On left, raw trap
grease with most of the free water removed; center, grease after filtering but
before final dewatering; right, biodiesel fuel. Image courtesy
Turning Grease into Fuel
McGinnis September 28, 2006
New work from the Agricultural Research Service (ARS) could someday help the nations
cars run like greased lightning, powered by biodiesel made from restaurant
Haas, a chemist at the ARS
Regional Research Center in Wyndmoor, Pa., is working with the
Philadelphia Fry-o-Diesel company
(PFOD) to demonstrate that trap grease-- the grease that restaurants and food
companies collect from their drains--can be converted into a clean-burning,
renewable fuel source. In May, the Philadelphia Federal Executive Board awarded Haas a gold
medal for his contributions to the project.
Trap grease is currently unmarketable. According to PFOD, restaurants
in southeastern Pennsylvania and New Jersey collect more than 2 million gallons
of trap grease every month that must be removed at a cost of about 5 cents per
gallon. Illegal disposal and sloppy collection can lead to clogged sewers and
PFOD enlisted Haas to help demonstrate trap greases potential as
a marketable biodiesel feedstock. Haas and ARS biologist
Scott helped characterize trap grease samples, advised the company on
operation design, and analyzed the products of trial runs as they explored and
improved the reaction chemistry needed to produce biodiesel.
How does it work? The scientists remove water and solids from the trap
grease, then process the feedstock to produce biodiesel. Initial small-scale
operations have successfully produced fatty acid methyl esters from trap
grease. The esters will be tested to determine whether they meet accepted
One challenge right now is economic. Removing impurities from trap
grease is expensive, but as the cost of petroleum-based diesel rises, its
becoming increasingly competitive.
If successful, this research could solve many problems. Giving trap
grease a new purpose would reduce waste and create a new market. Illegal
disposal would decrease, leading to improved water quality, and cleaner-burning
diesel fuels would improve air quality.
ARS is the U.S. Department of
Agricultures chief scientific research agency.