Because of their chemical composition, fats release concentrated amounts of energy when burned. This energy can be used as a biofuel. Current usage of rendered fats in the biofuels is estimated at 3 – 8% of the approximate 11 billion pound annual production of rendered fats (yielding 43 million to 116 million gallons of biodiesel). Existing biodeisel technology yields a gallon of fuel for each 7.6 lbs of fat.
Capacity and Infrastructure
The current method of splitting the methyl esters from fat molecules yielding biodiesel
and glycerin is somewhat limited by plant capacity and infrastructure to handle the
special fuel, but many plants are coming on line. Other methods of manufacturing
“renewable diesel” from rendered fats are in development that blend fats directly into the
oil refining process (ConocoPhillips/Tysons) or use catalysts to produce hydrocarbons
from fat will avoid the infrastructure problem because they can be blended directly with
diesel fuel of fossil origin.
Feed vs Fuel
The food versus fuel debate has many variables and political forces. For most rendered
products the debate becomes feed versus fuel with most of the same variables and moral
arguments. While many people believe rendered fats are far too valuable as animal feed
to be burned as fuel; commodity prices will ultimately determine how much of the total
rendered fats volume is converted to fuel.
Growth of the Rendering Base
During the last 30 years, the rendering industry has consolidated and the number of active
plants has decreased from 724 to 273. At the same time, the amount of raw material
rendered increased from 30 billion pounds annually to 54 billion pounds (Essential
Rendering, page 25). With trends of production growing, meat in the U.S., increased
case-ready retail meat products, and increased restaurant business (increasing collection
of used cooking oil for yellow grease), it’s probably safe to assume a continued 1%
annual growth in raw materials available to rendering (annual growth of animal fats and
greases of approximately 1% annually is supported by USDA/ERS predictions).
Share of Biodiesel for Rendered Products
The upper practical limit will be ultimately determined by markets. Renderers will sell
their product for the highest price, and fats have many uses for oleochemicals, pet food,
and livestock feed. Many also have the option of burning fats directly in their own
boilers without converting to biodiesel if market conditions are favorable to do so.