January 2007, Vol. 19, No.1

Research Notes

Turning Grease Into Fuel

New work from the U.S. Agricultural Research Service (ARS) someday could help cars run like greased lightning, powered by biodiesel made from restaurant grease.

Mike Haas, a chemist at the ARS Eastern 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 7.6 million L (2 million gal) of trap grease every month that must be removed at a cost of about $0.01/L ($0.05/gal). Illegal disposal and sloppy collection can lead to clogged sewers and polluted water.

PFOD enlisted Haas to help demonstrate trap grease’s potential as a marketable biodiesel feedstock. Haas and ARS biologist Karen 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.

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 biodiesel standards.

One challenge is an economic one. Removing impurities from trap grease is expensive, but as the cost of petroleum-based diesel rises, it’s becoming increasingly competitive.

For more information, contact Haas at Michael.Haas@ars.usda.gov or Scott at Karen.Scott@ars.usda.gov.

New Technique Could Lead to Quicker Warning System for Public Beaches

 A discovery by University of California–Irvine (UCI) scientists could help public health officials know instantly when pollution has moved into the coastal ocean — a breakthrough that could enable authorities to post warnings or close beaches in minutes rather than days.

The new technique analyzes temperature and salinity data collected by sensors located in the water along the Southern California coast, according to a UCI press release.

Researchers found that fluctuations in the sensor data correlate with changes in water quality as soon as they occur. This type of analysis may lead to detection methods that are far faster than the current method of physically collecting water and testing it in a lab.

Coastal ocean observing systems — devices that use technology to sense environmental conditions — collect large amounts of data, such as temperature, salinity, and water level. The data are streamed in near real-time via the Internet for scientists and coastal managers to process and interpret.

These sensors cannot measure bacteria levels that officials use to determine whether surf-zone water is safe for bathing, but UCI researchers discovered that changes in temperature and salinity can signal pollution if the data — using a mathematical equation — is transformed into a measurement of the range over which the data naturally fluctuate. The study shows for the first time that two measures of these fluctuations — known as Fisher Information and Shannon Entropy, respectively — can translate high-frequency sensor data into information suitable for near real-time management of the coastal ocean. Fisher Information and Shannon Entropy have been used in other cases to detect abnormalities in brain signals.

“At Newport and Huntington beaches, where we tested the idea, water quality violations were more likely to occur when, over the course of a single day, salinity fluctuated around a larger range of values, and temperature fluctuated around a more narrow range of values,” said Stanley Grant, UCI professor of chemical engineering and materials science. “These patterns of fluctuation reflect the mixing of different parcels of water — some contaminated and some not — into the coastal ocean.”

The research team analyzed data recorded during 3 months in early 2004 by a sensor located 1 m underneath the water at Newport Pier in Newport Beach, Calif. The sensor is part of a growing network of coastal sensors called the Southern California Coastal Ocean Observing System. During the period of data collection, local officials noted 35 days in which one or more water quality standards were violated at nearby Newport and Huntington beaches. Researchers then conducted a mathematical study to asses how water quality correlated with the daily average sensor measurements of salinity and temperature, and with the Fisher Information and Shannon Entropy measures calculated from these data.

Scientists found that water quality coincided with depressions in ocean salinity but not with changes in nearshore ocean temperature, UCI reports. However, when the sensor data were transformed using Fisher Information and Shannon Entropy, surf-zone water quality violations correlated with several resulting indices, most notably salinity and temperature. This indicates that changes in the range over which salinity and temperature fluctuate — measured by both Fisher Information and Shannon Entropy — appear to reflect the origin, transport, and mixing of pollutants in the coastal ocean.

For more information, contact Grant at sbgrant@uci.edu.