New Method Simplifies Biodiesel Production
Oil from soybeans is the usual starting material for biodiesel.
ARS scientists in Wyndmoor, Pennsylvania,
have modified biodiesel production technology. Their method eliminates a stepand
an air-polluting chemicalfrom the process of synthesizing the fuel.
Michael Haas, a biochemist with the Eastern Regional Research Center's Fats,
Oils, and Animal Coproducts Research Unit, and colleagues developed the new
In this country, soybean oil is the most prevalent starting material for biodiesel,
though other vegetable oils, animal fat, and waste grease are used too. But
soybean oil's relatively high cost results in biodiesel being expensive, which
discourages wider adoption of this desirable, renewable fuel.
In biodiesel production, hexane, a colorless, flammable liquid derived from
petroleum, is traditionally used to extract the oil from the soybeans. But hexane
is an air pollutant, and its release is regulated by the U.S. Environmental
Protection Agency. Working with ERRC biologist Karen M. Scott and chemist Thomas
A. Foglia, Haas eliminated hexane from the process simply by skipping the oil-extraction
step that relies on it. Instead, Haas explains, soybean flakes are incubated
with methanol and sodium hydroxidethe same agents that would be used to
process extracted oil.
"In the new method, soybean flakes are incubated in alkaline methanol,
eliminating the need to isolate and purify the oil before transesterification."
("Transesterification" is a reaction between fats and alcohol that
forms the simple fatty acid esters that are biodiesel.) The lipids don't have
to be isolated first because transesterification occurs in the raw soy flakes
containing the oil.
Next, when the researchers collaborated with Andrew McAloon, a process modeler/cost
engineer at their facility, to estimate and compare costs, they hit a snag.
Without even accounting for the cost of the soy flakes or soy oil, a gallon
of biodiesel produced by their new process was estimated to cost $3.14versus
38 cents per gallon if produced by the conventional process.
The researchers then noticed that their new method used considerably more methanol
than is typically needed in biodiesel synthesis. They reasoned that the moisture
naturally present in soybeans, as much as 10 percent in soy flakes, could be
the reason behind the high methanol requirement. They found that by drying the
flakes before starting the biodiesel synthesis, they could greatly reduce the
required methanol volume. As a result, the estimated cost went down to $1.02
Haas and his colleagues are presently refining their economic model to account
for income from selling the lipid-free, protein-rich flakes left after the biodiesel
reaction for use as animal feeds and to account for cost differences between
refined-oil and flaked-soybean starting materials.
ARS has filed a patent application on the process. Haas is exploring use of
this new method to produce biodiesel from the lipids in corn co-products from
ethanol plants that use corn as a starting material. He's also investigating
the suitability of canola seeds and meat and bone meal.By Jim
Core, Agricultural Research Service Information Staff.
This research is part of Bioenergy and Energy Alternatives, an ARS National
Program (#307) described on the World Wide Web at www.nps.ars.usda.gov.
Michael J. Haas is in the Fats,
Oils, and Animal Coproducts Research Unit, USDA-ARS Eastern
Regional Research Center, 600 East Mermaid Ln., Wyndmoor, PA 19038; phone
(215) 233-6459, fax (215) 233-6795.
"New Method Simplifies Biodiesel Production" was published
in the April 2005
issue of Agricultural Research magazine.