Part 4. Biodiesel: Can we eat enough French Fries?

The idea we could run our economy on discarded fried food grease is very amusing. For starters, you’d need to feed 7 million heavy diesel trucks getting less than 8 mpg. Seems like we're all going to need to eat a lot more French Fries, but if anyone can pull it off, it would be Americans. Spin it as a patriotic duty and you'd see people out the door before the TV ad finished, the most popular government edict ever.

Scale. Where’s the Soy? Biodiesel is not ready for prime time. Although John Deere is working on fuel additives and technologies to burn more than 5% accredited biodiesel (made to ASTM D6751 specifications – vegetable oil does not qualify), that is a long way off. 52 billion gallons of diesel fuel are consumed a year in the United States, but only 75 million gallons of biodiesel were produced – two-tenths of one percent of what’s needed. To get the country to the point where gasoline was mixed with 5 percent biodiesel would require 64 percent of the soybean crop and 71,875 square miles of land (Borgman 2007), an area the size of the state of Washington. Soybeans cause even more erosion than corn.

Biodiesel shortens engine life. Currently, biodiesel concentrations higher than 5 percent can cause “water in the fuel due to storage problems, foreign material plugging filters…, fuel system seal and gasket failure, fuel gelling in cold weather, crankcase dilution, injection pump failure due to water ingestion, power loss, and, in some instances, can be detrimental to long engine life” (Borgman 2007). Biodiesel also has a short shelf life and it’s hard to store – it easily absorbs moisture (water is a bane to combustion engines), oxidizes, and gets contaminated with microbes. It increases engine NOx emissions (ozone) and has thermal degradation at high temperatures (John Deere 2006).

On the cusp of energy descent, we can’t even run the most vital aspect of our economy, agricultural machines, on “renewable” fuels. John Deere tractors can run on no more than 5% accredited biodiesel (Borgman 2007). Perhaps this is unintentionally wise – biofuels have yet to be proven viable, and mechanization may not be a great strategy in a world of declining energy.