Page 92 - Advances in Eco-Fuels for a Sustainable Environment

66 Advances in Eco-Fuels for a Sustainable Environment

an entire corn kernel can be fed to an animal, so any use of corn for other purposes is
direct competition and upward pressure on the price.
Soybeans (Glycine max) belong to the legume crop family and are known as the
“golden bean.” Soybeans thrive well in warm and moist climates. A temperature of
26–32°C appears to be the ideal for most of the varieties of soybean and soil temper-
atures of about 16°C or above support rapid germination and vigorous seedling growth
[38]. It is best planted from the third week of June to mid-July and requires well dra-
ined and fertile loamy soils with a pH range between 6.0 and 7.5 for its cultivation
[38]. Land for soybean cultivation must not have been sown with a soybean crop
in the previous season to avoid volunteer plants that cause admixture. By following
crop rotation, endemic pathogens can be reduced. Any soil with high organic matter
defiantly helps in leading production of vigorous seed. Crop yield on the average is
1800–3500kg per hectare depending on the variety [38].
A mixture of 50% soybean oil and 50% Stoddard solvent (48% paraffins and 52%
naphthenes) from Union Oil had a viscosity of 5.12cSt at 38°C [37]. The soybean oil
passed the 200h EMA (Engine Manufacturers’ Association) test [37]. Short-term
performance tests were conducted to evaluate crude soybean oil, crude-degummed
soybean oil, and soybean ethyl ester as complete substitutes for No. 2 diesel fuel in a
2.59L, 3 cylinder 2600 series Ford diesel engine [37]. A longer-term evaluation of
the engine when using 100% crude soybean oil was prematurely terminated as a
result of severe injector coking leading to decreased power output and low thermal
efficiency [37]. A long-term performance test was conducted using a fuel blend of
75% unrefined mechanically expelled soybean oil and 25% diesel fuel. The fuel
blend was burned in a direct injection diesel engine for 159h before the test was
terminated because a constant load could not be held on the engine [37]. A test fail-
ure occurred 90h into the screening test due to a 670% increase in the lubricating oil
viscosity [37]. The performance of a direct injection 2.59L, 3 cylinder 2600 series
Ford diesel engine operating on B25% mechanically expelled unrefined soybean and
sunflower oil with petroleum diesel. The power remained constant throughout 200h
of operation. Excessive carbon deposits on all combustion chamber parts preclude
the use of these fuel blends, at least in this engine and under the specified EMA oper-
ating conditions.

3.2.1.10 Walnut
Walnuts are a global crop that has been cultivated since ancient times. Persian walnuts
(Juglans regia) grow in semiarid to humid warm temperate and Mediterranean cli-
mates. Carpathian walnuts are substantially more cold hardy and may grow in the cold
temperate zones but are less domesticated than the Persian walnuts. Persian walnuts
contain 13%–18% protein and 63%–67% fat. They are a major global commodity and
are also used to produce edible oil. Average global yield is 3.4tonnes per hectare in
shell (0.8tonnes per hectare dry deshelled nut kernels) but in fertile valleys, it can be as
high as 6.5–7.5tonnes per hectare (1.8tonnes per hectare dry deshelled nut
kernels) [24].