The University of Arizona

Give Back the Grease

By Daniel Stolte, University Communications | November 22, 2011

By collecting leftover cooking grease from Thanksgiving feasts and converting it into biodiesel, UA alumni and students are driving an initiative to keep waste cooking oil out of sewers and landfills, all while making vehicles more environmentally friendly.

Grecycle Driver Rachel Flores pumps donated waste cooking oil into her truck to haul it off to the biodiesel production facility. (Photo: Mike Kazz)
Grecycle Driver Rachel Flores pumps donated waste cooking oil into her truck to haul it off to the biodiesel production facility. (Photo: Mike Kazz)
Colleen Crowninshield from the Pima Association of Governments' Clean Cities Coalition (left) and Laura Fairbanks from the Pima County Regional Wastewater Reclamation Department next to a tank holding a ton of collected waste grease. (Photo: Mike Kazz)
Colleen Crowninshield from the Pima Association of Governments' Clean Cities Coalition (left) and Laura Fairbanks from the Pima County Regional Wastewater Reclamation Department next to a tank holding a ton of collected waste grease. (Photo: Mike Kazz)
A Tucson resident drops off leftover cooking oil at a collection station during the 2010 Day-After-Thanksgiving Grease Drive. (Photo: Mike Kazz)
A Tucson resident drops off leftover cooking oil at a collection station during the 2010 Day-After-Thanksgiving Grease Drive. (Photo: Mike Kazz)

On Nov. 25, when leftovers line fridge shelves and stuffing recipes slip back into kitchen drawers, Thanksgiving feasters will have the opportunity to get rid of their waste cooking grease and help the environment in the process.

During the 7th Annual Day-After-Thanksgiving Grease Drive, Tucson-based company Grecycle Arizona, LLC will collect used grease with several drop off points across Tucson.

"The idea is to get people to recycle their used cooking oil so it can be transformed into a biofuel rather than throwing it in the trash, or worse, dumping it down the drain where the grease can cause serious pipe clogging and pest infestations," said Hseth Burch of Grecycle.  

Joe Abraham, director of the University of Arizona's Office of Sustainability, added, "The Grease Drive gives people an opportunity to reduce the environmental footprint that comes with several gallons of cooking oil that normally would be turned into a waste stream in a matter of minutes."

Grecycle was founded by Mike Kazz, who graduated in 1992 from the UA's agricultural and biosystems engineering department, a joint program between the College of Agriculture and Life Sciences and the College of Engineering. Since then, Kazz has hired two more UA graduates: Burch, who is an associate chemical engineer and Grecycle's advertising lead, and Walter Diaz, an engineer who came to the UA from his native Mexico to obtain a master's degree in agricultural and biosystems engineering in 2007.

Each year since its inception in 2005, the grease drive has seen more participation and collected more waste grease from households and local restaurants.

"Last year we collected about 3,300 pounds or about 400 gallons of oil that converted into an equal amount of biodiesel," Kazz said, "and we hope to collect even more this year."

From a chemistry perspective, the oil used for frying turkeys to a crispy brown is not all that different from the stuff powering the semis hauling those very turkeys to grocery stores.

Just like cooking oil, diesel fuel contains hydrocarbons, chain-like molecules made up of carbon and hydrogen. Even though the two substances contain different kinds of hydrocarbons, both release energy when burned, only that in the case of cooking oil, that energy normally goes wasted, whereas in diesel fuel, it is harnessed to power the engine.

"Biodiesel is fuel that can be used today, not at some distant point in the future," said Mark Riley, professor and department head of agricultural and biosystems engineering. "The conversion of waste cooking oil to biodiesel is a relatively straightforward and mild chemical process, and we have a pretty good grip on how to do it safely and efficiently."

Riley's department has partnered with Grecycle on constructing a pilot plant at the UA's Campus Agricultural Center, or CAC, located at Campbell Avenue and Roger Road in Tucson, to convert waste cooking oil from the University's student unions into biodiesel to power vehicles of the UA's fleet. 

The partnership is funded by the UA Green Fund, financed through $24 per student per year, as part of tuition and intended to support projects that involve students and employees making the UA a more environmentally sustainable institution.

Grecycle, which already operates a small pilot scale facility with equipment for processing 100 gallons of waste cooking oil collected from local restaurants into biodiesel at the UA's Campus Agricultural Center, is donating equipment and expertise. Grecycle uses the equipment to translate the laboratory studies developed by Diaz for his masters thesis into a full-scale production and will soon complete construction in south Tucson. 

"Our goals are to find good use for the waste stream generated by restaurants on and off campus, to help power UA vehicles with cleaner fuel and, most importantly, teaching students," Riley said. "Students will gain extensive experience in production of this renewable fuel, in process engineering, and in quality control procedures – all areas of expertise desired by employers in engineering and science."

Three undergraduate students majoring in biosystems engineering, Benjamin Erlick, Aloys Ongla Pagal and Azar Mukhida, are currently working on the project, together with Naruekamol Pookhao, a doctoral student in agricultural and biosystems engineering, under the guidance of professors Riley and Steve Poe.

A crucial aspect of the project, which appears to be unique on a university campus, is its emphasis on teaching students how to run a biodiesel production plant to generate a product that can meet the standards set forth by the American Society of Testing and Materials, or ASTM, giving students an edge for future employment.

"By conforming with those standards, we make sure our biodiesel meets certain requirements in terms of performance, purity, stability and viscosity and is competitive," Riley said. "For example, if it has a lot of contaminants, it won't flow easily in colder climates."

Restaurants clean their fryers and grease traps regularly and store the waste grease in drums until they are hauled away for disposal, posing a challenge for the conversion into biofuel.

"It is one big mix of things with different chemical properties," Riley said. "Before we can process it any further, we have to pull solid particles out and remove any water that might be present."

In the next step, methyl alcohol is added along with an acid or a base to break down the fat molecules into glycerol and methyl esters, also known as biodiesel. Since methyl alcohol contains very little chemical energy, which lowers fuel mileage, it is removed along with any soapy molecules that have formed during the process. The methyl alcohol is then reused for the next batch.

Riley pointed out that because biodiesel burns more cleanly and is easier to make than regular diesel, which requires processing of petroleum, the facility's footprint is small.

Students will collect waste cooking oil from the UA's Student Union and Park Student Union kitchens, take it to the biodiesel pilot plant at the CAC, and pump it into a holding tank. Once sufficient waste grease has been collected – about 100 gallons – it will be chemically converted to biodiesel using procedures developed by Grecycle.

The biodiesel produced will be eventually used to power UA vehicles with a blend of B5, which consists of 5 percent biodiesel and 95 percent standard diesel.

According to Riley, students will benefit in many ways from this program, pointing out that student participation won't be restricted to a certain major.

"We will take any student showing interest in a continued level of activity," he said. "Those involved in activities either as part of club events, as part of the regular curriculum or as an independent study, will gain hands on experience in process engineering, quality assurance and control, logistics, biofuels and green chemistry."

Burch added: "This experience is an excellent opportunity because many jobs working in a plant require prior experience, which is almost impossible to get while in school unless there is an opportunity like this one."

In addition to feeding the used cooking oil collected during the Day-After-Thanksgiving Grease Drive into the pilot plant at the UA's Campus Agriculture Center, Grecycle is set to collect waste oil throughout the year and transform it into biodiesel starting with the opening of the company's new plant in January 2012. 

From its beginnings, the Thanksgiving collection event has partnered with the Pima County Regional Wastewater Reclamation Department, or RWRD, and goes hand in hand with the department's ‘Save our Sewers' campaign.

"The goal is to help clean up the city by cleaning the sewers and then cleaning the air, because biodiesel substantially reduces the green house gases emissions produced by vehicles," Burch said. "Biodiesel passes the EPA's tests required by the Clean Air Act and is an approved fuel set forth by the Energy Policy Act."

"This has been a true partnership between the UA's agricultural and biosystems engineering department and Grecycle," Riley said. "It is great to see UA alums having a positive impact on Tucson and also giving back to the University." 

In addition to the UA and RWRD, partners in the grease drive are the Pima Association of Governments' Clean Cities Coalition, EDG Fuels and the municipalities of Sierra Vista and Sahuarita.

Visit the Grecycle website for more information about the Day-After-Thanksgiving Grease Drive and for pickup locations in Tucson, Sahuarita and Sierra Vista.