Recovered chicken fat an alternative fuel source

March 15, 2010, Champaign, IL – “We use everything but the cackle” is an old adage that nicely captures the poultry industry’s approach to the efficient use of byproducts. That same attitude, according to the Poultry Science Association (PSA), is helping to drive recent work in converting recovered fat from poultry wastewater streams into an economically viable alternative fuel source for processors.

Participating in the effort is Dr. Brian Kiepper, Ph.D., an assistant professor and extension poultry scientist in the University of Georgia’s departments of poultry science and biological and agricultural engineering. 

“Our focus has been on isolating fat from wastewater broiler processing facilities and then seeking the means to provide the integrator with the option of using the recovered fat, on-site, in whatever way yields the highest value,” said Dr. Kiepper. 

One of those options is to use the recovered fat as a biofuel. 

Waste fat, oil and grease (FOG) are major components of many food-processing wastewater streams, including poultry production. According to Dr. Kiepper, recaptured fat can be purified and then burned to heat water in a processing plant’s boilers. It can also be used to make biodiesel – an attractive option to have available, particularly when petroleum-based fuel prices are high.

Such uses can be very attractive economically for the processor, particularly when compared to the traditional means of disposing of offal by selling it to rendering facilities at approximately $0.03/lb, a rate which values the fat at $0.22/gal. By comparison, once purified, fat recaptured from food processing wastewater can be used instead of fuel oil, which is currently priced at around $2.00/gal, to fire a plant’s boilers. Dr. Kiepper estimates that recovering only 10% (a conservative number) of the 44.6 million gallons of fat produced in the state of Georgia each year by this method would result in an estimated annual savings of nearly $9 million on fuel-oil purchases.

Best Sources for FOG Extraction in a Processing Facility

In a recent study led by Dr. Kiepper, he and fellow researchers evaluated five poultry waste streams as potential sources of alternative fuel: float fat after primary screens, secondary screen offal, tertiary screen offal, chemical and non-chemical DAF (dissolved air flotation) skimmings. Of the five, float fat and secondary screen offal were shown to have the greatest potential for further refinement and use as biofuel, given their relative ease of extraction and recovery efficiency.

Because secondary screen offal is already collected and (often inefficiently) belt- or screw-conveyed to offal trucks, modifying the collection system to divert the offal to a FOG extraction-and-purification system should, according to the researchers, be readily feasible. On the other hand, because float fat is harder to collect because of its tendency to gather in equalization pits and transfer troughs, accommodating float-fat collection for alternative fuels processing would likely require new systems to be installed in most facilities.

“Our ultimate goal,” said Dr. Kiepper, “is to develop a self-contained, low-temperature fat extraction and purification system that can be installed on-site at food processing plants to produce, in an economically feasible way, a usable quantity of fuel-quality fat for processors. This will generate greater benefits for processors by recovering more of the valuable byproducts generated during processing that are now lost in the wastewater stream. It also has the potential to create a very green loop in the processing environment, with fat gathered from birds processed in the morning possibly being used to heat the plant’s boilers during processing that same afternoon.”

Said PSA President Dr. Sally Noll: “Dr. Kiepper’s work may help an already efficient industry do an even better job of lowering processing costs by creating new value-added products from the existing byproducts stream.”