One-step Biodiesel Production from Yellow Grease

In the United States, the vast majority of biodiesel consumed is made from soybean oil by a homogeneous alkali-catalyzed process known as transesterification. This process is very inefficient and could be improved substantially; however, it has not changed much in the last two decades. In addition to the high separation and purification costs that result from the use of a homogeneous catalyst, the feedstock cost of soybean oil accounts for a significant portion of the biodiesel production cost. Yellow grease is available at substantially lower cost than soybean oil, and the US produces enough yellow grease annually to make 500 million gallons of biodiesel. However, the problem with yellow grease is that it contains high concentrations of free fatty acids that pose significant processing problems in alkali-catalyzed processes. The current two-step commercial processes used to convert yellow grease to biodiesel incur added costs for pretreatment of the yellow grease before transesterification to remove the free fatty acids by the addition of extra alkaline catalyst or esterification of the free fatty acids using a homogeneous acid catalyst, eliminating the advantage of the cheaper raw material. This proposed project aims at developing an innovative technology to convert yellow grease to low cost biodiesel in a ONE-STEP process using our patent pending heterogeneous catalyst and a continuous flow fixed-bed reactor. During Phase I, research will focus on investigating the optimal operating conditions for the fixed-bed reactor, evaluating the heterogeneous catalyst lifetime, quantifying the economic viability, and determining its technical feasibility. The success of this project will provide a highly energy efficient, cost-effective, and simplified process for one-step biodiesel production from yellow grease. It will create a value-added and more profitable market for yellow grease, reduce the biodiesel production and capital costs, eliminate waste streams produced from toxic acid or caustic solution, reduce air pollution, benefit consumers economically by reducing their vulnerability to petroleum price fluctuations, and reduce the US dependence on foreign energy sources.