New Game in Town: Tallow and Rendered Chicken Fat

Methanol is an ingredient in the conversion of seed oil to methyl ester fuel. Robert McLeod previously has suggested that excess of methanol is added to ensure complete conversion and reducing the amount of water and methanol could directly effect the energy used for distilling out glycerin and excess methanol post-transesterfication.

Schmaltz is a Yiddish word for liquid animal fat, especially chicken fat.

And, this blog also noted that research was underway at the University of Arkansas converting chicken fat to biodiesel. Two years ago, there was some question as to whether making biodiesel from rendered chicken fat would prove to be economically feasible.

Mike Millikin relays word
When oil / fat feedstock is converted into biodiesel using supercritical methanol, the biodiesel can be collected as oil phase by a simple phase separation. The methanol phase includes glycerol as a co-product, which then can be separated.

When the chicken fat was treated with supercritical methanol, a maximum yield of biodiesel yields in excess of 89% “was reached at 325°C and a 40-to-1 molar ratio. The process also produced a respectable yield of 80% at 300°C and the same amount of methanol. At 275°C and the same amount of methanol, the process was ineffective.”

The supercritical method hits the free fatty-acid problem head on. Because it dissolves the feed material and eliminates the need for the base catalyst, we now do not have the problems with soap formation and loss of yield. The supercritical method actually prefers free fatty acid feedstocks.

Unmentioned in the press release is that fatty acid methyl ester requires additives for better stabilization. Still high yields could be good news for poultry processing companies since biodiesel production would mean a greater market for tallow and rendered chicken fat, which has been selling for about 60 percent of the price of crude soy oil.

The one-step transesterfication of triglycerides with supercritical liquid is called the Saka method, named after Professor Saka at Kyoto University

The Green Car Congress article notes that other researchers also have investigated the use of supercritical methanol in the production of biodiesel, e.g.,:

Researchers at Kyoto University in Japan have applied a supercritical methanol process to the production of biodiesel from rapeseed oil. They obtained their best results at 350°C, 30 MPa and 240 sec with a molar ratio of 42-to-1. According to their calculations, a conventional transesterification process alone consumes 4.3 MJ/l, while the supercritical methanol method requires 3.3 MJ/l, or energy reduction of 1.0 MJ for each liter of biodiesel produced.

The Saka Laboratory at Kyoto has gone on to develop a two-step supercritical process that allows more moderate reaction conditions than those of the one-step method.

Researchers at Chulalongkorn University in Thailand used supercritical methanol to produce biodiesel from coconut oil and palm kernel oil. They obtained their best results at a reaction temperature of 350°C, molar ratio of 42-to-1, and space time of 400 s. The percentage methyl ester conversions were 95 and 96 wt% for coconut oil and palm kernel oil, respectively.

Researchers at Beijing University of Chemical Technology prepared biodiesel from soybean oil using supercritical methanol with CO2 as a co-solvent. With CO2 as co-solvent in the reaction system, there was a significant decrease in the severity of the conditions required for supercritical reaction. Optimal results produced a 98% yield of methyl esters, occurring at a reaction temperature of 280°C, methanol to oil ratio of 24 and CO2 to methanol ratio of 0.1, reaction time of 10 minutes and a reaction pressure of 14.3 MPa.


Biodiesel fuel for diesel fuel substitute prepared by a catalyst-free supercritical methanol (Kyoto University)

Kunchana Bunyakiat, Sukunya Makmee, Ruengwit Sawangkeaw, and Somkiat Ngamprasertsith. “Continuous Production of Biodiesel via Transesterification from Vegetable Oils in Supercritical Methanol” Energy Fuels, 20 (2), 812 - 817, 2006. 10.1021/ef050329b

Weiliang Cao, Hengwen Han and Jingchang Zhang. “Preparation of biodiesel from soybean oil using supercritical methanol and CO2 as co-solvent” Process Biochemistry
Volume 40, Issue 9, September 2005, Pages 3148-3151

biofuel, chemistry, economics, energy, environment, transportation
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