn Oil, Safflower Oil, Soybean Oil (Non-GMO), High Oleic Oils including Canola and Safflower. http://www.libertyvegetableoil.com/products.html

Iodine Values

Chemically, vegetable and animal oils and fats are triglycerides, glycerol bound to three fatty acids. Animal fat such as tallow or lard is saturated, meaning that in the fatty acid portion, all the carbon atoms are bound to two hydrogen atoms, and there are no double bonds. This allows the chains of fatty acids to be straighter and more pliable so they harden at higher temperatures (that's why lard is a solid).

As you increase the number of double bonds in a fatty acid, you reduce that ability for oils to gain a conformation that would make them solid, so they remain liquid. To picture it, imagine that you put a bunch of strings in a line. Now tie knots in various places on the strings and see how they don't fit together tightly.

To test a vegetable oil to see how many double bonds it has (how unsaturated it is) iodine is introduced to the oil. The iodine will attach itself over a double bond to make a single bond where an iodine atom is now attached to each carbon atom in that double bond. Higher iodine numbers do not refer to the amount of iodine in the oil, but rather the amount of iodine needed to "saturate" the oil, or break all the double bonds. Oils for the most part contain only trace amounts of iodine naturally.

How does this translate to biodiesel? When the fatty acid chains are broken from the glycerol and then re-esterified to methyl or ethyl groups, those fatty acids still have their double bonds. That means that the more double bonds, the lower the cloud point because they resist solidifying at lower temperatures. So, for instance, if you use lard or tallow, the biodiesel will solidify at a higher temperature because the fat it was formed from also solidified at a higher temperature.

(Image and text compliments of Jeff Welter)

High Iodine Values

See also Oxidation and polymerisation

The information below refers to straight vegetable oil fuel, but is also useful to show which oils are suitable for making biodiesel and which may not be suitable.

Many vegetable oils and some animal oils are 'drying' or 'semi-drying' and it is this which makes many oils such as linseed, tung and some fish oils suitable as the base of paints and other coatings. But it is also this property that further restricts their use as fuels.

Drying results from the double bonds (and sometimes triple bonds) in the unsaturated oil molecules being broken by atmospheric oxygen and being converted to peroxides. Cross-linking at this site can then occur and the oil irreversibly polymerises into a plastic-like solid.

In the high temperatures commonly found in internal combustion engines, the process is accelerated and the engine can quickly become gummed-up with the polymerised oil. With some oils, engine failure can occur in as little as 20 hours.

The traditional measure of the degree of bonds available for this process is given by the 'Iodine Value' (IV) and can be determined by adding iodine to the fat or oil. The amount of iodine in grams absorbed per 100 ml of oil is then the IV. The higher the IV, the more unsaturated (the greater the number of double bonds) the oil and the higher is the potential for the oil to polymerise.

While some oils have a low IV and are suitable for use as fuel without any further processing other than extraction and filtering, the majority of vegetable and animal oils have an IV which may cause problems if used as a neat fuel. Generally speaking, an IV of less than about 25 is required if the neat oil is to be used for long term applications in unmodified diesel engines and this limits the types of oil that can be used as fuel. The table below lists various oils and some of their properties.

The IV can be easily reduced by hydrogenation of the oil (reacting the oil with hydrogen), the hydrogen breaking the double bond and converting the fat or oil into a more saturated oil which reduces the tendency of the oil to polymerise. However this process also increases the melting point of the oil and turns the oil into margarine.

As can be seen from the table below, only coconut oil has an IV low enough to be used without any potential problems in an unmodified diesel engine. However, with a melting point of 25 deg C, the use of coconut oil in cooler areas would obviously lead to problems. With IVs of 25-50, the effects on engine life are also generally unaffected if a slightly more active maintenance schedule is maintained such as more frequent lubricating oil changes and exhaust system decoking. Triglycerides in the range of IV 50-100 may result in decreased engine life, and in particular to decreased fuel pump and injector life. However these must be balanced against greatly decreased fuel costs (if using cheap, surplus oil) and it may be found that even with increased maintenance costs this is economically viable.

Oils and their melting points and Iodine Values

Oil Approx.
melting point
deg C Iodine Value

Coconut oil 25 10

Palm kernel oil 24 37

Mutton tallow 42 40

Beef tallow - 50

Palm oil 35 54

Olive oil -6 81

Castor oil -18 85

Peanut oil 3 93

Rapeseed oil -10 98

Cotton seed oil -1 105

Sunflower oil -17 125

Soybean oil -16 130

Tung oil -2.5 168

Linseed oil -24 178

Sardine oil - 185

-- From "Waste Vegetable Oil as a Diesel Replacement Fuel" by Phillip Calais, Environmental Science, Murdoch University, Perth, Australia, and A.R. (Tony) Clark, Western Australian Renewable Fuels Association Inc.
http://www.shortcircuit.com.au/warfa/paper/paper.htm

Note: More Iodine Values here.

Talking about the weather

Generally, the higher an oil's Iodine Value, the lower the temperature at which it solidifies. Different terms are used for this -- melting point (MP), cloud point (CP), cold filter plugging point (CFPP), and pour point (PP). In practice they all mean about the same. It matters with both SVO systems using straight vegetable oil as fuel and with biodiesel, but more so with SVO systems.

As vegetable oils cool, wax crystals form, and the oil goes cloudy. The crystals can form a film on filters, blocking the flow of fuel. The temperature at which this occurs varies widely according to the oil type, from well below freezing point to well above freezing point.

It even varies for the same type of oil: new food-grade rapeseed or canola oil is usually "winterized" so that it doesn't cloud in the fridge and put people off. It will work nicely down to -10ºC, but once it emerges from the fryer, partly hydrogenated, degraded and probably containing some tallow from the food fried in it, it will only stay liquid and not plug filters down to freezing point or just above.

If you want to use an SVO system in a cold climate, you need a system configured to deal with the CFPP factor, and you need oil with a low CFPP. Coconut oil, palm oil, tallow and lard won't do, rapeseed or canola, peanut, corn or cottonseed are much better.

But if you live in a hot climate, cloud points won't bother you and the opposite is true: coconut and palm oil, tallow and lard all have higher cetane numbers than the others, and lower Iodine Values.

For biodiesel, the same applies, but to a lesser degree -- with most oils and fats, converting it into biodiesel tends to lower the CFPP. Biodiesel made with ethanol usually has a lower CFPP than biodiesel made with methanol. Additives and fuel-line heaters can solve the problem, and so can adding a proportion of petro-diesel or kerosene (up to 30% is usually recommended).

See: Biodiesel in winter

Summary

Vegetable and animal fats and oils are triglycerides, made up of three fatty acid chains linked to a molecule of glycerol.

The fatty acids can be saturated or unsaturated. Unsaturated fatty acids have carbon-to-carbon double bonds. In saturated fatty acids all the carbon atoms are linked to two hydrogen atoms and there are no double bonds.

The degree of saturation is indicated by the Iodine Value of the oil (IV). Low-IV oils are more saturated with fewer double-bonds (lard, tallow, palm oil, coconot oil). High-IV oils are more unsaturated with more double-bonds (linseed oil, tung oil, some fish oils and other "drying oils").

Low-IV oils have higher cetane values and are more efficient fuels than high-IV oils, but they also have higher melting points and are usually solid at room-temperature. Biodiesel made from low-IV oils also has a higher melting point and might only be suitable for use as summer fuel.

High-IV oils have lower melting points and make better cold-weather biodiesel, but with high-IV oils there is more risk of the biodiesel oxidising and polymerising (drying) into a tough, insoluble plastic-like solid. Biodiesel made from high-IV oils should be stored carefully and used quickly.

"Semi-drying" oils like soy and sunflower are also prone to oxidation and polymerisation, though not as quickly as the drying oils.

See also Oxidation and polymerisation
Storing biodiesel

Hydrogenated oil, shortening, margarine

(See above, Iodine Values)

Biodiesel freshly made from vegetable shortening (Todd Swearingen)

Hydrogenated oils and shortening can be used to make biodiesel. Margarine is more problematic and should be avoided, unless you're an expert.

When oils are hydrogenated hydrogen atoms are added to the carbon-to-carbon double bonds in unsaturated fatty acids, which then become saturated. This results in higher melting points. Fully hydrogenated oil is solid at room temperature, partly hydrogenated oils range from liquid to creamy to solid.

Hydrogenation also lowers the Iodine Value (IV) of the oil. "The typical IV for unhydrogenated soybean oil is 125-140, for foodservice salad and cooking oils made from partially hydrogenated soybean oil it is 105-120, for semi-solid household shortenings made from partially hydrogenated soybean oil it is 90-95." (Institute of Shortening and Edible Oils.)

So biodiesel made from hydrogenated oil is less likely to oxidise and polymerise but will have a higher melting point than if it were made from unhydrogenated oil of the same kind. It increases the risk of filters plugging in cold weather or even just cool weather and is best used as summer fuel.

In processing, treat hydrogenated oil the same as ordinary oil. The more solid it is when you get it the more difficult it is to handle, but once you heat it for processing it melts and behaves like any other oil.

Shortening is fat used for baking and frying. Shortening is made from many kinds of vegetable oils, as well as lard and tallow. The oil is usually partly hydrogenated and different oils are blended for the desired effect.

For making biodiesel, treat shortening the same as hydrogenated oil.

Margarine and spreads are a blend of fats and oils with water, milk products, edible proteins, vitamins, salt, flavouring and colouring. Margarine is usually only 80% oil or fat or less. Extracting the triglycerides from the other liquids and proteins to make biodiesel is not easy. Margarine is best avoided.

Next: Oil yields and characteristics - Page 2
-- Quality standard for rapeseed oil fuel

Biofuels
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Biodiesel
Make your own biodiesel
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Do diesels have a future?
Vegetable oil yields and characteristics
Washing
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Straight vegetable oil as diesel fuel

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Is ethanol energy-efficient?

© Copyright of all original material on this website is the property of Keith Addison, unless otherwise stated, and may be copied and distributed for non-commercial education purposes only as long as the source of the material is stated and a reference to the Journey to Forever website URL is included (http://journeytoforever.org/). All material is provided “as is” without guarantees or warranty of any kind, either expressed or implied.