Course: BFM 202 Biodiesel Production

Lecture

Other Feedstocks
Credits
BFM 202 Biodiesel Production Unit 4 Lecture has been adapted from "ENGY 131 Lesson 4 Alternate Biodiesel Feedstocks” by Southeastern Illinois College.

ENGY 131 Biodiesel Production course content by Southeastern Illinois College is licensed under a Creative Commons Attribution 3.0 Unported License. Except where indicated otherwise.

Other Feedstocks

Worthy feedstock sources are: coconut oil, rice bran, safflower, palm
kernel, Jatropha curcas, Ethiopian mustard, rapeseed, canola, and
crambe with the most promising research involving Jatropha and microalgae.

Jatropha curcas

This plant has become an attractive source since it is a drought-resistant
perennial bush that lives on poor soil in arid-to-moist climates. Its seed
yields about 35% lipids and conversion methods are being developed
that ensures oil stability and cold weather fluidity. Its yield per acre
compares favorably with soybean oil. Harvesting remains an issue since
the seeds do not ripen at the same time and repeated, labor-intensive
harvests are necessary.

Microalgae

Microalgae is aggressively being researched as a feedstock choice. Algae
is an organism grown through photosynthesis and as much as 70% of their
mass can be lipids. It's estimated that the lipid production from algae
can be 100-300 times greater than that of soy oil. Their capability to
use CO_2 as a food source provides an avenue for carbon sequestration and
squelches the food vs fuel debate along with the need for fertile land
to grow the feedstock. Gray and black water may be used as a growth
medium as well. Researchers and investors are hopeful that algae might
provide the majority of the nation's transportation fuel.

Ethanol By-products

Eighty percent of the corn kernel used in ethanol production is starch
which is converted to sugars then fermented into ethanol. However, the
germ of the kernel contains 3.6% oil and is considered a by-product of that
process. With a production of 25 MMT of ethanol per year, a 2.82 MMT
by-product of corn oil is created. Subsequent to fermentation, centrifuges
can be used to separate this oil as a side-stream that then becomes a
feedstock for biodiesel.

This process is new and should be monitored closely for success. The conversion of corn oil to biodiesel is achieved through direct transesterification, or “in situ” transesterification. Biorefineries that include both ethanol and biodiesel processes are now being developed.

Other Low Quality Feedstocks

The feasibility of using a feedstock is determined by its compliance with
ASTM specifications, supply logistics, volume of supply, cost, and quality.
There have been significant research pathways. A few additional are noted below.

Soapstock is a by-product of vegetable oil refining and U.S. production
is approximately 100 million lbs per year. It is rich in fatty acids. Its largest
use is in animal nutrition and does not look likely to become a biodiesel feedstock.

Trapgrease is a lipid from the waste streams of commercial kitchens.
While it is low-cost, it has excessive amounts of water, FFA, and contaminants,
making it a difficult material to handle and clean up. It is estimated that an
average of 13 lbs of trap grease, or used frying oil, is available in most cities
at a very low cost. Although this used grease contains large amounts of water,
free fatty acids, and other contaminants, it can be refined into biodiesel.

Used coffee grounds are a potential biodiesel feedstock source through
its initial conversion to FAME so that it can meet ASTM biodiesel specs.